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An atomic force microscopy study on the effect of bleaching agents on enamel surface
Abstract
The aim of the present study was to evaluate the effect of three peroxide-containing bleaching agents, Opalescence, Nite White and a 30% hydrogen peroxide solution, on enamel surfaces using Atomic Force Microscopy (AFM).
Fifteen non-carious human incisors (ten maxillary and five mandibular, extracted for periodontal reasons) were used. The teeth were divided randomly into three groups of five, according to the bleaching agents. The labial surface of each tooth was imaged by AFM before and after treatment. Each bleaching agent was applied for a total of 28 h (in individual 4 h treatments). The specimens were examined only after 28 h of treatment.
On comparing the AFM images of untreated and treated enamel, surface alterations were observed after 28 h of treatment with Opalescence, Nite White and 30% hydrogen peroxide solution. Several grooves present in the enamel surface of untreated teeth became deeper after the bleaching procedure. The depths of the grooves increased in each case. The increase in the depth of grooves was more pronounced in the case of the 30% H2O2 solution.
Home-use bleaching agents are capable of causing enamel surface alterations. It is hypothesized that the peroxide-containing bleaching agents affect the organic phase of enamel. Peroxides can affect not only the surface but also the inner structure of enamel. As a result of its low molecular weight, hydrogen peroxide can penetrate into the enamel. Thus, inner oxidative effects are more likely to occur in the subsurface enamel where more organic material is present and oxidation is capable of altering the outer enamel and the surface.
... (4,5) Dentro de las modalidades de blanqueamiento existe la profesional aplicada en el consultorio y la domiciliaria con control profesional. (6,7,8,9) Dentro de las sustancias aplicadas el peróxido de hidrógeno en sus diferentes concentraciones es uno de los más empleados. (10) El peróxido de hidrógeno (H202) es un agente oxidante altamente reactivo de presentación líquido claro, sin color ni olor, altamente soluble en agua, inestable y cáustico. ...
... (10) El peróxido de hidrógeno (H202) es un agente oxidante altamente reactivo de presentación líquido claro, sin color ni olor, altamente soluble en agua, inestable y cáustico. (9) Su peso molecular es bajo, lo que facilita su elevado poder de difusión a través de los tejidos. Al entrar en contacto con la saliva el peróxido de hidrógeno se disocia en oxígeno y radical hidroxilo (HO), siendo el oxígeno el responsable del efecto blanqueador, actuando como agente oxidante formando radicales libres, aniones de peróxido de hidrógeno y moléculas de oxígeno reactivo, los cuales son los encargados de romper los dobles enlaces de las cadenas presentes en los cromóferos para hacerlos partículas pequeñas, mediante un proceso de óxido -reducción. ...
... (2) También se estudió que el uso continuo de los peróxidos puede alterar la flora y favorecer el crecimiento de candida albicans e hipertrofia de las papilas. (9) La Candida albicans es un miembro frecuente de la microflora bucal, aislándose entre el 30 al 50 % de la población. Su taxonomía es la siguiente: ...
Introduction: Tooth whitening has been widely used as an esthetic procedure, growing in demand since its initial description in 1864. This process uses chemical agents such as hydrogen peroxide, capable of oxidizing chromogens present in tooth enamel, lightening the teeth. However, its continued use can have side effects, including demineralization of the enamel and alterations in the oral microbiota, such as the growth of Candida albicans.Development: Several studies have analyzed the effects of hydrogen peroxide at different concentrations. At high concentrations, such as 35%, its capacity to alter the morphology and mineral content of dental enamel, increasing its roughness and favoring the adhesion of microorganisms has been demonstrated. The formation of biofilms by bacteria and fungi, such as Streptococcus mutans and Candida albicans, has been the subject of debate, with contradictory results regarding their prevalence on surfaces treated with bleaching agents. This study found that the control group, without peroxide treatment, presented greater adhesion of C. albicans, which could be attributed to an antimicrobial effect of the oxidizing agent.Conclusion: Tooth whitening, although effective as an esthetic procedure, presents clinical challenges due to its potential adverse effects. The findings highlight the need for further research to fully understand the impact of these agents on the oral microbiota and enamel. Future studies should include larger samples and employ advanced techniques to improve the validity of the results and optimize the safety of the procedures.
... On one hand, the profilometer was selected since it is an instrument that has a large dimensional scale capable of measuring rough surfaces [30]. On the other hand, the AFM was used, because it is a suitable microscopic method to analyze biological objects at nanoscale under natural conditions (no exhaustive preparation) [31]. ...
... Regarding the qualitative evaluation of the deciduous and permanent enamel via the AFM images, it was observed that both substrates presented a typical morphology of healthy enamel as described in the literature [31,43]. Additionally, the deciduous enamel surface exhibited a greater amount of shallow or deep grooves of variable amplitude and irregular direction in comparison with permanent enamel. ...
... Additionally, the deciduous enamel surface exhibited a greater amount of shallow or deep grooves of variable amplitude and irregular direction in comparison with permanent enamel. Those grooves have been reported by Hegedüs et al. [31] as sketches. The presence of grooves in both tissues has been attributed to the abrasion process present in erupted teeth due to tooth-brushing, diet, or certain habits [44], as well as the progressive changes that a tooth undergoes during life. ...
The adhesion of some bacteria has been attributed to critical levels of roughness in hard tissues, which increases the risk of developing caries. The objective of this work was to assess the effect of deciduous and permanent tooth enamel surface roughness on bacterial adhesion. One hundred and eight samples of deciduous and permanent enamel were divided into two groups (n = 54). G1_DE deciduous enamel and G2_PE permanent enamel. The surface roughness was measured by profilometry and atomic force microscopy (AFM). Subsequently, the evaluation of bacterial adherence was carried out in triplicate by means of the XTT cell viability test. Additionally, bacterial adhesion was observed using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The average values of the micrometric roughness in both groups were similar; however, in the nanometric scale they presented significant differences. Additionally, the G1_DE group showed the highest amount of adhered S. mutans and S. sanguinis compared to the G2_EP group. Although the roughness of deciduous and permanent enamel showed contrasting results according to the evaluation technique (area and scale of analysis), bacterial adhesion was greater in deciduous enamel; hence, enamel roughness may not be a determining factor in the bacterial adhesion phenomenon.
... The hydrogen peroxide/carbamide peroxide contents of the bleaching agents used by these four studies were in the range of 6-22%. Alterations in enamel surface morphology were recorded by five studies using either SEM analysis, AFM analysis or light microscopic observation [13,26,[45][46][47] and these changes included: ridged and scored, scattered depressions of various diameters and depths, a muted texture of rounded enamel rods with depressed rod boundaries, the unclear structure of dental enamel, seen by the blurring of the striae of Retzius and a darkening of the subsurface zone of enamel, indicating mineral loss in this region; a partially etched surface with many shallow depressions and an increase in surface porosity; white precipitate that could be seen in association with the enamel surface, giving it a frosted appearance. Three studies recorded greater enamel surface changes in specimens treated with 30% or more concentrations of hydrogen peroxide solution compared to the specimen treatment with bleaching agents with lower concentrations of hydrogen peroxide [45][46][47]. ...
... Alterations in enamel surface morphology were recorded by five studies using either SEM analysis, AFM analysis or light microscopic observation [13,26,[45][46][47] and these changes included: ridged and scored, scattered depressions of various diameters and depths, a muted texture of rounded enamel rods with depressed rod boundaries, the unclear structure of dental enamel, seen by the blurring of the striae of Retzius and a darkening of the subsurface zone of enamel, indicating mineral loss in this region; a partially etched surface with many shallow depressions and an increase in surface porosity; white precipitate that could be seen in association with the enamel surface, giving it a frosted appearance. Three studies recorded greater enamel surface changes in specimens treated with 30% or more concentrations of hydrogen peroxide solution compared to the specimen treatment with bleaching agents with lower concentrations of hydrogen peroxide [45][46][47]. ...
... The concentration of hydrogen peroxide/carbamide peroxide has also been shown to influence the surface alteration of enamel. Studies recorded greater enamel surface changes in specimens treated with a 30% or higher concentration of hydrogen peroxide solution than specimen treatments with bleaching agents with lower concentrations (range of 6-22%) of hydrogen peroxide [45][46][47]. The study by Hegedüs et al., (1999) examined the effect of bleaching agents (Opalescence, Nite White, 30% hydrogen peroxide solution) on the enamel surface with atomic force microscopy and found that the depth of grooves present on the enamel surface post bleaching is directly proportional to the concentration of hydrogen peroxide [46]. ...
The increase in aesthetic demands has increased the use of ceramic dental restorations in dentistry. Ceramic restorations are bonded to the tooth structure using adhesives. There is a lack of standard guidelines in terms of post-bleaching time intervals and bond strengths of ceramic restorations. Bleaching products have also been stated to affect the morphology of enamel. Therefore, the purpose of this systematic review is to evaluate the bond strength between ceramic and enamel and the changes in the surface roughness of enamel post teeth bleaching. An electronic search was performed in the databases PubMed, OVID MEDLINE, Scopus, and Web of Science with MESH terms: “adhesion OR bonding”, “ceramic OR ceramics OR dental porcelain”, “tooth bleaching OR teeth bleaching OR tooth whitening OR teeth whitening” and “enamel OR dental enamel OR enamels OR dental enamels”. The articles were screened, and the final selection of articles was obtained by using the inclusion and exclusion criteria. Of the 170 studies identified from the search, only 12 studies met the inclusion criteria and were selected for full-text review. A further search by hand was performed, and additional 48 studies were selected. From the 60 full-text studies, 18 studies met the inclusion criteria and were included for data extraction. The results were based on a descriptive analysis of the effect on bond strength of ceramic to enamel after a bleaching protocol and the changes in the surface roughness of enamel post bleaching protocol. In conclusion, bleaching protocols alter the surface roughness of enamel and, thus, the shear bond strength between ceramic and enamel. Bleaching treatments with a higher concentration of hydrogen peroxide reduce the bond strength between ceramic and enamel. Delaying bonding after bleaching for up to 7 days increases the bond strength between ceramic and enamel.
... Nevertheless, it remains unclear whether the tooth enamel is damaged by bleaching procedures with peroxides. Some studies report changes in the enamel surface caused by bleaching with peroxides [12][13][14][15][16][17][18][19][20], while others did not report any surface alterations [14,15,18,21]. In vitro studies have demonstrated demineralization effects, such as a reduction of the mineral content or changes in the calcium/phosphate ratio [22][23][24][25][26]. ...
... H 2 O 2 has a low molecular weight (34 g/mol) and has the capability to penetrate into enamel [40]. Enamel surface alterations induced by H 2 O 2 have been reported in many studies [12][13][14][15][16][17][18][19][20], but most of these changes have not been seen in studies where teeth were stored in saliva or remineralizing agents [41][42][43]. In our study, mild interprismatic dissolution was observed, even though teeth were stored in artificial saliva. ...
(1) This study investigated the whitening effect, cytotoxicity and enamel surface alterations induced by different over-the-counter (OTC) bleaching agents in comparison to hydrogen peroxide. (2) Human teeth (n = 60) were randomly assigned into 6 groups (n = 10), stained with coffee solution for 7 d, followed by a whitening period of 7 d with either placebo, bromelain, sodium bicarbonate, sodium chlorite, PAP or hydrogen peroxide. Color measurements were performed with a spectrophotometer. Scanning electron micrographs (SEM) were taken to assess the enamel structure. Cytotoxicity of the tested substances was assessed based on the cell viability of primary human fibroblasts. (3) The application of all whitening gels resulted in a greater color difference of the enamel (ΔE) in comparison to the negative control. Hydrogen peroxide caused the greatest color difference. Bromelain and PAP treatment showed no enamel surface changes, in contrast to hydrogen peroxide treatment, which showed very mild interprismatic dissolution. Bromelain was the only non-cytotoxic agent. (4) The maximum effect achieved by all OTC bleaching agents was the removal of stains, whereas hydrogen peroxide was capable of further whitening the teeth. Bromelain treatment was neither cytotoxic, nor resulted in enamel surface alterations, and its whitening effect was less, yet still effective, compared to hydrogen peroxide.
... 14 In addition to needing minimal sample preparation and without changing the natural conditions of specimen structure, it is capable of revealing the surface along the X, Y and Z axes. 14,15 As a result, both two-and three-dimensional images of the surfaces can be obtained at the same time. ...
... There have been studies 14,[16][17][18][19][20] which have investigated the effects of bleaching agents on color changes or on the surface characteristics of permanent teeth by different methods. However, to the best of our knowledge, with regards to in vitro studies, samples were generally the intersections of enamel or dentine, with the exception of a recent study in which the color susceptibility of premolars and the efficacy of whitening toothpaste was investigated. ...
... (4,5,6,7,8) Entonces puede crecer en al menos tres morfologías diferentes: levadura, pseudohifas e hifas. (9) Existen otras formas morfológicas durante el cambio de colonias; por ejemplo, las células de la fase opaca son oblongas, en lugar de la forma ovalada de las células de levadura. Las pseudohifas y las hifas son alargadas y, a veces, no se puede distinguirlas, ya que ambas son "formas filamentosas" del hongo. ...
Introduction: *Candida albicans* is a fungus that is part of the oral microflora in 30-50% of the population. Its ability to alternate between different morphological forms, such as yeasts, pseudohyphae and hyphae, gives it a remarkable biological plasticity. This study evaluated the impact of tooth whitening with 35% hydrogen peroxide on the adherence of *C. albicans* to tooth enamel, exploring the factors that influence its colonization and virulence. Development: It was observed that *C. albicans* uses specific adhesins and components of its cell wall to adhere to surfaces such as dental enamel. This process, together with the formation of biofilms, increases its resistance to treatment and protection against the immune system. The action of hydrogen peroxide, although effective as an oxidizing agent, can modify the enamel surface, favoring the adherence of *C. albicans* and the interaction with bacteria such as *Streptococcus mutans*. These interactions enhance the formation of mixed biofilms, which represents a significant risk to oral health. Conclusions: The study concluded that tooth whitening with hydrogen peroxide can facilitate colonization of *C. albicans* due to changes in tooth enamel composition. Furthermore, it reaffirmed the importance of this fungus as an opportunistic pathogen and highlighted the need to implement preventive strategies in esthetic dental treatments. These strategies include the use of remineralizing agents and the strengthening of hygiene protocols to minimize associated risks. Future research will be key to better understand these interactions and develop more effective therapeutic approaches.
... Bleaching agents, commonly composed of hydrogen peroxide or carbamide peroxide, are widely used in aesthetic dentistry to enhance tooth whiteness. However, bleaching has been shown to reduce the SBS of orthodontic brackets [1,2], likely due to alterations in the enamel's organic matrix and the formation of residual oxygen as a by-products that interfere with Volume 66-December 2024 ISSN: 1110-435X ONLINE ISSN: 281-5258 adhesive polymerization [3][4][5][6]. Achieving optimum SBS is crucial for resisting the forces Operating at a wavelength of 2940 nm, Er:YAG lasers specifically target water and hydroxyapatite, inducing micro-explosions that generate an irregular surface topography akin to that produced by acid etching. ...
... However, there were fewer and more fragmented resin pegs in the bleached enamel than in the unbleached enamel (22). Bleaching also causes calcium loss, a lack of microhardness, and changes in organic matter (23). The interfaces between the resin and bleached enamel were observed by scanning electron microscopy (SEM). ...
Background
The purpose of this study was to evaluate the effect of sage extract, a natural antioxidant, on the shear bond strength (SBS) of metal orthodontic brackets bonded to bleached enamel with 40% hydrogen peroxide (HP).
Methods and Materials
The sample consisted of 100 maxillary premolars, which were divided into five groups: group I (control, no bleaching), group II (bleaching using HP40% + immediate bonding after bleaching), group III (bleaching using HP40% + SA10% + bracket bonding), group IV (bleaching using HP40% + sage extract 10% + bracket bonding) and group V (bleaching using HP40% + sage extract 20% + bracket bonding). All teeth were bonded using composite resin cement and immersed in distilled water for 24 hours. The shear bond strength (SBS) was assessed by a universal testing machine (Instron) after 24 hours of bracket bonding. After debonding the brackets, the residual adhesive remnant index (ARI) was checked using a stereoscope at 20x magnification. The statistical analysis was carried out using one-way ANOVA to determine differences among the five groups and the least significant difference (LSD) test for bilateral comparisons of the average shear bond strength of the brackets. For the ARI, the Kruskal‒Wallis test was performed.
Results
ANOVA revealed statistically significant differences among the five groups (р<0.001). Compared with those in the bleached group without antioxidant treatment, the shear bond strengths of the groups treated with 10% and 20% sage extracts significantly improved. According to the LSD test, there was no significant difference between the groups treated with 10% and 20% sage extracts (р>0.05). The Kruskal‒Wallis test revealed no statistically significant differences between the frequencies of the residual adhesive remnant index (ARI) among the five study groups, with the most frequent score being (2).
Conclusion
The shear bond strength of brackets bonded to bleached teeth can be improved by applying 10% and 20% sage extracts immediately after bleaching and before bracket bonding.
... [22] Enamel demineralization from bleaching primarily stems from ionic differences between the enamel and the bleaching solution. [23] This interaction results in the exchange of substances like calcium, phosphate, and hydroxyl ions. [1,10] The undersaturation of the bleaching solution compared to enamel prompts ion release to attain equilibrium, depending on calcium availability and pH levels. ...
Context and Aims
This study evaluated the effect of calcium silicate and sodium phosphate (CSSP) dentifrice and serum on the surface of enamel bleached with hydrogen peroxide (H 2 O 2 ).
Materials and Methods
A total of 160 bovine enamel slabs were bleached with 35% H 2 O 2 and treated with sodium fluoride (NaF) dentifrice-GI, CSSP dentifrice-GII; CSSP dentifrice + CSSP serum-GIII, or NaF dentifrice + NaF gel-GIV. The dentifrices were applied using a brushing machine three times daily for 7 days. After brushing, sodium phosphate gel and CSSP serum were applied. The microhardness (KNH, n = 14), surface roughness (Ra, n = 14), energy dispersive spectroscopy (n = 6), and scanning electron microscopy (n = 6) were assessed at t 0 (before bleaching), t 1 (after bleaching), and t 2 (after postbleaching treatments).
Statistical Analysis Used
The data were subjected to a two-way analysis of variance and Bonferroni’s test.
Results
The KNH decreased at t 1 (P < 0.001) but recovered at t 2 for all treatments, although only GII showed restored baseline values (P = 0.0109). The surface roughness increased at t 1 (P < 0.001) and reduced at t 2 (P < 0.001) for all groups, with no significant differences among groups. Enamel composition and morphology did not differ after the treatments, except for silicon accumulation in GIII.
Conclusions
Postbleaching treatment with CSSP dentifrice and serum yielded superior remineralizing effects on bleached enamel.
... Haywood [20], Perdigao et al. [21], Hegedu et al. [22] and Adibfar et al. [23] for decreasing the shear bond strength postbleaching is presence of residual oxygen in enamel and it leached out by time, that the residual oxygen interferes with rein penetration to enamel and dentin preventing the polymerization of resin, this explanation is in agreement with the results of the current study, because of the improvements of shear bond strength of antioxidants application. ...
... Furthermore, several in vitro studies reveal that bleaching agents used in bleaching techniques can cause morphological changes in mineralized structures [30,71]. Decreased dentin microhardness [43], increased permeability [20] and change in surface morphology [71] have been reported after bleaching procedures. ...
To evaluate the correlation between the dental crown’s color and the pulse oximeter result in healthy teeth before and after 30 days of the end bleaching procedures. Material and methods: The dental crown’s color of 70 healthy maxillary central incisors were evaluated using a spectrophotometer and the oxygen saturation level of the pulp was recorded using a pulse oximeter. The bleaching was performed using the combined technique, with 35% hydrogen peroxide bleaching gel, in the office stage, and 10% carbamide peroxide, in the at-home, for 16 days. The variables symmetry was verified by the Kolmogorov Smirnov test, and the quantitative variables described by mean and standard deviation. The correlation between quantitative variables was established using Pearson’s correlation coefficient. The significance level considered was 5%. Results: A significant change was observed between values recorded by the pulse oximeter before (85.0% ± 4.1) and after (86.4% ± 2.3) 30 days of the end. Thirty days after the end of the bleaching procedures, the dental crowns were lighter with the difference between L*s equal to 1.4, more greenish with a difference between a*s equal to 1.3, and more bluish with a difference between b*s equal to -7.2. There was no correlation between the values of coordinates L*, a* and b* and the results recorded by the pulse oximeter in the initial period, respectively, or 30 days after the bleaching procedures, respectively. Conclusion: Changes in pulse oximeter recordings did not correlate with the change in the dental crown’s color promoted by bleaching procedures.
... All the articles have shown SBS values for the samples that were not treated with bleaching agents, literature demonstrates that the decrease of the SBS value after bleaching is related to the morphological changes on the enamel which can result from the reaction between peroxide and the organic components [50]. ...
Background
Nowadays bleaching procedures have gained popularity in orthodontic patients. Peroxide and Carbamide acids are the common agents which are used in in-office and at home bleaching techniques.
Consequently, the Bonding adhesion to the enamel can be influenced by the orthodontic phase and the residual peroxide might interfere with the polymerization and the adhesion of the brackets.
Frequent debonding of the brackets from teeth after the bleaching procedure could cause the lengthening of the therapy and promote irregularities on enamel surface derived from an additional bonding phase of the brackets.
The aim of this systematic review is to appraise the influence regarding the effect of the bleaching procedure on the bond strength of orthodontic brackets.
Methods
An electronic database search was performed. Search terms included: bleaching, brackets, adhesion; data were extracted and summarized. Risk of bias was assessed using the Chocrane risk of bias tool, adapted for in vitro studies.
Results
A total of 8689 articles were screened and 11 studies met the inclusion criteria of this systematic review.
1000 teeth of human and bovine origin were analyzed for the shear bond strength (SBS) of stainless and ceramic brackets after the bleaching treatments. All the authors divided the groups in different subgroups with different bleaching agents and in different concentration.
The SBS value allowed to demonstrate the necessity to delay the bonding of the brackets for two weeks after a bleaching treatment and its improvement when tooth mousse or antioxidants agents are used.
Conclusions
The SBS values and the delay of the bonding procedure must be considered in dental practice and clinical strategies are necessary in order to avoid drawbacks which could cause the debonding of the brackets after bleaching due to the alterations of the dental substrate, thus interfering with the orthodontic treatments.
... 7 Penetration of HP through enamel and dentin into the pulp chamber is a major concern in tooth bleaching. [8][9][10][11][12][13] Animal studies have reported the increase in HP concentration and the prolonged activation of CD5-positive cells and a significant increase in the levels of pain-related neuropeptides in pulp. 14 Benetti et al. showed that interleukin (IL)-6 and IL-17 caused inflammation in the pulp tissue of rats after tooth bleaching, particularly at 2 days. ...
Background: In-office bleaching is one of the most commonly used procedures for discolored tooth treatment. Although the efficacy of tooth bleaching has been investigated, depending on the applied technique and the used materials, bleaching procedures might irritate the tooth pulp and induce surface changes in enamel. The aim of this study was to evaluate the effect of four different bleaching techniques on the penetration of hydrogen peroxide (HP) into the pulp chamber. Materials and methods: Seventy-two single-rooted sound human teeth were used. The samples were prepared and evaluated in four groups. Group 1: 35% HP gel alone (HP Gel); group 2: Nd:YAG laser (0.25 W and 10 Hz with a fiber tip size of 200 μm) irradiation was added (HP Gel+laser); group 3: HP gel mixed with graphite particles (10th of millimeter in size) derived from crashed pencil lead in association with Nd:YAG laser (HP Gel+laser+graphite); and group 4: HP gel in association with light-emitting diode (LED) (litex 686, 50 Hz, 450-490 nm) (HP Gel+LED). The amount of HP penetrating into the pulp chamber was evaluated using acetate buffer and standard graphs. Data were analyzed with one-way ANOVA test, using SPSS 17. Post hoc Tukey test was used for between-group comparisons (α = 0.05). Results: Statistical analyses showed that the HP Gel+laser+graphite group had significantly higher level of HP penetration than other groups (p < 0.001). Moreover, pulp chamber penetration of HP in the HP Gel+laser group was greater than the LED and control groups (p < 0.001). The difference between control and LED groups was not significant (p = 0.99). Conclusions: Laser bleaching associated with HP Gel and graphite particles resulted in increased penetration of HP into the pulp chamber compared with the LED and control groups.
... These observations were suggestive of the modified physical and mechanical properties of the enamel. As described earlier, morphological changes induced by bleaching agents are not only pH-related, but are also a result of the interaction of peroxide and free radicals with organic and inorganic structures on the surface, or even subsurface, of the substrate, as these molecules have low molecular weight and thus, can penetrate the enamel [44]. Previously, it was shown that surface changes of dental enamel in the form of porosities, exposure of enamel prisms, and loss of surface smoothness are dependent on the type, concentration, and application time of the bleaching agent [45]. ...
In-office bleaching with high concentrations of hydrogen peroxide (H2O2) agents causes undesirable alterations in the enamel. Surface pre-reacted glass-ionomer (S-PRG) filler is a functional material known for its acid-neutralizing and demineralization-inhibition properties. This study evaluates the effect of S-PRG filler incorporation in H2O2-based bleaching on the enamel surface. Bovine enamel surfaces were bleached using a bleaching paste formulated with a liquid (35% H2O2) and a powder containing 5% or 10% S-PRG filler. The surface roughness and the Vickers microhardness of the treated enamel surfaces were evaluated. The enamel surfaces were observed under a scanning electron microscope (SEM) and analyzed using energy dispersive X-ray (EDX) technology. The surfaces were challenged by citric acid and observed by SEM. The specimens bleached with the paste containing the S-PRG filler showed lower enamel surface roughness and higher microhardness values than did those bleached with the plain paste (0% S-PRG filler); meanwhile, there were no significant differences between the 5% or 10% S-PRG filler groups. The S-PRG filler groups showed enamel surface morphologies similar to those of the non-bleached enamel, according to SEM observation, and EDX analysis detected the presence of fluoride and strontium ions. The S-PRG filler groups showed a higher resistance to erosion. The S-PRG filler mitigated the detrimental effects of bleaching agents on the enamel surface and provided resistance to erosion.
... Carbamide peroxide may promote changes in the mechanical properties of the enamel due to the action of its by-products, such as urea and oxygen. Free radicals of hydrogen peroxide, a component in which carbamide peroxide degrades, have no specificity and react with and degenerate the dental tissues (9,10) . ...
... Hydrophilic monomers found in adhesion boosters may contribute to improved bond strength by facilitating infiltration of the resin into the internal areas of the enamel layer, enhancing integrity and reducing interfacial porosity. [13] The structural alterations and the surface roughness of the tooth morphology may be to blame for the reduction in SBS following bleaching. [14] Increased binding strength in bleached teeth may have been made possible by adhesion boosters' capacity to decrease interfacial porosity. ...
Introduction:
The bleaching of the teeth is known to reduce the bonding of the orthodontic brackets. Hence, this in vitro study was piloted to analyze if there was any variance between the teeth that were and were not bleached when the adhesive boosters were used and for its effect on the shear bond strength.
Materials and procedures:
Hundred premolars (maxillary) that had been excised were randomly split into two groups: bleached teeth and unbleached teeth. The bleaching agent was gel composed of 22% carbamide peroxide. Maxillary premolar brackets were bonded, and each group was subdivided as control and adhesive booster Enhance LC groups. A universal testing device was used for debonding. The SBS thus recorded was compared for the subgroups and groups.
Results:
Significant variance was obtained for between the groups and between the subgroups. Higher bond strength was for the non-bleached teeth than the bleached teeth and was seen in the adhesive booster subgroup than the control group.
Conclusion:
In summary, adhesive boosters dramatically raised the shear bond strength of teeth irrespective of the bleaching. Further in vivo studies are suggested.
... These irregularities may be related to byproducts resulting from the oxidizing reaction of the bleaching agent, mainly urea and oxygen. Urea can denature proteins present in organic portions of the tooth structure 36,37 , and has the potential to penetrate the enamel, affecting not only the surface but also the interprismatic portion of the enamel. Urea penetration may thus contribute to higher enamel permeability and microstructural changes 34 . ...
Unlabelled:
After ozone therapy for bleaching, it is important to evaluate enamel surface properties, to ensure that bleaching provides adequate conditions for sound dental substrate. Aim: The aim of this in vitro study was to evaluate the effects of a bleaching treatment with 10% carbamide peroxide (CP), with or without ozone (O), on the microhardness, roughness and micromorphology of the enamel surface.
Materials and method:
Bovine enamel blocks were planed and distributed among the following three bleaching treatment groups (n=10): CP - 1 hour per day/14 days (Opalescence PF 10%/ Ultradent); O - 1 hour per day every 3 days/3 sessions (Medplus V Philozon, 60 mcg/mL and oxygen flow rate of 1 L/min); and OCP - CP with O, 1 hour per day every 3 days/3 sessions. Enamel surface microhardness (Knoop), roughness (Ra), and micromorphology by scanning electron microscopy (5,000x magnification) were determined before and after the treatments.
Results:
ANOVA and Tukey-Kramer’s test showed that enamel microhardness remained unchanged by treatment with O and OCP (p=0.0087), but decreased by treatment with CP. Treatment with O promoted higher enamel microhardness than the other groups (p=0.0169). Generalized linear mixed models for repeated measures over time indicated treatment with CP increased enamel roughness more than OCP or O (p=0.0003). CP produced slight irregularities in enamel micromorphology after the whitening treatment. O, with or without CP, maintained the mechanical and physical properties of microhardness and enamel surface micromorphology, and either maintained or reduced surface roughness, compared to the conventional tray-delivered CP bleaching treatment.
Conclusions:
Treatment with 10% carbamide peroxide in trays promoted greater changes in enamel surface properties than treatments with ozone and with 10% ozonized carbamide peroxide in the office.
... The first is related to the oxidation potential of hydrogen peroxide that acts in the organic content of tooth structure, such as the enamelin and amelogenin proteins, facilitating peroxide diffusion through tooth structures. 20 The second factor is the absence of minerals including calcium and phosphate in bleaching gels formulation. Without these compounds, the bleaching gel is under saturated in relation to hydroxyapatite, causing the loss of calcium and phosphate ions from tooth surface to the gel. ...
Objective:
To evaluate if distinct 20%-22% carbamide peroxide bleaching gels present similar decomposition pattern and pH during the clinical use in both arches, as well as gels viscosity.
Methods:
Participants randomly received treatments with carbamide peroxide gels (n = 10): OPF (OpalescencePF-20%); PNT (Polanight-22%); and WPC (Whiteness Perfect-22%) in three different days, with 2-day washout. Decomposition pattern was assessed by peroxide concentration. Both PC and pH of bleaching gels were measured in different time points in upper and lower trays during a total of 120 min of clinical use. Viscosity of bleaching gels was measured in triplicate. ANOVA and Tukey's test were applied (α = 0.05).
Results:
Regarding decomposition pattern, no significant differences were observed for the interaction between gel, time, and tray position factors. The peroxide concentration progressively reduced until 120 min of trays use (p < 0.001), being overall more notable in lower trays (p < 0.001). Regarding pH, the lowest values were verified in WPC within time. At 120 min, an increase of pH was observed for both WPC and OPF (p < 0.001) compared to baseline means. PNT exhibited constant pH values over time. The values of viscosity were: OPF (1.682.000 ± 19 cP)a, WPC (1.388.667 ± 172.63 cP)ab, PNT (579.567 ± 0.98 cP)b.
Conclusions:
The bleaching gels presented overall decomposition pattern clinically equivalent, being more notable in lower trays over time. Nevertheless, distinct pH and viscosities were observed among the products.
Clinical significance:
Although the manufacturers recommend different times of use for bleaching gels with similar peroxide concentrations, the commercial products tested did not exhibit clinically relevant difference in the decomposition pattern during the 120 min of clinical procedure.
... Dental bleaching promotes the diffusion of bleaching agents that interacts with pigmented molecules, but this interaction seems to promote alterations on sound enamel and dentin structure [10]. This process can result in the dissolution of inorganic components of enamel penetrating the intra and interprismatic spaces, causing the enamel surface to become rough and reduce the hardness [11]. ...
Aim:
This in vitro study assessed the efficacy and adverse effects of violet LED bleaching with or without bleaching agents.
Material and methods:
Dental blocks (n=40) were randomly distributed in 4 groups: violet LED (VL), 35% hydrogen peroxide (HP35), the association of hydrogen peroxide 35% with violet LED (VHP35) and the association of hydrogen peroxide 35% with blue LED (BHP35). Specimens were analyzed for Vickers microhardness initially, immediately after and seven days after ending bleaching protocol. The color analysis of the specimens was evaluated for bleaching effectiveness (ΔE2000, ΔE1976) and whiteness index (ΔWID) with EasyShade spectrophotometer, before bleaching protocol and seven days after ending bleaching protocol. The mineral composition of the enamel was evaluated by percentage of phosphorus and calcium on the enamel surface with energy dispersive spectroscopy (EDS). The color and the microhardness data were analyzed using one-way ANOVA with post-hoc Tukey (α=0.05).
Results:
The microhardness test showed a difference among the groups only immediately after the completion of the protocol, in which there was a reduction in the value for the groups HP35 from 277,36 ± 21,56 to 198,76 ±32,2 (p<0,01); and BHP35 from 261,14 ± 36,01 to 212,66 ± 25,99 (p<0,01), but the microhardness was reestablished after seven days. Regarding EDS analysis, a reduction in the mineral percentage immediately after bleaching with the use of VL was observed, however, after seven days it was reestablished. Regarding the color analysis, there was no difference among the groups evaluated.
Conclusions:
The use of VL was effective as a dental bleaching tool and did not adversely affect the enamel surface after seven days of the ending of the bleaching protocol.
... [20] Such caustic treatment can cause burns to gingival and mucosal tissues, [21] and may also lead to dentine hypersensitivity. [22] It has been reported that H 2 O 2 not only destroys the morphology and reduces the hardness of enamel, [23] but also increases surface porosities, which may lead to tooth recoloration and adherence of certain cariogenic microorganisms on teeth. [24] As aforementioned, both tooth biofilm inhibition and tooth whitening are thorny issues, and it will be great if we can tackle these two issues in one combined treatment. ...
Dental caries is among the most prevalent dental diseases globally, which arises from the formation of microbial biofilm on teeth. Besides, tooth whitening represents one of the fastest‐growing areas of cosmetic dentistry. It will thus be great if tooth biofilm eradication can be combined with tooth whitening. Herein, a highly efficient photodynamic dental therapy strategy is reported for tooth biofilm eradication and tooth discoloration by employing a photosensitizer (DTTPB) with aggregation‐induced emission characteristics. DTTPB can efficiently inactivate S. mutans, and inhibit biofilm formation by suppressing the expression of genes associated with extracellular polymeric substance synthesis, bacterial adhesion, and superoxide reduction. Its inhibition performance can be further enhanced through combined treatment with chlorhexidine. Besides, DTTPB exhibits an excellent tooth‐discoloration effect on both colored saliva‐coated hydroxyapatite and clinical teeth, with short treatment time (less than 1 h), better tooth‐whitening performance than 30% hydrogen peroxide, and almost no damage to the teeth. DTTPB also demonstrates excellent biocompatibility with neglectable hemolysis effect on mouse red blood cells and almost no killing effect on mammalian cells, which enables its potential applications for simultaneous tooth biofilm eradication and tooth whitening in clinical dentistry. In this work, an aggregation‐induced‐emission‐active photosensitizer, DTTPB, with high reactive oxygen species sensitizing efficiency and broad absorption band is employed for photodynamic killing of planktonic bacteria, inhibition of biofilm formation, and eradication of biofilm. Besides, DTTPB‐mediated photodynamic therapy could efficiently whiten both colored oral tooth models and clinical teeth without destroying tooth structure.
... Original magnification: 140 × . Scale bar: 500 μm latter, it triggers a demineralization process, increasing the presence of oxygen and decreasing that of calcium and gives rise to surface morphological alterations (Rotstein et al. 1996;Hegedüs et al. 1999;Chen et al. 2002;Baldión et al. 2011). These processes have been related to those found on bone material (Chen et al. 2002). ...
The preparation of samples for traceological analysis is a key methodological aspect in the correct interpretation of use-wear; however, it is often poorly reflected in the archaeological literature. The treatment of osseous tissues is particularly overlooked, and receives even less attention than lithic raw materials. The presence of residues and contaminants on the surface of artefacts can conceal or even be mistaken for use-wear features, thereby affecting their interpretation. Therefore, the objective of this work is to contribute to the systematization of cleaning protocols and the preparation of experimental bone tools for traceological analysis. Through a sequential experiment, we tested the effects of different cleaning agents on experimental samples. Microscopic observation of the samples was complemented with microhardness testing. Our results made it possible to evaluate the cleaning effectiveness of the tested products, to determine how each product affects the bone surface at a microscopic level, and to assess the effects of these products on the treated bone tools in terms of cutting performance.
... To minimize effects of tooth discoloration, teeth whitening has been developed as a relatively inexpensive and fast treatment approach against extrinsic-pigmentation discoloration. 1 Teeth whitening has a high degree of satisfaction among patients with different personalities 2 . However, current teeth-whitening protocols include tooth bleaching by using hydrogen peroxide 3 and carbamide peroxide 4,5 formulations, which can lead to tooth sensitivity, gingival irritation 6,7 , , soft-tissue burns 4,8 , throat irritation, nausea, irreversible pulp damage 9 , decreased dentin microhardness 10 , and microscopic effects on the enamel including its demineralization 5,11,12 , organic matrix degradation 12,13 , calcium loss, decreased protein concentration, variations on the calcium to phosphate ratio [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] , and increased porosity on the enamel surface. The potential damage caused by tooth bleaching has led the cosmetic dentistry community to look for alternatives which can prioritize biological safety over the relative speed of the teeth-whitening treatment, despite potentially decreased whitening effectiveness of these alternatives. ...
... 22 Hydrogen peroxide has a high capacity for oxidation and reduction, as well as diffusion ability. 27 Thus, it can also affect the resin-fill-interface in the lower layers of the composite and cause the separation of the filler-matrix bond. 28 However, in another laboratory study, the surface microhardness remained unchanged when a bleaching agent ( 10% CP) was used at room temperature (25 °C) while significant surface softening was found on the composite resin when a bleaching agent was used at body temperature (37 °C). ...
EFFECT OF HIGH CONCENTRATION PEROXIDE BLEACHING AGENTS ON THE SURFACE PROPERTIES OF COMPOSITE RESTORATIONS
... The AFM analysis after the cyclical period of 14 days of whitening treatment with two commercial products on the healthy patients' teeth demonstrated the presence of some microporosities on the enamel surface. These observations are consistent with those presented by Hegedüs et al. [14], who concluded that whitening products are capable of altering the surface of the enamel. The hypothesis that peroxide bleaching agents affect the organic component of the enamel is mentioned. ...
(1) Background: What is the effect of 16% and 40% concentration bleaching agents on dental structures in healthy patients compared to predialysis patients? (2) Methods: Forty teeth were included in the study (20 from healthy patients and 20 from predialysis patients). Each group was randomly divided into another two subgroups (n-10), depending on the bleaching agent concentration (16% and 40% gels). Color parameters were registered before and after the whitening process using a spectrophotometer. To determine enamel ultramicroscopic modifications, SEM and AFM analysis were performed before and after bleaching. (3) Results: An increasing trend was identified in the average values of ∆E and ∆L within the groups of predialysis teeth between teeth whitened with 40% concentration gel and those whitened with 16% concentration gel, while for the enamel samples from healthy patients the trend was reversed. The average values for roughness in the case of the two bleaching agents in healthy and predialysis teeth presented statistically significant differences (p < 0.05). (4) Conclusions: The effects of bleaching agents are less significant on teeth from predialysis compared to healthy patients. A direct link exists in terms of the clinical effect between the concentration of the whitening gel and color modifications.
Tooth whitening is nowadays one of the most requested aesthetic procedures by patients. Hydrogen peroxide contains unstable peroxides that produce oxygen free radicals, capable of breaking down the pigmented organic carbon components contained in the enamel matrix, converting them into shorter chain molecules and less pigmented, defined as oxidation, which continues for some time, and can decompose the organic materials into carbon dioxide and water, which would represent the loss of the enamel matrix1. One of the effects is the alteration of surface roughness and deeper cracks, as well as an increase in surface porosity, which could increase the adhesion of microorganisms. Objective: to determine if the adhesion of Candida albicans is greater in enamel subjected to bleaching with 35% hydrogen peroxide.Methods: The sample consisted of 20 healthy premolars extracted with orthodontic indication from patients between 13 and 35 years old with a post extraction time of less than 6 months.Two groups were randomly assigned, control group (no bleaching only sterile water) and experimental group (professional bleaching with 35% hydrogen peroxide). The teeth were sterilized and then incubated with Candida albicans for 36 hours. Then a sample of the vestibular side of the teeth was taken with sterile microbruhs to be centrifuged, and the seeding was performed in plates with sabouraud glucose agar from the supernatant of the centrifugation with a volume of 7 microliters, streaked with ansa. The CFU of both groups were quantified after 36 h of incubation in an oven at 37ºC. Results: The data were processed in Excel through the real statistics add-in system, the Shapiro Wilk test was applied to determine the normal distribution of the data, the F test for variances of two samples which resulted in equal variances; therefore, the parametric T-student test for independent samples for equal variances was selected. The result for one-tailed analysis was P value of 0.04 so we can think that this difference between control and experimental group exists, and in which case there was greater adherence of Candida in the control group compared to the experimental group. Conclusion: The literature is controversial, we can assume that the greater adherence of Candida albicans in the control group was due to the antimicrobial action of the bleaching agent on the experimental group.
There has been an increased demand for dental bleaching globally irrespective of age and gender. Main drawbacks associated with conventional tooth bleaching agents have been compromised strength and mineral-content of tooth enamel which results in sensitivity, discomfort, roughness, and structure loss of human teeth. Currently, nanoparticles synthesized by green synthesis have gained popularity especially in medical and dental applications because of their versatile and beneficial nano-scaled features. Titanium dioxide nanoparticles (TiO 2 Nps) in this study were prepared from green ecofriendly source using the aloe vera plant extract and were then characterized via dynamic light scattering (DLS), scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD), and energy dispersive X-ray (EDX), for size, shape, composition and true-phase. These TiO 2 Nps were incorporated in commercial bleaching gel containing hydrogen peroxide to form a novel TiO 2 -bleaching gel which was used to bleach extracted anterior teeth belonging to four different age groups: 20–29 years, 30–39 years, 40–49 years and ≥50 years. These teeth were investigated for micro-hardness (Vickers microhardness tester) and mineral-content (EDX spectroscopy) including sodium, magnesium, phosphorus, calcium in an in-vitro environment both before and after bleaching. Results revealed that TiO 2 Nps prepared by aloe vera plant were nanos-sized of about 37.91–49 nm, spherical shape, true anatase phase with pure titanium and oxygen in their composition. The values of Vickers micro-hardness and mineral-content (Na, Mg, P, Ca) of enamel specimens belonging to different age groups enhanced in a linear pattern before bleaching with the increase in age ( p value < 0.05). There was negligible reduction observed in Vickers micro-hardness and mineral-content elements (Na, Mg, P, Ca) of all enamel specimens belonging to different ages after the bleaching ( p value > 0.05). The novel TiO 2 -bleaching gel prepared was effective enough in preventing the declination in Vickers micro-hardness strength and mineral-content of all the enamel specimens belonging to different age groups even after the bleaching procedure which makes it a promising biomaterial.
Dental aesthetics is an important part of clinical practice in today’s time. Since bleaching is most conservative, less destructive, and economical, it is most opted method by the people for tooth whitening. This review article will help clinicians understand bleaching procedures, bleaching types, components, mechanisms, and their effects on soft tissue, tooth structures, sensitivity and restorations. However, because of the variability in experimental design, there is a lack of consensus concerning the bleaching effects on tooth and its surrounding tissues and further studies need to be done over it.
Objectives
This study was aimed to obtain an experimental bleaching agent by adding casein phosphopeptide‐amorphous calcium phosphate (CPP‐ACP) in order to eliminate the mineral loss on the tooth surface after bleaching and to evaluate the bleaching effectiveness.
Materials and Methods
In this study, experimental bleaching agents containing 1%, 3% CPP‐ACP and without CPP‐ACP were obtained. Bleaching effectiveness (color change), the effect of bleaching agents on mineral content (energy dispersive x‐ray spectroscopy), surface morphology (scanning electron microscope), and surface hardness of enamel (Vicker's microhardness) before and after bleaching were evaluated. The obtained data were statistically analyzed.
Results
When the bleaching levels of the groups were compared, no statistically significant difference was observed between the control and 1% CPP‐ACP groups ( p > 0.05) while the addition of 3% CPP‐ACP decreased significantly the effectiveness of the bleaching agent ( p < 0.05). When the effects of experimental bleaching agents on surface hardness were examined, while the enamel surface hardness decreased statistically significantly after application in the control group ( p < 0.05), no statistically significant change was observed in surface hardness after the application of 1% CPP‐ACP containing bleaching agent ( p > 0.05). However, a statistically significant increase was observed in surface hardness after the application of 3% CPP‐ACP containing bleaching agent ( p < 0.05). When the Ca and P ratio of the groups were compared, no statistically significant difference was observed between the control and 1% CPP‐ACP groups ( p > 0.05), while they increased significantly in 3% CPP‐ACP group ( p < 0.05).
Conclusions
The addition of 1% CPP‐ACP to the bleaching agent had positive effects on the mineral content and surface hardness of the enamel, and did not negatively affect the whitening effectiveness.
Clinical Significance
Adding CPP‐ACP to the bleaching agent at appropriate concentrations can eliminate possible negative effects without compromising the effectiveness of the bleaching agent.
Introduction: In recent times, there has been an increase in the number of esthetic smile makeovers. As a part of these procedures, achieving a brighter smile is considered essential. The treatment options for such makeovers range from simple bleaching to complex restorations. Bleaching, a conservative and straightforward method to manage discolored teeth, has become popular. Therefore, vital bleaching has gained immense popularity. To evaluate and compare the color changes on human enamel bleached with different concentrations of hydrogen peroxide, containing pineapple extract as an additive, and determine the bromelain content in pineapple, by reversed-phase ‑ HPLC method. Material and Methods: Twenty permanent single-rooted artificially stained maxillary anterior teeth were decoronated at CEJ, the crown component was divided into two vertical halves, further divided into four groups containing 10 samples each and bleached accordingly. Group I (A) 15% H 2 O 2 only, Group I (B) 2 mL of pineapple extract and 28 mL of 15% H 2 O 2 . Group II (A) 25% H 2 O 2 only and Group II (B) 2 mL of pineapple extract and 28 mL of 25% H 2 O 2 . The samples were checked for color change with the help of a reflectance spectrophotometer. RP-HPLC method was used to find the proportion of bromelain in pineapple extract. Statistical analysis: carried out using one-way ANOVA for comparison between two groups and Scheffe’s post hoc test for comparison between more than two groups. “Significance level” for all statistical tests was set at P < 0.05 (significance level <5%). All these analyses were carried out using the SPSS Version 22 software. Results: Group II B showed the maximum change in color means Δ E compared to the other three groups. The mean color change Δ E between Group II A and Δ E Group I B showed no statistical difference. The mean color change Δ E of Group I A showed the least color change compared to all other groups. Group II B showed a statistically significant change in color with “ P −0.001” compared to all other groups. Linearity overlay on chromatogram by RP-HPLC method showed the concentration of bromelain in pineapple extract is 64.99 mcg/mL. Conclusion: Pineapple extracts along with hydrogen peroxide showed promising results with a new gateway of success in whitening teeth.
Background
There are various methods proposed to prevent the reduction of substrate micro tensile bond strength to bleached enamel. Therefore, this study aims to evaluate and compare the effectiveness of two common methods, namely 10% sodium ascorbate and Er:YAG laser irradiation, in increasing the microtensile bond strength of composite resins to bleached enamel.
Methods
In this in vitro study, 72 maxillary premolar teeth were divided into four equal groups: bleached control group, unbleached control group, treated with 10% sodium ascorbate, and Er:YAG laser-treated group (60 mJ, frequency = 10 Hz, and power of 0.6 W with a 400-µm diameter tip). The samples were cut by a CNC cutting machine for a microtensile bond strength test.
Results
The Er:YAG laser group showed the highest mean bond strength (27.3 MPa), while the bleached control group had the lowest (15.06 Mpa). There was a significant difference between the bleached and unbleached control groups (P<0.001). Samples prepared with 10% sodium ascorbate and the Er:YAG group had higher tensile bond strength than the bleached control group (P<0.0001). Tensile bond strengths were not significantly different between the 10% sodium ascorbate and the Er:YAG laser preparation groups (P=0.361).
Conclusion
The findings of this study indicate that the microtensile bond strength of composite resins to bleached enamel can be increased by 10% sodium ascorbate and Er:YAG 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.
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.
Objective
To investigate the effect of fluoride-containing whitening products on sound enamel and on artificial caries lesions during a cariogenic challenge.
Materials and methods
Bovine enamel specimens (n = 120) with three areas [non-treated sound enamel (NSE), treated sound enamel (TSE), and treated artificial caries lesion (TACL)] were randomly assigned to the four groups: whitening mouthrinse (WM: 2.5% hydrogen peroxide-100 ppm F⁻), placebo mouthrinse (PM: 0% hydrogen peroxide-100 ppm F⁻), whitening gel (WG: 10% carbamide peroxide-1130 ppm F⁻), and deionized water (negative control; NC). The treatments (2 min for WM, PM, and NC, and 2 h for WG) were carried out during a 28-day pH-cycling model (6 × 60 min demineralization/day). Relative surface reflection intensity (rSRI) and transversal microradiography (TMR) analyses were performed. Fluoride uptake (surface and subsurface) was measured in additional enamel specimens.
Results
For TSE, a higher value of rSRI was observed in WM (89.99% ± 6.94), and a greater decrease in rSRI was observed for WG and NC, and no sign of mineral loss was verified for all groups (p > 0.05). For TACL, rSRI significantly decreased after pH-cycling for all experimental groups with no difference between them (p < 0.05). Higher amounts of fluoride were found in WG. WG and WM exhibited intermediate values of mineral loss, similar to PM.
Conclusions
The whitening products did not potentialize the enamel demineralization under a severe cariogenic challenge, and they did not exacerbate mineral loss of the artificial caries lesions.
Clinical relevance
Low concentrated hydrogen peroxide whitening gel and mouthrinse containing fluoride do not intensify the progression of caries lesions.
The purpose of this study was to investigate the effect of the BisCover LV application on the microhardness, surface roughness, and color change after bleaching treatment application. 120 bovine teeth were collected for this study. Spectrophotometric color analysis of the samples was performed as an initial step and after bleaching. The samples were randomly divided into 8 groups (n=15) as BisCover LV and Biscover LV-free samples, submerged in discoloring solutions (coffee, wine, cola, water) for 15 min, 7 h, and 3.5 days. Spectrophotometric color analysis was performed and recorded at each evaluation period. ΔE color change was calculated. BisCover LV applied samples were significantly less colored than BisCover LV-free samples regardless of solution type and evaluation period, after bleaching (p<0.001). BisCover LV applied water-submerged samples showed the least ΔE value (2.35±1.13) and this difference was statistically significant (p<0.001). BisCover LV-free samples kept in wine showed the maximum ΔE (25.60 ± 7.28) and this difference was shown to be statistically significant (p<0.001). Teeth come to the fore in providing esthetics therefore bleaching has become more common. It is important to maintain tooth color after bleaching treatment. Biscover LV can protect the teeth after bleaching.
Objectives: To investigate the application of toothpaste either containing calcium sodium phospho-silicate bioglass (NovaMin) or calcium fluorosilicate bioglass (BioMinF) on the surface mineral composition and morphology of enamel after bleaching procedure. Methods: Thirty extracted noncarious human teeth were allocated into five groups (n = 6). Group 1: Bleaching using 40% hydrogen peroxide (HP) and fluoridated toothpaste containing bioactive glass (1450 ppm fluoride). Group 2: Bleaching using 40%HP and toothpaste containing calcium fluorosilicate bioglass (540 ppm fluoride). Group 3: Bleaching using 40%HP and fluoridated toothpaste (1450 ppm fluoride). Group 4: Bleaching alone using 40%HP. Group 5: Negative control with distilled water alone. The surface morphology was evaluated using Scanning Electron Microscope (SEM) and Scanning Probe Microscope (SPM). The concentration of elements as atomic percentages were determined by X-ray Photoelectron Spectroscopy (XPS) and Energy-Dispersive X-ray Spectroscopy (EDS). Results: This laboratory-based study reported that SPM and SEM detected minor changes on the surfaces of all toothpaste-treated enamel samples (Groups 1–3) after 45 days. Bioactive glass deposits were observed on enamel surfaces in Groups 1 and 2, whilst the bleaching-alone samples (Group 4) had rough enamel surfaces. XPS reported that toothpaste containing calcium fluorosilicate bioglass (Group 2) had a high atomic% of calcium and phosphate, whilst silicon values were high in the toothpaste containing bioactive glass and 1450 ppm fluoride (Group 1) after bleaching procedure when compared to other groups (p < 0.05). In addition, EDS detected the highest %F in Groups 1, 2 and 5. Conclusions: Within the limitations of this laboratory-based study, there was no significant decrease in the Ca%, P% values and surface properties of enamel after the bleaching procedure following the use of different formulations of toothpastes for a period of 45 days. However, the Ca% and P% values were significantly high for the toothpaste containing calcium fluorosilicate bioglass (BioMinF) on the bleached enamel. Clinical relevance: The bleaching process can provide optimum aesthetic outcomes, but the effect of peroxides on hard tissues is still in question. Toothpastes containing different formulations of fluoride and bioactive glass might have the potential to prevent mineral loss on bleached enamel. However, further laboratory-based studies and controlled double-blind randomised clinical trials are required to interpret the effects of toothpastes with different fluoride and bioactive glass formulations on enamel surfaces following bleaching procedures.
At-home tooth whitening solutions with good efficacy and biosafety are highly desirable to meet the ever-growing demand for aesthetic dentistry. As a promising alternative to the classic peroxide bleaching that may damage tooth enamel and gums, piezocatalysis has been recently proposed to realize non-destructive whitening by toothbrushing with piezoelectrical particles. However, traditional particles either pose potential threats to human health or exhibit low piezoresponse to weak mechanical stimuli in the toothbrushing. Here, biocompatible and biodegradable polylactide particles constructed from interlocking crystalline lamellae have been hierarchically designed as next-generation whitening materials with ultra-high piezocatalytic activity and biosafety. By simultaneously controlling the chain conformation within lamellae and the porosity of such unique lamellae network at the nano- and microscales, the particles possessing unprecedented piezoelectricity have been successfully prepared due to the markedly increased dipole alignment, mechanical deformability, and specific surface area. The piezoelectric output can reach as high as 18.8 V, nearly 50 times higher than that of common solid polylactide particles. Consequently, their piezocatalytic effect can be readily activated by a toothbrush to rapidly clean the teeth stained with black tea and coffee, without causing detectable enamel damage. Furthermore, these particles have no cytotoxicity. This work presents a paradigm for achieving high piezoelectric activity in polylactide, which enables its practical application in tooth whitening.
This in vitro study investigated the extrinsic tooth-whitening effect of bleaching products containing polyphosphates on the dental enamel surface compared to 10% carbamide peroxide (CP). Eighty human molars were randomly allocated into four whitening-products groups. Group A (control) was treated with 10% CP (Opalescence). The other groups with non-CP over-the-counter (OTC) products were group B = polyphosphates (iWhiteWhitening-Kit); group C = polyphos-phates+fluoride (iWhite-toothpaste); and group D = sodium bicarbonate (24K-Whitening-Pen). L *, a *, b * color-parameters were spectrophotometer-recorded at baseline (T0), one day (T1), and one month (T2) post-treatment. Changes in teeth color (ΔEab) were calculated. Data were analyzed using ANOVA and the Bonferroni test (α = 0.05). Groups A, B, and D showed significant differences in ΔL*&Δa
Whitening agents, such as hydrogen peroxide and carbamide peroxide, are currently used in clinical applications for dental esthetic and dental care. However, the free radicals generated by whitening agents cause pathological damage; therefore, their safety issues remain controversial. Furthermore, whitening agents are known to be unstable and short-lived. Since 2001, nanoparticles (NPs) have been researched for use in tooth whitening. Importantly, nanoparticles not only function as abrasives but also release reactive oxygen species and help remineralization. This review outlines the historical development of several NPs based on their whitening effects and side effects. NPs can be categorized into metals or metal oxides, ceramic particles, graphene oxide, and piezoelectric particles. Moreover, the status quo and future prospects are discussed, and recent progress in the development of NPs and their applications in various fields requiring tooth whitening is examined. This review promotes the research and development of next-generation NPs for use in tooth whitening.
Objectives
The aim of this study was to evaluate the mineral content, expressed by calcium (Ca) and phosphate (P), in dental enamel exposed to bleaching agents using micro-computed tomography (micro-CT), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and atomic force microscopy (AFM).
Methods
Sixty bovine dental enamel specimens were randomly divided into three groups (n=20): HP35ca (bleached using 35% hydrogen peroxide with Ca); HP35wca (bleached using 35% hydrogen peroxide without Ca); and control (without bleaching). Five specimens from each group were used for SEM and EDS analyses, 10 specimens were used for AFM analysis, and the remaining five specimens were used for micro-CT analysis. The pH of the gels was measured using a pH meter. The EDS and micro- CT data were analyzed using one-way ANOVA and Pearson’s correlation test. The AFM data were analyzed using one-way ANOVA (α=0.05).
Results
The weight percentages of Ca and P obtained using EDS were similar between the bleached and control groups. Small, superficial changes were observed by SEM in the HP35wca group. The HP35ca group showed similar patterns to the control group. AFM results showed no significant changes in the enamel roughness in any of the tested groups. No significant difference in the volume or depth of structural enamel loss was found between gels with and without Ca. No mineral loss was observed in the dentin substrate. The EDS and micro-CT analysis data exhibited a high correlation (p<0.001).
Conclusion
The addition of Ca to the bleaching gel had no beneficial effect on the bleached tooth enamel in terms of composition, mineral loss, and surface roughness. Micro-CT results exhibited a high correlation with the EDS results.
Aim This review article will help clinicians improve their thoughtful of the history of bleaching procedures, bleaching types, components, mechanisms, and their effects on tooth enamel and their micromorphology, surface Roughness, and microtensile bond strength to resin composite restorative material. Methods The debatable issues about activated bleaching procedures and their effects are reviewed. Additionally, the consequences of pre-and post-bleaching on the enamel surface and bonding potential of composite resin restorations are discussed. Conclusion The overall goal of the paper is to help reduce risks for patients.
Teeth whitening or bleaching has pleased people with aesthetic concerns for long. To improve the efficacy of bleaching and reduce the ill effects on the tooth surface, a combination of power bleaching (PB) and home bleaching (HB) can be used. Objective. To compare the efficacy and effects of combinations of PB/laser bleaching (LB) and HB protocol on human natural tooth structure. Materials & methods: Eighty-eight permanent maxillary central incisors were randomly divided into four groups (n=22). After staining, teeth were bleached using different bleaching protocols: Group 0 (control), Group 1 (Laser White 20 46% hydrogen peroxide (HP) + Opalescence PF 20% carbamide peroxide (CP) – HB sequence for 3 days), Group 2 (Laser White 20 46% HP + Opalescence PF 20% CP – HB sequence for 7 days), Group 3 (Opalescence PF 20% CP – HB sequence for 14 days). Colorimetric measurement was performed, enamel surface roughness and microhardness were measured. Scanning Electron microscope (SEM) evaluation was done to compare the surface topography. Pre and post bleaching data were analysed using paired T-test. Multiple comparison between groups was carried out using one-way ANOVA complemented by Post hoc test (Bonferroni), with significance level set at P<0.05. Results: All protocols demonstrated significant efficacy to whiten stained enamel. All groups demonstrated significant increase in hardness (P<0.05). Surface roughness reduced significantly in Group 1 and 2. SEM showed that Group 1 had a similar microscopic surface appearance as unbleached enamel, while Group 3 had accentuated irregularities. Conclusion: LB followed by HB for 3 days is the most effective in whitening stained teeth with positive effects on tooth surface hardness while maintaining surface topography of dental hard tissues.
This study evaluated the effects of four over‐the‐counter (OTC) bleaching products on the properties of enamel. Extracted human molars were randomly assigned into four groups (n = 5): PD: Poladay (SDI), WG: White Teeth Global (White Teeth Global), CW: Crest3DWhite (Procter & Gamble), and HS: HiSmile (HiSmile). The hydrogen peroxide (H2O2) content in each product was analyzed via titration. Twenty teeth were sectioned into quarters, embedded in epoxy resin, and polished. Each quarter‐tooth surface was treated with one of the four beaching times: T0: control/no‐bleaching, T14: 14 days, T28: 28 days, and T56: 56 days. Materials were applied to enamel surfaces as recommended. Enamel surfaces were examined for ultramicrohardness (UMH), elastic modulus (EM), superficial roughness (Sa), and scanning electron microscopy (SEM). Ten additional teeth were used to evaluate color and degree of demineralization (DD) (n = 5). Data were statistically tested by two‐way ANOVA and Tukey's tests (α = 5%). Enamel surfaces treated with PD and WG presented UMH values significantly lower than the controls (p < .05). Elastic modulus (E) was significantly reduced at T14 and T28 for PD, and at T14 for HS (p < .05). A significant increase in Sa was observed for CW at T14 (p < .05). Color changes were observed in the PD and WG groups. Additionally, DD analysis showed significant demineralization at T56 for CW. Overall, more evident morphological alterations were observed for bleaching products with higher concentrations of H2O2 (p < .05), PD, and WG. Over‐the‐counter bleaching products containing H2O2 can significantly alter enamel properties, especially when application time is extended. High concentrations of hydrogen peroxide can significantly alter enamel properties Prolonged use of hydrogen peroxide changed the enamel surface morphology The use of hydrogen peroxide increased the degree of demineralization
A stand‐alone atomic force microscope (AFM) featuring large scan, friction measurement, atomic resolution, and liquid operation, has been developed. Cantilever displacements are measured using the optical beam deflection method. The laser diode and focusing lens are positioned inside the piezo tube and the cantilever at the end of the piezo tube. Because the laser beam stays on the cantilever during scanning, the scan range is solely determined by the characteristics of the piezo tube. In our case 30×30×9.5 μm3 (xyz). The optical beam deflection detection method allows simultaneous measurement of height displacements and torsion (induced by lateral forces) of the cantilever. AFM images of dried lymphocytes reveal features in the torsion images, which are only faintly visible in the normal height images. A new way of detecting the nonlinear behavior of the piezo tube is described. With this information the piezo scan is linearized. The nonlinearity in a 30‐μm scan is reduced from 40% to about 1%, as is illustrated with images of a compact disk. The stand‐alone AFM can be combined with a (confocal) inverted microscope, yielding a versatile setup for biological applications.
This chapter describes dental enamel as a unique biological system that provides a hard surface for the teeth and enables them to reduce food to particles sufficiently small for effective attack by the digestive enzymes. Provided that it remains free from disease, human enamel can withstand a lifetime of crushing work without becoming fractured or completely worn away. Enamel is capable of performing this function only because of its most abundant constituent, hydroxyapatite, which gives it a hardness intermediate between that of iron and carbon steel. Three main aspects of tooth structure determine how physical stress is distributed within enamel. The gross morphology of the enamel cap defines the shape of both the occlusal surface and the amelodentinal junction. Forces within the enamel are transmitted to the underlying dentine, which is softer and more elastic than enamel, and acts as a firm cushion. The internal structure of enamel at histological and ultrastructural levels has an important bearing on its elastic behavior. This concerns the division of enamel into prismatic structures; the shapes, directions, and mutual interlacing of the prisms; and the arrangement of the crystallites within the prisms. In freshly secreted enamel, crystals first appear near the ameloblasts and, as soon as they do so, the enamel takes on the pattern of its final form, an intricate beautifully arranged two-phase system that may not only last throughout life but may also survive in fossil form for millions of years.
Extrinsic stain resides in the dental pellicle and can be caused by introduction of chromogenic materials or therapeutic agents into the oral cavity. In contrast, intrinsic tooth stain is found within the tooth structure and can be caused by a variety of agents, including hematological and developmental abnormalities and drugs such as tetracycline. The mechanisms of extrinsic stain formation differ with respect to the causative agent. For example, stain induced by chlorhexidine (CH) can be explained by an increased rate in the non-enzymatic browning reactions occurring at the pellicle surface, while food stains are retained on the surface via ion exchange mechanisms. Although most extrinsic dental stain can be removed by abrasive and/or surface-active materials, removal of certain types of surface stain, e.g., staining due to cationic antimicrobial agents, requires specific agents such as aminoguanidine to reduce the stain.
A broad-spectrum approach to reduce both intrinsic and extrinsic dental stains clinically requires oxygenating agents. To evaluate this approach and understand the mechanisms of stain removal, we developed a spectroscopic method for measuring stain in vivo. A series of clinical studies was performed to evaluate stain removal by the agents. The results showed that carbamide peroxide in combination with surfactants and anti-redeposition agents, e.g., sodium pyrophosphate, was more effective in bleaching dental stain compared with carbamide peroxide alone. A detailed examination of the tooth structure by microhardness measurements, x-ray photoelectron spectroscopy, and scanning electron microscopy showed that stain decolorization with this system did not have any adverse effects.
Bleaching is an effective method of whitening teeth. It is not predictable and has a sufficient history of adverse effects to warrant concern by the profession. Above all, procedures used in dental practice should preserve and protect the oral tissues environment. To date the clinical safety of bleaching has not been demonstrated. Most of the published research indicates that there should be concern for its safety when used in prolonged treatment.
Sections of human tooth enamel were exposed to concentrated hydrogen peroxide solution for periods of time ranging from 1 to 60 min. Some sections were posttreated with 37% phosphoric acid for 60 s and others were pretreated (etched) with 37% phosphoric acid for 60 s. Each of the sections used in the study was compared with a control specimen from the same tooth area which was exposed only to saline before and after treatment with 37% phosphoric acid for 60 s. A comparison of control and experimental sections indicated that exposure to concentrated hydrogen peroxide solution produced a precipitate on the enamel surface. The amount of precipitate appeared to be related to the length of the hydrogen peroxide exposure. The combination of hydrogen peroxide and acid etching resulted in an enamel surface that displayed more precipitate and appeared to be more porous than enamel surfaces used as controls. The significance of these findings relative to the adhesion of dental materials to bleached enamel surface is discussed.
Fifty-one human tooth pulps were evaluated histologically to determine the effect of bleaching procedures on vital teeth. Thermostatically controlled heat and 35% hydrogen peroxide were applied externally to premolars indicated for orthodontic extraction. The treatment consisted of three visits of 30 minutes' duration each. The teeth were then extracted after postoperative intervals of an hour, three days, 15 days, and 30 days. Histologic observations of the experimental groups were consistent with those of the control group. Under the conditions of this study, the bleaching of vital teeth may be considered harmless to pulpal tissue.
Three 10% carbamide peroxide home bleaching agents were evaluated to determine their effects on tensile bond strength of resin to enamel and enamel surface hardness. Eighty extracted bicuspid crowns were divided into four groups (three bleaching agents and control), and treated with the bleaching agents for five consecutive days. A bonding site on the buccal surface of each crown was etched with phosphoric acid and an orthodontic bracket bonded in place. The specimens were thermocycled and loaded to failure in an Instron Universal Testing Machine. Five hardness specimens per group were measured prebleaching and after five days' exposure. Analysis by one-way ANOVA indicated no significant differences in bond strength between the four groups (P > 0.05). There were also no differences in pre- or postbleaching Knoop hardness values for the four groups (P > 0.05). This study indicated that in short-term regimens 10% carbamide peroxide does not significantly affect enamel surface hardness or bonding ability.
The effect of bleaching agents on the enamel surface was examined by scanning electron microscopy. The comparison of treated to untreated enamel revealed that the treated surface had increased surface change and porosity after the equivalent of 30 hours of exposure to the bleaching agent. The degree of alteration of enamel surface was not uniform and was influenced by cleanliness (oral hygiene) of the treated teeth and apparent variation in calcification. The enamel surface developed varying degrees of surface porosity and alteration.
Extracted intact human teeth (n = 4) were treated for 30 days by three protocols: Home 1 (Proxigel, n = 4) for 8 hours daily, Home 2 (White & Bright, n = 4) for 24 hours with 3 minutes of stannous fluoride gel, or an Office protocol (n = 4) using 30% hydrogen peroxide (Superoxol) warmed by a high-intensity light while the controls remained untreated. "Home" bleaching agents contain approximately 10% carbamide peroxide. After treatment, the coronal surfaces were examined with a scanning electron microscope (SEM) at 2000 power magnification, and the surface topography was measured by a profilometer. The SEM photomicrographs of the controls and office-treated groups were similar to previously reported descriptions, while the home bleached surfaces appeared similar to each other. Profilometric analysis was used to examine surface roughness and surface waviness. Mean surface roughness in microns was: control, 1.9; Home 1, 0.6; Home 2, 0.9; and Office, 0.6. Surface waviness was ranked control > office > Home 1 = Home 2. Enamel surface alterations were evident after the three bleaching methods. The differences between the office and home-treated surfaces were unrelated to the pH of the bleaching agents.
The effect of a carbamide peroxide bleaching gel on the microleakage of Class V resin composite restorations with two dentin bonding agents was evaluated using extracted human teeth. Class V cavity preparations were placed at the cementoenamel junction of the facial and lingual surfaces of 20 teeth for a total of 40 preparations. Half of the teeth were restored with Scotchbond 2/Silux Plus and half were restored with Prisma Universal Bond 3/AP.H. Five teeth were randomly selected from each of the two groups and were stored in water at 37 degrees C to serve as controls. The remaining teeth were exposed to a carbamide peroxide gel for three 2-hour periods per day for 9 days. The specimens were stored in distilled water at 37 degrees C except during treatment periods. All teeth were then thermally stressed for 100 cycles. Microleakage was assessed by dye penetration. The results demonstrated that the carbamide peroxide agent adversely affected the marginal seal of both restorative systems.
The conservative technique for bleaching vital teeth using a nightguard and a 10% carbamide peroxide solution has captured the esthetic interests of the dental profession. The purpose of this article is to assess the safety of the products used in this bleaching technique based on results from past related research and current research. Ten percent carbamide peroxide solutions used in numerous studies have demonstrated tissue-healing properties as well as a propensity for the reduction of plaque and gingivitis. None of these clinical studies revealed any untoward or detrimental side effects, and all demonstrated beneficial effects. Although some concern exists regarding the potentiating effects of peroxide solutions in the presence of known carcinogens, concerns of toxicity or damage to hard and soft tissues appear unfounded. The majority of current and past research and literature indicates that the current use of a 10% carbamide peroxide solution in the method advocated for bleaching vital teeth is apparently safe when administered properly under the supervision of a dentist.
The effect of concentrated hydrogen peroxide solution, alone and in combination with acid-etching with 37% phosphoric acid for 60 s, on the surface morphology of cut human dentin was investigated by SEM and compared to controls in which saline solution rather than hydrogen peroxide solution was used. Examination of the specimens revealed that the smear layer on the surface of cut dentin was not removed by hydrogen peroxide alone, and that a dense amorphous precipitate was formed on the surface of the smear layer after extended exposure. The precipitate accumulation was first noted after 20 min of exposure. Examination of the dentin after hydrogen peroxide exposure followed by acid-etching revealed the presence of a fine granular deposit on an otherwise clean dentin surface. A modest amount of amorphous precipitate was seen over the entire dentin surface after 60 min of hydrogen peroxide exposure. Examination of specimens that were acid-etched before being exposed to hydrogen peroxide indicated that the smear layer was effectively removed and the orifices of the dentinal tubules were enlarged to permit more effective penetration of the peroxide solution. It also resulted in less accumulation of precipitate on the dentin surface than the other methods.
1.1. Six patients with cystic fibrosis, ranging in age from 6 to 18 years, were selected at random for a preliminary study of a technique for bleaching vital teeth which were stained by tetracycline administration.2.2. Bleaching was accomplished by warming a 30 per cent hydrogen peroxide solution to approximately 88° F. with a hand-held heating source which was placed over the external surface of the tooth for 30 minutes. The peroxide solution was kept in contact with the tooth by means of a gauze matrix.3.3. Each patient was given eight treatments, generally at one-week intervals, and was seen and treated monthly thereafter.4.4. There was significant esthetic improvement in five of the six patients. The results were evaluated on the basis of the clinician's observations, pre- and postoperative color photographs, and the recorded comments of the patients and their parents.
In this study, the influence of urea solutions on both young and mature enamel was investigated. The urea concentrations were 5 and 0.1 M; the interaction period varied between 3 h and 3 months. The hydrogen (H)-bond destruction due to urea produces tiny micro-channels. The scanning electron microscope (SEM) investigations on replicas and by direct observations indicated that: (i) urea solutions destroy H-bonds in specific areas; (ii) these areas are most likely isolated prisms in the perikymata; (iii) interprismatic regions are, in contrast to these prisms, hardly influenced by the urea solutions. It is suggested that the special areas with relatively weak H-bonding are similar to the area attacked initially in artificial caries-like enamel lesions.Copyright © 1983 S. Karger AG, Basel
In this paper the interaction of urea on plaque-free sound human enamel is described. In 1 week urea penetrates in the enamel several hundred micrometers. It weakens or destroys part of the peptide structure, especially interprismatically. Urea does not or not measurably attack the organic matrix between the crystallites. Due to the urea interaction organic material normally plugging natural defects in the enamel surface, especially in the perikymata, is removed.Copyright © 1984 S. Karger AG, Basel
The application of heat ranging from 115 to 124 F and a 35% solution of hydrogen peroxide to intact human premolars causes a mild superficial inflammation (graded 0.5 to 1.0) in a significant number of pulps. Peroxide alone, or heat with saline solution, was judged to be less irritating since it did not cause a significant number of inflammatory responses.
Hydrogen peroxide and heat are two components of a technique commonly used to bleach human teeth. The effects of these two components on pulp tissue of dog teeth were evaluated histologically. Hydrogen peroxide alone or with heat caused obliteration of odontoblasts, hemorrhage, resorption, and inflammatory infiltration, while heat alone was not detrimental. Pulpal changes demonstrated evidence of reversibility after 60 d.
Studies on home-use bleaching agents containing carbamide or hydrogen peroxide demonstrate minimal topographic alteration and insignificant organic change to tooth material. This in vitro study evaluated the effects of a three-step commercial home-use bleaching agent on extracted human incisors over time. Each tooth was digitized by baseline and sequential profilometry and analyzed using computer software. Statistically significant volume loss was evident in cementum and dentin after simulations of 4 and 8 weeks of use.
Conservative techniques for improving the appearance of discolored teeth have become popular in the past decade. These include: in-office bleaching with 30% hydrogen peroxide, which is applied on etched enamel with a gauze pad and then exposed to a bleaching light; home bleaching with a mild form of peroxide, such as 10% carbamide peroxide, which is applied on the tooth surface with custom-made mouthguards; and enamel micro-abrasion with 18% hydrochloric acid, which is applied in a pumice slurry. In this study, the in-office bleaching and enamel micro-abrasion techniques were performed on extracted teeth for investigation of their microscopic effects on the surface enamel. Specimens treated only with 37% phosphoric acid showed an enamel loss of 5.7 +/- 1.8 microns. The specimens treated with 37% phosphoric acid followed by 30% hydrogen peroxide showed enamel loss of 5.3 +/- 1.6 microns; this loss was probably not caused by the hydrogen peroxide, but rather by the etching with 37% phosphoric acid which preceded the hydrogen peroxide application. A direct application of 18% hydrochloric acid for 100 s resulted in a loss of 100 +/- 47 microns. The extent of enamel loss was much greater when the 18% hydrochloric acid was applied in a pumice slurry for the same period of time (360 +/- 130 microns), and the effect was time-dependent. Thus, the pumice and rotary prophy cup used in conjunction with the 18% hydrochloric acid contributed markedly to the loss of surface enamel, enhancing the non-selective stain-removing action of the hydrochloric acid. Therefore, the hydrochloric acid-pumice technique must be used clinically with caution.
It has been well documented that bleaching whitens teeth, but has its safety been documented? This paper reviews bleaching's predictability, esthetics, longevity, and side effects. A discussion of the bleaching reaction on teeth and soft tissue raises concerns over the safety of the procedure.
Whitening enamel with carbamide peroxide (CP) to remove cosmetically displeasing stains has become common-place in dental practice. This in vitro study evaluated CP treatment effects on enamel surface morphology and caries-like lesion susceptibility. Tooth quarters were prepared from 10 caries-free human molars following a fluoride-free prophylaxis. The tooth quarters were assigned to the following treatment groups: 1) Distobuccal-10 percent NW gel (Nite White, Discus Dental); 2) Distolingual-10 percent PL paste (Platinum, Colgate); 3) Mesiobuccal-16 percent NW gel; and 4) Mesiolingual-Control. Following the manufacturers' recommended treatment, each quarter was sectioned with one portion prepared for SEM and the other portion for caries-like lesion formation. Intact enamel surfaces were present with all treatments. Enamel prism markings with exaggerated prism peripheries and mild to moderate prism core loss were seen with both 10 percent NW and 16 percent NW gels, but was more prominent with 16 percent NW gel. Amorphous surface layers with occasional exposure of indistinct prism markings occurred with 10 percent PL paste. Body of lesion mean depths were 135 microns control, 159 microns 16 percent NW, 144 microns 10 percent NW, and 122 microns 10 percent PL. Lesion depths were significantly different (p < 0.05 DMR paired design) between 10 percent PL and 16 percent NW, and between control and 16 percent NW. Whitening enamel surfaces in vitro with 10 percent carbamide peroxide paste containing dicalcium phosphate dihydrate (Colgate-Platinum) produced an amorphous surface layer and reduced caries susceptibility when compared with 16 percent carbamide peroxide gel (Nite White).
The effects of four bleaching agents (Opalescence, HiLite, 30% hydrogen peroxide, and 30% hydrogen peroxide mixed with sodium perborate) and 37% phosphoric acid on the external surface of human enamel were examined with the scanning electron microscope. The materials were applied to the enamel surfaces of 60 specimens obtained from 10 teeth. Each test agent was applied to one specimen from each tooth. One specimen of each tooth was left untreated. Comparison to the untreated control surfaces revealed that enamel exposed to the bleaching agents underwent slight morphologic surface alterations. The enamel surfaces treated with phosphoric acid, in contrast, showed severe morphologic alterations.
The literature on the methods of removing dental stain and whitening teeth is extensive. By comparison, little has been published on the chemical mechanisms that cause dental discolorations. This article proposes a classification for extrinsic dental stain and describes the chemical mechanisms involved in causing tooth discolorations. It also discusses the current theories of the chemistry of stain removal processes.
Since the mid-1980s, bleaching teeth has grown significantly in popularity. This article provides an overview of current practitioner trends relative to this procedure.
Discolored teeth are the primary aesthetic concern among dental patients. While many seek professional advice and treatment, an alarming number opt for non-professional quick-fix solutions. The in-office bleaching modality often is overlooked in favor of at-home vital bleaching. But this option has been proven to be effective, quick and safe-either alone or in combination with other aesthetic treatments-as a method of brightening and enhancing a patient's smile.
Kinetics of carbamide peroxide degradation in bleaching trays
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Pulpal response to bleaching of teeth in dogs
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Penetration of radioactive isotopes through enamel and dentin
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