To evaluate and compare the effect of different light-curing modes and different liners on cuspal deflection in premolar teeth restored with bulk filled or incrementally filled composite measured at different time intervals

Aim The aim of this study is to evaluate and to compare the effect of different light-curing modes and different liners on cuspal deflection in premolar teeth restored with bulk filled or incrementally filled composite measured at different time intervals. Materials and Methods The study was divided into two parts (Part 1-different curing modes, Part 2-different liner) each with sixty extracted human upper premolar teeth with standardized large mesio-occlusal-distal cavities prepared. Each part was divided into two groups according to the composite used (Group A-Filtek Z350 XT, Group B-Sonic fill). Each group was then divided into three subgroups according to the light-curing modes (soft-start, pulse, and continuous curing mode) and liner (Filtek Z350 XT Flowable, Vitremer) used. The cuspal deflection was then measured with a digital micrometer gauge and subjected to statistically analysis using analysis of variance and Tukey's post hoc test. Results Sonic fill composite, resin-modified glass ionomer cement (RMGIC) liner and curing with soft-start/pulse curing mode had significantly lower cuspal deflection compared to Filtek Z350 XT, flowable liner, and continuous curing mode, respectively. Conclusion Sonic fill composite, RMGIC liner under the restorations and composites cured with soft start/pulse curing mode resulted in reduced cuspal deflection.