Influence of Sonic Application on Surface Roughness of Bulk-fill Composites

Objectives: To evaluate the influence of sonic application on the surface roughness of bulk-fill composite resin restorations. The null hypotheses tested were that 1) sonic application does not reduce surface roughness of bulk-fill composite resins when compared to conventional placement, and 2) the time of sonic application does not reduce surface roughness when compared to conventional placement.
Methods: Eighty intact bovine incisors had their incisal thirds removed, their buccal surfaces flattened, and standard preparations mimicking Class II preparations performed on their buccal surfaces. Specimens were then randomly assigned for restoration with the bulk-fill composite resins Tetric EvoCeram Bulk Fill, SureFil SDR flow, and SonicFill 2, with sonic application for 15s and 30s as well as no sonic application. Filtek Supreme Ultra applied without sonic application served as control. Sonic application was accomplished with the aid of the KAVO SONICflex handpiece. Surface roughness was measured using a 3D scanner and data were analyzed using the Kruskal-Wallis and Mann-Whitney tests at a significance level of 0.05.
Results: No statistical differences were found between groups treated with and without sonic application. When materials were compared, Tetric EvoCeram Bulk Fill showed the lowest surface roughness in the 15-s sonic application subgroup; and SureFil SDR flow showed the highest surface roughness when applied without sonic application and in the 30-s sonic application subgroups. Results are summarized in the table.
Conclusions: None of the test materials presented improved surface roughness when applied using sonic energy. The low-viscosity composite resin SureFil SDR bulk fill flow presented the worst surface roughness and should be treated with caution. The high-viscosity composite resins tested had performance similar to the control material Filtek Supreme Ultra.