Prevention of demineralization during multi-bracketed fixed orthodontic treatment

Abstract

Enamel demineralization, clinically manifesting as White Spot Lesion (WSL), is an undesirable but frequent after-effect of multi-bracketed fixed orthodontic treatment. The systematic reviews conducted as a part of this thesis identified the potential research gaps regarding the lack of well-controlled clinical trials that have assessed the prevention of WSLs. Thus, a randomized controlled clinical trial was conducted to investigate the efficacy of two different fluoride varnishes in prevention of WSLs during multi-bracketed fixed orthodontic treatment. Ninety-nine patients were randomly allocated into three intervention groups: Group A- routine oral hygiene instructions (OHI); Group B- 3-monthly topical application of 5% Sodium Fluoride (NaF) varnish with routine OHI; and Group C- 3-monthly application of 5% NaF plus tricalcium-phosphate (TCP) varnish with routine OHI. The outcome was assessed at 6-month intervals using quantitative laser fluorescence device, clinical evaluation, and photographic evaluation on six maxillary anterior teeth. Generalized estimating equations with intervention group, time, and their interaction were used to compare occurrence of WSLs, whereas Kruskal-Wallis independent-samples test to compare the means of fluorescent values among different groups at p=0.05. Generalized estimating equations showed that only the effect of time was found to be significant (p<0.001), whereas there was no significant difference among three intervention groups (p=0.305) using clinical assessment or photographic assessment (p=0.599). Three-monthly application of both the study varnishes with OHI has no additional benefit compared to standard OHI alone in preventing WSLs. There were higher odds of developing WSLs with increased duration of orthodontic treatment. The secondary analysis of the data from the trial aimed to compare the validity of quantitative laser fluorescence and clinical photographs to the visual assessment of WSLs during multi-bracketed fixed orthodontic treatment. A total of 1607 observations of the clinical photographs, visual and laser fluorescent examination from 6-months, 12-months and 18-months follow-ups were used for this investigation. Receiver operating curves were constructed, and areas under the curve (AUC) were calculated for the outcomes at two levels: distinguishing presence/absence of WSLs and distinguishing slight and severe non-cavitated WSLs. Sensitivities and specificities were calculated and AUC for the outcomes at p<0.05 and 95% confidence intervals. The values of sensitivity and specificity of laser fluorescence were found to be good (0.78 and 0.82, respectively) to distinguish the presence/absence of WSLs (AUC= 0.855; 95% CI: 0.820-0.889) and for digital photographs was excellent (AUC= 0.973, 95% CI: 0.956-0.991) with sensitivity and specificity of 0.96 and 0.99, respectively. However, the sensitivity (0.31) and accuracy (AUC= 0.543, 95% CI: 0.418-0.668) of laser fluorescence was poor in delineating slight and severe WSLs; while the value of sensitivity and specificity for this outcome was good for clinical photographs (0.96 and 0.99, respectively) with an excellent accuracy (AUC=0.978, 95% CI: 0.936-1.000). Laser fluorescence and photographs can serve as helpful aid to identify the presence of WSLs around the brackets, although both have their limitations.