No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Hydrogen peroxide whitens teeth by oxidizing the organic structure
Abstract
Objectives:
The mechanism of tooth bleaching using peroxide oxidizers is not fully understood. It is unknown whether peroxide radicals make teeth whiter by deproteinizing, demineralizing, or oxidizing tooth tissues. This study was designed to define the mechanism of tooth bleaching and determine which of tooth enamel chemical components is/are affected by bleaching.
Methods:
Sixty sound teeth were collected from adult patients. The teeth were divided into 6 equal groups (n=10). Groups 1, 2, 3 and 4 were treated for 4 days with one of the following solutions: deproteinizing (NaOH) that removes organic content, demineralizing (EDTA) that decalcifies the mineral content, oxidizing (H(2)O(2)) and distilled water (control). Group 5 and 6 were pre-treated with either deproteinizing or demineralizing solutions before treating them with oxidizing solutions for 4 days. Changes in enamel elemental ratios, crystallinity index and tooth shade parameters of the treated teeth were examined by means of EDS, Raman spectroscopy and shade-spectrophotometry. The data obtained was analysed with Wilcoxon Signed-Ranks Test, and the statistical significance was set at p<0.05.
Results:
Tooth deproteinization increased the lightness by 4.8 ± 2.7°, tooth demineralization resulted in 8.5 ± 5.6° decrease in the lightness and tooth oxidization induced 19.9 ± 6.5° increase in the lightness. Oxidization of the deproteinized teeth did not influence shade parameters, but oxidation of the demineralized teeth resulted in 10.7 ± 5.8° increase in the lightness.
Conclusion:
Hydrogen peroxide does not induce significant changes in tooth enamel organic and inorganic relative contents, and it whitens teeth just by oxidizing their organic matrix. These findings are of great clinical significance since they explain the mechanism of tooth bleaching, and help understanding its limitations and disadvantages.
... While dental bleaching continues to be a popular cosmetic treatment, there are growing concerns about the long-term effects of bleaching agents on dental health. As a result, researchers and dental professionals have increasingly focused on examining the impact of commonly used bleaching agents, such as hydrogen peroxide (HP) and carbamide peroxide (CP), on dental structures [3][4][5][6]. ...
... HP acts as a strong oxidizing agent by producing free radicals, reactive oxygen molecules, and HP anions [7]. Although several hypotheses have been proposed to explain HP's bleaching effect [8], the most widely accepted theory suggests that HP whitens teeth by oxidizing the organic matrices within the enamel, without altering its relative organic or inorganic content [4]. This oxidative process results in tooth whitening by reducing the relative translucency of enamel [5,9]. ...
... To prevent dehydration, which can cause clinically significant shade changes [31,32], all teeth were kept moist throughout the measurement process. The color of each tooth was analyzed using the Munsell color system (L*, C*, and H*), as it is the basis for most tooth shade guides used in dental practice [4]. The Munsell scale system was selected due to its ability to correlate to the chemical composition of materials [4,33]. ...
... [11][12][13][14][15][16] Once the gel is applied to the tooth structure, ROSs are released and can spread through the enamel and dentin, interacting with the chromophore molecules present in the tooth structure, cleaving them and increasing the luminosity of the tooth. [17][18][19][20][21] Des pite this information being relatively well known, to date no study has been specifically designed to determine the importance of hard tissue thickness in the effectiveness of bleaching treatment. In this context, the molars are the largest teeth, followed by the premolars, canines, and incisors. ...
... These individual characteristics are due to variations in the thickness of the mineralized hard tissue: the thickness of enamel is 2 to 3 mm, while that of dentin is 2 to 5 mm. [17][18][19][20][21] In addition, different hard tissue thicknesses are associated with differing pulp cavity volumes, which can potentially lead to varying intensities of the side effects related to the presence of H 2 O 2 in the pulp. [22][23][24][25] Tooth sensitivity is one of the main adverse effects reported by patients undergoing tooth bleaching. ...
... H 2 O 2 and its reactive radicals have a short shelf life, suggesting that thinner teeth with less enamel or dentin tissue may respond more quickly to bleaching than thicker teeth. 18 Thus, the bleaching effect is inversely proportional to the amount of enamel or dentin tissue present, requiring more sessions for thicker teeth to achieve an optimal whitening result. ...
Aim:
The objective of the present study was to investigate the association between the anatomical characteristics of different tooth groups and the diffusion and bleaching effect of hydrogen peroxide (H2O2).
Materials and methods:
Computed tomography (CT) images from five patients were used to assess the hard tissue thickness and pulp volume (PV) of four tooth groups: lower (mandibular) incisors (LI), upper (maxillary) incisors (UI), canines (C), and premolars (PM). Additionally, 80 bovine tooth disks were divided into four groups (n = 20) to match the thickness of each tooth group studied. All the specimens were exposed to a 35% H2O2 bleaching gel, with 50 µL applied for 45 min during the first, second, and third sessions. Diffusion was evaluated using the peroxidase enzyme method. Color change analyses (∆E, ∆E00, and ∆WID) were performed after the three application sessions and 7 days after the bleaching treatment using a spectrophotometer.
Results:
The PM group showed greater thickness and PV, followed by the C, UI, and LI groups (P 0.001). The LI group had six times greater H2O2 diffusion compared with the PM group (P 0.001), while the PM group exhibited a PV nine times larger than the LI group. Furthermore, the LI and UI groups achieved color saturation with one fewer session than the C and PM groups.
Conclusions:
Specific tooth groups have anatomical characteristics that interfere with bleaching treatment in terms of the diffusion and whitening effect of H2O2. Furthermore, the diffusion capacity of H2O2 was inversely proportional to the thickness of the tooth groups.
... Dental staining or discoloration occurs due to extrinsic factors (diet, smoking, poor oral hygiene, among others) and intrinsic factors (metabolic causes, congenital factors, and tetracycline use, among others). The pigments are organic compounds containing long conjugated double bonds [1][2][3][4]. When these pigments form a molecule capable of reflecting light at a visible wavelength, the intensity exceeds the light reflected by the dental structure, resulting in a predominance of darkened dental color [1,5]. ...
... The pigments are organic compounds containing long conjugated double bonds [1][2][3][4]. When these pigments form a molecule capable of reflecting light at a visible wavelength, the intensity exceeds the light reflected by the dental structure, resulting in a predominance of darkened dental color [1,5]. ...
... The released oxygen penetrates the dentinal tubules and acts on highly pigmented carbon compounds, transforming them into lighter compounds. Additionally, pigmented carbon compounds with double bonds are converted into hydroxyl groups, which are colorless [1,5]. ...
Aims: To evaluate the efficacy of ozonated sunflower oil in managing sensitivity during and after in-office dental bleaching. Methodology: Thirty patients were selected and allocated into two distinct groups - 5% Potassium Nitrate and 2% Sodium Fluoride (NF) and ozonated sunflower oil (OGO). Desensitization was performed before the application of the bleaching gel for 10 minutes. Hydrogen peroxide was applied for 30 minutes. The evaluation of the degree of sensitivity (DS) was performed on an illustrative scale from 0 to 4, and the patients were questioned during bleaching (05 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, and 30 minutes) and after bleaching (1 hour, 24 hours, 48 hours and 7 days). The degree of whitening (DW) was assessed before and 7 days after treatment. The data were subjected to Wilcoxon statistical analysis (p<0.05). Results: In the intra-group analysis, there was a statistical difference between the times. In the inter-group analysis, ozonated sunflower oil compared to the conventional desensitizing agent resulted in statistical differences for the times of 25 minutes, 30 minutes and 1 hour post-bleaching. In the color saturation analysis, both groups showed statistical differences between the initial color and the final color. Conclusion: Ozonated sunflower oil demonstrates significant management of sensitivity during and after in-office dental bleaching, in addition to not interfering with the degree of color saturation of the bleached teeth and the efficiency of hydrogen peroxide.
... Hydrogen peroxide, typically in concentrations ranging from 10% to 40%, acts as a potent oxidizing agent that penetrates enamel and dentin to break down chromogenic compounds [4]. Carbamide peroxide, often used at concentrations of 10% to 37%, decomposes into hydrogen peroxide and urea, releasing approximately one-third of its weight as hydrogen peroxide in the process [5]. ...
... [34][35][36][37] Hydrogen peroxide (HP) is a common bleaching agent used both in professional clinical settings and in products for at-home use. 38,39 HP is a potent oxidizing agent that breaks down long-chain organic pigment molecules into shorter-chain compounds, thereby facilitating bleaching. 40 However, due to its short shelf life and safety restrictions, its use in mouthwashes is problematic, and typically, mouthwashes contain low concentrations of HP, around 1%-2%. ...
Aim: The aim of this study was to evaluate the effects of different whitening mouthwashes on the color change of stained four different one-shade composite resins and to compare them with a multi-shade composite.
Materials and Methods: A multi-shade (Filtek Ultimate) and four one-shade (Omnichroma, Charisma Diamond One, Essentia Universal, Vittra Unique) composite resins were used. A total of 160 samples, 32 of each composite were prepared and the initial color parameters of the composite samples were measured with a spectrophotometer and the composite samples in each group were divided into four groups (n=8). Then, the samples were kept in coffee and second color measurements were made. After the samples were kept in four whitening mouthwashes (Colgate Optic White, Listerin Advanced White, Pasta del Capitano Whitening, SPLAT® Professional Bio-Active), third color measurements were made and color changes were calculated with the CIEDE2000 formula. Statistical analyzes were performed using one-way ANOVA and post-hoc Tukey's test.
Results: The color changes observed in the stained composite resins after immersion in mouthwash were statistically significant, varying by mouthwashes and composites (p≤0.05). Average color change values (ΔE00) were between 0.85 and 4.87. While the highest color change was observed in the Charisma Diamond One group using Pasta del Capitano Whitening (ΔE00=4.87), the lowest color change in all groups was observed in the use of SPLAT® Professional Bio-Active.
Conclusion: One-shade composites showed more color change than the multi-shade composite, with variations depending on the mouthwash used. Almost all groups, whitening mouthwashes caused a color change above the perceptibility threshold level.
... Despite the shorter application time of in-office bleaching gels compared to at-home treatments, several studies over recent decades have consistently confirmed the efficacy of in-office procedures [1,[3][4][5][6]. Hydrogen peroxide (H 2 O 2 ) remains the most widely used bleaching agent in these treatments [3,4], due to its ability to oxidize organic dental structures [1,3,7]. ...
Abstract: This in vitro study evaluated the effects of incorporating quercetin (QC) at varying concentrations (0.25%, 0.5%, and 1%) into a 35% hydrogen peroxide (H 2 O 2) bleaching gel on esthetic outcomes, enamel hardness and roughness, and H 2 O 2 transamelodentinal diffusion. Bovine enamel/dentin discs (n = 180; 12/per group for each analysis) were allocated into five groups: (1) negative control (NC), (2) 35% H 2 O 2 (HP), (3) HP + 0.25% QC, (4) HP + 0.5% QC, and (5) HP + 1% QC. Treatments were applied for 40 min per session across three sessions with 7-day intervals. Color changes were evaluated using the CIELab* color system (∆E ab), with further analysis performed using the CIEDE2000 formula (∆E 00) and the whitening index (∆WI D). Enamel surface hardness, roughness, cross-sectional hardness, and H 2 O 2 diffusion were also evaluated. Data were analyzed using ANOVA, followed by the Student-Newman-Keuls test, with statistical significance set at p < 0.05. All experimental gels resulted in significant color changes (p < 0.001), with similar ∆E ab , ∆E 00 , and ∆WI D across QC groups. The HP group showed greater reductions in hardness and increased roughness compared to others (p < 0.0001), while the HP/1%QC group resulted in no statistically significant alterations under the tested conditions. H 2 O 2 diffusion was significantly greater in the HP group, while it was notably lower in the HP/1%QC group (p < 0.05). The incorporation of 1% quercetin into a 35% H 2 O 2 gel maintains its bleaching efficacy while protecting enamel properties and reducing hydrogen peroxide diffusion. Quercetin-enriched H 2 O 2 gels may enhance bleaching safety by protecting dental tissues while maintaining esthetic benefits.
... In alkaline conditions, free radicals are formed, which oxidize and break chromophores into less complex molecules that reflect more light (HAYWOOD, 2005a;JOINER, 2006;ARAUJO et al., 2010;COSTA et al., 2010;MARKOWITZ, 2010;THIESEN et al., 2013). Although the use of concentrations of 20-35% of hydrogen peroxide present effective and fast clinical results, the most common side effect (63% in average) is the sensitivity reported by patients, who may interrupt the treatment in some cases (AL-MEIDA et al., 2012;EIMAR et al., 2012;BONAFÉ et al., 2014). ...
This study aimed to assess the effect of using potassium nitrate in gel and dentifrice for reducing sensitivity during and after bleaching. Seventy-five patients were randomly divided into three groups according to treatment: Previous placebo gel + Colgate Total 12™ (PL + CT); Previous placebo gel + Sensodyne™ (PL + SD); Previous 5% potassium nitrate gel + Colgate Total 12™ (NT). Tooth sensitivity was registered in a verbal scale and a Visual Analogue Scale at the 40th minute, immediately after removing the bleaching gel, and 24 hours after each session. The descriptive analysis of color was performed and Cochran's Q test was applied for the comparative analysis of sensitivity. The Kruskal-Wallis test, Dunn's post-test, and Friedman's ANOVA were used for sensitivity intensity. The intergroup assessment showed that in PL + CT, the occurrence of sensitivity was significantly higher than in PL + SD and NT (p < 0.05). The assessment 24 hours after the second session showed that patients from PL + SD reported less sensitivity (40.0%) than NT (64.0%) and PL + CT (96.0%). As for color, all groups succeeded after 14 days. It can be concluded that the use of potassium nitrate in both presentations reduces tooth sensitivity.
... However, it is known that hydrogen peroxide and its reactive radicals have a very short half-life, and teeth with a greater volume of dentine tissue would require greater exposure to the bleaching gel to reach the ideal chromatic saturation. 30,31 Thus, it is observed that the bleaching effect becomes inversely proportional to the thickness of the tissue to be whitened, meaning that thicker teeth require a higher number of sessions to achieve the ideal bleaching response. A previous study 32 stated that bleaching and gloss are significantly increased for incisors after the first bleaching session compared to canines. ...
Objective:
This prospective case series aimed to clinically evaluate the bleaching effect, spontaneous tooth sensitivity and variation in the thermal sensation threshold of different groups of teeth undergoing in-office bleaching.
Method and materials:
Ten patients received conventional bleaching treatment: 35% hydrogen peroxide with 3 bleaching sessions of 45 minutes, evaluating color change (ΔE and ΔE00), whitening index (WID), and tooth sensitivity (VAS). Thermal stimulus-generating devices were used to simulate sensitivity caused by low temperatures through Quantitative Sensory Tests (QST). Analyses were conducted individually on different teeth groups (n=20) (lower incisors LI, upper incisors UI, canines C, upper first premolars PM).
Results:
Regarding color change, LI and UI did not statistically differ from each other but showed significant difference and greater bleaching potential compared to C and PM (P =.018). Regarding sensitivity, LI and UI presented the highest spontaneous sensitivity values (P =.032), while PM did not display painful symptoms, also observed in provoked sensitivity analysis (P =.025).
Conclusions:
The general analysis of the results indicates that the tooth type responds differently to the whitening treatment, both in relation to the aesthetic benefit and the occurrence of tooth sensitivity. It was observed that lower incisors reach the degree of chromatic saturation before canines and premolars, in addition to presenting greater bleaching sensitivity. Personalizing the treatment, based on prior knowledge of the degree of saturation, anatomical factors and the risk of sensitivity, can provide considerable advantages in the whitening technique.
... HP penetrates the tooth structure and generates various free radicals, which interact with and decompose stain molecules [2]. Nevertheless, the high concentration of HP might induce heightened tooth sensitivity and pulp inflammation after the whitening procedure [3]. Additionally, it even has an impact on the protein matrix and mechanical properties of the enamel, leading to alterations in the surface microhardness, surface roughness, modulus of elasticity, and morphology [2,4]. ...
Background
This study aimed to explore the effects of the titanium dioxide (TiO2) concentration and particle size in hydrogen peroxide (HP) on tooth bleaching effectiveness and enamel surface properties.
Methods
TiO2 at different concentrations and particle sizes was incorporated into 40% HP gel to form an HP/TiO2 gel. The specimens were randomly divided into 8 groups: C1P20: HP + 1% TiO2 (20 nm); C3P20: HP + 3% TiO2 (20 nm); C5P20: HP + 5% TiO2 (20 nm); C1P100: HP + 1% TiO2 (100 nm); C3P100: HP + 3% TiO2 (100 nm); C5P100: HP + 5% TiO2 (100 nm); C0: HP with LED; and C0-woL: HP without LED. Bleaching was conducted over 2 sessions, each lasting 40 min with a 7-day interval. The color differences (ΔE00), whiteness index for dentistry (WID), surface microhardness, roughness, microstructure, and composition were assessed.
Results
The concentration and particle size of TiO2 significantly affected ΔE00 and ΔWID values, with the C1P100 group showing the greatest ΔE00 values and C1P100, C3P100, and C5P100 groups showing the greatest ΔWID values (p < 0.05). No significant changes were observed in surface microhardness, roughness, microstructure or composition (p > 0.05).
Conclusions
Incorporating 1% TiO2 with a particle size of 100 nm into HP constitutes an effective bleaching strategy to achieve desirable outcomes.
... 24 Bu sebepten ötürü bir çok araştırmacı da, hidrojen peroksitin ağartma etkisinin esas olarak transparan mine organik matrisinin opaklığını artıran oksidasyonu ile ilişkili olduğunu öne sürmektedir. 22,25 GÜNCEL AĞARTMA ÇALIŞMALARI Ağartma işlemi, hidrojen peroksitin ayrışması sırasında serbest oksijen radikallerinin açığa çıkmasıyla meydana gelir. Bu serbest radikaller mine ve dentin yoluyla yayılarak dişlere sarımsı görünüm veren pigmentli makromolekülleri parçalamaktadır. ...
ÖZET
Devital ağartma, içsel kaynaklı renk değişikliğine maruz kalan dişlerin rengini iyileştirmedeki rolü düşünüldüğünde diğer girişimsel tekniklere göre konservatif olması nedeniyle popülerlik kazanan bir te-davi tekniğidir. Uygulama yolları, ilgili riskleri en aza indirirken öngörülebilir uzun vadeli sonuçlar elde etmek amacıyla yıllar boyunca modifikasyona uğrayarak farklı formülasyonlar, dağıtım sistemleri ve aktivasyon yolları ile uygulanmakla beraber günümüzde ağartma mekanizması esas olarak peroksit salan bileşiklere dayanmaktadır. Günümüzde devital dişlerin ağartılmasında geleneksel yöntemler yüz güldü-rücü sonuçlar verse de dezavantajları düşünüldüğünde tekniğin geliştirilmesi ya da güvenli yeni teknik-lerin önerilmesi ihtiyacı doğmaktadır. Farklı ışık kaynakları, lazer sistemleri, soğuk atmosferik basınçlı plazma cihazı, ve güncel olarak birçok alana entegrasyonu sağlanan nanoteknoloji ve nanoyapıların ağartma işlemleri için oldukça umut verici çalışmaları mevcuttur. Bu derleme devital ağartmanın önemli yönlerinin bir özetini sunarak güncel ve gelecek vaat eden uygulama yöntemlerine yönelik çalışmalara odaklanmaktadır.
Anahtar Kelimeler: Beyazlatıcı ajanlar; endodonti; ışıkla ağartma; lazerler; nanopartiküller
ABS TRACT
Considering its role in improving the color of teeth exposed to internal discoloration, de-vital bleaching is a treatment technique that has gained popularity because it is more conservative than other interventional techniques in solving the aesthetic problems of patients. Although applications have been modified over the years and used with different formulations, delivery systems, and activation routes to achieve predictable long-term results while minimizing the associated risks, today, the bleaching mechanism is mainly based on peroxide-releasing compounds. Today, the effectiveness achieved by traditional methods presents satisfactory results in devital bleaching; however, considering the disadvantages , there is a need to improve or recommend new, safer techniques. There are promising studies on bleaching processes using various light sources, laser systems, cold atmospheric pressure plasma devices , and nanotechnology and nanostructures, which are currently integrated into many fields. This review summarizes the essential aspects of devital bleaching, focusing on current practices and promising strategies.
... Treatment for extrinsic stains may involve teeth whitening procedures. [24][25][26] These pro cedures have shown to be very successful, with patients reporting satisfaction with color changes after 2 weeks of bleaching gel application. The color demonstrated sta bility for up to 12 months. ...
Focal microdontia is a dental anomaly characterized by the presence of a single abnormally small anterior or posterior tooth. The objective of this article is to provide an updated review of the literature on the
advanced restorative management of focal microdontia, and to document a clinical case where the reviewed advanced restorative approaches were applied to treat a young adult presenting with a non-syndromic asymmetrical focal microdontia.We conducted a preliminary examination of the existing literature on the advanced restorative management of focal microdontia. Additionally, we presented a minimally invasive approach to the treatment of an 18-year-old female patient with non-syndromic asymmetrical focal microdontia. The primary advantage of adhesive dentistry is that it can better preserve the structure of smaller teeth. A review of literature reveals a paucity of reports on localized microdontia in the maxillary anterior region of the mouth. However, novel minimally invasive restorative procedures satisfy patients’ aesthetic and functional preferences. Well-executed additive diagnostic wax-ups and intraoral mock-ups can serve as a permanent restoration blueprint, providing predictable results for focal dental anomalies in the aesthetic zone. In conclusion, the use of minimally invasive dental approaches in young patients with focal microdontia can result in long-term satisfactory aesthetic outcomes.
... In the case of light powered bleaching, it's used to activate peroxide to accelerate the chemical redox reactions of the bleaching agent [6,7]. Hydrogen peroxide (H 2 O 2 )-based bleaching agents at high concentrations (typically 15-38%) are widely used for in-office techniques due to their high oxidizing ability [8,9]. ...
Objective: To investigate effect of 15% carbamide peroxide bleaching gel on color of Class V resin composite restoration. Materials and methods: 60 class V cavities were made in maxillary premolars Teeth were randomly divided into four groups of 15 specimens each (2 control and 2 experimental or bleached groups). Group A to be restored with light nanocomposite resin (Filtek Z350 XT) with no post-restoration bleaching procedure (control). Group B to be restored with light nanocomposite resin (Filtek Z350 XT, with post-restoration bleaching procedure (Experimental). Group C to be restored with microhybrid resin (Filtek 250 XT) with no post-restoration bleaching procedure (control). Group D to be restored with microhybrid resin (Filtek 250 XT), with post-restoration bleaching procedure (Experimental). The bleaching was made with 15% at home bleaching agent (Opalescence PF). Color, opacity and fluorescence were analyzed by taking digital photos for the specimens at baseline and 24 h after completion of the bleaching procedure. The color pattern was evaluated according to the CIE - L*, a* and b* color system. Bleaching according to the following equation (25) ΔE = [(ΔL) 2+(Δa) 2+(Δb) 2] 1/2 For optical analysis, the specimens were subjected to the color measurements on white and black patterns, considering only the L* coordinate, which was calculated according to the formula: Opacity = L*b/L*w, where L*b corresponds to the reading of the L* coordinate against a black background and L*w against a white background. This procedure was performed before after bleaching, and the difference in opacity between the two periods was calculated in percentage. While for fluorescence comparison, the Fluorescence parameter (FL) was calculated, at baseline and post bleaching procedure, as the difference in color (ΔE) depending on the inclusion or exclusion of the UV component according to the equation: FL = [(CIE L*100 – CIE L*0) 2 + (CIE a*100 – CIE a*0) 2 + (CIE b*100 – CIE b*0) 2] 1/2, where subscripts 100 and 0 denote the 100% UV-included and the UV-excluded conditions respectively. The recorded data for the tested materials' color, opacity and fluorescence were collected and statically analyzed with IBM® SPSS® statistical version 20 with the significance level set at P ≤ 0.05. Results: There was no statistically significantly different between the two materials before as well as after bleaching. Conclusion: the color change of the nanofilled and microhybride light activated composite after bleaching (home-bleaching) was not perceptible or significant.
... Hydrogen peroxide is a compound unstable and decomposes in water and reactive oxygen radicals, being highly soluble and acidic with a pH that differs according to concentration. The free radicals released by hydrogen peroxide react more effectively with organic chromogens through an oxidizing process that breaks the strong double bonds, destabilizing them, and culminating in a change in the color of the tooth structure [1][2][3]. ...
Aims: Investigate possible changes in the microhardness of tooth enamel associated with the use of ozonized sunflower oil during the whitening procedure. Study Design: In vitro study. Place and Duration of Study: Department of Dentistry of the State University of Western Paraná - UNIOESTE between January 2023 and December 2023. Methodology: 30 healthy bovine incisor crowns were stored in 0.01% thymol solution (4ºC/30 days). Blocks measuring 4x4x2.5mm were made. With the exception of the buccal side, all sides were waterproofed and stored in artificial saliva and phosphate buffer. The specimens were divided into 3 groups (n=10) - CT (control), NP + H2O2 (desensitizing agent based on potassium nitrate and 35% hydrogen peroxide) and OL + H2O2 (ozonized sunflower oil and 35% hydrogen peroxide). The desensitizing agents were applied before the whitening gel. Color was recorded before and after the whitening procedure. Knoop surface microhardness was measured at 7, 14 and 21 days. The data obtained was submitted to Shapiro Wilk statistical analysis, Friedman ANOVA (p<0.05), Durbin-Conover (p<0.05) and Kruskal-Wallis ANOVA (p<0.05). Results: In the intra-group analysis, the groups tested showed a statistical difference in enamel surface hardness, except for the OL + H2O2 group, before bleaching (234 + 95) and after bleaching (200 + 99). In the inter-group analysis, there was a significant statistical difference between the groups in the periods of 14 and 21 days after bleaching and no significant change in the period before and immediately after bleaching. In the analysis of color saturation, statistical changes were observed in the bleached groups. Conclusion: Ozonated sunflower oil did not influence the microhardness values of the enamel surface, confirming its safety as a desensitizing agent during treatment.
... Its success in clinical trials is well-documented, with numerous studies demonstrating its efficacy and safety [1][2][3][4][5]. While the exact mechanism behind tooth bleaching is still being unraveled, it's believed to work by increasing the opacity of tooth enamel and oxidizing phosphoproteins within the dentin, which contribute to tooth discoloration [6][7][8]. Among various whitening techniques, in-office bleaching using highly concentrated hydrogen peroxide gels has gained favor due to its controlled application and faster results [9][10][11]. ...
Background
Light-cured resins are widely used as gingival barriers to protect the gums from highly concentrated peroxides used in tooth bleaching. The impact of barrier brand on clinical outcomes is typically considered negligible. However, there is limited evidence on the effects of different brands on operator experience, barrier adaptation, and patient comfort.
Objective
This clinical trial assessed the impact of four commercial gingival barrier brands (Opaldam, Topdam, Lysadam, and Maxdam) on operator perception, adaptation quality, and patient comfort.
Methods
Twenty-one undergraduate students placed gingival barriers in a randomized sequence using blinded syringes. Photographs of the barriers were taken from frontal and incisal perspectives. After bleaching procedures, operators rated handling features and safety using Likert scale forms. Two experienced evaluators independently assessed barrier adaptation quality on a scale from 1 (perfect) to 5 (unacceptable). The absolute risk of barrier-induced discomfort was recorded. Data were analyzed using Friedman and Chi-square tests (α = 0.05).
Results
Opaldam and Topdam received the highest scores in most handling features, except for removal, which was similar among all brands. No significant difference was observed in barrier adaptation quality between the evaluated brands. Discomforts were mainly reported in the upper dental arch, with Maxdam having the highest absolute risk (35% for this arch and 24% overall).
Conclusions
This study suggests that gingival barrier brands can influence operator perception and patient comfort. Opaldam and Topdam were preferred by operators, but all brands demonstrated comparable adaptation quality.
Clinical trial registration
The study was nested in a randomized clinical trial registered in the Brazilian Clinical Trials Registry under identification number RBR-9gtr9sc.
... Избелването на зъбите е неинвазивна техника за подобрение на цвета на зъбите с висока успеваемост (14,17). Избелващият ефект се постига с химични продукти на основата на пероксид, като при разграждането му се генерират свободните радикали, които разграждат органичната структура на пигментните молекули в дентина и той изсветлява (7). Професионалното избелване на зъби може да се постигне или с процедури в кабинета чрез прилагане на избелващи агенти с висока концентрация на водороден пероксид (5), или чрез използване на домашни техники, назначени от лекар по дентална медицина (пациентът използва индивидуални шини с избелващ агент у дома), или с комбинация от двете техники. ...
Tooth whitening is a non-invasive procedure for tooth color improvement with a high success rate. The aim of the present survey is to investigate the patients’ awareness, attitude, and experience regarding tooth whitening. The findings confirm that as age increases, dissatisfaction with tooth color also rises. Surprisingly, a significant proportion of individuals who are familiar with the method have never visited a dentist for tooth color improvement through bleaching. In terms of experience with bleaching products, no relationship was found between experience and age, but a connection between experience and gender was established. Female respondents reported greater experience with whitening products, although satisfaction with these products did not show a clear trend. Furthermore, a relatively high number of respondents expressed uncertainty about the safety of tooth bleaching methods. These results emphasize the necessity for increased awareness about tooth whitening methods and the conditions for their safe application, as well as the pursuit of greater satisfaction with these methods.
... They enter the enamel and dentin porosities and break down the double bonds in chromogens of organic molecules into carbon dioxide and water. 6 Researchers have considered it a safe and effective treatment for discolored teeth, 7 however, they reported various adverse effects including changes in enamel surface morphology, 8 composition, 9 surface micro-hardness, 10 and reduction in bond strength of adhesives. 11 Although the process of bleaching results in an instant and enduring alteration in the visual color and brightness of teeth, the hue tends to transform within 24-48 h. ...
Materials like carbamide peroxide or hydrogen peroxide are commonly used for vital teeth bleaching. However, there have been concerns regarding their effect on composite-to-bleached enamel bonding strength. The study investigated the impact of organic and antioxidant agents on composite bond strength in bleached enamel with different dental adhesive solvents. Human third molar teeth were sectioned into buccal and lingual halves. The two main adhesive solvent groups evaluated were acetone and alcohol. Each main group was divided into six groups. The positive control group received no bleaching, the negative control group consisted of bleaching with no surface deoxidization; and other experimental categories involved post-bleach treatments with 95% ethanol, sodium ascorbate (10%), acetone solution, or sodium fluoride solution (1.1%). Following the surface treatment and enamel bonding procedure, nano-hybrid composite cylinders measuring 3 × 2 mm were directly cured over the bleached enamel substrate. The shear bond test was performed after 24-h storage and 12,000 thermocycles on a universal testing machine. In this study, one-way ANOVA was used along with Tukey’s HSD tests at a significance level of 0.05. The negative control groups showed significantly lower bond strength than the positive control group. Ethanol surface treatment had superior mean bonding strength in acetone and alcohol-based adhesive solvent groups. The utilization of sodium ascorbate for surface treatment resulted in a significant enhancement of adhesion between the composite material and bleached enamel surface. Sodium fluoride application showed no significant recovery in shear bond strength in both dental adhesive groups. It was concluded that hydrogen peroxide severely compromised the immediate bond strength of composite resin. Surface treatment of bleached enamel with ethanol, sodium ascorbate, and acetone solutions is an effective option for restoring bond strength.
... In the case of light powered bleaching, it's used to activate peroxide to accelerate the chemical redox reactions of the bleaching agent [6,7]. Hydrogen peroxide (H 2 O 2 )-based bleaching agents at high concentrations (typically 15-38%) are widely used for in-office techniques due to their high oxidizing ability [8,9]. ...
Shade of every tooth is determined by a mixture of the different optical characteristic of enamel, dentin and pulp. Tooth stains vary in cause, appearance, localization, difficulty and adherence to tooth structure. Due to technological advances in dentistry, there is also an increased patients’ awareness of oral appearance. Most people are looking for “whiter” teeth to improve their overall smile
... 1 Radicals derived from hydrogen peroxide can also react with the organic enamel matrix, making it more opaque. 2 As a result of this action, some adverse effects can occur when tooth bleaching is performed. Changes to the enamel surface, such as demineralization, the appearance of irregularities and porosity, reduced microhardness, and increased permeability can occur. ...
Objectives
The present study aimed to evaluate the desensitizing effect of toothpaste for sensitive teeth on patient tooth sensitivity and on bleaching efficacy of the 38% hydrogen peroxide bleaching agent used for in-office bleaching compared to a regular toothpaste in a randomized clinical trial.
Methods and Materials
Forty-eight patients having maxillary right central incisors with darkness greater than A1 were selected for the present double-blind randomized clinical trial. Patients were randomly allocated into two groups: the placebo group, which used regular toothpaste, and the experimental group, which used sensitivity toothpaste. The intervention consisted of applying toothpaste with the aid of an individual tray for a period of 4 minutes daily, starting one week before the first bleaching session and interrupting use immediately after the second session. After allocation to one of the groups, individuals received in-office dental bleaching with a 40-minute application of 38% hydrogen peroxide for two sessions with an interval of one week. The incidence and intensity of sensitivity were assessed using a visual analogue scale and a numeric analogue scale. Sensitivity was measured immediately before each session, 1 hour, 24 hours, and 48 hours after each bleaching session and four weeks after the second bleaching session. Tooth shade was evaluated using a spectrophotometer and by comparison with the VITA Classical Shade Guide (Vita Zahnfabrik, Bad Säckingen, Germany). Tooth shade was evaluated before the first bleaching session, one week after the first bleaching session, one week after the second bleaching session and four weeks after the second bleaching session. Participants and professionals who performed the bleaching, shade, and sensitivity assessments were blinded to the group of patients they were treating or assessing. For the incidence of hypersensitivity, the results were evaluated by comparing the groups at different evaluation times with the Mann-Whitney test for comparison between groups, the Friedman test for repeated measures, and the Tukey test for comparison of times. Shade change on the guide was analyzed using the Mann-Whitney test for comparison between groups and the Wilcoxon test for comparison between times. Shade change by the spectrophotometer was analyzed using the t-test for comparison between groups and the paired t-test for comparison between times. All analyses were performed with a significance level of 5%.
Results
There was no difference in the pattern of dental hypersensitivity between groups. For all shade measures, there was no difference between the bleaching results, and no statistically significant difference was observed between the study groups.
Conclusion
The use of arginine-based desensitizing toothpaste did not interfere with the bleaching ability of hydrogen peroxide and was not effective in reducing the sensitivity caused by in-office tooth bleaching.
... First, changing teeth intrinsic color by using hydro-gen or carbamide peroxides. These agents diffuse into the teeth and interact with stain molecules, leading to alteration in teeth structure surface, reflecting the light differently and giving whiter teeth (1,4). Meanwhile, the use of bleaching components remains highly controversial according to safety. ...
To assess the effect of different whitening toothpastes on enamel surface morphology, chemical profile and their whitening efficiency. Sixty teeth were divided into 5 groups (12 teeth/group); Gp I: brushed with no toothpaste. Gp II: brushed with Pearl-based toothpaste. Gp III: brushed with Charcoal-based toothpaste. Gp IV: brushed with Alumina-based toothpaste. Gp V: brushed with salt and lemon-based toothpaste. Each tooth was brushed with a bean sized toothpaste wetted with distilled water twice daily by using standard electronic toothbrush for four weeks. Enamel surface morphology, chemical profile and color of each tooth were investigated. Chemical profile results and color measurements were analyzed statistically. Gp I revealed normal enamel surface morphology and chemical profile. Gp II and Gp III demonstrated surface morphology close to Gp I with insignificant reduction in mineral content. Gp IV showed obvious shallowing of perikymata ridges, exposure of fish-scale appearance, with pits and depressions, alongside to the significant reduction in mineral content. Gp V presented the most enamel surface alteration with widening of prism sheath and depressions all over the surface, besides the highest significant reduction in mineral content. Gp V, followed by Gp IV, demonstrated the highest color and whiteness changes, followed by Gp III, then Gp II, while the lowest value was in Gp I. Salt & lemon-based toothpaste, followed by Alumina-based, exerted the most considerable changes in the morphology and chemical profile of the enamel surface, beside to the higher whitening effects on teeth than the others.
... This percentage decreased after bleaching which may be due to the presence of pain after the bleaching session which agrees with their answers regarding the source of pain where 47% and 50% in the Fläsh WS and P Zoom WS participants respectively recorded pain from their teeth. This agrees with several studies [52], [53], [20] , [54], [21] who reported that the highest penetration of (HP) and its subproducts to the pulp chamber occurred when 35% (HP) bleaching agent was used in one session 3x15 minutes and the most intense pulp reaction was observed. This lead to pulp cells affection with the release of in ammatory mediators [ That is why extra care should be done to protect the gingival margin. ...
Objective
This study was carried out to examine the effect of two in-office bleaching systems by measuring the level of catalase enzyme (CAT) and nitric oxide (NO) in the gingival fluid (GCF) before and after bleaching. In addition, each participant was asked to fill out an online survey to examine their satisfaction with the bleaching procedure.
Materials and Methods
Thirty-six healthy young participants were selected. They were divided into two groups according to the bleaching system used; Philips Zoom White of 25% H2O2 or Fläsh White Smile of 32% H2O2. Three sessions, 15 minutes each were performed in the same visit for each participant. The (GCF) samples were collected using a sterile periopaper before and after the bleaching session. A survey link was sent to all participants to examine their satisfaction.
Results
There was a statistically significant increase in (CAT) and (NO) in the (GCF) of the Fläsh group when compared to the Zoom group. Participants reported 94% satisfaction with both bleaching systems. There was no statistically significant difference between the Fläsh and Zoom groups in all participant's answers except in the degree of gingival pain where the number of participants who reported no or mild pain in the Fläsh were greater than those in the Zoom.
Conclusion
The higher percentage of H2O2 in Fläsh group resulted in the increase of (CAT) and (NO) release in the (GCF). Participants in both groups were equally satisfied.
Clinical relevance
Risks from dental materials have to be evaluated to prevent endangering human health.
... Specimens were randomly allocated into three groups with three different treatment approaches. In group (A), bleaching was performed before RI since the existence of cured resin within the enamel impairs the effectiveness of bleaching agents (11) while bleaching by peroxide does not induce significant changes in tooth enamel organic and inorganic contents (12) . In Group (B), microabrasion was performed for 60 seconds to remove less than 10% of the enamel thickness (20) . ...
... These benefits have led to its popularity in the field of cosmetic dentistry [1]. Hydrogen peroxide, the active ingredient in whitening agents, can be applied directly to the tooth surface or produced through the chemical reaction of carbamide peroxide [2]. ...
Objective:
This in vitro study aimed to evaluate the effects of different whitening toothpastes on a composite resin during at-home bleaching with 10% carbamide peroxide.
Materials and methods:
Sixty samples (7 mm × 2 mm) were used for color and roughness analyses, while another 60 samples (3 mm × 2 mm) were utilized to assess microhardness. The factors analyzed included toothpaste, for which 5 options with varying active agents were tested (distilled water; conventional toothpaste; whitening toothpaste with abrasive agents; whitening toothpaste with abrasive and chemical agents; and whitening toothpaste with abrasive, chemical, and bleaching agents). Brushing and application of whitening gel were performed for 14 days. Surface microhardness (SMH), surface roughness (Ra), and color (∆L*, ∆a*, ∆b, ∆E*ab, and ∆E00) were analyzed. The Ra and SMH data were analyzed using mixed generalized linear models for repeated measures, while the color results were assessed using the Kruskal-Wallis and Dunn tests.
Results:
Between the initial and final time points, all groups demonstrated significant increases in Ra and reductions in SMH. No significant differences were found between groups for SMH at the final time point, at which all groups differed from the distilled water group. Conventional toothpaste exhibited the lowest Ra, while whitening toothpaste with abrasive agent had the highest value. No significant differences were observed in ∆L*, ∆a*, and ∆b.
Conclusions:
While toothpaste composition did not affect the color stability and microhardness of resin composite, combining toothbrushing with whitening toothpaste and at-home bleaching enhanced the change in Ra.
... Contudo, também está sujeita aos mesmos efeitos colaterais e injúrias (DONASSOLO, 2021 permeabilidade dos dentes (HENRIQUE et al., 2017). A dentina é um substrato rico em matéria orgânica e sua cor pode ser considerada a responsável pela cor o dente, enquanto o esmalte apenas determina pequenas modificações nessa cor (TEN BOSCH et al., 1995); sendo assim, quanto maior o teor de matéria orgânica, maior o resultado do clareamento, ou seja, quanto mais amarelado o dente, melhores são os resultados do procedimento (EIMAR, et al., 2012). ...
A crescente demanda por clareamento dental vem acompanhada de queixas em relação a seus efeitos adversos. Sendo a sensibilidade dentária um desses principais efeitos, o objetivo dessa revisão foi avaliar a relação entre o tempo de exposição ao agente clareador, a presença e a intensidade da sensibilidade dentária, independente do protocolo clareador ser o caseiro ou de consultório. Trata-se de uma revisão integrativa realizada nas bases de dados PubMed, SciELO, LILACS e BBO, utilizando as palavras chaves extraídas do Descritores em Ciências da Saúde (DeCS) e do Medical Subject Headings (MeSH): “Dentin sensitivity”; “Tooth bleaching”; “Hydrogen peroxide”; “Carbamide peroxide”, o operador booleano “AND” e o operador booleano “OR”, resultando em: “Dentin sensitivity AND Tooth bleaching AND (Hydrogen peroxide OR Carbamide peroxide)”. A seleção dos artigos iniciou-se por duas pesquisadoras utilizando a plataforma Rayyan com cegamento da seleção individual. As escolhas divergentes foram encaminhadas para um terceiro revisor, também utilizando o cegamento, a fim de se obter uma decisão final. Todos os pesquisadores passaram por um processo de calibração quanto ao uso do programa e aos critérios de inclusão e de exclusão dos artigos. Foram apuradas as publicações entre os anos 2011 e 2022, nos idiomas inglês, português e espanhol, com delineamento de estudo ensaio clínico randomizado. Sete artigos foram elegíveis para essa revisão. A maior parte desses estudos foi realizada no Brasil, sendo mais comum os ensaios clínicos randomizados cego, com abordagem de clareamento caseiro e amostragem menor que 50 pacientes. As divergências nos resultados dos artigos sugerem que o maior tempo de exposição ao agente clareador não é um fator determinante no surgimento da sensibilidade, apesar de poder influenciar nela e na sua intensidade.
... Hydrogen peroxide (H 2 O 2 ) is the most popular material used in tooth bleaching, and its concentration determines the application mode [9]. The H 2 O 2 gel diffuses into the enamel and elaborates free radicals leading to bleaching [10]. Theoretically, the objective of using light source units (light-emitting diodes [LEDs]) is to heat the H 2 O 2 , which speeds up the reaction and facilitates the formation of oxidant-free radicals [11]. ...
This in-vitro study evaluates the efficacy of the teeth bleaching approach using different laser wavelengths (405 nm blue diode, 940 nm infrared diode, and Er,Cr:YSGG 2780 nm lasers) in comparison to the conventional method using light-emitting diode (LED) sources (420–480) nm. Eighty caries-free sound human premolars were randomly divided into four groups ( ). Each group received a different bleaching procedure. Then each group was further subdivided into two subgroups ( ) stained with different solutions. The pulp chamber temperature rise was recorded using an optical fiber sensor with a novel design and fabrication. The color was analyzed using a digital spectrophotometer. Five samples of each subgroup were tested for surface roughness, while the others were tested for Vickers microhardness. The bleaching process with a short wavelength 405 nm blue diode laser showed the best results for the shade, with a minimum pulpal temperature increase indicating no possible necrosis and hence maintaining tooth vitality. Additionally, a remarkable reduction in bleaching time was achieved compared to the conventional approach. This process also yielded the highest color change ( ) and increased microhardness, with no noticeable change to the tooth roughness. The 405 nm blue diode laser applied for bleaching showed the best bleaching activity against tested stains and negligible pulpal temperature rise with a noticeable reduction in the bleaching time. The proposed novel method to measure temperature change could be used to develop a promising smart sensor for quick, effective, repeatable, and in-situ monitoring of human body temperature.
... These intermediaries cause the vasodilatation and the growth in the vascular permeability of the pulp calve. As the pulp tissue is located in the pulp chamber , i.e. strictly defined space, any state which is accompanied by the edema causes the rise in the intra-pulp pressure (24)(25)(26). The rise of the pressure makes additional burden and the reaction on the nociceptors which at the slightest stimulation generate painful impulses and then transmit it through the nerval fibres to the zones of the brain when we become aware of the painful sensation. ...
This paper aims to collect all the necessary information and conclusions which deal with the anti-inflammatory drugs within the scope of teeth bleaching, and which are rooted in scientific research. It is a well-known fact that the teeth whiteners / bleachers are at the same time a very aggressive agents, which opened up the question of the safety of their application. The most frequently applied bleaching agents are the hydrogen-peroxide (H 2 O 2 ) and carbim peroxide (CH 6 N 2 O 3 ), therefore this paper will be based on the research which included these two agents. The first studies were directed towards investigating the outcome / impact on the enamel, i.e. if there is direct surface damage of the enamel layer after the use of such agents. However, bearing in mind that the clinical practice has shown that in a number of cases there arises the sensitivity of teeth in the form of painful sensation after the bleaching treatment, some researches were directed towards the estimation of the permeability of the enamel and dentin for the bleaching agent, and later the effect on the pulp tissue. Along with the existing proof about the irritability of these agents to the pulp tissue, the modern research have the idea of looking into the effects of the anti-inflamatory drugs as the accompanying and prevention therapy of any of the irreversible damage of the pulp. On one hand the application of these drugs can reduce the sensitivity and painfulness of the teeth, which makes the intervention pleasant for the patient, but on the other hand the intervention becomes completely justifiable from the aspect of safety and the basic principle primum non nocere. The anti-inflammatory drugs which will be the topic of this study are H hydrocortisone, acetaminophen, ipobruphen and etodolac. Taking into consideration the vasoconstrictive and anti-oxidative effect, the anti-inflammatory effect of the carvedilol will be looked into, which belongs to the group of beta blockers. Based on available informations it can be noticed that the most efficient anti-inflammatory effect in teeth whitening is achived by hydrocortisone.
... In this context, dental bleaching consists of a popular, effective and conservative treatment [2,3]. Hydrogen Peroxide (HP) is the most commonly used bleaching agent and is manufactured in concentrations ranging from 3% to 40% [4,5]. There are several protocols available for in-of ice bleaching: applying only peroxide bleaching gels; bleaching using only violet LED light or bleaching using HP gel associated with a light source [6,7]. ...
To reduce bleaching side effects, the use of low concentrations of Hydrogen Peroxide (HP) agents associated with hybrid light (violet LED/Diode Laser) has gained interest. Case report: The aim of this report is to describe a case of a 16-year-old patient that presented a complaint related to the color of his teeth and a maxillary midline diastema. In-office bleaching with 6% HP associated with hybrid light (violet LED/Diode Laser) was performed. The bleaching gel was applied once on the teeth and light-activated for 1 minute (15 times) followed by 1min intervals (15 times) with a total bleaching time of 30 minutes. After the bleaching procedure, the teeth were polished and the desensitizer was applied for 4 minutes. Two bleaching sessions were performed at a 1-week interval. The diastema was closed with direct resin composite restorations without any tooth preparation. The conventional 3-step bonding agent was used and A1 dentin shade and B1 enamel shade were used followed by polishing discs. At 3-year recall, discoloration and fractures were not found on the the teeth or restorations and patient was completely satisfied. Conclusion: the conservative and safe option of bleaching with a low-concentrated HP gel associated with violet LED light is an interesting option for young patients and presents longevity over time.
... 颜色反弹速度的比较 与漂白后第 1 月相比，漂白后第 9、12 月牙体 中 部 及 颈 部 颜 色 反 弹 速 度 的 差 异 有 统 计 学 意 义 (F 中 =6.033，F 颈 =6.191，P<0.05)。Bonferroni 多重 及颈部在漂白后第 1 个月时 ΔE*显著减小，但是其 ΔE* 切 =8.88，ΔE* 中 =15.67，ΔE* 颈 =15.56，仍远高于 肉眼可见的 ΔE*≥3，说明漂白的效果是显著的。 本试验结果显示，在牙体切端，漂白时主要 影响颜色变化的是明度 L*增加，漂白后主要影响 颜色反弹的也是明度 L*。在牙体中部和颈部，漂 白时主要影响颜色变化的是明度 L*增加，以及 a* 值减小变得更绿，同时在牙体中部还会出现 b*减 小变得更蓝，这与其他学者 [15-16] 的研究结果相似。 漂白后主要影响颜色反弹的依然主要是明度 L*， 与 a*、b*关系不大。据此可以得出如下临床提示： 内漂白不仅可以将无髓变色牙变白，还可以消除 牙齿的黄棕色或黑褐色，尽管在漂白后的 1 年时间 内患牙颜色会因为反弹变得有所灰暗，但黄棕色 或黑褐色不会再次出现。 一 些 早 期 的 研 究 [17-19] 曾 报 道 内 漂 白 后 颜 色 复 发，2 年复发率为 10%，5 年复发率为 25%，8 年复Fig 5 Changes in the rebound velocity of the neck, middle, and incisal end of the tooth at each time point发生变化[4,20] 。切端处牙本质小管较少，釉质较多， 在漂白时釉质因漂白剂的作用，变得不透明，所 以导致其光化学性能变化与其余两处不一致[21][22] 。 此外，切端由于釉质及无机物较多，牙髓及红细 胞等有机物较少[23] ，故有机物还原反应较少[24] 。 在漂白后第 9 个月时，牙体中部和颈部颜色反 弹的速度显著下降，第 12 个月与第 9 月反弹速度 应或异物反应；也可能为 pH 值下降导致破骨细胞 被激活，使得牙颈部出现吸收[26] 。为避免出现这种 并 发 症 ， 本 试 验 严 格 按 照 去 除 釉 牙 骨 质 界 下 2 mm 牙胶尖并充填光固化玻璃离子形成隔障，观 察期内无 1 例出现明显牙颈部外吸收。 ...
Objectives:
This study aimed to observe the color rebound and rebound rates of non-pulp discolored teeth within 1 year after routine internal bleaching to guide clinical practice and prompt prognosis.
Methods:
In this work, the efficacy of bleaching was observed in 20 patients. The color of discolored teeth was measured by using a computerized colorimeter before bleaching; immediately after bleaching; and at the 1st, 3rd, 6th, 9th, and 12th months after bleaching. The L*, a*, and b* values of the color of cervical, mesial, and incisal parts of the teeth were obtained, and the color change amounts ΔE*, ΔL*, Δa*, and Δb* were calculated. The overall rebound rate (P*) and the color rebound velocity (V*) were also analyzed over time.
Results:
In 20 patients following treatment, the average ΔE* of tooth color change was 14.99. After bleaching, the neck and middle of the teeth ΔE* and ΔL* decreased in the 1st, 3rd, 6th, 9th, and 12th months, and the differences were statistically significant. Meanwhile, from the 9th month after bleaching, the rebound speed was lower than that in the 1st month, and the difference was statistically significant. The incisal end of the tooth ΔE* and ΔL* decreased in the 6th, 9th, and 12th months after bleaching, and the differences were statistically significant. No significant difference was found in the rebound speed between time points. However, this rate settled after the 9th month, with an average color rebound rate of 30.11% in 20 patients.
Conclusions:
The results indicated that internal bleaching could cause a noticeable color change on pulpless teeth. The color rebound after bleaching was mainly caused by lightness (L*), which gradually decreased with time, and it was slightly related to a* and b*. The color of the teeth after internal bleaching rebounded to a certain extent with time, but the color rebound speed became stable from the 9th month. Clinically, secondary internal bleaching can be considered at this time according to whether the colors of the affected tooth and the adjacent tooth are coordinated and depending on the patient's needs.
... This group presented a decrease in luminosity in both models Codes: T 0 : color measurement performed at baseline (polished samples, without staining or brushing protocols); T 1 : color measurement after 14 days of staining; T 2 : color measurement after experimental model (alternate cycles of staining and brushing). Hydrogen Peroxide is normally present in bleaching products for professional application [39] because it degrades and diffuses into the tooth structure, acting directly on colored substances [40]. In toothpastes, the concentration of hydrogen peroxide is lower than that found in products for professional application. ...
Objectives:
To compare the effect of whitening toothpastes with different mechanisms of action on discolored teeth subjected to additional staining/or not.
Methods:
One hundred twenty tooth specimens were stained for 14 days (staining broth under constant agitation and pH=7) and then allocated into the groups of toothpastes with different whitening ingredients (n=10): 1. Regular - Colgate Total 12 Clean Mint; 2. CLWI - Colgate Luminous White Instant (blue pigment); 3. CLWA - Colgate Luminous White Advanced Expert (hydrogen peroxide); 4. CLWAC - Colgate Luminous White Activated Charcoal (activated charcoal); 5. OB3D - Oral-B 3D WHITE Brilliant Fresh (abrasive); 6. TW - Teeth Whitening (charcoal powder). Specimens were submitted to two experimental models: A. Daily staining-toothbrush cycling: staining solution (5min), toothbrushing (45 strokes) and artificial saliva (3h), 2x/day, for 5days; B. Only toothbrushing (30.000 brushing strokes). Color change was determined with a spectrophotometer (CIEDE2000 and Whitening Index for Dentistry - WID) and statistically analyzed (α=0.05).
Results:
For both models, ΔE00 and Δa did not differ significantly between the whitening toothpastes and the regular. All groups showed a decrease in tooth yellowness (-Δb) and an increase in WID. Group Teeth Whitening exhibited a decrease in luminosity (-ΔL). In model A, Groups did not differ significantly from the Regular in terms of ΔL (p=0.35) and Δb (p=0.74). Groups CLWI and OB3D exhibited a decrease in luminosity. Reduced redness (-Δa) occurred only in Group CLWI. In Model B, Groups OB3D (p=0.021) and CLWA (p=0.001) exhibited higher change in luminosity than in Group Teeth Whitening. All exhibited increased redness (+Δa) and lightness (+ΔL), except the Regular, CLWAC and Teeth Whitening. Group OB3D had a significantly higher change in Δb than the Regular (p=0.021).
Conclusions:
Irrespective of the mechanism of action, all toothpastes reduced tooth yellowness and promoted similar overall color change. Exposure of the teeth to additional staining during the toothbrushing cycles did not influence the effect of the whitening toothpastes.
Clinical significance:
Whitening toothpastes should be tested in conditions that more closely simulate their use in a clinical scenario, in which alternate cycles of staining and brushing occur on a daily basis. However, even in such conditions, they were unable to promote a color change that differed from that of a regular toothpaste.
... The whitening efficacy of peroxide, a common whitening agent used in gel or liquid form, is well known in the literature. 19,20 This powerful oxidizing agent allows bleaching by breaking down long chain organic molecules into short chain compounds. However, adding peroxide to the ingredients of whitening mouthrinses is difficult due to safety restrictions, so hydrogen peroxide can be added at low concentrations of 1% to 2%. 8 In the formula of the mouthrinses we use in the study, bleaching is provided with hydro- In an in vitro study on teeth, Lima et al 8 investigated the effect of mouthrinses containing hydrogen peroxide, and found that the tested mouthrinses had a whitening effect. ...
Purpose: Recently, many whitening mouthrinses have appeared on the market with different ingredients due to their ease of use and low costs. Whether these mouthrinses change the color of composite resins has been a matter of curiosity. The aim of this study was to investigate the effect of whitening mouthrinses with different chemical structures on the color stability of a Bis-GMA free resin composite. Materials&methods: Seventy disc-shaped specimens (8 mm x 2 mm) were prepared from a Bis-GMA free composite resin and randomly divided into seven groups, according to the mouthrinses (n=10): Listerine Advanced White, Colgate Optic White, Perfect White Black, Crest 3D White, Pasta Del Capitano, Oral B 3D White Luxe. The control group used in the study was distilled water. After the baseline color measurement values were recorded with a spectrophotometer (Vita Easy Shade V, Vita Zahnfabrik, Bad Sackingen, Germany). At the end of the keeping period, color measurements were repeated and changes in color values were calculated (ΔEab) using the CIE L*a*b* color system. Statistical analysis of the values obtained was made according to Kruskal Wallis test (p
White spot lesions (WSLs) are early clinical stages of enamel demineralization, often related to orthodontic treatment or poor oral hygiene. The use of gels such as fluoride for topical application inhibits demineralization and promotes remineralization of dental tissues through various mechanisms. A variety of therapeutic approaches are available; however, recent research indicates that combined treatment strategies may yield superior clinical outcomes compared to monotherapy. The aim of this study was to critically compare the efficacy of combining multiple treatment techniques for WSLs compared to using these techniques alone. A systematic search was conducted in PubMed, Scopus, and Cochrane databases according to PRISMA guidelines. The PICO strategy was used to formulate the research question: Which clinical approaches combined or isolated (C) influence the treatment and prevention effectiveness (O) of white spot lesions (I) in humans (P) in the last ten years (T)? Inclusion criteria focused on clinical studies from the last ten years evaluating the combined use of at least two treatment techniques for WSL, resulting in a total of 8 randomized controlled trials selected from an initial pool of 1185 articles. Our results suggest that combined treatment strategies, including resin infiltration with fluoride varnish and ozone therapy combined with fluoride application, demonstrated enhanced efficacy in lesion masking and remineralization compared to single-treatment approaches. CPP-ACP and hydroxyapatite-based creams improved aesthetics, particularly when used alongside fluoride varnish. Our study concluded that the combination of remineralization agents like fluoride gel, infiltrative resins, and antimicrobial treatments offers superior outcomes on white spot lesion treatment than using these techniques alone. However, long-term clinical studies are needed to standardize treatment protocols and confirm durability.
Objective: This study is aimed at assessing the bleaching efficacy of titanium dioxide (TiO2) nanoparticle suspensions at different concentrations and exposure times for photocatalysis and evaluating their potential as a peroxide-free alternative to carbamide peroxide in dental bleaching.
Materials and Methods: Sixty bovine incisors were stained with black tea and treated with different bleaching protocols: (1) control (16% carbamide peroxide), (2) TiO2-50 wt% for 10 min (TiO2 50/10), (3) TiO2-50 wt% for 50 min (TiO2 50/50), (4) TiO2-10 wt% for 50 min (TiO2 10/50), and (5) TiO2-10 wt% for 10 min (TiO2 10/10). The agents were exposed to UV light (395 nm) for photocatalysis before application. All treatments were applied daily for 2 h over 21 days. Color change ΔE00 was measured using a digital spectrophotometer (VITA Easyshade V), and pH was assessed using pH strips.
Results: The data were analyzed using one-way ANOVA and Tukey’s test. TiO2 50/50 showed significantly superior bleaching effects compared to all other groups (p<0.001). TiO2 10/50 and TiO2 10/10 demonstrated intermediate bleaching results, with no significant difference between them (p=0.0875). The control and TiO2 50/10 groups exhibited the lowest color variation (p=0.102). All groups maintained a pH of 6 before and after 2 h of the at-home bleaching protocol.
Conclusion: TiO2 nanoparticle suspensions may be a viable peroxide-free alternative for dental bleaching, particularly at higher concentrations and longer photocatalysis exposure times.
Objective
This study evaluated the color match of restorations made with single‐shade composites following two protocols of tooth bleaching.
Materials and Methods
Cavities in the cervical third of bovine crowns were restored using single‐shade composites (Omnichroma or Vittra Unique) or a multi‐shade composite restoration strategy (Filtek Z350 XT). The color of both the restoration and the middle third of the unrestored tooth were recorded. The Whiteness Index for Dentistry (WID) and color differences (Δ E 00 ) between the two areas were calculated. Specimens underwent bleaching using in‐office or at‐home protocols, and color evaluations were repeated at 24 h, 7 days, and 14 days post‐bleaching. Data were analyzed using MANOVA and repeated measures ANOVA.
Results
Bleaching protocols did not significantly affect WID or Δ E 00 values. The highest WID values were observed for Vittra Unique, and the lowest for Filtek Z350 XT. Tooth bleaching did not affect Δ E 00 values for restorations made with the multi‐shade strategy, but it resulted in a reduction for those made with the single‐shade strategy, regardless of the composite brand.
Conclusion
Tooth bleaching protocols differentially affected the color match of restorations made using single‐shade composites compared to multi‐shade restorations.
Clinical Relevance
Tooth bleaching protocols have a limited effect on the color of composites but can influence the color match between the restoration and the surrounding enamel. Specifically, color mismatches tend to decrease for lighter materials, such as single‐shade composites, after tooth bleaching, improving the overall esthetic integration of the restoration with the natural tooth structure.
Objective
To examine the effects of six whitening mouthwashes on tooth color and immediate bond strength to the enamel.
Materials and Methods
Human incisors were divided into seven groups ( n = 10) according to mouthwashes (R.O.C.S Black Edition White, Splat White Plus, Colgate Plax White Charcoal, Signal White Now, Listerine Advanced White, Colgate Optic White, and distilled water). After the initial color measurements, the teeth were exposed to mouthwash for 4 weeks. Then, the color measurements were repeated. Then, cylindrical composite resin blocks were immediately applied to the enamel surfaces and subjected to shear bond strength tests. Data were analyzed using Kruskal‐Wallis and Bonferroni tests ( α = 0.05).
Results
Δ𝑏, Δ𝐿, and Δ E 00 values did not present significant differences among the groups. Significant differences among the groups were determined for Δ𝑎 and ΔWI D values ( p < 0.05). R.O.C.S Black Edition White and Splat White Plus produced clinically acceptable color changes. Signal White Now, Splat White Plus, and Listerine Advanced White created acceptable whiteness changes. The mouthwashes did not statistically affect the bond strength compared to the distilled water ( p > 0.05).
Conclusions
Whitening mouthwash containing blue covarine revealed more acceptable color and whitening changes. Mouthwash containing charcoal led to the lowest enamel bond strength values.
Clinical Significance
The content of whitening mouthwashes affected the degree of tooth whitening and shear bond strength to enamel.
This study evaluated the mechanical properties of demineralized dentin matrix submitted to different bleaching treatments, as well as the changes in mass and collagen biodegradation brought about by endogenous protease. Dentin collagen matrices were prepared to receive the following treatments (n=12): no bleaching treatment (C–control), 10% carbamide peroxide (CP–Opalescence PF, Ultradent, South Jordan, UT, USA) 10%/8 hours/ day/14 days, and 40% hydrogen peroxide (HP–Opalescence Boost, Ultradent), 40 minutes per session/3 sessions. The dentin matrices were evaluated for elastic modulus and mass before and after treatments and ultimate tensile strength after treatments. The solution collected during storage was evaluated for hydroxyproline release. There was no statistically significant difference between CP and C in terms of the elastic modulus (p=0.3697) or mass variation (p=0.1333). Dentin beams treated with HP and C presented significant mass loss after the first session (p=0.0003). HP treatment led to complete degradation of collagen matrices after the second bleaching session. After the second session, CP showed higher hydroxyproline concentration than C (p<0.0001). Ultimate tensile strength was lower for CP than C (p=0.0097). CP did not affect the elastic modulus or the dentin collagen matrix mass but did promote hydroxyproline release by endogenous protease and reduce the ultimate tensile strength. HP significantly affected the mechanical properties of dentin and promoted complete degradation of the demineralized dentin collagen matrix.
A pleasingly attractive smile is composed of a harmonious balance of a well-aligned set of teeth with healthy anatomic contour of the gingiva and lips. Patients’ demand for aesthetic dentistry can be met with the practitioner’s choice of procedures and materials. Dental lasers can certainly be integrated into the treatment plan, and this chapter will provide details about modifying the color of the dental soft and hard tissues to help attain the desired outcome. The first section will describe on treatment for pigmentation of nonneoplastic origin. The second section will provide details about whitening.
Laser-activated tooth bleaching is discussed as a means to optimize results, while minimizing adverse side effects, but it lacks consensus in the scientific literature. Therefore, this systematic review aims to evaluate the protocols and outcomes of laser-activated vs. non-activated bleaching methods for safe and effective approaches. The PubMed, Cochrane, Scopus, ScienceDirect, and Google Scholar search engines, with the following MeSH terms and keywords: (bleaching OR whitening) AND laser AND (tooth OR dental OR enamel OR dentine), were used to identify human clinical trials and in vitro studies regarding laser-activated dental bleaching. After applying the keywords and additional filters, and inclusion and exclusion criteria, the final number of included articles was 19 clinical and 20 in vitro studies. Laser activation yielded no significant color improvement, but reduced gel contact time (10 min). Laser-activated bleaching required 24% less hydrogen peroxide (HP) concentration to achieve similar results. Additionally, there were no significant differences in terms of sensitivity and hard tissue alterations between the laser-activated and conventional groups. The benefits associated with laser-activated bleaching render it a compelling option. Nevertheless, a comprehensive evaluation of bleaching gels and activation protocols is imperative. Ultimately, this analysis provides clinical guidance pertaining to the facilitatory employment of laser irradiation.
Intracoronal bleaching is a minimally invasive procedure that was introduced into dentistry in the 19th century. The role of that procedure in enhancing the colour of teeth subjected to internal discolouration while being conservative made it extremely popular amongst dental professionals. Different materials and techniques have been utilized over the years attempting to obtain predictable long‐term results while minimizing any associated risks. Contemporarily, bleaching agents are mainly based on peroxide‐releasing compounds in different formulations and delivery systems. Different theories have been formulated on the bleaching mechanism of such agents, but the exact mechanism is yet to be proven. The effect of hydrogen peroxide‐based bleaching agents on the organic structure of enamel and dentine has been extensively investigated to address the effects of bonding of resin‐based restorative materials to hard tooth structure. Multiple case reports raised a concern about the contribution of intracoronal bleaching in developing invasive root resorption. Modification of intracoronal bleaching techniques was thus necessary to address such concerns. This review will provide a summary of the important aspects of intracoronal bleaching, focusing on how it applies to the contemporary clinical setting. © 2023 Australian Dental Association.
In this chapter we will present the step-by-step procedure of in-office whitening (or in-office bleaching) and the respective efficacy and side effects. We will also address other characteristics of in-office bleaching, including the number of clinical appointments required to reach effective whitening, the concentration of the peroxide-based bleaching products, and the effects of dentin dehydration and demineralization on the outcome, as well as bleaching-induced tooth sensitivity. Some frequently asked questions (FAQ) will be answered at the end of the chapter.
Tooth discoloration is classified as extrinsic or intrinsic, with extrinsic stains arising from the accumulation of residue on the surface of the tooth and intrinsic discoloration from stains within the enamel or dentin. For both types of stains, tooth whitening with hydrogen peroxide is a common treatment. Hydrogen peroxide likely exerts its effects by interacting with chromophores within the tooth structure, acting via what is known as the “chromophore effect.” Despite having the desired cosmetic effect, however, hydrogen peroxide treatment likely also may affect sound tooth tissue; and the unknowns surrounding unwanted side effects remain a concern. Here, the etiology of extrinsic and intrinsic stains is summarized, as is our current understanding of hydrogen peroxide treatment and mechanisms of action. This information might guide further research and development efforts to create new technology for the treatment of tooth discoloration.
This clinical trial investigated the effects of pre-application enamel moistening on the impact of a 37% carbamide peroxide whitener on tooth color changes and the influence of repositioning guide colors. Forty participants were randomly assigned to in-office tooth bleaching with either moistened enamel (experimental) or dry enamel (control). The whitener was applied for 45 min over two sessions. Tooth color was visually measured or assessed using a spectrophotometer with purple or green silicone guides. Tooth bleaching was assessed using CIE76 (ΔEab ) and CIEDE2000 (ΔE00 ) formulas and by whitening and bleaching index score changes. Moistening the enamel did not significantly affect tooth color. However, the guide color choice only impacted tooth color when measured instrumentally. At baseline, the green guide resulted in statistically significantly whiter teeth than the purple guide. Less pronounced differences in the b* coordinate between baseline and final measurements were found using the green guide. The green guide also produced lower ΔEab values and less change in indexes. In conclusion, moistening the enamel did not significantly impact tooth color changes. However, the repositioning guide color influenced the tooth bleaching measured instrumentally, except for ΔE00 .
Background:
Tooth bleaching imparts whitening effects along with adverse effects such as increased tooth sensitivity and enamel surface changes. Herein, we employed optical coherence tomography (OCT), a nondestructive optical detection technique, for evaluation of tooth enamel after treatment with peroxide-based bleaching agents.
Methods:
Fifteen enamel samples were bleached using 38% acidic hydrogen peroxide-based bleach, subjected to OCT scanning, and then cross-sectioned and imaged under polarized light microscopy (PLM) and transverse microradiography (TMR). OCT cross-sectional images were compared with PLM and TMR. The depth and severity of demineralization produced in the bleached enamel were measured by OCT, PLM, and TMR. Comparison between the three techniques was performed using Kruskal-Wallis H non-parametric test and Pearson correlation.
Results:
In comparison with PLM and TMR, OCT clearly detected the changes in the enamel surface after hydrogen peroxide bleaching. Significant correlations (p<0.05) were observed in lesion depth between OCT and PLM (r=0.820), OCT and TMR (r=0.822), and TMR and PLM (r=0.861). There was no statistically significant difference in demineralization depth values measured by OCT, PLM, and TMR (p>0.05).
Conclusion:
OCT can allow real-time, non-invasive imaging of artificially bleached tooth models and automatically measure the early changes in the enamel lesion structure upon exposure to hydrogen peroxide-based bleaching agents.
Context-The desire for whiter, younger-looking, healthier teeth has raised the market for dental whitening. Carbamide peroxide is commonly used in home bleaching procedures as it is safer and causes fewer side effects. Strawberries are one of the natural components that are now utilised to whiten discoloured teeth as it contains both ellagic and malic acids. However bleaching agents results in mineral loss resulting in decreased enamel microhardness. After bleaching, remineralizing therapy using a remineralizing chemical like anticay can restore the enamel's lost surface hardness. Aim-The aim of this invitro study was to evaluate the effect of anticay on the microhardness of enamel after bleaching with carbamide peroxide and strawberry extract. Materials and methods-Twenty-five freshly extracted teeth decoronated and divided mesiodistally into two halves to obtain a total of fifty samples. Samples were randomly divided into three groups as follows. Group 1: Control group(n=10) Group 2: (n=20) Subgroup 2A (n=10): Bleaching with 10% carbamide peroxide Subgroup 2B (n=10): Bleaching with 10% Carbamide peroxide and an additional Anticay application for 1 minute after treatment. Group 3: (n=20) Subgroup 3A (n=10): Bleaching with 2% strawberry gel Subgroup 3B (n=10): Bleaching with 2% strawberry gel and an additional Anticay application for 1 minute after treatment The samples were subjected to indentation to test the microhardness using Knoops hardness analyser. Statistical Analysis-Data was analysed using Student t test and ANOVA. p value <0.05. Results-It was observed that Group 1 has maximum microhardness value (369.80) whereas Subgroup 2A shows lowest microhardness value (285.20). A highly significant difference in the values of microhardness was seen between Subgroups treated with and without anticay application. Subgroups subjected to anticay application post bleaching showed higher microhardness value than Subgroups without anticay application. [p-value < 0.001]. Thus, it indicates that application of anticay post bleaching with carbamide peroxide and strawberry gel significantly increased the microhardness when compared to carbamide peroxide and strawberry gel used alone. Conclusion-The application of remineralizing agent containing calcium sucrose phosphate/anticay after bleaching increased the microhardness of enamel.
This in vitro study evaluated the effect of three different in-office bleaching techniques on bovine enamel microhardness and the pH variation of peroxide agents during the protocols. Methodology: For Knoop microhardness (KNH) analyses, enamel fragments were divided into 3 groups (n=10): LEDv–hybrid violet LED/Laser light (10x2’ LEDv + 10x30” light-off, 2 cycles); HP6%LEDv–6% HP gel + LEDv/Laser (15x1’ LEDv + 15x1’ light-off); HP35%- 35% HP (1x45’). For pH measurements, bovine teeth were divided into 2 groups (n=10): HP35% and HP6%LEDv. KHN was measured at baseline (T0), 24h after bleaching (T1) and after 7 days in artificial saliva (T7). Initial and final bleaching gels pHs were obtained utilizing a pH-meter. KHN was evaluated by the Wald-type permutation statistic, aligned rank transformation statistical test, Wilcoxon and Mann-Whitney tests; pH levels were evaluated by the Welch-James and Wilcoxon tests (p<0.05). Results: HP35% and HP6%LEDv presented a decrease in KHN from T0 to T1, with no difference among them; baselines values were recovered at T7. For LEDv, no significant difference was found between KHN at T1 and T0; at T7 KHN increased in comparison to T0. The initial pH mean was 7.66 for HP35% and 9.28 for HP6%LEDv; the final pH mean was 7.53 and 8.68, respectively. Conclusions: Bleaching with LEDv alone was the only treatment that didn’t reduce enamel microhardness. HP6%LEDv led to a decrease in KHN values similar to the high-concentrated gel. After seven days in artificial saliva, initial KHN was recovered. Although the pH of both gels decreased during the treatment, it remained above the critical value.
Infrared spectroscopy (IR) was applied to study changes in solid teeth tissues of persons exposed to low (0.12–0.20 Gy) and high (0.5–1.7 Gy) doses of ionizing radiation during their work in the Chernobyl zone after the accident. Changes in the inorganic and organic matrix of teeth were noted for both high and low radiation doses. The obtained results demonstrated that high doses of radiation lead to imbalance between phosphate–carbonate phases level (because of increasing of CO3 ²⁻ content) and accumulation of soluble phosphates in the mineral part of the teeth. These changes have an effect on dental matrix strength. Low doses of radiation do not induce appreciable negative changes in the mineral part of all tooth tissues but lead to changes in organic matrix of teeth (in collagen).
The present results demonstrated that pathological effect of radiation touches upon all dental tissue and obviously all bone systems of irradiated people.
Over the last decade, much research has focused on the potential health benefits of antioxidants and indeed many synthetic and natural compounds have been evaluated for their antioxidant profile. However, in several studies only a limited number of assays, often poorly validated, are used and the techniques available frequently lack specificity. These limitations may incorrectly influence the results. This review will therefore focus on several pitfalls that may emerge in vitro and in vivo antioxidant research. First, different in vitro techniques to determine antioxidant potential are discussed, including radical scavenging assays and fingerprinting methods. As a rule, a panel of different assays is indispensable to characterize and establish in vitro antioxidant activity. Furthermore, as problems of absorption, distribution, metabolism and excretion are only accounted for by in vivo studies, the need for in vivo antioxidant research is pointed out. Several methods to characterize the in vivo activity of antioxidants, including major drawbacks and pitfalls of some assays, have been discussed. The availability of both a representative “oxidative stress” animal model and a battery of well-validated assays to assess the broad diversity of oxidative damage and antioxidative defence parameters, are crucial for antioxidant research in vivo.
Powder from carious human tooth enamel and dentine were structurally, chemically and thermally analysed and compared against those from sound (healthy) teeth. Structural and chemical analyses were performed using x-ray diffraction, energy-dispersive x-ray spectroscopy and transmission electron microscopy. Thermal analysis was carried out by thermogravimetric analysis, Fourier transform infrared spectroscopy and x-ray diffraction. Results demonstrate partially dissolved crystals of hydroxyapatite (HAP) with substitutions of Na, Mg, Cl and C, and a greater weight loss in carious dentine as compared with carious enamel. A greater amount of thermal decomposition is observed in carious dentine as compared with sound dentine, with major variations in the a-axis of the HAP unit cell than in the c-axis. Variations in shape and intensity of the OH−,
and
FTIR bands were also found.
In vitro comparison of the efficacy of two bleaching procedures, one based on carbamide peroxide (CP) and the other on hydrogen peroxide (HP), simulating clinical conditions.
Two groups of 20 teeth in each group were selected. Group A: 22% CP, one hour a day for 21 consecutive days. Group B: 37.5% HP, in 2 treatment sessions with an one week interval between each session. At each session the product was applied three successive times for eight minutes. Colour was recorded before treatment, when it was finished and one week after finishing it, with the Vita EasyShade spectrophotometer. CIEL*a*b* and ΔE were established at each moment in the study. Intra-group data was compared using the paired t-test and inter-group data with the independent groups t-test. Scores from the Vita Classical guide provided with the device were recorded and the colour improvement percentage was calculated.
In both groups significant whitening was achieved by the end of treatment. Lightness remained significantly high when treatment was finished and one week after in both groups. The percentage of bleaching was significantly higher in group A.
Both 22% CP and 37.5% HP were effective for bleaching teeth. Bleaching effect was greater in CP group.
Biological organisms possess an unparalleled ability to control the structure and properties of mineralized tissues. They are able, for example, to guide the formation of smoothly curving single crystals or tough, lightweight, self-repairing skeletal elements. In many biominerals, an organic matrix interacts with the mineral as it forms, controls its morphology and polymorph, and is occluded during mineralization. The remarkable functional properties of the resulting composites-such as outstanding fracture toughness and wear resistance-can be attributed to buried organic-inorganic interfaces at multiple hierarchical levels. Analysing and controlling such interfaces at the nanometre length scale is critical also in emerging organic electronic and photovoltaic hybrid materials. However, elucidating the structural and chemical complexity of buried organic-inorganic interfaces presents a challenge to state-of-the-art imaging techniques. Here we show that pulsed-laser atom-probe tomography reveals three-dimensional chemical maps of organic fibres with a diameter of 5-10 nm in the surrounding nano-crystalline magnetite (Fe(3)O(4)) mineral in the tooth of a marine mollusc, the chiton Chaetopleura apiculata. Remarkably, most fibres co-localize with either sodium or magnesium. Furthermore, clustering of these cations in the fibre indicates a structural level of hierarchy previously undetected. Our results demonstrate that in the chiton tooth, individual organic fibres have different chemical compositions, and therefore probably different functional roles in controlling fibre formation and matrix-mineral interactions. Atom-probe tomography is able to detect this chemical/structural heterogeneity by virtue of its high three-dimensional spatial resolution and sensitivity across the periodic table. We anticipate that the quantitative analysis and visualization of nanometre-scale interfaces by laser-pulsed atom-probe tomography will contribute greatly to our understanding not only of biominerals (such as bone, dentine and enamel), but also of synthetic organic-inorganic composites.
A theoretical model of the scattering of light by dentin is presented. The model that results is a superposition of several scattering contributions, i.e., scattering by mineral crystals, collagen fibrils, and dentinal tubules. These tubules are oriented so that they cause an asymmetrical scattering process. The angular intensity functions are calculated for planes that are parallel or perpendicular to the plane of the tubules. The shape of the measured intensity function in the plane perpendicular to the tubules and the values of the scattering coefficient can be explained by the model that we present.
The purpose of this study was to validate and calibrate an in vitro test method for screening the performance of peroxide-containing toothpastes against actual clinical whitening performance. An additional objective was to estimate the whitening performance of a new peroxide-additive gel using the in vitro methodology.
A one-month longitudinal clinical study was performed to provide a benchmark for the in vivo intrinsic whitening performance of a peroxide-containing fluoride toothpaste. An in vitro study was then conducted, using freshly prepared slurries of the same peroxide-containing toothpaste in artificial saliva, to repeatedly treat extracted human teeth with natural intrinsic stain. The effect of cumulative treatment time on whiteness was determined using objective chromometer whiteness measurements (L*, a*, and b*), and more subjective Vita Shade guide (Vitapan) comparisons, and the results were correlated. A non-peroxide fluoride toothpaste was used as a negative control. The peroxide gel additive, combined in a 1:1 ratio with each of two non-peroxide toothpastes and diluted in artificial saliva, was evaluated using the same instrumental and subjective measures for in vitro whitening efficacy. The previously evaluated peroxide toothpaste and one of the non-peroxide toothpastes were used as positive and negative controls, respectively.
In the clinical study, the peroxide-containing toothpaste produced a linear increase in tooth whiteness with time, achieving an approximately two Vita Shade guide improvement in whiteness at the end of four weeks. The same peroxide toothpaste in vitro produced a curvilinear increase in tooth whiteness versus cumulative treatment time, with a two-shade increase being achieved in 116 minutes. The non-peroxide control toothpaste produced less than half a shade guide increase in whiteness within the first 30 minutes, and none thereafter. Both the clinical and in vitro studies indicated that further whitening can be obtained with longer use of the peroxide-containing toothpaste or peroxide-additive gel.
Treatment of naturally stained teeth in vitro with the peroxide toothpaste for 116 cumulative minutes produced the same two-shade increase in whiteness as obtained with twice-daily brushing for four weeks in vivo. The peroxide-additive gel, combined with a non-peroxide toothpaste, is projected to provide a similar two-shade increase in whiteness when used twice daily for four weeks. There are indications that greater intrinsic whiteness increase would be achieved with the peroxide toothpaste or with the peroxide-additive gel plus non-peroxide toothpaste with more extended regular twice-daily use in vivo.
Hardness of human tooth, both in enamel and dentin, has been measured at different sites using a Vicker's diamond. In this work we show that these values are almost constant all along the enamel and dentin thicknesses. Indentations were done from outer enamel surface to inner dentin layer, going through the enamel-dentin junction, both in transverse and longitudinal samples. Geometrical well-shape indentation uniformity was checked both with light and with scanning electron microscopes, and the chemical composition of the tooth was analyzed with characteristic X-ray energy dispersive spectroscopy. Hardness measurements were in the range from 270 to 360 VHN for enamel and 50 to 60 VHN for dentin. Cervical zone in longitudinal section showed the lowest value while in transverse sections the highest. All the hardness values were statically significative. Tour results indicate that the difference between enamel and dentin hardness has nothing to do with the content of Na, Cl and Mg, but the percentage of organic and inorganic materials in enamel and dentin.
Hydrogen peroxide (H(2)O(2)) is a powerful oxidising agent. It gives rise to agents known to be effective bleaching agents. The mechanisms of bleaching involve the degradation of the extracellular matrix and oxidation of chromophores located within enamel and dentin. However, H(2)O(2) produces also local undesirable effects on tooth structures and oral mucosa. In clinical conditions, the daily low-level doses used to produce tooth whitening never generate general acute and sub-acute toxic effects. Genotoxicity and carcinogenicity only occur at concentrations that are never reached during dental treatments. Some transient adverse effects have been reported on the oral mucosa and the digestive tract if the product is swallowed. Local effects may occur on the oral mucosa and dental tissues during whitening, namely, pulp sensitivity, cervical resorption, release of selected components of dental restorative materials, and alteration of the enamel surface. Most of the local effects are dependent of the technique and concentration of the product so far used, but as the results of bleaching obtained are not stable, repeated treatments add to the adverse effects. The informed decision to administer or not and the control of bleaching effects should stand in the hand of dental surgeons and certainly not as it appears at present, as cosmetics sold without any restriction despite the potential health hazards of peroxides.
The purpose of this study was to evaluate the nanohardness and elastic modulus of human enamel after treatment with tray and strip bleaching systems.
Fifty-five human enamel samples were exposed to five different bleaching agents. Nanoindentations were made before and after bleaching treatments following the manufacturer's directions using a Nanoindenter XP (MTS Systems Corporation, Oak Ridge, TN, USA). Nanohardness and elastic modulus measurements were obtained and the results were statistically analyzed using a repeated measures analysis of variance with a post-hoc Tukey-Kramer multiple comparison test.
Nanohardness and elastic modulus measurements showed decrease of mean values for each group except the control which remained the same. There were significant differences due to time (before and after treatment) and material effects in nanohardness (P<0.0001) and elastic modulus (P=0.0241). Measurements after treatment showed significant decrease in nanohardness between all groups and the control group. There was a significant difference in hardness between CP and TO after treatment. Additionally, there were significant differences in elastic modulus between the control group when compared to OB and TO after treatment. While there were significant changes in the elastic modulus due to treatment for both CP and TO, there were no significant differences between any of the groups after treatment.
Nanohardness and elastic modulus of human enamel were significantly decreased after the application of home-bleaching systems.
Tooth whitening products may be in contact with intraoral structures for several hours or they may be used daily to whiten the teeth. Consequently, these products should have a relatively neutral pH to minimize potential damage. This study measured the pH of 26 commercially available tooth-whitening products. The pH of the different whitening products ranged from 3.67 (highly acidic) to 11.13 (highly basic). The dentist-supervised home-bleaching products had a mean pH of 6.48 (range 5.66 to 7.35). The over-the-counter whitening products had a mean pH of 8.22 (range 5.09 to 11.13), and the whitening toothpastes had a mean pH of 6.83 (range 4.22 to 8.35). The 3 in-office bleaching products had a pH between 3.67 and 6.53. One-way ANOVA showed that there was a significant difference between the 4 product categories. The most basic pH of all the products tested was 11.13 for the whitening gel of Natural White-Rapid White. The most acidic pH of all products tested was 3.67 for Opalescence Xtra 35% hydrogen peroxide in-office bleach. The Least-Squares-Means test showed that the over-the-counter category had a pH significantly different from the other categories (p < 0.05).
Objective To carry out an extensive review of the literature on tooth staining with particular regard to some of the more recent literature on the mechanisms of tooth staining involving mouthrinses.Design Comprehensive review of the literature over four decades.Conclusions A knowledge of the aetiology of tooth staining is of importance to dental surgeons in order to enable a correct diagnosis to be made when examining a discoloured dentition and allows the dental practitioner to explain to the patient the exact nature of the condition. In some instances, the mechanism of staining may have an effect on the outcome of treatment and influence the treatment options the dentist will be able to offer to patients.
Establishing a colorimetric guideline to predict the effectiveness of tooth bleaching could produce a more reliable dental treatment. The purpose of this study was to evaluate the effectiveness of tooth bleaching and to test the predictability of tooth color changes. A 10% carbamide peroxide bleaching system was used in studies at Harvard University and at Iwate Medical University in Japan. L*, a*, and b* values (CIELAB) for pre- and postbleaching were obtained and color differences (ΔE) were calculated. The b* and L* values of the original tooth color indicated a relatively strong to moderate correlation with ΔE values, whereas a* showed a weak correlation. The multiple-regression equation obtained from the color data of Harvard subjects performed better than the predictive model. The predicted ΔE correlated strongly with the observed ΔE (r = 0.78). The validation of this equation on data collected from Iwate confirmed the strong correlation (r = 0.74). © 2004 Wiley Periodicals, Inc. Col Res Appl, 29, 390–394, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20048
Objectives: Through the understanding of tooth enamel science and insights into the beneficial role calcium can play in the caries process, a novel fluoride toothpaste has been developed containing micro-calcium. This paper describes a series of in vitro studies to assess delivery of the micro-calcium to a plaque biofilm, delivery of radiolabelled micro-calcium to subsurface enamel lesions and the rehardening of acid softened enamel by this novel toothpaste. Two clinical studies evaluated the delivery of calcium to the mouth.Methods: Uptake of micro-calcium to a plaque biofilm was assessed using a Calgary Biofilm Device and measuring the calcium levels delivered to the biofilm from the micro-calcium containing toothpaste, a calcium carbonate toothpaste, a silica toothpaste or water controls. Sound and subsurface enamel lesions were treated with 45Ca labelled micro-calcium toothpaste in an in vitro pH cycling study and the uptake of labelled calcium determined. Acid softened enamel specimens were treated with either the micro-calcium containing toothpaste, a calcium carbonate toothpaste or a non-fluoride silica toothpaste in an in vitro remineralisation protocol and the changes in surface microhardness measured. Calcium delivery in vivo was determined in two double-blind, randomised cross-over studies. Subjects brushed their teeth for one minute with either the micro-calcium containing toothpaste or a silica toothpaste. Immediately after brushing and at fixed time intervals up to one hour, unstimulated saliva samples were taken and the total calcium concentration determined.Results: Significantly (p<0.05) more calcium was delivered to a plaque biofilm from the micro-calcium containing toothpaste than the controls. The radiolabelled micro-calcium study demonstrated the uptake of calcium to subsurface enamel lesions. In the remineralisation study, acid softened enamel became significantly harder (p<0.05) following treatment with the micro-calcium containing toothpaste than compared to the control toothpastes. It was shown in the two clinical studies that more calcium was delivered to the mouth following the use of the micro-calcium containing toothpaste than compared to the silica toothpaste. The product differences were in excess of 50% and were of statistical significance (p<0.001).Conclusions: The studies show that the new toothpaste containing micro-calcium delivered elevated levels of calcium to the mouth, promoted enhanced remineralisation of demineralised enamel lesions and thus can help repair early signs of tooth decay.
Objective: Evaluate a light-enhanced in-office tooth whitening system in order to assess tooth color and safety.
Methods: Thirty-three adults were randomly assigned to one of three treatment groups. Professional treatment involved application of a 25% H2O2 gel (Discus Dental ZOOM!) with light enhancement, H2O2 gel alone, or the light alone with no peroxide. The 12 anterior teeth were treated three times for 20 minutes each. Efficacy was measured objectively as L*a*b* color change using digital images, tooth shade was measured, and safety was evaluated immediately after treatment and at posttreatment days 7 and 30.
Results: After adjusting for baseline and age, immediate (end-of-treatment) means (SE) for Δb* (yellowness) were –3.1 (0.25) for the gel + light, –2.0 (0.25) for the gel-only group, and –2.4 (0.25) for the light-only group. Significant (p < 0.05) color rebound was evident at posttreatment day 7. By day 30, adjusted means (SE)for Δb* were –1.7 (0.20) for the gel + light group, –1.1 (0.20) for the gel-only group, and –0.5 (0.20) for the light-only group. Both peroxide groups differed significantly (p < 0.05) from light alone on Δb* and ΔL*. In the gel + light group, 91% of subjects experienced tooth sensitivity, the majority of which was moderate or severe. Adverse events were low in the light-only group.
Conclusion: Use of light enhancement for in-office whitening leads to immediate color change, after which there was significant color and shade rebound within 7 days as well as moderate-to-severe tooth sensitivity during and after treatment.
Increased tooth sensitivity during treatment and appreciable short-term color rebound after treatment may impact the utility of in-office tooth whitening with peroxide and light as a stand-alone esthetic procedure.
Purpose: Vital tooth bleaching has become a popular procedure for whitening teeth. Most home bleaching products contain 10% carbamide peroxide. The purpose of this in vitro study was to measure the quantity of hydrogen peroxide that reaches the pulp chamber from three carbamide peroxide products: Opalescence™, Sparkle™, and Rembrandt™.
Materials and Methods: Seventy roots of extracted premolars were amputated approximately 3 mm apical to the cementoenamel junction, and the pulp tissues were removed. They were divided into three experimental groups (n = 20) and a control group of 10 teeth. An acetate buffer solution was placed in the pulp chamber before the crown was exposed to the bleaching agent at 37°C for 25 minutes. The buffer solution was removed and reacted with leukocrystal violet and horseradish peroxidase. The optical density of blue color that developed was measured at a wavelength of 596 nm and read from a standard curve for hydrogen peroxide quantity.
Results: The measured amounts of hydrogen peroxide were 3.605 ± 1.405,1.282 ± 0.762, and 0.339 ± 0.251 pg for the Opalescence™, Sparkle™, and Rembrandt™ groups, respectively. A statistically significant difference in the hydrogen peroxide levels was observed by analysis of variance (p < .05) among the three groups. It was concluded that the penetration of commercial bleach ing products was different even though the products were labeled as having the same 10% carbamide peroxide.
Sodium hypochlorite has been used as an endodontic irrigant for more than 70 years, and is now one of the most common solutions for this purpose. The chemical properties and production of commercial sodium hypochlorite are reviewed. Domestic bleaches and an infant sanitizer are compared from the point of view of cost and ease of use—Milton being recommended where a 1% solution is required. The cost of syringes and needles for endodontic irrigation is many times greater than the hypochlorite they contain, and total annaul practice costs for hypochlorite are low. Brief quidelines for clinical use, storage, handling and disposal are included.
Enamel is a composite biomaterial comprising a minor organic matrix (~2%) and a hierarchically organized inorganic ultrastructure (~96-98%). Surprisingly, to date there is no available information in the literature regarding the possible role of the enamel ultrastructure on the nanoscale level in tooth macroscopic properties. Understanding this relationship is of special interest for restorative purposes in dentistry. Accordingly, this study was designed to investigate how enamel nanocrystals regulate its hardness. We performed microindentation analysis on 100 extracted human teeth. The tooth enamel hardness was quantified and correlated with changes in enamel chemical composition and crystallographic dimensions obtained from Fourier transform infrared spectroscopy and X-ray diffraction, respectively. Enamel hardness was not related to the variability in organic content, but was associated with the size of apatite crystals along the c-axis. This association followed the Hall-Petch model for polycrystalline materials, indicating that the optimal size of apatite nanocrystals (larger than the critical size) provides enamel with the greatest hardness, which enables teeth to survive the heavy wear over a human lifetime.
Tooth shade is influenced by a combination of extrinsic-stains that are adsorbed to the enamel surface and by its intrinsic-shade resulting from the interaction of light with tooth structures. This study was designed to investigate how the variations in enamel ultrastructure may affect tooth optical properties.
One-hundred extracted teeth were collected from adult patients attending McGill-Undergraduate Dental Clinics. Shade-spectrophotometry, FTIR and XRD were used to assess tooth shade, enamel chemical composition and crystallography. The data obtained was analysed for Pearson correlation analysis and multiple linear regression analysis. The statistical significance was set at P < 0.05.
Tooth shade parameters varied dramatically within the studied population. Pearson correlation analysis demonstrated that tooth hue was associated with enamel hydroxyapatite (HA) crystal size (R = -0.358; B = -0.866; P = 0.007), tooth chroma was associated with enamel HA carbonization (R = -0.419; B = -99.06; P = 0.005), and tooth lightness was associated with both enamel HA crystal size (R = -0.313; B = -1.052; P = 0.019) and the degree of HA carbonization (R = -0.265; B=-57.95; P = 0.033). Multiple linear regression analysis demonstrated that the size of enamel HA crystals and the relative content of mineral carbonate were the most important predictors for tooth shade lightness (P = 0.018) and chroma (P=0.008), respectively. In contrast, enamel organic content had no correlation with tooth shade.
In the present study we have revealed that the tooth shade is regulated by the size of their HA enamel crystals. On the other hand, variation in the degree of enamel HA carbonization can also affect the tooth shade. These findings are of great relevance in dentistry since it provides better understanding of tooth aesthetics.
The aim of this study was to evaluate the separate contribution of enamel (E) and dentine (D) to the colour change of tooth which subjected to 10% carbamide peroxide (CP) gels using a novel recombined enamel-dentine (Recombined-ED) study model.
120 enamel-dentine (ED) samples (four homogeneous premolar ED from each patient; total=30×4 ED) were involved in the present study. Two homogeneous ED samples were bleached with 10% CP and the other two ones were stored in artificial saliva for one, two or four weeks. After treatment, four kinds of layers were prepared from each four homogeneous ED samples by removing enamel or dentine part: bleached-enamel (BE), bleached-dentine (BD), control-enamel (CE) and control-dentine (CD). Initial and final colour records of samples were taken with a spectrophotometer in CIELab system. The contribution of enamel/dentine to the colour change of tooth (CTCC) was calculated by measuring the colour difference ΔE between two different enamel-dentine combinations (ΔE between BE/BD and CE/BD for enamel; ΔE between BE/BD and BE/CD for dentine). Translucency parameter (TP) was obtained by calculating the colour difference between enamel on black and white backings.
ED and recombined-ED were significantly correlated in L(*)a(*)b(*) values both for unbleached samples and bleached samples. Bleaching resulted in a significant colour change (ΔE) of E, D and ED samples. The TP of BE was significantly lower than that of CE. The CTCC of enamel was significantly higher than that of dentine all through the time points.
Enamel played a more important role than dentine in tooth bleaching due to the changes in translucency and colour.
Hunter-Schreger Bands (HSBs) are an optical phenomenon visualised when a cut or fractured enamel surface is viewed under reflected light. These bands demonstrate the synchronous decussation of individual or groups of enamel prisms. While the role of HSB patterns has been investigated in comparative anatomical studies, until recently there has been little consideration of HSB patterns in human teeth. The aim of this paper is to consider the significance of HSB patterns in the human dentition and in relation to clinical dentistry. It is concluded that within the human dentition, HSB patterns have evolved to optimise resistance to attrition, abrasion and tooth fracture. It appears that certain aspects of HSB packing densities and distributions have beneficial roles in enamel bonding. Hunter-Schreger Band patterns seem to passively facilitate conditions such as abfraction and cracked tooth syndrome.
The purpose of the study was to evaluate gloss and color changes of resin composites after exposure to different bleaching agents.
Products used, were: Nite White ACP (10% carbamide peroxide gel), Crest Classic and Supreme Whitestrip (6.5% and 14% hydrogen peroxide strips, accordingly). A hybrid (Herculite XRV) and a nanohybrid (Premise) resin composite were exposed to the bleaching agents. Twenty-four disk-shaped specimens per composite were subjected to bleaching by each of the agents (n=8) for up to 2 weeks. Color changes using CIE-L*a*b* system (50:50% acceptability threshold: ΔE*=3.3) were recorded after 1 and 2 weeks bleaching cycles relative to baseline measurements. In addition, gloss measurements (in gloss units) were performed at the same bleaching intervals and gloss changes were calculated.
All bleaching agents tested provided decrease in gloss of both composites after 2-week bleaching (p<0.05). No differences were detected among the three bleaching regimens, for up to 2-week application, in terms of color and gloss changes on both composites. After the 2-week bleaching period, hybrid composite presented higher gloss reduction (%) than nanohybrid regardless of the bleaching agent (p<0.05). Color change (ΔE*) was lower than 3.3 for all composite-bleaching agent combinations. After 1- and 2-week bleaching time, the nanohybrid composite provided higher color change than the hybrid under all bleaching procedures (p<0.05). No strong correlation was proved between color (ΔE*) and gloss changes caused by bleaching treatments.
After 2-week bleaching cycles, composites showed significant gloss reduction (p<0.05). Color alteration was below the 50:50% acceptability threshold (ΔE*<3.3) and it was product-depended. There was no significant difference in color and gloss changes between the evaluated bleaching strips and 10% carbamide peroxide gel.
To investigate the morphologic, chemical and crystallographic characters of remineralized surface on initial carious enamel treated with Galla chinensis, scanning electron microscopy equipped with energy dispersive analysis spectroscopy were used, and X-ray microdiffraction (microzone XRD) was used for the first time to analyze in situ the microzone crystallite of remineralized surface on carious enamel. Bovine sound enamel slabs were demineralized to produce initial carious lesion in vitro. Then, the lesions were exposed to a pH-cycling regime for 12 days of remineralization. Each daily cycle included 4x1 min applications with one of the three treatments: distilled and deionized water (DDW); 1 g/L NaF; 4 g/L G. chinensis extract (GCE). After the treatments, some rod-like deposits and many irregular prominences were found on GCE-treated enamel surface, and the intensities of Ca and P signals showed a tendency to increase; Ca:P ratio was significantly higher than that of DDW-treated enamel. X-ray microdiffraction showed hydroxyapatite was still the main component of GCE-treated enamel, and the crystallinity was increased, the crystal lattice changed gently with decreased lattice parameter a. These results indicated the potential of GCE in promoting the remineralization of initial enamel carious lesions, and supported the previous hypothesis about GCE mechanism. Combined with the anti-bacteria and demineralization inhibition properties of GCE, the natural G. chinensis may become one more promising agent for caries prevention.
To investigate the changes in color and translucency properties of enamel following 14 days treatment with carbamide peroxide.
24 extracted premolars were used in this study. Two enamel-dentin specimens were prepared from each tooth and randomly assigned to be bleached with carbamide peroxide for 14 days or stored in artificial saliva as control. A spectrophotometer (Spectrascan PR650) was employed to measure the color of specimens according to the CIELab system. Color measurement of enamel-dentin specimens was performed prior to and after bleaching. After 14 days bleaching, enamel slabs were prepared by removing dentin parts using a low-speed saw. Then the color and translucency parameter (TP) of enamel slabs was measured over a black and a white background. Data between the experimental group and the control group were analyzed by paired t-test.
After bleaching, the color of enamel slabs and controls differed significantly both over the black and white background in L* and b* values (all P < 0.001). The translucency parameter (TP) of bleached enamel slabs was significantly lower than that of controls (P < 0.01). Both the deltaE values of enamel on the two backgrounds were significantly correlated to that of enamel-dentin specimens (P = 0.003; P = 0.012).
To evaluate the colour regression of bleached teeth in four experimental environments, and to explore the relationship between colour change and bulk miners loss.
Forty freshly extracted sound human incisors were in vitro treated using an in-office bleaching gel containing 38% hydroxide carbamide. The bleached teeth were subsequently divided into four groups and stored in four different environments: purified water, artificial saliva, a commercial remineralisation gel, and a desiccator. A spectrophotometer and a mu-CT were used to investigate the colour parameters (L*, a*, and b*) and the mineral content of the teeth pre- and post-bleaching. ANOVA and Tukey's post hoc analysis were performed to investigate the effect of time on the colour coordinates. Paired t-tests were used to compare the mineral content changes. Linear regression test was performed to explore the relationship of the colour coordinates and mineral content change in the colour regression process.
Colour regression occurred in the mineral containing environment accompanying with the mineral content remarkable increase in the outer layers of teeth tissue (P<0.05). No colour regression and mineral content change were found in the anhydrous environment (P>0.05). The regression of lightness is significantly correlated with the density change of teeth hard-tissue (P<0.001, r=0.611).
In this in-office bleaching system, the colour regression is mainly resulted by the reversal of lightness, and is correlated with the presence of the remineralisation processes within the teeth tissue.
This study aimed to determine whether gender, age, and initial tooth hue impacted the effect of laser tooth whitening.
Ninety-one subjects were enrolled in a laser tooth whitening study at Kaohsiung Medical University. Sensitivity was evaluated by asking the patients about any tooth sensitivity they experienced after the whitening procedures were performed. The LaserSmile tooth whitener, containing 35% hydrogen peroxide, was applied to the tooth surfaces of both arches from the central incisor to the second premolar, and the LaserSmile Twilite diode laser was applied to the same maxillary and mandibular teeth. After removal of the whitening gel, shade matching was immediately performed with the ShadeEye NCC Dental Chroma Meter. Patients were classified into the following groups: tetracycline stain, gender, age, and initial tooth hue. Only 5 of the 91 individuals had tetracycline staining.
The initial tooth shade and the amount of shade change showed no significant differences between female and male patients, but a significant difference was found between hue and age group.
Teeth with hue A showed greater shade improvement than teeth with hue C and hue D. Whitening response was better in younger individuals, and gender was not a factor that affected the whitening response. Sensitivity is common during the whitening procedure but can be tolerated by the patients.
Recent reports of clinical cases suggest that cervical root resorption may follow bleaching of endodontically treated teeth. Inflammatory root resorption may be arrested by placement of calcium hydroxide into the root canal. The dentinal tubules are assumed to be a possible route of action for both agents. pH Values of the medium surrounding the tooth after placement of bleaching agents and calcium hydroxide within the root canals were determined in this study. Thirty extracted single-rooted human teeth were divided into three equal groups. The pulp cavity of the experimental teeth was filled with either bleaching agents or calcium hydroxide. In the control group it was left empty. Dipping in paraffin sealed the access cavity and the apical foramina and isolated the teeth except at the cervical root surface. The teeth were placed in vials containing distilled water and the pH of the medium was measured after 1 h, 3 days, and 7 days following renewal of the medium. The level of the pH in the first group increased, indicating that the bleaching agents leaked from the root canal to the medium surrounding the teeth. The pH in other two groups did not change noticeably. The results suggest that bleaching agents may leak from the root canal toward the periodontal tissues but calcium hydroxide does not alkalinize the medium surrounding the teeth. Leakage of the bleaching agents through dentin may, therefore, be considered as a possible etiological factor that initiates an inflammatory process around the teeth that may be followed by cervical root resorption.
The impact of fluoride is being felt with a decline in caries incidence over the past 25 to 30 yr. Restorative dentistry is focusing a great deal more on cosmetic applications, among which is bleaching of stained vital teeth. Although studies have shown that vital bleaching procedures can severely inhibit pulpal enzymes, deleterious effects have been minimal. This study attempts to measure the quantity of H2O2 that reaches the pulp during a bleaching treatment. Roots of extracted maxillary anterior teeth were amputated approximately 3 mm apical to the cementoenamel junction and pulpal tissues were removed. A buffer solution was placed into the pulp chamber and the labial surface was exposed to 1, 10, or 30% H2O2 at 37°C for 15 min. Hydrogen peroxide uptake by the pulpal buffer solution was determined colorimetrically. Results showed significant amounts of H2O2 in the pulp chamber and uptake was greatly enhanced by the application of heat (50°C) along with the H2O2.
Tooth color is determined by the paths of light inside the tooth and absorption along these paths. This paper tests the hypothesis that, since the paths are determined by scattering, a relation between color and scattering coefficients exists. One hundred and two extracted incisors were fixed in formalin, mounted in a standardized position in brass holders, and pumiced. A facet was prepared near the incisal edge on the labial plane to allow for Knoop hardness measurements with a 500-gram load. Light scattering by the enamel was measured in a 45 degrees/0 degrees geometry; light scattering by both enamel and dentin was measured in a 0 degrees/0 degrees geometry. The reflection spectrum of the tooth was measured from the labial plane with a spectroradiometer in a 45 degrees/0 degrees geometry, with standard illuminant A and standard illuminant D65. To include all volume-reflected light, we used entire-tooth illumination and small-area measurement. CIELAB color coordinates were calculated from the spectra. Neither spectra nor coordinates showed evidence of a contribution of fluorescence to tooth color. Averaged values and standard deviations for L*,a*,b* were 69.9 (4.1), 1.22 (1.4), and 17.9 (2.9), respectively. Both scattering coefficients averaged to 0.6 (0.4) mm-1; Knoop hardness number was, on average, 271 (39) kg/mm2. L* correlated with a* (r = -0.51), with the enamel scattering coefficient (r = 0.60), and slightly with hardness (r = 0.17, p = 0.03). The colors of 28 teeth from which the enamel was removed correlated strongly with the colors of the complete tooth.(ABSTRACT TRUNCATED AT 250 WORDS)
In this clinical trial of nightguard vital bleaching for six weeks, 92 percent of the patients experienced some lightening of treated teeth. About 97 percent of patients with teeth stained through aging, inherent discoloration, brown fluorosis or trauma experienced lightening, as did 75 percent with tetracycline-stained teeth. Sixty-six percent experienced side effects, which resolved in 24 to 48 hours. Earliest re-treatment was done after one year in less time. Minimal color change occurred for 74 percent after 1 1/2 years and 62 percent after three years.
The purpose of this investigation was to evaluate the effect of three 10% carbamide peroxide bleaching agents on enamel microhardness and surface morphology. Seventy-two enamel slabs were subjected to one of three carbamide peroxide solutions or an artificial saliva solution for 15 hours a day for 2- and 4-week periods. During the remaining 9 hours, slabs were exposed to human saliva in vivo. Although differences were not statistically significant, microhardness values of all treated specimens 2 weeks after treatment were less than those of control specimens. These trends, however, were not evident at 4 weeks. Scanning electron microscopic evaluation revealed significant surface alterations in enamel topography for slabs treated with the bleaching solutions for 4 weeks. The most severe alterations were found in slabs exposed to the lower-pH solutions.
Knowledge of the optical properties of tooth enamel and an understanding of the origin of these properties are necessary for the development of new optical methods for caries diagnosis and the measurement of tooth color. We measured the scattering intensity functions for HeNe-laser light of 80- to 100- micrometers-thick human dental enamel slabs. The asymmetry factors were calculated to be g = 0.68 at 633 nm. By measuring the collimated beam attenuation, we determined the scattering coefficient to be s = 6.6mm(-1). From Fraunhofer diffraction patterns, obtained from transmission of the laser beam, we calculated the periodicity of the prismatic structure as 5.4 micrometers. We present a model containing scattering by crystals and by prisms. It shows that the prisms are the most important scatterers but that the crystals are responsible for the back-scattering.
For some patients, sensitivity and discomfort follow vital tooth bleaching. Clinical observations, however, suggest these are reversible episodes with no irreversible long-term effects. Using milder peroxide formulations or gels diminishes postoperative discomfort. The author recommends careful treatment when patients have large restorations, cervical erosion or enamel cracks. Fluoride treatment, sealing restorations and premedication may lessen discomfort.
Vital tooth bleaching has become a popular procedure for whitening teeth. Most home bleaching products contain 10% carbamide peroxide. The purpose of this in vitro study was to measure the quantity of hydrogen peroxide that reaches the pulp chamber from three carbamide peroxide products: Opalescence, Sparkle, and Rembrandt.
Seventy roots of extracted premolars were amputated approximately 3 mm apical to the cementoenamel junction, and the pulp tissues were removed. They were divided into three experimental groups (n = 20) and a control group of 10 teeth. An acetate buffer solution was placed in the pulp chamber before the crown was exposed to the bleaching agent at 37 degrees C for 25 minutes. The buffer solution was removed and reacted with leukocrystal violet and horseradish peroxidase. The optical density of blue color that developed was measured at a wavelength of 596 nm and read from a standard curve for hydrogen peroxide quantity.
The measured amounts of hydrogen peroxide were 3.605 +/- 1.405, 1.282 +/- 0.762, and 0.339 +/- 0.251 micrograms for the Opalescence, Sparkle, and Rembrandt groups, respectively. A statistically significant difference in the hydrogen peroxide levels was observed by analysis of variance (p < .05) among the three groups. It was concluded that the penetration of commercial bleaching products was different even though the products were labeled as having the same 10% carbamide peroxide.
Carbamide peroxide penetration to the pulp varies significantly for various commercial bleaching products. This may result in different levels of tooth sensitivity or bleaching efficacy.
To carry out an extensive review of the literature on tooth staining with particular regard to some of the more recent literature on the mechanisms of tooth staining involving mouthrinses.
Comprehensive review of the literature over four decades.
A knowledge of the aetiology of tooth staining is of importance to dental surgeons in order to enable a correct diagnosis to be made when examining a discoloured dentition and allows the dental practitioner to explain to the patient the exact nature of the condition. In some instances, the mechanism of staining may have an effect on the outcome of treatment and influence the treatment options the dentist will be able to offer to patients.
The Kubelka-Munk (K-M) theory provides a reflectance model for translucent materials placed on backings of different colors. We hypothesize that Kubelka-Munk (K-M) theoretical diffuse reflectance spectra of dentin and enamel are in good agreement with observed diffuse reflectance. The aim of this study was to measure the reflectance of enamel and dentin specimens and to compare the measured values of reflectance with K-M theoretical values. Disc-shaped specimens of enamel, dentin, and enamel/dentin were prepared from extracted teeth. Diffuse reflectance spectra were measured on three backings by means of a reflectance spectrophotometer over every wavelength (lambda) from 400 to 700 nm at three thicknesses. The measured reflectance values were fit by non-linear regression to corrected K-M theory. The low value of the reported errors associated with the application of K-M theory illustrated that the theoretical diffuse reflectance spectra of dentin and enamel are in good agreement with the observed diffuse reflectance.
Three solutions of EDTA--a 15% concentration of the alkaline salt, a 15% concentration of the acid salt, and a 25% concentration of the alkaline salt--were evaluated for smear layer removal in root canal systems. All solutions were adjusted to pH 7.1 using either NaOH or HCl. When the EDTA solutions were alternately used for root canal irrigation with 5.25% NaOCl, they completely removed the smear layer in the middle and coronal thirds of canal preparations, but were less effective in the apical third. None of the EDTA solutions by themselves were effective at completely removing the smear layer at any level. The alkaline tetrasodium salt, pH adjusted with HCl, is more cost effective and performed equally as well as the more commonly used disodium salt.
Three commercially available dentist-prescribed home-applied bleaching systems were evaluated to identify the incidence of sensitivity and to compare the efficacy of whitening the maxillary anterior teeth of 18 patients.
NiteWhite Excel 2Z (Discus Dental), fx (Challenge Products), and Rembrandt Xtra-Comfort (DenMat Corp.) were randomly assigned to six patients each. The fx product was used as a control since it was not advertised as a zero sensitivity product. The manufacturers' instructions for tray fabrication and use were followed while the patients bleached for 2 weeks. The patients kept a diary and were recalled at 1 week, 2 weeks, and 4 weeks. The shade change and the presence or absence of any sensitivity were evaluated at each recall.
NiteWhite Excel 2Z was used for 83 days of treatment with the following percentage of positive sensitivity reported: 0% hot and cold, 2.4% throat sensitivity, 2.4% tongue sensitivity, and 25.3% gingival sensitivity. Rembrandt Xtra-Comfort was used for 84 days with 0% hot and cold, 0% throat, 11.9% tongue, and 27.4% gingival sensitivity reported. The fx product was used for 83 days and resulted in 14.5% hot and cold, 3.6% throat, 1.2% tongue, and 16.9% gingival sensitivity. All products lightened the teeth an average of eight shade tabs on the Vita guide. There was a statistically significant difference between the groups when comparing the presence of sensitivity (chi-squared test, p < .001) but not when comparing the shade tab change.
Of the products tested, all produced similar change in shade tab value, none were sensitivity free, but NiteWhite Excel 2Z and Rembrandt Xtra-Comfort did not produce thermal sensitivity.
A randomized, double blind clinical trial was conducted to evaluate initial color improvement and post-treatment color retention following vital bleaching with a strip-based tooth whitening system.
After balancing for baseline color, 57 healthy adults were randomized to either whitening strips with a 5.3% hydrogen peroxide bleaching gel (Crest Whitestrips) or placebo strips without hydrogen peroxide. Maxillary and mandibular anterior teeth were treated twice daily for 30 minutes each over a 2-week period, and efficacy was measured objectively by comparing digital images of teeth collected at baseline, end-of-treatment (Week 2) and 6 months after treatment (Month 6).
The whitening strip group experienced a highly significant (P< 0.0001) reduction in yellow of -2.0 deltab* units versus baseline and -1.95 deltab* units versus placebo, with similar results noted for the other color parameters in the study. Most of the initial color change remained at 6 months post-treatment, with the whitening strip group continuing to demonstrate highly significant (P< 0.0001) improvements in tooth color relative to baseline and placebo. Age was found to significantly contribute to initial color improvement, with younger subjects experiencing a greater initial reduction in yellowness compared to older participants, but not to post-treatment color retention. The whitening strips were well tolerated, with minor tooth sensitivity and oral irritation representing the most common findings during treatment. There were no persistent or new treatment-related adverse events during the 6-month monitoring period.
Rapid innovation in vital bleaching has increased the popularity of tooth whitening among dental professionals and patients. A broad range of peroxide-based treatments are currently available including those that are professionally-administered (in-office), professionally-dispensed (custom-tray-based systems), and self-directed (over-the-counter). Recently, a novel, flexible polyethylene bleaching strip was introduced that delivers a hydrogen peroxide bleaching gel to the anterior dentition. This “trayless” system, available in professional-strength and over-the-counter versions, reportedly offers advantages with respect to overall peroxide dose, contact time, and ease-of-use compared to other delivery systems. This paper reviews the relevant published clinical research on whitening strips tested among a broad range of patients commonly encountered in contemporary dental practices.
Citation
Gerlach RW, Zhou X. Vital Bleaching with Whitening Strips: Summary of Clinical Research on Effectiveness and Tolerability. J Contemp Dent Pract 2001;(2)3: 001-016.
To develop and evaluate a reproducible intrinsic discolouration model in vitro, based on tea, which would allow the effectiveness of bleaching to be evaluated.
The crown portions of extracted human third molars were sectioned bucco-lingually in half. Colour assessments were made at baseline, post staining and post whitening using a standard clinical shade guide (SG), a shade vision clinical colorimeter system (SVS) and a reflectance chromometer. Internal staining employed a standard tea solution into which groups of five specimens were placed from 1 to 6 days. All assessments demonstrated maximum staining within one day. Groups of stained specimens were exposed to 1. Water (placebo control) 2. Enamel polished 3. Enamel polished and bleached through enamel 4. Bleached through enamel 5. Bleached through dentine 6. Bleached through enamel and dentine 7. Exposed to the bleach vehicle (minus active control). Control and bleach gel treatments were for 30 min. Comparisons of treatment effects were made using unpaired t-test on groups selected a priori for analysis.
SG and SVS revealed that control and polish treatments had no or little effect respectively on tooth shade but all bleach treatments produced marked and statistically significant whitening effects and to a similar magnitude. Bleaching treatments returned the majority of specimens to the original shade or beyond representing a SG mean change of 13.8-15 shade guide units (SGU). Chromometer readings were consistent except that polishing alone increased tooth lightness slightly.
Teeth were reproducibly stained internally, to provide a model in vitro by which to evaluate bleaching. The model, could be used to study many aspects of vital tooth bleaching, but has the limitation, without in vivo or in situ data, of cautiously extrapolating the effects in vitro to outcome clinically.
The aims of this study were to evaluate the in vitro tooth whitening effects of a novel 6% hydrogen peroxide containing tooth whitener Xtra White (XW) on extrinsic stain and intrinsic tooth colour and the effects on enamel and dentine microhardness. In addition, to determine the levels of peroxide found in tooth pulp chambers after treatment with XW in vitro.
Extrinsic stain changes were determined by measuring colour changes of tea stained hydroxyapatite discs after treatment with water, placebo gel, XW or Colgate Simply White (CSW). Intrinsic tooth colour changes were determined by treating extracted human teeth in vitro with a placebo gel, XW or CSW for a simulated two weeks use and measuring colour differences with a chroma meter. Teeth treated with placebo gel and XW were cross-sectioned and the subsurface enamel and dentine was polished and the microhardness determined. The peroxide concentration found in extracted tooth pulp chambers was determined spectrophotometrically.
XW gave significantly more extrinsic stain removal (p<0.0001) and an increase in tooth whiteness (p<0.05) than a placebo gel, but was not significantly different to CSW. There were no significant differences in subsurface enamel and dentine microhardness values for the placebo and XW treated teeth. The mean concentration of peroxide found in the tooth pulp chambers was 0.44 mM, which is over 3000 times below the concentration reported to cause pulpal enzyme damage.
XW has been shown to be an effective tooth whitening product in vitro with support for its safety on subsurface enamel and dentine together with its safety on tooth pulp tissue.
To review current knowledge with respect to tooth colour and its measurement.
'Medline' database for the period 1966 to the present day and 'ISI Web of Science' database for the period 1974 to the present day were searched electronically with key words tooth, teeth, colour and color.
The colour and appearance of teeth is a complex phenomenon, with many factors such as lighting conditions, translucency, opacity, light scattering, gloss and the human eye and brain influencing the overall perception of tooth colour. The measurement of tooth colour is possible via a number of methods including visual assessment with shade guides, spectrophotometry, colourimetry and computer analysis of digital images. These methods have successfully been used to measure longitudinal tooth colour changes when the dentition has undergone tooth whitening procedures.
The purpose of this study was to investigate the effect of long-period exposure of 30% hydrogen peroxide on bovine enamel. Polished labial surfaces were scanned using an atomic force microscope after bleaching for 120 hours. Compositional change and microhardness of the enamels were evaluated using a Fourier transform Raman spectrophotometer and Vickers hardness tester. The same tests were performed on enamels stored in distilled water. In the FT-Raman spectra of both the unbleached and bleached enamels, peaks remained unchanged except for negligible decrease in intensity. As for microhardness, it significantly decreased after bleaching when compared to the original value (p < 0.0001). However, the microhardness values of enamels stored in the bleaching agent and distilled water did not show any statistical difference. Based on the results of this study, the use of 30% hydrogen peroxide solution for dental bleaching should be safe due to its negligible effects on tooth morphology and structure.
The aim of the present work was to investigate how the native signal observed in the electron paramagnetic resonance (EPR) spectrum of tooth enamel and dentin is associated with the organic content of the two tissues. This was achieved by comparing the EPR native signal and the optical bands (Raman and infrared, IR) associated with organic components of tooth enamel and dentin, in natural and deproteinated samples. The main results were: (a) in natural samples, the organic optical bands are more intense in dentin than in enamel, in contrast with the EPR native signal which shows similar intensity in the two tissues; (b) after deproteination, the optical organic bands are completely suppressed in both dentin and enamel, while the EPR native signal is eliminated only in dentin. It is suggested that the IR and Raman organic bands are originated in the bulk of the organic matrix, while the paramagnetic centres associated with the EPR native signal are located in the organic-mineral interface.
To evaluate the influence of various bleaching systems on subsurface microhardness of enamel and dentin.
60 bovine crowns were distributed among seven groups (A: Opalescence Xtra Boost, B: Opalescence Quick, C: Rapid White, D: Whitestrips, E: Opalescence 10%, F: Opalescence PF 15%). The crowns were sectioned and baseline hardness (Knoop) of enamel and dentin was assessed on the sectioned surface at various distances from the enamel surface. The sectioned surface was covered with wax and the enamel was treated for 10 days with the bleaching agents A-F according to manufacturers' instructions. Bleaching with C-F was conducted each day (C: twice per day for 10 minutes, D: twice per day for 30 minutes, E: 8 hours, F: 4 hours), systems A-B were applied on first and fifth days (A: twice for 10 minutes, B: 1 hour). Finally, hardness was re-assessed. Data were statistically analyzed to compare baseline hardness and final hardness in the respective groups (P< 0.05).
Analysis showed that in Group C, hardness was significantly reduced in both enamel and dentin. In the remaining groups, significant reduction of hardness was observed up to the following depths [microm] in enamel; A: 250, B: 700, D: 300, E: 150, F: 150. In these groups no significant hardness changes were recorded in subsurface dentin.