Effects of silane coupling treatment on the clinical performance of direct repaired resin-based composite (RBC) restorations with or without prior surface sandblasting: A randomized controlled trial.

ABSTRACT

OBJECTIVE: To evaluate the effects, of using silane coupling agent within the procedures of repairing old composite restorations with or without sandblasting their surfaces, on the clinical performance of repaired composite restorations. METHODS: The study involved repairing 130 Class I and II defective composite restorations. After recurrent caries removal, the repair process included etching with 37 % phosphoric acid, Adper Single Bond 2 application for bonding and Filtek Z250 composite for restoring all defects. The restoration surfaces were subjected to one of the following additional surface treatments within the repair process Control No additional treatment; the Silane-Adhesive treatment A separate step involved the application of a silane coupling agent after acid etching; and the Sandblast-Silane-Adhesive treatment included intra-oral sandblasting of old composite surfaces followed by silane application. Two calibrated examiners evaluated all repaired restorations according to a modified USPHS criteria after 6 months. Comparisons of the clinical performance between the treatment groups were made using Chi-square test, while responses to cold tests before and after repair treatment were made using Wilcoxon's Signed Rank's (α = 0.05). RESULTS: Of 130 cases, only 116 cases turned up for evaluation. The primary reasons for composite repair were recurrent caries and anatomical deficiencies. No statistically significant differences were found between the groups for all clinical criteria (p > 0.05). The control group experienced one total and two partial retention losses. CONCLUSIONS: The application of a silane coupling agent, with or without intra-oral sandblasting, demonstrated no improvement on the clinical performance of repaired posterior composites after 6-months. CLINICAL SIGNIFICANCE: Surface treatment of defective composite restorations using silane with intra-oral sandblasting within their repair process offered marginal improvement in their clinical performance over conventional etching technique, but insignificantly so. Repair reduced exaggerated cold test responses and eliminated POS within 6-months. Repair reduces cold sensitivity and promotes restoration longevity. This clinical trial was registered at ClinicalTrials.gov with the registration number NCT06005571.