Cuspal deflection of fiber-reinforced composite versus conventional bulk fill composite

Abstract Objective: To evaluate cuspal deflection of mesio-occluso-distal cavities restored with two different composite resin restorations; short fiber-reinforced and conventional bulk fill composite resin restorations. Materials and methods: A total of 32 sound maxillary human premolars were selected for the cuspal deflection test and each tooth received mesio-occluso-distal cavity preparation. The sample were divided into two groups and restored according to the manufacturer’s instructions with two different composite resins, group I: restored with conventional bulk fill (X-tra fil), group II: restored with short fiber-reinforced composite (ever-X posterior), both of the tested restorative materials were bonded with a universal adhesive system (Futurabond U), then cuspal deflection reading were recorded after three different durations: 6 min after completing restorations, after simulated periods of 24 h and 3 months of chewing conditions, a highly sensitive digital micrometer was used to evaluate the cuspal deflection degree, the four stations chewing simulator CS-4 was used for chewing simulation. The collected data were recorded tabulated, and then statistically analyzed. Repeated measure analysis of variance followed by a Tukey test was performed for multiple comparisons, the level of significance was set at P value less than 0.05. Results: There was a significant increase in the degree of cuspal deflection in group I than group II after the three durations (after 6 min of finishing restorations and simulated periods of 24 h and 3 months of chewing in oral cavity), with P value of 0.009, P value of 0.028, P value of 0.001, respectively, there was no significant difference in the degree of cuspal deflection after 6 min and 24 h of chewing simulation in both groups. Also there was highly significant difference between the degree of cuspal deflection after the three different durations, where there was decreased degree of cuspal deflection in group II than group I. Conclusion: Both the tested restorative materials exhibited a degree of cuspal deflection however conventional bulk fill composite exhibited higher cuspal deflection values than that reinforced with short fibers.