Survival rate of approximal-ART restorations using a two-layer technique for glass ionomer insertion

Objective Good survival rates (SR) have been reported for occlusal-atraumatic restorative treatment (ART) restorations but not for approximal-ART restorations. The high-viscosity consistency of the glass ionomer cement (GIC) may lead to its incorrect adaptation into the cavity and thus to failure of the restoration. Because the use of a flowable GIC layer seemed to improve its adaptation in approximal restorations in vitro, we evaluated whether the use of an intermediate flowable GIC layer would improve the SR of approximal-ART restorations. Methods A total of 208 children (6–7 years old) with at least one occluso-proximal carious lesion in a primary molar were selected and randomly allocated to two groups: G1, conventional technique, one-layer GIC (powder/liquid ratio 1:1); and G2, two-layer technique, consisting of a first layer of GIC with a flowable consistency (powder/liquid ratio 1:2) and a second layer of a regular consistency. Restorations were made by final-year students and evaluated after 1, 6, 12 and 18 months. Restoration survival was evaluated using Kaplan–Meier survival and logrank test. Poisson regression analyses (α = 5) were used to verify the influence of factors such as insertion technique, restoration surface and operators. Results The overall SR of the restorations after 18 months was 68 %. There was no difference in SR between the techniques, neither did the other factors influence the SR. Conclusions Over 18 months, the use of an intermediate flowable GIC layer in approximal-ART restorations does not improve the restoration survival. Clinical relevance This study suggests that the two-layer technique is not the answer for increasing approximal-ART restoration longevity