The objective of the study was to evaluate marginal adaptation of Class II mesial–occlusal–distal (MOD) restorations before and after thermo-mechanical loading and volumetric shrinkage of the bulk-fill vs conventional composite resin. For marginal adaptation assessment, 24 Class II MOD cavities with cervical margins extending 1.0 mm below (distal) and 1.0 mm beyond (mesial) the cement–enamel junction were prepared in extracted human molars. The teeth were filled as follows: Group A — bulk-fill with SureFil SDR flow (first increment, 4 mm; second increment, 2 mm); Group B — bulk-fill with SureFil SDR flow as a base (first increment, 4 mm) and covered with the conventional nanohybrid composite Esthet-X HD (second increment, 2 mm); and Group C — incrementally filled with Esthet-X HD. Marginal adaptation was evaluated by scanning electron microscopy before and after thermomechanical loading (240,000 loading cycles and simultaneous 600 thermal cycles). To evaluate volumetric polymerization shrinkage, a semi-spherical mold was filled with the tested composites and placed in an AccuVol device after light curing. Both before and after loading, marginal adaptation in cervical dentin was superior (p < 0.05) for Groups A and B compared with Group C. In cervical enamel, Group B showed better marginal adaptation than Group C, and Group A presented intermediary results, between Groups B and C. Furthermore, bulk-fill flow resulted in greater shrinkage than Esthet-X HD. A significant improvement of marginal adaptation was observed when bulkfill flow was used instead of conventional composite resin both before and after thermomechanical loading. However, the bulk-fill flow presented higher volumetric polymerization shrinkage than the conventional composite.
KEY WORDS: composite resins, dental marginal adaptation, dental cavity preparation, polymerization.
How to cite this article
JASSÉ, F. F. A.; ALENCAR, C. M.; ZANIBONI, J. F.; SILVA, A. M. & CAMPOS, E. A. Assessment of marginal adaptation before and after thermo-mechanical loading and volumetric shrinkage: bulk fill vs conventional composite. Int. J. Odontostomat., 14(1):60-66, 2019.