Which self-etch acidic composition may result in higher dental bonds at the long-term? A network meta-analysis review of in vitro studies.

Objectives: This review evaluated the effects of the acidic composition of self-etch (SE) adhesives at the long-term bond strengths to dentin and enamel.
Data: The review followed the PRISMA Extension Statement for network meta-analysis. Studies were identified by a systematic search in PubMed, Web of Science, and Scopus databases.
Study Selection: The inclusion criteria were in vitro studies that evaluated bond strength data of samples analyzed at both immediate and long-term (after aging simulation) periods and that were bonded to sound dentin/enamel using SE adhesives, with at least one group of adhesives being based on 10-MDP (10-methacryloyloxy-decyl-dihydrogen-phosphate; control) and the other group being comprised of alternative acidic monomers. Statistical analyses were conducted using two methods: standard pairwise meta-analysis (SPMA) and Bayesian network meta-analysis (NMA). Heterogeneity was assessed by using the Cochran Q test and I ² statistics.
Results: From 5220 studies identified, 87 met the eligibility criteria and 83 were meta-analyzed. Seventeen adhesives were based on 10-MDP and 44 systems were based on alternative acids. The resin-dentin/enamel bonds were predominantly reduced after aging (∼84% of cases). From the SPMA findings, the following acidic compositions showed lower bond strength values (effect size: mean difference [MD] with 95% confidence interval [95% CI]) than 10-MDP: 4-META (MD -4.99, 95% CI: -7.21, -2.78; p<0.001); sulfonic acids (MD -9.59, 95% CI -12.19, -6.98; p<0.001); unspecified phosphate esters (MD -8.89, 95% CI -17.50, -0.28; p = 0.04); or mixed acids (MD -11.0, 95% CI -13.62, -8.38; p<0.001). The dental bonds were benefited from the presence of 10-MDP upon longer aging (>6 months). From the NMA probabilistic findings, adhesives based on 10-MDP and phosphonic acids ranked as having the best and the worst bonding potential to dentin, respectively. More than one composition (phosphonic acids and mixed acids) ranked similarly to 10-MDP in enamel. The studies scored as having moderate risk of bias (58.6%), followed by low (39.1%) and high (2.3%) risk of bias.
Conclusion: 10-MDP is an outstanding acidic monomer that contributes to higher bonds to dentin at the long-term. In enamel, there is no evidence that one acidic composition prevails over the other.
Clinical Significance: The acidic composition of SE adhesives affects the resistance of dental bonds after simulated aging, with 10-MDP playing a significant role in the adhesion to dentin but not to the enamel.
Registration Number: This report is registered at the Open Science Framework (osf.io/urtdf).
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2022. Published by Elsevier Ltd.)