Volumetric Cuspal Deflection of Premolars Restored With Different Paste-like Bulk-fill Resin Composites Evaluated by Microcomputed Tomography.

OBJECTIVES: The aim of this study was to measure the volumetric cuspal deflection of premolars restored with different paste-like bulk-fill resin composites using microcomputed tomography (micro-CT). METHODS AND MATERIALS: A total of 35 freshly extracted human maxillary second premolars were selected for this study. Standardized large MOD cavities were prepared in each premolar with a bucco-lingual width of 4 mm and a cavity depth of 4 mm measured from the palatal cusp tip. After cavity preparation, all samples were scanned immediately using a micro-CT system. After the initial micro-CT scanning, restorative procedures were performed. Four groups received different paste-like bulk-fill composites-Beautifil-Bulk Restorative (BBR), Admira Fusion x-tra (AFX), x-tra fill, and Sonic Fill-and the control group received a conventional universal composite and Clearfil Majesty Esthetic (CME). Immediately after the restorative procedure, each tooth was scanned by micro-CT in the same manner as the initial scanning. The buccal and palatal regions of each restoration were evaluated separately in terms of cuspal deflection. One-way analysis of variance was used to compare the effect of the composite resin, and multiple comparisons were performed by the Tukey test with a level of significance of alpha = 0.05. RESULTS AND DISCUSSION: Multiple comparisons showed that teeth restored with the conventional paste-like composite and CME (control) had significantly different cuspal deflection from those filled with paste-like bulk-fill composites (p<0.05). Among the bulk-fill composites, a significant difference was observed between BBR and AFX (p<0.05). CONCLUSIONS: Paste-like bulk-fill resin composites had significantly lower cuspal deflection than the conventional paste-like resin composite tested.