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