The aim of this study was to evaluate voids formation in Class II cavity restored with different placement
methods of bulk-fill resin composites using micro-computed tomography (micro-CT). Standardized Class II cavities
were prepared in 40 extracted human premolars which were divided into 4 groups. Group1: one bulk placement
with syringe type; Group2: incremental placement with syringe type; Group3: one bulk placement with injection
capsule type; Group4: one bulk placement with injection SonicFill Handpiece type. Percent of voids (% Void) in
restored cavity was evaluated with micro-CT after storage in 100 % relative humidity at 37 degrees Celsius for 24
hours. Statistical analysis was done using One-way ANOVA and Tukey post hoc test at confidential level of 95 %.
Results: Percent of voids in group 2 (1.62 %) was significant higher (p = 0.05) than the other groups (0.49 %, 0.33 %
and 0.21 %, respectively). Conclusion: Incremental placement created the highest voids when restore Class II cavity
with bulk-fill resin composite.