Clinical Performance of Filled/Nanofilled Versus Nonfilled Adhesive Systems in Noncarious Cervical Lesions: A Systematic Review and Meta-analysis

Objective: The aim of this meta-analysis was to investigate the clinical performance of filled vs unfilled adhesive systems when applied in noncarious cervical lesions. Methods and Materials: A systematic search was performed in PubMed, Scopus, Web of Science, LILACS, BBO, Cochrane Library, and SIGLE. Gray literature was also screened. Only randomized controlled clinical trials were included. The risk of bias of the studies was evaluated using the Cochrane Collaboration's tool. A random-effects meta-analysis was conducted to compare the retention rate, marginal discoloration, and secondary caries of noncarious cervical lesions restored with filled adhesives vs unfilled adhesives. The quality of the body of evidence was assessed using the GRADE approach. Results: A total of 3662 studies were identified after removal of duplicates. Twenty-nine studies remained for qualitative analyses and 28 studies for the meta-analysis. Only one study was judged to have a low risk of bias, and the other 28 were considered to have unclear risk of bias. There was no statistically significant difference between filled adhesives compared with unfilled adhesives in relation to loss of retention, marginal discoloration, or secondary caries at any of the follow-up periods (12-18 months, 24-30 months, 3 years, and 5 years or longer). The quality of evidence was graded as moderate for most outcomes at the respective follow-ups, except when there was an explained heterogeneity, which occurred mainly for loss of retention at the 12-month to 3-year follow-up. The results did not depend on whether microfilled or nanofilled adhesives had been investigated. Conclusions: The addition of fillers into the composition of adhesive systems did not increase the clinical performance (retention rates, marginal discoloration, or secondary caries) of composite restorations placed in noncarious cervical lesions when compared with unfilled adhesives.