[Show abstract][Hide abstract] ABSTRACT: Transverse microradiography (TMR) and electron probe microanalysis (EPMA) are commonly used for characterizing dental tissues. TMR utilizes an approximately monochromatic X-ray beam to determine the mass attenuation of the sample, which is converted to volume percent mineral (vol%min). An EPMA stimulates the emission of characteristic X-rays from a variable volume of sample (dependent on density) to provide compositional information. The aim of this study was to compare the assessment of sound, demineralized, and remineralized enamel using both techniques. Human enamel samples were demineralized and a part of each was subsequently remineralized. The same line profile through each demineralized lesion was analyzed using TMR and EPMA to determine vol%min and wt% elemental composition and atomic concentration ratio information, respectively. The vol%min and wt% values determined by each technique were significantly correlated but the absolute values were not similar. This was attributable to the complex ultrastructural composition, the variable density of the samples analyzed, and the nonlinear interaction of the EPMA-generated X-rays. EPMA remains an important technique for obtaining atomic ratio information, but its limitations in determining absolute mineral content indicate that it should not be used in place of TMR for determining the mineral density of dental hard tissues.
Microscopy and Microanalysis 02/2014; 20(3):937-945. · 1.76 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Objective:
To test whether allocating Continuous Professional Development (CPD) points increases the number of adolescents screened by clinicians to a clinical trial known as “ACE MID” (Assessing Cost Effectiveness of Implementing a Minimal Intervention Dentistry approach for adolescent public patients at high risk to dental caries).
Participant recruitment to ACE MID is a two stage process involving community dental clinicians (CDCs) and researchers. Clinicians working at 12 participating clinics are responsible for screening their patients’ suitability to join the study, using an electronic screening tool. Research staff then telephone suitable adolescents to undertake the consent process.
Each clinic is required to recruit 42 adolescents.
A confounding factor in recruiting participants to this study is that the first screening stage of the recruitment process is undertaken by a third party, the CDC.
To address this factor, research staff initially developed a training PowerPoint to be delivered by clinic managers, and attended team meetings at some clinics to deliver this training. On request, they also provided one- on-one instructions on how to use the electronic screening tool.
Despite these strategies, initial screening was variable and often slow amongst some CDCs.
A CPD on-line training initiative was launched to boost the number of adolescents screened. Each CDC who completes the online CPD and actively screens patients for their clinic receives four CPD points once 42 participants are recruited from that clinic.
The CPD initiative has increased the number of adolescents screened for the study.
A multi-strategy approach is required to recruit suitable participants to any clinical trial. In this study, motivating time-poor clinicians, who face increasing demands with competing priorities, is the first challenge in participant recruitment. A CPD initiative is effective in motivating CDCs to screen participants for a clinical trial.
10th World Congress on Preventive Dentistry 2013; 10/2013
[Show abstract][Hide abstract] ABSTRACT: Objective: To evaluate the ability of calcium and fluoride containing varnishes to inhibit demineralization.
Six fluoride varnishes were selected for analysis: 1) Enamel Pro containing amorphous calcium phosphate; 2) Clinpro White containing functionalized tricalcium phosphate (fTCP); 3) Profluorid 5 containing calcium fluoride; 4) MI containing casein phosphopeptide amorphous calcium phosphate (CPP-ACP); and 5) Duraphat (no added calcium positive control); and 6) Placebo (no added calcium or fluoride). Thirty-six extracted human teeth collected were sterilized and a window in each slab was created using nail varnish. Each slab was cut into two halves. For one half-slab, two-thirds of the window was covered with one of the six different dental varnishes and the other one-third of the window was not covered with varnish. For the other half-slab, two-thirds of the window was covered with acid-resistant nail varnish and the other one-third of the window was not covered with varnish. The half-slabs were then immersed in an acid solution for four days at 37oC with a change of solution each day. After the four days, each test half-slab was then matched with its corresponding control half-slab for sectioning and microradiographic image analysis to compare the effect of the different dental varnishes on demineralization inhibition.
Result: All fluoride and calcium containing varnishes tested in this in vitro study showed significantly greater inhibition of demineralization of enamel subsurface lesions as well as significantly reduced lesion depths than Placebo varnish, where MI Varnish produced the highest demineralization inhibition and significantly greater than Duraphat Varnish. The order of demineralization inhibition was: MI Varnish >Clinpro White >Enamel Pro>Profluorid>Duraphat> Placebo.
Conclusion: Dental varnish containing calcium and fluoride significantly inhibited demineralization of enamel subsurface lesion, while MI Varnish which contains CPP-ACP and fluoride produced the highest demineralization inhibition in this in vitro study.
IADR Asia/Pacific Region (APR) Regional Meeting and Co-Annual Scientific Meeting of IADR Divisions 2013; 08/2013
[Show abstract][Hide abstract] ABSTRACT: OBJECTIVES: To investigate and clarify physical and chemical properties of enamel affected by Molar Incisor Hypomineralisation (MIH). METHODS: A series of in vitro studies were performed on extracted molars affected by MIH and sound teeth for controls. Tooth sections underwent Vickers microhardness testing before lapping and subsequent transverse microradiographic analysis and examination under polarised light microscopy. Carbonate content was determined by CO2 release from acid digestion. Unprepared and fractured surfaces were examined under scanning electron microscopy. RESULTS: MIH-affected molars demonstrated a severe degree of hypomineralisation with an average mineral content of only 58.8% vol% mineral. Vickers microhardness was significantly reduced in MIH compared with controls (1.8±1.1 v 4.4±1.0GPa, p<0.05) and polarised light microscopy revealed the bulk of MIH lesions had a porosity of ≤ 5% but also substantial areas of ≥ 10% and smaller areas exceeding 25% porosity. A surface layer was frequently observed on both intact and broken-down lesions and cervical regions of MIH teeth were typically spared. Carbonate content of MIH enamel was higher than control samples (6.6±2.1 v 4.4±1.1 wt%, p<0.05). Scanning electron microscopy showed that both the enamel rod and surface ultrastructure were defective. Clinical characteristics did not consistently correlate with all properties. CONCLUSIONS: The properties of MIH-affected enamel significantly differ from those of normal enamel and were highly variable, however some common characteristics were observed. Implications for aetiology and clinical management are discussed.
Journal of dentistry 05/2013; · 3.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A new glass-ionomer cement (GIC) (Fuji VII™ EP) includes 3% (w/w) casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) to enhance ion release. OBJECTIVES: To assess this new GIC compared with a GIC without CPP-ACP (Fuji VII™) with respect to ion release, changes in surface hardness and in mass under a variety of acidic and neutral conditions. METHODS: Eighty blocks of Fuji VII™ (F7) and Fuji VII™ EP (F7EP) were subjected to three acidic solutions (lactic and citric acids pH 5.0, hydrochloric acid pH 2.0) and water (pH 6.9) over a three-day period. Ion release, surface hardness and weight measurements were carried out every 24h. RESULTS: Higher calcium ion release from F7EP was observed under all acidic conditions. Increased inorganic phosphate ion release was observed for F7EP in hydrochloric and citric acids. Fluoride ion release was similar between F7 and F7EP under all conditions but was significantly higher in acids compared with water. After three days there was no significant difference in surface hardness (p>0.05) between the two materials under all conditions except hydrochloric acid. Minimal change in mass was observed for F7 and F7EP in water, lactic and hydrochloric acids, however citric acid caused significantly more mass loss compared with water (p<0.001). CONCLUSION: Incorporation of 3% (w/w) CPP-ACP into F7 enhanced calcium and phosphate ion release, with no significant change in fluoride ion release and no adverse effects on surface hardness or change in mass. CLINICAL SIGNIFICANCE STATEMENT: GICs have the potential to release fluoride ions particularly under acidic conditions associated with dental caries and erosion. A new GIC containing CPP-ACP and fluoride releases not only fluoride ions but also calcium and phosphate ions under acidic conditions which should help to inhibit demineralisation associated with caries and erosion.
Journal of dentistry 02/2013; · 3.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Molar-incisor hypomineralisation (MIH) is a problematic and costly condition. Caries remineralising agents are often recommended for MIH management despite the lack of evidence that these lesions have the capacity for increasing their mineral content. Following surface layer removal ± NaOCl pre-treatment and 14-day exposure to a CPP-ACFP solution at pH 5.5, MIH lesions were analysed using transverse microradiography and polarised light microscopy. Lesions were highly variable but treatment with the remineralising solution increased mineral content (1,828 ± 461 vol% min·µm, %R = 17.7 ± 5.7) and porosity decreased demonstrating the proof of concept that the mineral content of developmentally hypomineralised enamel can be improved after eruption.
Caries Research 01/2013; 47(3):259-263. · 2.50 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Quantitative light-induced fluorescence (QLF) and digital photography (DP) have been proposed as clinical methods for measuring changes in enamel mineral content. The aim of this study was to compare the ability of QLF and DP with the in vitro gold standard transverse microradiography (TMR) to measure the remineralization of enamel subsurface lesions.
Subsurface lesions were formed in enamel (n = 40) and exposed to remineralization solutions for 10 days. Changes were analysed by DP, QLF and TMR to determine percentage changes in luminescence (%L), fluorescence (%F) and mineral content (%R), respectively and correlation between these parameters determined.
The correlations between TMR and QLF (r = 0.63), TMR and DP (r = 0.59), and DP and QLF (r = 0.64) were all moderate but statistically significant (p < 0.001). The variability in %L and, to a lesser extent, %F values significantly impacted on the potential role of DP and QLF as methods by which mineral content changes produced by remineralization treatments could be accurately measured.
Both QLF and DP provided data that correlated moderately with TMR data. QLF images were easier to analyse, free of glare and had less variability compared with those produced using DP.
Australian Dental Journal 09/2012; 57(3):271-6. · 1.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Phosphoproteins/phosphopeptides with clusters of acidic residues are found throughout nature, where they aid in the prevention of unwanted precipitation of solid calcium phosphates. The acidic residues, particularly phosphoserine, interact with calcium and stabilize clusters of calcium and phosphate. Saliva and milk are two examples of biological fluids that contain such phosphoprotein/phosphopeptide-stabilized calcium phosphates, and both share a similar evolutionary pathway. Saliva has been shown to have remineralization potential and is of critical importance in maintaining the mineral content of teeth in the oral environment. Milk can be enzymatically modified to release casein phosphopeptides that contain the clusters of residues that allow milk to stabilize high concentrations of calcium and phosphate. These casein phosphopeptide-stabilized amorphous calcium phosphate nanocomplexes (CPP-ACP) can stabilize even higher concentrations of calcium and phosphate than milk and can be considered a salivary biomimetic, since they share many similarities to statherin. The mechanisms of action and the growing body of scientific evidence that supports the use of CPP-ACP to augment fluoride in inhibiting demineralization and enhancing the remineralization of white-spot lesions are reviewed.
[Show abstract][Hide abstract] ABSTRACT: The aim of this in vitro study was to determine the effect of four different orthodontic adhesive removal techniques on sound, demineralized and remineralized enamel.
Composite resin adhesive was bonded to 100 teeth which were divided into four groups with each comprising five sound teeth and 20 teeth with demineralized and remineralized lesions adjacent to the adhesive. Adhesive was removed with either: (1) slow speed bur (SS); (2) high speed bur (HS); (3) aluminium oxide disc (DC); or (4) ultrasonic scaler (US). Damage to the enamel was assessed using white light profilometry, digital photography and scanning electron microscopy.
The least to greatest mean depth of damage with the four different adhesive removal techniques to sound enamel was DC = SS < US = HS and to demineralized and remineralized enamel were DC < HS < US = SS. Sound enamel experienced the least amount of damage. Remineralization prior to adhesive removal significantly reduced the amount of damage produced by all techniques compared with demineralized enamel. Discs were the least damaging to demineralized and remineralized enamel compared with the other removal techniques.
When demineralization was present discs were found to be the least damaging adhesive removal technique and remineralization further reduced the amount of enamel damage.
Australian Dental Journal 09/2012; 57(3):365-72. · 1.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: During the ICNARA 2 conference, a workshop was held on remineralization models. The group considered the role of remineralization models, whether there was one ideal in situ model design, what essential features should be incorporated into an in situ model, other alternative models, and what new methods for measuring remineralization were on the horizon. This paper summarizes the discussion. In situ and other caries models can be used as a surrogate for caries clinical trials but only when data exist to validate the model. In situ model design should be flexible to allow for investigation of different aspects of the caries process; however, several essential features were identified that should be incorporated into the study design. A range of other caries models was discussed, including the study of non-cavitated lesions, lesions post-orthodontic therapy, plaque retention models to form more standardized lesions, and the study of root caries lesions. Numerous new methods for quantifying remineralization were discussed, but it was considered that these require validation before they can be used in clinical trials.
Advances in dental research 09/2012; 24(2):129-32.
[Show abstract][Hide abstract] ABSTRACT: Dental erosion is an increasingly prevalent problem in Australia, with the consumption of sports beverages suggested as a risk factor. The aim of this study was to compare the erosive potential of Australian sports beverages.
Ten beverages were selected and analysed to determine their pH, titratable acidity and apparent degree of saturation with respect to apatite. The erosive potential of the beverages was measured by human enamel surface loss and surface softening following a 30-minute exposure. A taste testing panel was established to determine the palatability of the sports beverages.
All sports beverages except Sukkie and Endura produced substantial surface loss and surface softening. Compared with the other sports beverages, Sukkie and Endura had a higher pH, lower titratable acidity and higher calcium content. However, Sukkie and Endura were deemed to be less palatable than the other more acidic sports beverages.
The majority of the sports beverages tested produced dental erosion in this in vitro model. However, two new products Sukkie and Endura have lower erosive potential but also lower palatability.
[Show abstract][Hide abstract] ABSTRACT: Soy beverages are water extracts of whole soybeans and are often promoted as a healthy alternative to bovine milk. Little analysis has been carried out to determine the effects of soy beverages on oral health, especially their potential acidogenicity.
The aim of this study was to determine the potential acidogenicity of a range of soy and bovine milk beverages.
In vitro acid production by Streptococcus mutans was measured in soy and milk beverages at a constant pH of 6.5 or 5.5, as was the fall in pH over a 10 min period. The acid buffering capacity and calcium and phosphate concentrations (total and soluble) of the beverages were also determined.
The rate of acid production by S. mutans in the milk beverages was five to six times lower at pH 6.5 than in the soy beverages and three to five times lower at pH 5.5. Whilst the pH fall in the presence of S. mutans over 10 min was negligible in the milk beverages there was a significant decrease in pH in the soy beverages. This was also reflected in the lower buffering capacity of the soy beverages. The levels of soluble calcium in the soy beverages were lower than those in the milk beverages although total calcium contents were similar.
Soy beverages have a higher potential acidogenicity than bovine milk beverages. CLINICAL SIGNIFICANCE STATEMENT: Patients consider soy beverages to be a healthy, low cariogenic alternative to other beverages, including bovine milk. This study shows that soy beverages have a higher potential acidogenicity than bovine milk and therefore may have a greater potential cariogenicity.
Journal of dentistry 05/2012; 40(9):736-41. · 3.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Carbonate determination in dental apatites such as dentine and enamel is important for studying the dynamics of dental caries and developmental defects of these tissues. Traditionally, these determinations have been performed by acidic digestion with the subsequent measurement of released carbon dioxide gas. As an alternative, Raman spectroscopy has been used for the determination of carbonate in synthetic carbonated apatites with at least four analytical methods published thus far. However, these methods have not been applied to biological apatites. The aim of this comparative study was to test the suitability of these four methods for the determination of B-type carbonate in human enamel and dentine. A method for determining the A-type carbonate content of enamel using the Raman technique is also presented. Raman spectra were obtained from 10 human enamel and dentine samples and analysed with each of the four methods using either a single or multiple ν(1)(PO(4)(3-)) band spectral fitting model. Each of the methods resulted in a different determination for the carbonate content when using the same measurement data. The method that used the full-width-at-half-maximum of the ν(1)(PO(4)(3-)) band to determine the B-type carbonate concentration was found to be in best agreement with (i) the results (using the acid digestion method) of teeth collected from the same sample population and (ii) previously reported values for both enamel and dentine. The use of a multiple-band spectral fitting model produced the highest determination precision (particularly in the case of dentine).
Caries Research 05/2012; 46(4):353-60. · 2.50 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Remineralisation has been shown to be an effective mechanism of preventing the progression of enamel caries. The aim of this double-blind, randomised, cross-over in situ study was to compare enamel remineralisation by chewing sugar-free gum with or without casein phosphopeptide amorphous calcium phosphate (CPP-ACP) where the enamel lesions were exposed to dietary intake and some were covered with gauze to promote plaque formation. Participants wore removable palatal appliances containing 3 recessed enamel half-slabs with subsurface lesions covered with gauze and 3 without gauze. Mineral content was measured by transverse microradiography, and plaque composition was analysed by real-time polymerase chain reaction. For both the gauze-free and gauze-covered lesions, the greatest amount of remineralisation was produced by the CPP-ACP sugar-free gum, followed by the gum without CPP-ACP and then the no-gum control. Recessing the enamel in the appliance allowed plaque accumulation without the need for gauze. There was a trend of less remineralisation and greater variation in mineral content for the gauze-covered lesions. The cell numbers of total bacteria and streptococci were slightly higher in the plaque from the gauze-covered enamel for 2 of the 3 treatment legs; however, there was no significant difference in Streptococcus mutans cell numbers. In conclusion, chewing sugar-free gum containing CPP-ACP promoted greater levels of remineralisation than a sugar-free gum without CPP-ACP or a no-gum control using an in situ remineralisation model including dietary intake irrespective of whether gauze was used to promote plaque formation or not.
Caries Research 04/2012; 46(2):147-55. · 2.50 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: White-spot enamel lesions are an early presentation of dental caries and are ideally managed by non-invasive procedures. The aim of this study was to characterize white-spot enamel lesions by x-ray microtomography. In particular, mineral content across the lesion from the surface to the base of the lesion was measured and surface layers defined. Molars with long buccal white-spot enamel lesions were collected, photographed, and each sectioned to produce 3 500-µm-thick sections. The sections were mounted and imaged by quantitative x-ray microtomography at a 15-µm voxel size. We analyzed line profiles through the middle of each 3D image to determine mineral content and depth. The surface layer thickness of the lesions ranged from 35 to 130 µm, with the maximum mineral content in this layer being 74% to 100% of that of sound enamel. The average mineral content across the lesions ranged from 1.73 to 2.48 g/cm(3). No significant differences could be found between lesions clinically categorized as active and those categorized as inactive. However, for depth-matched active and inactive lesions, the active lesions exhibited a more porous surface layer than the inactive lesions. White-spot enamel lesions are highly variable, with surface layers of considerable thickness.
Journal of dental research 11/2011; 91(2):185-91. · 4.14 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Dental products containing calcium phosphate and fluoride are claimed to enhance enamel remineralization over fluoride products.
To compare remineralization of enamel subsurface lesions by dental products with added calcium phosphate in a double-blind, randomized, cross-over in situ study.
Human enamel specimens with subsurface lesions were prepared and inserted into intra-oral appliances worn by volunteers. A slurry (1g product plus 4 ml H(2)O) of each product was rinsed for 60s, 4 times per day for 10 days. Six products were tested (i) placebo, (ii) 1000 ppm F, (iii) 5000 ppm F, (iv) Tooth Mousse (TM), (v) TM plus 900 ppm F (TMP) and (vi) Clinpro with 950 ppm F. Calcium, inorganic phosphate and fluoride levels were measured in post-rinse/saliva samples using ion chromatography. Mineral content was measured using transverse microradiography.
Only TM and TMP significantly increased salivary calcium and phosphate levels. The products produced remineralization in the following order from lowest to highest: placebo<1000 ppm F=Clinpro<5000 ppm F<TM<TMP.
Clinpro was not significantly different to 1000 ppm F whereas TM and TMP were superior to 5000 ppm F with TMP producing the highest level of enamel lesion remineralization.
Journal of dentistry 07/2011; 39(7):518-25. · 3.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: White-spot lesions (WSL) might be susceptible to mechanical damage during orthodontic bracket and adhesive removal. The aims of this in-vitro study were to investigate enamel loss on bracket and adhesive removal when the brackets were surrounded by WSL and to determine the effect of remineralizing these lesions with a 1% (w/v) casein phosphopeptide amorphous calcium fluoride phosphate (CPP-ACFP) solution before bracket and adhesive removal.
Precoated metal mandibular incisor brackets were centrally bonded onto polished third molars and WSL produced by exposure to a demineralization buffer for 4, 12, and 30 days (n = 20 per group). Half of the demineralized window was covered with acid-resistant nail varnish, and the specimens were then subjected to remineralization with 1% CPP-ACFP. Brackets and residual adhesive were removed, and enamel damage was assessed by digital photography, profilometry, and scanning electron microscopy. Lesion depth, mineral loss, and remineralization were measured by transverse microradiography.
WSL enamel around the bracket was more susceptible to iatrogenic damage at adhesive removal compared with sound enamel. Remineralization of lesions with 1% CPP-ACFP before adhesive removal significantly (P <0.002) reduced the area and depth of damage.
Remineralizing WSLs with CPP-ACFP before adhesive removal reduced iatrogenic enamel damage.
American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 06/2011; 139(6):e543-51. · 1.33 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Dental caries is a highly prevalent diet-related disease and is a major public health problem. A goal of modern dentistry is to manage non-cavitated caries lesions non-invasively through remineralization in an attempt to prevent disease progression and improve aesthetics, strength, and function. Remineralization is defined as the process whereby calcium and phosphate ions are supplied from a source external to the tooth to promote ion deposition into crystal voids in demineralized enamel, to produce net mineral gain. Recently, a range of novel calcium-phosphate-based remineralization delivery systems has been developed for clinical application. These delivery systems include crystalline, unstabilized amorphous, or stabilized amorphous formulations of calcium phosphate. These systems are reviewed, and the technology with the most scientific evidence to support its clinical use is the remineralizing system utilizing casein phosphopeptides to stabilize and deliver bioavailable calcium, phosphate, and fluoride ions. The recent clinical evidence for this technology is presented and the mechanism of action discussed. Biomimetic approaches to stabilization of bioavailable calcium, phosphate, and fluoride ions and the localization of these ions to non-cavitated caries lesions for controlled remineralization show promise for the non-invasive management of dental caries.
Journal of dental research 11/2010; 89(11):1187-97. · 4.14 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To investigate, in vitro, the effect on enamel erosion of the addition of 0.2% w/v casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) to four commercially-available soft drinks, two of which were carbonated.
Enamel specimens (n=27) were sectioned from sound extracted human third molar teeth and polished to a mirror finish. Exposed enamel windows of 1 mm2 were created by painting the surface with acid-resistant nail varnish. Four citric flavoured soft drinks (pH range 2.2 to 2.4) and distilled deionized water (DDW) were tested. Each drink was tested with and without 0.2% CPP-ACP w/v. The specimens were placed into 50 mL of solution at 37 °C for 30 minutes, rinsed and varnish removed. The samples were profiled with a white light profilometer and erosive depths recorded.
All soft drinks tested caused enamel erosion but adding 0.2% w/v CPP-ACP significantly reduced (p<.05) erosive depth in all test solutions in comparison with the solutions without CPP-ACP. The erosive depths for all solutions with 0.2% CPP-ACP did not differ significantly from those of DDW.
Adding CPP-ACP at 0.2% w/v significantly decreased the erosivity of all four soft drinks. The erosivity of the soft drinks with 0.2% CPP-ACP added did not differ significantly from that of distilled water.
Australian Dental Journal 09/2010; 55(3):275-9. · 1.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Objectives: It has been reported that 2 to 96% of orthodontic patients develop white spot lesions. Anecdotally, these lesions are more susceptible than sound enamel to iatrogenic damage during adhesive removal. The aims of this in vitro study were to determine the effect of severity of demineralisation and the effect of different removal techniques on damage at adhesive removal. In both cases the effect of remineralising the demineralised enamel prior to adhesive removal was also assessed to determine whether this would reduce its susceptibility to damage.
Methods: Extracted human molars were polished and bonded with orthodontic adhesive. A Carbopol demineralisation buffer was used to create lesions of three severities by exposure for 0(n=20), 4(n=20), 12(n=100) or 30(n=20) days. Half of each lesion was remineralised with 1% casein phosphopeptide stabilised-amorphous calcium fluoride phosphate (CPP-ACFP) solution for 30 days. Adhesive was removed with a slow speed tungsten carbide bur(SS), high speed tungsten carbide bur(HS), ultrasonic scaler(US) or aluminum oxide disc(DC). Damage was assessed using non-contact white light profilometry, digital image analysis and scanning electron microscopy. Demineralisation and remineralisation were quantified using transverse microradiography.
Results: All adhesive removal techniques damaged demineralised enamel significantly more than sound enamel. Lesions with greater mineral loss had a deeper depth of damage. The order of most to least damaging adhesive removal technique to the demineralised and remineralised enamel were SS=US>HS>DC. The CPP-ACFP treatment produced high percentages of remineralisation. In all cases, remineralisation of the demineralised enamel prior to adhesive removal significantly reduced the depth and area of damage.
Conclusions: Demineralised enamel was more susceptible to damage at adhesive removal than sound or remineralised enamel with the aluminum oxide disc being the least damaging removal technique. Remineralisation of the demineralised enamel prior to adhesive removal significantly reduced damage in all cases.
Supported by the Australian Dental Research Foundation.