Survival Rate of Atraumatic Restorative Treatment (ART) Restorations Using a Glass Ionomer Bilayer Technique with a Nanofilled Coating: A Bi-center Randomized Clinical Trial

Purpose: The high-viscosity consistency of glass ionomer cement (GIC) contributes to its inappropriate adaptation, while the material's premature exposure to humidity decreases its mechanical properties. This study's purposes were to: (1) investigate approximal atraumatic restorative treatment (ART) restorations' survival in primary molars using two different insertion techniques and two surface protection materials; and (2) compare the results of cities where treatments were performed. Methods: A total of 389 six- to seven-year-olds were selected from two cities in Brazil and randomly assigned into four groups: (1) ART restorations plus petroleum jelly (PJ); (2) bilayer-ART restorations plus PJ; (3) ART restorations plus nanofilled coating for GIC (NC); (4) bilayer-ART restorations plus NC. Restorations were evaluated after one, six, 12, 18, and 24 months. Kaplan-Meier survival analysis, log-rank test, and Cox regression analysis were performed. Results: Restorations' cumulative survival was 46.4 percent. There was a higher survival of bilayer-ART restorations (P=0.03). No difference was observed between surface protection materials (P=0.57). Restorations made in Barueri were almost 2.5-fold more likely to survive than those from Recife (P<0.001). Conclusions: The bilayer technique improves approximal ART restorations' survival in primary molars. The nanofilled coating does not influence restorations' survival rate, and the city where treatments were performed influences restoration survival.