Influence of different size of prophylaxis brush on marginal microleakage and hybrid layer morphology of composite restorations

Tooth cavity cleaning is a fundamental step to achieve greater adhesion in composite resins restorations. This study aimed to evaluate the influence of different sizes of prophylaxis brush on marginal microleakage and hybrid layer morphology in composite restorations.

Thirty Class V tooth preparations were distributed into 3 groups according to the type of cavity cleaning (n=10): G1: no prophylaxis; G2: Prophylaxis brush with regular size (Robson Brush Prophylaxis/DHPro); G3: Prophylaxis brush with reduced size (Robson Microtuft®/DHPro brush). After the respective cleaning protocol, third human molars were restored using a universal adhesive system (Single Bond Universal - 3M ESPE) and composite resin (FiltekTM Z350 XT 3M ESPE). To characterize the dentin substrate, the samples were prepared until the selective conditioning step and evaluated by scanning electron microscope (SEM) and hybrid layer's morphology was also evaluated after the restorative procedure (n=2). To assess the marginal microleakage, the sample were submitted to the thermocycling process, finished, and polished. After this step, the images were obtained by Micro-CT, and two calibrated evaluators scored the depth of dye penetration as 0 to 3. The Kruskal-Wallis test was used to compare groups regarding marginal microleakage (p<0.05).

G1 and G2 showed the presence of a gap between restoration and dentin, however, G3 showed greater regularity compared to the other groups. In microleakage scores, G1 showed more frequency for score 3 followed by G3 e G2 (p>0.05).

Therefore, the Robson Microtuft® brush did not influence the marginal infiltration of the adhesive restorations, but the absence of prior prophylaxis increased the levels of infiltration and obtained a more irregular adhesive interface. Key words:Microleakage. marginal adaptation. universal adhesives.