Randomized clinical trial of four adhesion strategies in posterior restorations - 18-month results

Purpose To evaluate the 18-month clinical performance of four adhesive strategies in posterior composite restorations placed in private practice. Materials and Methods Upon approval by an institutional review board, 144 restorations were inserted in 45 subjects (average age = 32.6) to treat caries lesions or to replace existing restorations in vital molars and premolars. The adhesives OptiBond FL (three-step etch-and-rinse), OptiBond SOLO Plus (two-step etch-and-rinse), OptiBond XTR (two-step self-etch), and OptiBond All-in One (one-step self-etch) were applied as per manufacturer's (Kerr Co.) instructions followed by a nanofilled resin composite (Filtek Z350XT, 3M ESPE) under rubber dam isolation. Restorations were evaluated at baseline and at 18 months using United States Public Health Service (USPHS)-modified criteria and high-resolution digital photographs. Statistical analyses included the McNemar and the Mann-Whitney non-parametric tests (p < 0.05). Results A total of 137 restorations were evaluated after 18 months. The number of alfa ratings did not change significantly from baseline to 18 months for any of the adhesion strategies. When the 18-month evaluation criteria were pooled by pairs of adhesives, none of the adhesives resulted in a significantly different number of alfa ratings for any of the criteria compared with the other adhesives. Conclusion Bonding strategy did not influence the clinical performance of posterior composite restorations under the clinical conditions used in this study. Clinical Significance When used in ideal clinical conditions, the composition of current dentin adhesives may be more clinically relevant than their adhesion strategy.