Bilayer technique and nano-filled coating increase success of approximal ART restorations: a randomized clinical trial.

Background: The high-viscosity consistency of glass ionomer cement (GIC) may lead to its incorrect adaptation into the cavity and therefore to restoration failure.

Aim: To compare two different insertion techniques for GIC in approximal atraumatic restorative treatment (ART) restorations and two different surface protection materials.

Design: Approximal caries lesion in primary molars from 208 schoolchildren was randomly assigned into four groups: G1, conventional GIC insertion protected with petroleum jelly (PJ); G2, bilayer technique protected with PJ; G3 conventional GIC insertion protected with nano-filled particles coating for GIC (NPC); G4, bilayer technique protected with NPC. Restorations were evaluated after 1, 6, 12, 18, 24, and 36 months. Kaplan-Meier survival analysis and log-rank test were performed. Cox regression analysis (α = 5%) was used to verify the influence of clinical factors.

Results: Restoration survival was 52.8%. Log-rank test indicated a better survival of the bilayer technique restorations, compared to conventional restorations (P = 0.005), whereas the coated conventional restorations presented higher survival than the uncoated ones (P = 0.035). Cox regression analysis showed no influence of any clinical tested variables.

Conclusion: The survival rate of the approximal ART restorations is positively influenced by the bilayer technique, and the application of nano-filled coating increases the longevity of the conventional approximal ART restorations.