Evaluation of the efficacy of a 2-step etch-and-rinse, 2-step self-etch and 1-step self-etch adhesive systems, in class II primary molars restorations. An one year prospective, randomized clinical trial.

Purpose: To evaluate the clinical efficacy at 6 months (6 M) and 12 months (12 M) of 3 adhesive strategies (two-step etch-and-rinse; two-step self-etch; one step self-etch) used in composite resin restorations in primary molars.

Methods: This randomized clinical study involved 101 class II restorations in primary molars of 34 children (4-8 years old), distributed by 3 groups according to the 3 tested adhesive systems: GI- Clearfil^TMS³Bond Plus (CSB); GII- Clearfil^TMSE Protect Bond (CSEPB); GIII- Prime&Bond®XP (PBXP). Restorations were evaluated according to FDI criteria, immediately after execution, at 6 M and 12 M. All ethical and legal requirements were met. Statistical analysis was performed using IBM®SPSS®v26 and MS Excel® (5% significance level).

Results: The aesthetic, biological and most of the functional parameters evaluated remained without significant changes over time. Statistically significant differences were only found regarding the "marginal adaptation" parameter at 12 M, with worsening of scores for the three groups (p < 0.001). Comparing the groups, no significant differences were detected between any of the evaluated parameters (aesthetics properties: p = 0.721; functional properties: p = 0.122).

Conclusions: After a one-year period, the self-etch adhesives tested presented a clinical efficacy similar to the etch-and-rinse adhesive in restoring class II cavities in primary molars.

Trial registration number: ISRCTN11458186.