The influence of weekly 1.25% fluoride or placebo gel applications on the development of initial caries lesions after multibracket treatment

The study aimed to monitor the effect of a weekly application of a high fluoridated gel on the development of white spot lesions (WSL) after orthodontic treatment with fixed appliances and to compare it to a placebo. The applied gel was elmex® gel with a fluoride concentration of 1.25 %. The null hypothesis was that there is no difference between verum and placebo group.The study design was a prospective placebo-controlled randomized and double-blind clinical trial. Patients and their parents gave a written informed consent to participate in the study. 48 patients, having at least one WSL with a modified score 1 or 2 according to Gorelick et al. (1982) on at least one of the four upper front teeth after debonding, were included in the study. Mean age at start of treatment was 15.3 years. The clinical trial lasted 24 weeks including 6 appointments (T0 T5). At baseline, T1 and T2 the operator applied the gel in a standardized way, after T2 the patients were instructed to use the gel under home conditions. A digital photograph of the upper front teeth was taken at every appointment under standardized conditions and was used for the quantification of WSL. The Software Adobe Photoshop CS5 Extended was used to analyse the luminance of WSL and of normal tooth colour. Changes of luminance of WSL in the course of the study were determined relating to normal tooth colour. At every visit, the general health status was documented and the clinical parameters plaque index, gingival bleeding index, WSL-Index and caries activity index were assessed. At T0 and T5, in addition, also the DMFT index was assessed. Saliva buffer capacity was measured at T0, T1, T4 and T5, salivary flow rate was measured at T0, T4 and T5. 9 patients were excluded from the study because of protocol violations. 39 patients remained and were used for the efficacy analysis (Intention-to-treat population). There was an improvement of WSL in the elmex group as well as in the placebo group. Tooth 21 showed a higher improvement (p<0,1) of luminance of WSL relating to normal tooth colour in the elmex group compared to placebo group after 12 weeks. The difference between the groups was not statistically significant at any appointment concerning the assessed clinical parameters. Based on the results of this study, it was concluded, that the application of elmex® gel cannot be recommended for the treatment of post-orthodontic WSL, because there was no clinical relevant benefit in using elmex® gel compared to placebo.