Enamel demineralisation assessed by computerised image analysis of clinical photographs

Effectiveness of resin infiltration (ICON) and microabrasion-remineralization technique with two remineralizing agents (Tooth Mousse and Toothmin) on permanent incisor hypoplasia - A randomized clinical trial

Aims

The study aims to compare the effect of resin infiltration and microabrasion-remineralization (MAb-Re) with Tooth Mousse and Toothmin on permanent incisor hypoplasia.

Materials and Methods

The study included children with permanent incisor hypoplasia above 9 years of age, 171 teeth divided randomly into four groups: Group A - ICON, Group B - MAb-Re using Tooth Mousse, Group C - MAb-Re using Toothmin, and Group D - control group. Process involved taking standardized photographs at T1 - before intervention, T2 - immediately after treatment, and T3 - 6-month follow-up. Color evaluation, area calculation, participant and expert opinion using a Likert scale, treatment time, and cost-effectiveness were all taken into consideration during the assessment.

Statistical Analysis Used

Data were collected, entered into a computer, and analyzed; one-way ANOVA was used for intergroup assessment.

Results

Overall color change was evident immediately after treatment in the ICON group compared to other groups (P < 0.05). However, no significant difference in color change was visible between the groups after 6 months. Reduction in hypoplastic area was seen in all the groups. The mean time was similar for all the groups. Toothmin was found to be the most cost-effective in comparison with the other two interventions.

Conclusions

ICON proved to be more effective immediately after treatment for masking incisor hypoplasia. However, at 6-month follow-up interval, all the groups gave similar results.

Effect of sodium fluoride plus tricalcium phosphate with and without CO2 laser on remineralization of white spot lesions

Objectives

The aim of this in vitro study was to evaluate the effect of NaF plus TCP with and without CO₂ laser irradiation on management of demineralized enamel using microhardness test and digital microscopy.

Methods

Eighty intact extracted human premolar teeth were randomly divided into 4 groups (20/each). Each group was subjected to a demineralizing solution to create white spot lesion. Group 1 was treated with 3M Vanish™. Group 2 was irradiated with CO₂ laser. Group 3 was subjected to CO₂ laser followed by 3M Vanish™. Group 4 was treated by 3M Vanish™ then CO₂ laser. The teeth were immersed in artificial saliva. Surface microhardness was measured for each tooth before demineralization at base line (M1 as a control), after demineralization (M2) and after management (M3). Comparison of microhardness values between groups was performed using one way ANOVA test with significant level (0.05) followed by multiple comparisons post-hoc Tukey test between groups. Enamel surface was photographed by digital microscope.

Results

All intervention methods used in the current study significantly increased microhardness values of demineralized enamel (P < 0.001). Little improvement of enamel appearance was observed in all groups meanwhile using CO₂ laser on demineralized enamel directly led to signs of white and black dots affecting the appearance of enamel surface.

Significance

The most effective intervention regarding microhardness was group 2 followed by group 3, group 4 and group 1. Coating the enamel surface with 3M Vanish™ before CO₂ laser irradiation acted as a protective layer from the undesirable effects of laser on the teeth with increasing enamel microhardness values more than using Vanish alone. So the promising intervention method regarding both microhardness and appearance was group 4.

In vivo Comparative Evaluation of Esthetics after Microabrasion and Microabrasion followed by Casein Phosphopeptide-Amorphous Calcium Fluoride Phosphate on Molar Incisor Hypomineralization-Affected Incisors

Background:

Molar incisor hypomineralization (MIH) is an esthetic setback for the patient as well as for the dentist, treatment options for MIH includes minimally invasive techniques like microabrasion which has a limited literature of its effect. Furthermore, the effect of remineralizing such as casein phosphopeptide–amorphous calcium phosphate (CPP-ACP) agent on MIH-affected teeth is minimally studied.

Aim:

Comparative evaluation of the esthetic after microabrasion and microabrasion followed by Tooth Mousse Plus on hypomineralized incisors of MIH-affected patients.

Settings and Design:

The study was a randomized clinical trial.

Materials and Methods:

The study comprised Grade I MIH patients in the age strata of 7–16 years having lesions on incisors. As per inclusion criteria, 46 lesions were divided into two groups of microabrasion and microabrasion followed by CPP-amorphous calcium fluoride phosphate (ACFP). Photographs were obtained before treatment, just after treatment, and 6 months after treatment. The photographic evaluation was done using the CIE L*a*b* scoring method.

Statistical Analysis Used:

ANOVA and posthoc Tukey's test were applied to compare the difference in lightness ΔL and total color change ΔE of these two groups.

Results:

In microabrasion group, the overall change in ΔL of white tooth discoloration came −0.9 standard deviation (SD) 7.3. In microabrasion followed by CPP-ACFP group, statistically significant difference was found between both these groups with P value of P ≤ 0.001.

Conclusions:

Microabrasion followed by the remineralizing agent can improve the esthetics of white tooth discoloration with time.

The reproducibility of assessment of white spot lesions adjacent to orthodontic brackets, with a quantitative light induced fluorescence digital camera at different rotations of teeth - an in vitro study

Background

A quantitative light-induced fluorescence digital (QLF-D) camera is able to assess demineralizations adjacent to orthodontic brackets. Rotations of teeth during and the presence of the orthodontic appliances may influence the longitudinal follow-up of such lesions over time.

Methods

Brackets were bonded on extracted teeth: 54 incisors and 31 canines. Demineralizations were formed in vitro directly cervical of the bracket. Images were captured using a QLF-D camera mounted on an optical bench, equipped with a goniometer on a turntable. The teeth were placed in the goniometer simulating buccolingual rotation (0°, 10°, 20°), the turn-table was used for mesiodistal rotations (0°, 10°, 20°). Standardized QLF-D images were made before (with and without a wire) and after debonding at combinations of aforementioned angles of rotation. The image after debonding at 0° buccolingual and 0° mesiodistal rotation served as a control.

Results

The presence of a bracket resulted in a significantly higher fluorescence loss, yet a smaller lesion area (p < 0.05) in comparison to the control. A significant higher fluorescence loss was seen for rotations towards lingual relative to the 0° buccolingual and 0° mesiodistal rotation, while the effect was less explicit towards buccal.

Conclusions

Fluorescence loss and lesion size are influenced by the angle of rotation under which the demineralization is photographed. The full extent of demineralizations is only apparent after debonding when photographed at rotations of 0° mesiodistal and up to 20° buccal. Precaution must be taken into account assessing demineralizations of patients undergoing treatment with fixed appliances when using a QLF-D camera.

Electronic supplementary material

The online version of this article (10.1186/s12903-018-0667-3) contains supplementary material, which is available to authorized users.

Changes in white spot lesions following post-orthodontic weekly application of 1.25 per cent fluoride gel over 6 months-a randomized placebo-controlled clinical trial. Part I: photographic data evaluation

Background

White spot lesions (WSLs) are a frequent side-effect of multibracket appliance treatment. The effect of local fluoridation on post-orthodontic WSL is however inconclusive.

Objective

Assessment of WSL changes in response to weekly 1.25 per cent fluoride gel application after multibracket appliance treatment.

Trial design

Randomized, single-centre, double-blind, parallel-group, placebo-controlled study.

Participants

Patients with not less than 1 WSL (modified score 1 or 2) on not less than 1 upper front teeth after debonding.

Interventions

Professional fluoride/placebo gel application during weeks 1-2; self-administered home application (weeks 3-24).

Outcomes

Photographic WSL assessment (dimension and luminance) of the upper front teeth (T0-T5).

Randomization

Random assignment to test (n = 23) or placebo group (n = 23) using a sequentially numbered list (random allocation sequence generated for 50 subjects in 25 blocks of 2 subjects each).

Recruitment

The clinical study duration lasted from March 2011 to September 2013.

Blinding

Unblinding was performed after complete data evaluation.

Numbers analysed

Intent-to-treat analysis set comprising 39 participants (test: n = 21, placebo: n = 18).

Outcome

Dimensional WSL quantification showed limited reliability. Luminance improvement (%) of WSL, however, was seen after 6 months (test/placebo: tooth 12, 24.8/18.0; tooth 11, 38.4/35.4; tooth 21, 39.6/38.3; and tooth 22, 15.2/25.0). No statistically significant group difference existed. Data suggest that WSLs are difficult to measure with respect to reliability and repeatability and methods for monitoring WSLs in clinical trials require improvement/validation.

Harms

Similar adverse events occurred in both groups; none was classified as possibly related to the study product.

Limitations

The number of dropouts was higher than expected and the socio-economic status was not assessed. Furthermore, the unknown level of compliance during the home application phase must be considered as limitation.

Conclusion

Based on the results of this study, no difference could be detected with respect to the development of WSL under post-orthodontic high-dose fluoride treatment.

Registration

The study was registered with ClinicalTrials.gov (Identifier: NCT01329731).

Protocol

The protocol wasn't published before trial commencement.

Quantitative light-induced fluorescence images and digital photographs - Reproducibility of manually marked demineralisations

OBJECTIVE

Hard tooth tissue demineralisation is an undesirable side effect of orthodontic treatment with fixed appliances. Whereas both clinically and in digital photographs (DP), demineralisations appear as white spot lesions, WSLs appear as dark areas when quantitative light-induced fluorescence (QLF) imaging is used. This study aims at comparing the reproducibility of the detection of decalcified tooth areas in DP and QLF.

MATERIALS AND METHODS

DP and QLF pairs were acquired from 139 teeth of 32 patients after braces removal. Three raters manually marked the decalcified area on both DP and QLF images. The markings were repeated after 2 weeks. A ground truth was estimated for each tooth and modality using the simultaneous truth and performance level estimation (STAPLE) algorithm. The Dice coefficients (DC) of each rater marking to the ground truth were calculated for all teeth and modalities to quantify the spatial agreement. A three-way repeated measures analysis of variance (ANOVA) was used to compare the means of the DCs for both modalities ([Formula: see text]). Intra-observer and intercycle variabilities were assessed comparing the means across the raters and the cycles for both modalities.

RESULTS

ANOVA revealed a statistical significant difference between the modalities [[Formula: see text], [Formula: see text]]. The standard deviation of the DC for the photographs are lower than those for the QLF images. Intra-observer and intercycle differences are rather small as compared to the intermodality differences.

CONCLUSIONS

The results indicate a higher spatial reproducibility in identifying a decalcified area on a tooth surface using visual inspection of DP rather than QLF images.

A practice-based evaluation of the prevalence and predisposing etiology of white spot lesions

OBJECTIVE

To use an alumni-centered, practice-based research network to evaluate white spot lesions (WSLs) among treated orthodontic patients.

MATERIALS AND METHODS

An initial survey was conducted to ascertain whether orthodontic alumni from Texas A&M University Baylor College of Dentistry were willing to participate. Twenty randomly selected alumni participated, providing 158 treated cases. Each alumnus (1) obtained internal review board consent; (2) submitted pre- and posttreatment photographs of 10 consecutively finished cases; (3) completed a treatment survey; and (4) had the patient/parent complete the American Dental Association (ADA) Caries Risk Assessment.

RESULTS

Almost 90% of the alumni surveyed were willing to participate in the practice-based research, primarily because a fellow alumnus asked them to. Approximately 28% of the patients developed WSLs. The average patient developed 2.4 white spots, affecting 12.7% of the teeth examined. WSLs were significantly (P < .001) more (2.3-3.2 times) likely for patients who were identified on the ADA Caries Risk Assessment. The risk of developing WSLs during treatment was also increased for those with fair (2.7 times) or poor (3.5 times) oral hygiene, poor gingival health (2.3 times), and extended treatment times (2.1 times).

CONCLUSIONS

There is a substantial risk of developing WSLs among private practice patients, depending partially on the length of treatment. Patients at greatest risk can be identified prior to treatment based on the ADA Caries Risk Assessment, oral hygiene, and gingival health.

Impact of body mass index on oral health during orthodontic treatment: an explorative pilot study

AIM

To answer the question: is there a correlation between body mass index (BMI), oral health, and patient cooperation during multibracket (MB) appliance therapy?

MATERIALS AND METHODS

All adolescent MB patients started and finished between 2007 and 2012 were analysed. According to their pre-treatment BMI, patients were divided into one of the following groups: normal weight, overweight, or obese. Using the patients' records, the cooperation during treatment was classified as good, bad, or poor and the treatment duration was calculated. Using pre- and post-treatment photographs, white spot lesion (WSL) formation and gingivitis before and after MB therapy were assessed.

RESULTS

Of the 175 subjects, 138 had a normal BMI (79 per cent), 22 were overweight (12.5 per cent), and 15 obese (8.5 per cent). Whereas 42.8 per cent of the normal weight patients showed a good cooperation, only 22.7 per cent of the overweight and 20.9 per cent of the obese patients cooperated sufficiently. On average, normal weight patients were treated for 22.2 months, overweight patients for 23.0 months, and obese patients for 27.7 months. Normal weight patients developed less WSL (41.3 per cent) during MB treatment than overweight (50 per cent) or obese (66.7 per cent) patients. Furthermore, patients with a normal weight or overweight had less gingival inflammation (79.5 per cent) after treatment than obese individuals (93.3 per cent).

CONCLUSION

An increased BMI appears to be a risk factor for less cooperation, a longer treatment duration, and more oral health-related problems during MB treatment, indicating that these patients require special attention during orthodontic therapy.

Diagnosing the severity of buccal caries lesions in orthodontic patients at de-bonding using digital photographs

OBJECTIVE

The aims of this study were (1) to evaluate the severity of buccal caries lesions according to the International Caries Detection and Assessment System (ICDAS) criteria via scoring buccal caries lesions on digital photographs at the time of de-bonding and (2) to compare this method with clinical examination.

MATERIALS AND METHODS

In total, 89 patients treated with upper and lower fixed appliances were clinically examined immediately after de-bonding by the first author and buccal caries were scored according to the ICDAS-II. Close-up digital photographs were taken of 245 teeth with different buccal caries lesion scores according to the ICDAS-II. Thirteen postgraduate orthodontics students independently scored the buccal caries lesions in the digital photographs using the modified clinical criteria (ICDAS-II). Intra- and inter-examiner reliabilities were evaluated by calculating the weighted kappa. To evaluate the validity of diagnosing the severity of buccal caries lesions using digital photographs compared to clinical examination, Spearman's correlation coefficient was calculated.

RESULTS

Intra-examiner reliability and the reliability between each examiner and the clinical examination showed moderate-to-excellent agreement, with kappa values of 0.52-0.83. Scoring buccal caries lesions via clinical examinations and scoring via photographs were well correlated according to the modified ICDAS-II criteria (Spearman's correlation coefficient, 0.76).

CONCLUSIONS

Thus, scoring buccal caries lesions on digital photographs according to ICDAS-II criteria is a reliable and valid method for assessing the severity of buccal caries lesions.

Reliability analysis of two methods for measuring active enamel demineralization: An in vitro study

OBJECTIVE

The aim was to evaluate the intra- and inter-examiner reliability of two methods, namely, digital caliper [DC] and computerized image analysis software (Image Tool [IT] version 4.1) for measuring the area of an active enamel demineralization lesion. The effect on that measurement of a window that delimits the lesion was also assessed.

MATERIALS AND METHODS

Thirty-eight circular artificial enamel demineralization lesions (r = 2 mm) were produced on bovine teeth in vitro, which were then measured three times by three examiners, with and without the presence of a window delimiting the area to be measured. The data were analyzed by the intraclass correlation coefficient (ICC) with 95% confidence interval (CI) and by the Altman and Bland analysis.

RESULTS

The intra-examiner correlation using the IT method showed excellent reproducibility (mean ICC values 0.922-0.970 with the delimiting window and 0.915-0.990 without the window). However, the intra-examiner correlation using the DC method showed comparatively less reproducibility in the measurements (mean ICC values 0.458-0.648 with the delimiting window and 0.378-0.665 without the window). The inter-examiner correlations showed very good reproducibility of the measurements regardless of the presence or absence of the window for both the DC method (0.811-0.846) and IT method (0.953-0.994). However, the latter method showed less variability within the measurements.

CONCLUSION

However, statistically no significant difference was found between both methodologies. Nevertheless, computerized image analysis with the Image Tool software demonstrated higher intra- and inter-examiner reliability than the digital caliper method, in estimating the area of the enamel demineralization lesion, regardless of the delimiting window.

Effectiveness of MI Paste Plus and PreviDent fluoride varnish for treatment of white spot lesions: a randomized controlled trial

INTRODUCTION

White spot lesions are a common sequela of orthodontic therapy. In this parallel-group randomized trial, we assessed the effectiveness of 2 agents commonly used to ameliorate white spot lesions compared with a normal home-care regimen.

METHODS

Patients aged 12 to 20 years were recruited from the offices of orthodontists and dentists who belonged to the Practice-based Research Collaborative in Evidence-based Dentistry network. The patients had their orthodontic appliances removed within the past 2 months and had at least 1 white spot lesion affecting their maxillary incisors. The subjects were randomized to 1 of 3 arms: (1) an 8-week regimen of MI Paste Plus (GC America, Alsip, Ill), (2) a single application of PreviDent fluoride varnish (Colgate Oral Pharmaceuticals, New York, NY), and (3) usual home care (control). Photographs were taken at enrollment and 8 weeks later. Two panels consisting of 5 dental professionals and 5 laypersons assessed the before-and-after pairs of photographs in a blinded fashion. Objective assessments and self-assessments were also performed.

RESULTS

One hundred fifteen subjects completed the study; 34 were assigned to the MI Paste Plus group, 40 to the fluoride varnish group, and 41 to the control group. The mean improvements assessed by the professional panel were 21%, 29%, and 27% in the MI Paste Plus, fluoride varnish, and control groups, respectively.The results from the lay panel were 29%, 31%, and 25%, respectively. Objective improvements in the surface affected were 16%, 25%, and 17%, respectively; self-assessments of improvement were 37% in all 3 groups. No assessments indicated significant differences between subjects in the active arms compared with the control arm.

CONCLUSIONS

MI Paste Plus and PreviDent fluoride varnish do not appear to be more effective than normal home care for improving the appearance of white spot lesions over an 8-week period.

Comparison of quantitative light-induced fluorescence, digital photography and transverse microradiography for quantification of enamel remineralization

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

The evaluation of resin infiltration for masking labial enamel white spot lesions

OBJECTIVE

The aim of this study was to clinically assess the effectiveness of masking white spot enamel lesions using a resin infiltration technique that was recently developed to arrest incipient caries in a micro-invasive concept.

METHODS

Twenty teeth with a Developmental Defect of Enamel (DDE) and 18 teeth with Post-orthodontic Decalcification (POD) were selected and treated with resin infiltration. Standardized photographs were taken before, immediately after, and 1 week after treatment and were analysed using image analysing software to calculate the ΔE values. The results were classified into three groups: completely masked, partially masked, and unchanged.

RESULTS

Among the 20 teeth with DDE, five teeth (25%) were classified as completely masked, whereas seven (35%) and eight teeth (40%) were partially masked and unchanged, respectively. Among the 18 teeth with POD, 11 teeth (61%) were completely masked, six teeth (33%) were partially masked, and one tooth (6%) was unchanged. In some teeth, the result was more improved after 1 week than immediately after infiltration.

CONCLUSION

The masking effect was dramatic in some cases but not in others. The long-term colour stability of the result should be followed up through continuous clinical and scientific studies.

Analysis of the effect of CPP-ACP tooth mousse on enamel remineralization by circularly polarized images

OBJECTIVE

To evaluate the effect of casein phosphopeptide-amorphous calcium phosphate tooth mousse on the remineralization of bovine incisor by circularly polarized images.

METHODS

Eighty bovine incisors, each with a 4 x 4 mm artificially demineralized area, were used. The samples were divided into four groups: Group A, casein phosphopeptide-amorphous calcium phosphate tooth mousse; Group B, fluoride toothpaste; Group C, casein phosphopeptide-amorphous calcium phosphate tooth mousse and fluoride toothpaste; and Group D, no treatment. Circularly polarized images were taken after the specimens were treated for 3, 6, 9, or 12 weeks, and the size of the demineralized area and the mean grey level were measured. Data analysis was done using repeated measures variance analysis. Pearson correlation coefficients were computed to evaluate the correlation between the size of the demineralized area and the mean grey level.

RESULTS

In all four groups, the size of the demineralized area and the mean grey level declined with time. The size of the demineralized area of Group C was significantly smaller than that of Group A at the end of the third and sixth weeks (P = .039, P = .000, respectively), and the mean grey level of Group C was lower than that of Group A at the end of the 6th and 12th weeks (P = .037, P = .004, respectively). At the end of the 6th, 9th, and 12th weeks, the size of the demineralized area of Group C was smaller (P = .000, P = .005, P = .005, respectively) and the mean grey level was lower (P = .000) than those of Group B. No statistically significant correlations were detected between the size of the demineralized area and the mean grey level.

CONCLUSION

Casein phosphopeptide-amorphous calcium phosphate tooth mousse can reduce the size and mean grey level of demineralized areas and promote the remineralization of bovine enamel. Combined application with fluoride toothpaste strengthens the effect.

Polarized versus nonpolarized digital images for the measurement of demineralization surrounding orthodontic brackets

OBJECTIVE

To compare the assessment of demineralized white lesions surrounding orthodontic brackets using images produced with and without polarizing filters to reduce incidental flash reflection.

MATERIALS AND METHODS

Thirty teeth with orthodontic brackets and a systematic arrangement of artificially induced demineralization were used. Standardized digital images of the teeth were taken with and without a cross-polarizing filter. These were repeated after 1 week. All the images were randomly numbered and assessed by an investigator, unaware as to the nature of the study. The presence or absence of demineralization was recorded and compared with the actual demineralization pattern. The lesion area and degree of whiteness (LI%) were measured using computerized image analysis. Twenty images from each group were randomly chosen and duplicated for an assessment of measurement error.

RESULTS

The positive and negative predictive values were better from the polarized images (0.97 and 0.84, respectively) than from the nonpolarized images (0.90 and 0.74, respectively). The percentage agreements for the repeat assessments of the same slide were better for the polarized images (96%) than for the nonpolarized images (89%). The limits of agreement and intraclass correlation coefficients between measurements of repeated images were lower for lesion area from cross-polarized images, suggesting better reproducibility, but not for LI%.

CONCLUSION

A cross-polarization filter enhances the subjective assessment of demineralized lesions surrounding an orthodontic bracket and improves the reproducibility of measuring the lesion area. The filter did not improve the assessment of changes in enamel gray levels with demineralization.

Management of postorthodontic demineralized white lesions with microabrasion: a quantitative assessment

INTRODUCTION

The aim of this study was to quantify changes in postorthodontic demineralized enamel lesion surface areas after microabrasion.

METHOD

The study group comprised 8 orthodontic patients (mean age,17.3 years) with multiple decalcified enamel lesions after fixed orthodontic therapy. Two demineralized areas were randomly selected for interventive treatment in each patient. Microabrasion was undertaken on these lesions by using a well-accepted 18% hydrochloric acid and pumice technique. Standardized intraoral images were taken of the lesions before and immediately after microabrasion. Image-processing software was used to quantify (mm2) the visible areas of the demineralized lesions before and after microabrasion. The total labial surface area of each tooth was also determined, and the area affected by demineralization was expressed as a percentage of total tooth surface. Images were reanalyzed a month later to determine the repeatability of the method.

RESULTS

Microabrasion significantly reduced visible enamel demineralization (P < .001, paired t test). The mean reduction in lesion size after treatment was 83% (SD, 8.2%; range, 61%-92%). The quantification methodology was found to be highly repeatable with an intraclass correlation coefficient of 0.98.

CONCLUSIONS

Microabrasion is an effective treatment approach for the cosmetic improvement of long-standing postorthodontic demineralized enamel lesions.

Microscopic investigation of artificially demineralized surface enamel exposed to controlled intra-oral periods

BACKGROUND

Arrest and regression of enamel caries is generally followed by clinical surface changes in enamel. The aim of this study was to evaluate microscopic surface changes in demineralized enamel submitted to toothbrushing with a fluoridated dentifrice or to a fluoridated gel in situ.

METHODS

Enamel blocks demineralized by an acidic gel, were built in plates of five volunteers during three periods of 14 days each: exposure to the oral cavity (C+); brushing with a fluoridated dentifrice three times a days (B); application of a 2 per cent sodium fluoride gel and exposure to the oral cavity (F). Eight blocks were kept in 100 per cent humidity under refrigeration as negative controls (C-).

RESULTS

Stereomicroscopic examination revealed that 15, 47.4 and 30 per cent of samples from C+, B and F presented enamel cavitation after the experimental period. The demineralized enamel area in these groups decreased considerably compared to C-, both in cavitated and non-cavitated samples, although it was statistically significant only in cavitated samples from B (p=0.003; t test). Scanning electron microscopy revealed that C+ and F retained irregularities caused by the acid challenge, while B presented a more leveled profile of the enamel surface.

CONCLUSIONS

Exposure of demineralized enamel to intra-oral periods reduced the demineralized enamel area. Tooth brushing enhanced this reduction, because of surface abrasion.

Effect of Imaging Geometry on Evaluating Natural White-Spot Lesions Using Quantitative Light-Induced Fluorescence

The objective of this study was to determine the effect of imaging geometry on evaluating natural white-spot lesions with quantitative light-induced fluorescence (QLF). A total of 34 specimens were prepared from extracted human premolars and permanent molars with white spots on the interproximal surface. The specimens were each adjusted to a final thickness of 3.0 mm. Images were acquired with the QLF system perpendicular to the white spots and at 5 degrees intervals up to 30 degrees above and below the perpendicular. The specimens were rotated around the buccolingual axis of the tooth (pitch angle) and around the long axis of the tooth (roll angle). The averages of fluorescence loss (DeltaF, %) and lesion size (mm2) were determined with QLF. Another variable, DeltaQ, which was defined as the fluorescence loss integrated over the lesion size (% x mm2), was also calculated. DeltaF was smaller when lesions were viewed from the cervical direction (angles less than 90 degrees ), and became bigger when viewed from the coronal direction. Roll angle did not significantly affect DeltaF. Apparent lesion size diminished with deviations from 90 degrees in both directions for pitch and roll angles. DeltaQ was affected by pitch and roll angles with the largest value at 90 degrees and values decreasing in both directions from 90 degrees. In general, there were significant differences for angles larger than 20 degrees from the perpendicular for all three QLF variables. This study suggests that angle is an important factor to control when performing QLF studies; however, small changes (deviations within 20 degrees ) have a minimal effect on QLF variables.

The use of QLF to quantify in vitro whitening in a product testing model

BACKGROUND

Professional and consumer interest in whitening products continues to increase against a background of both increased oral health awareness and demand for cosmetic procedures. In the current legal climate, few dentists are providing 'in-office' whitening treatments, and thus many patients turn to home-use products. The most common of these are the whitening toothpastes. Researchers are keen to quantify the effectiveness of such products through clinically relevant trials.

AIM

Previous studies examining whitening products have employed a variety of stained substrates to monitor stain removal. This study aimed to quantify the removal of stain from human enamel using a new device, quantitative light-induced fluorescence (QLF). The experimental design follows that of a product-testing model.

MATERIALS AND METHODS

A total of 11 previously extracted molar teeth were coated with transparent nail varnish leaving an exposed window of enamel. The sound, exposed enamel was subject to a staining regime of human saliva, chlorhexidine and tea. Each of the eleven teeth was subjected to serial exposures of a positive control (Bocasan), a negative control (water) and a test product (Yotuel toothpaste). Following each two-minute exposure QLF images of the teeth were taken (a total of 5 applications). Following completion of one test solution, the teeth were cleaned, re-stained and the procedure repeated with the next solution. QLF images were stored on a PC and analysed by a blinded single examiner. The deltaQ value at 5% threshold was reported. ANOVA and paired t-tests were used to analyse the data.

RESULTS

The study confirmed the ability of QLF to longitudinally quantify stain reduction from human enamel. The reliability of the technique in relation to positive and negative test controls was proven. The positive control had a significantly (alpha = 0.05) higher stain removal efficacy than water (p = 0.023) and Yotuel (p = 0.046). Yotuel was more effective than water (p = 0.023).

CONCLUSION

The research community, the practicing clinician and the consumer all require sound product evaluation data. The use of human enamel specimens may offer more relevant clinical data. QLF has been designed as an in vivo device. Further development of the technique should permit in vivo clinical whitening trials.