No adverse effect of eugenol-based temporary materials on bonding to dentin after 14 days: A systematic review and meta-analysis of in vitro studies

Statement of problem: Eugenol reacts with free radicals and may inhibit the polymerization of resin monomers, including adhesive systems, consequently reducing their bond strength values.Purpose: To evaluate through a systematic review and meta-analysis the time elapsed after eugenol-based tem-porary materials restorations on bonding adhesive systems to dentin.Materials and methods: A literature search was conducted at PubMed, Web of Science, and Scopus electronic databases. Laboratory studies that evaluated the influence of eugenol-based temporary materials on bonding of adhesive systems to dentin were searched with no year or language restriction. Two reviewers independently selected the studies, extracted the data, and assessed the risk of bias. Meta-analysis was performed using the inverse variance and a random-effects model (p < 0.05). In addition, heterogeneity was assessed with the Cochran Q test and I2 statistics.Results: From 603 potentially eligible studies, 35 were selected for full-text analysis, 27 were included in the systematic review, and 26 in the meta-analysis. Eugenol-based temporary materials were associated with lower bond strength values (p < 0.00001). Subgroup analysis considering the exposure time of eugenol-based tem-porary materials also showed a significant reduction of bond strength after 24 h (p = 0.003) and seven days (p < 0.00001) from placement, but no significant effect was observed after 14 days-45 days from eugenol-based temporary materials application (p = 0.92). Subgroup analysis considering luting cement (p = 0.02), total-etch systems (p = 0.0003), and self-etch systems (p = 0.0001) separately also showed a significant reduction of bond strength.Conclusions: The meta-analysis based on laboratory evidence suggests that the adverse effect of eugenol-based temporary materials on adhesive systems' bond strength to dentin is no longer perceived after 14 days of placement.