Comparison of resin modified glass ionomer cement and composite resin in class II primary molar restorations: a 2-year parallel randomised clinical trial

Aim To compare the 2-year success rates of a Resin Modified Glass Ionomer Cement (RMGIC) with a composite resin in class II primary molar restorations. Methods Healthy, cooperative children aged 4-7.5 years with at least one carious primary molar requiring a class II restoration were included in this parallel randomised trial and allocated on a 1:1 basis to composite resin (Z250, 3M ESPE) or RMGIC (Vitremer, 3M ESPE). Restorations were assessed semiannually up to 2 years clinically and radiographically using modified United States Public Health Service criteria, with the primary outcome being all-cause failure. Data were analysed per protocol by binomial linear regression with Relative Risks (RR) and their 95% confidence intervals (CI). Results 55 patients were randomly allocated to either group and 44 analysed at 2 years; with 49 teeth in the Z250 and 55 teeth in the Vitremer group. The all-cause failure rate for both materials was 3% after 1 year (4 and 2% for Z250 and Vitremer, respectively) and 16% after 2 years (16% for both Z250 and Vitremer). Overall, no difference between materials could be found at 2 years (RR = 1.4; 95% CI 0.8, 2.4; P=0.30). However, Vitremer was associated with more favourable gingival health compared to composite (RR = 0.2; 95% CI 0.1, 0.9; P=0.03), but also occlusal wear, which was observed exclusively for Vitremer. Conclusion No significant difference was found in the overall performance of the two materials, making them suitable for class II primary molar restorations, although RMGIC presented more pronounced occlusal wear of limited clinical importance after 2 years.