Demineralization adjacent to orthodontic brackets after application of conventional and self-etching primer systems.

objectivesThe goal of this work was to compare the demineralization of enamel associated with two different self-etching primers and traditional acid etching. MATERIALS AND

methodsA total of 15 volunteers (23-32 years, 8 male and 7 female) were provided with a removable archwire/resin appliance to be worn 20 h/day for 28 days. The device was attached to the mandibular posterior teeth and included samples of human enamel (from extracted third molars) located in both posterior vestibules. Both sides featured the same distribution of samples, including one untreated control sample (group A) and three samples with brackets (Victory™ APC II) bonded to their surface after conditioning with a self-etching non-fluoride primer (iBond™ Gluma® Inside; group B), a self-etching fluoride-releasing primer (Transbond™ Plus; group C), or traditional acid-etching with 35% phosphoric acid and Transbond™ XT (group D). Mineral loss was assessed extraorally under standardized conditions using quantitative light-induced fluorescence (QLF) with a specialized camera system (Inspektor Pro). Results were expressed as relative fluorescence loss (ΔF in %). A baseline measurement (T0) was taken before the appliance was first inserted but with the brackets already bonded. Fluorescence loss was analyzed after 3 (T1), 7 (T2), 14 (T3), and 28 days (T4) and compared to the baseline loss (T0) for each of the four study groups (A to D). Kruskal-Wallis and Mann-Whitney U tests were used to compare the results for statistical significance.

resultsThe lowest percentages of fluorescence loss both at baseline and during the follow-up assessments was found in group C. While all three experimental groups (B, C, D) presented total decreases in fluorescence loss after 28 days, indicating remineralization, the decrease in group C was the largest. The Kruskal-Wallis test yielded no significant differences between the three groups other than a significantly lower percentage of fluorescence loss in group C than in group D during the last assessment (T4). The untreated samples of control enamel (group A) revealed increasing percentages of fluorescence loss over the entire study period.

conclusionUse of the self-etching primers (groups B and C) was not associated with patterns of enamel demineralization different from those noted after traditional etching with phosphoric acid (group D). The only significant difference we observed was between the self-etching fluoride-releasing primer (group C) and traditional etching (group D) at the final assessment (T4). Thus, the fluoride-releasing system Transbond™ Plus was advantageous.