Fracture Resistance of Various Bulk-fill Composite Resins in Class II MOD Cavity on Premolars: An In Vitro Study

Abstract

Ab s t r Ac t Background: Class II MOD cavity in maxillary premolar creates a specific challenge for the restoration material in terms of longevity and fracture resistance due to the anatomical shape of premolars that render them susceptible to fracture and the microleakage issue of composite restoration at the gingival margin of the proximal boxes. Bulk-fill composite was introduced to provide more strength and resistance and also to provide less polymerization shrinkage and better cure depth. With the advances in dental material science and technology, several attempts have also been made to increase the advantage of bulk-fill composite: by modifying the monomers, utilizing special restoration placement instrument, and adding fiber reinforcement to its composition, which have not been compared adequately. Hence, this study was undertaken to evaluate the effect of different bulk-fill composites in class II MOD cavities on upper premolars in terms of fracture resistance. Materials and methods: A total of 30 sound upper premolars were divided into three groups of 10 each. Teeth were prepared in the form of class II MOD cavity and restored accordingly: group I restored with Filtek bulk-fill (3M), group II with Sonicfill bulk-fill (Kerr), and group III with EverX bulk-fill (GC). Afterward, samples were thermocycled at 5°C and 55°C for 500 cycles. Fracture resistance test was done using Torsee’s Electronic System Universal Testing Machine. Data obtained were analyzed with one-way ANOVA and post hoc least significant difference (LSD) test to determine the difference between groups. Results: ANOVA statistical test showed no significant differences (p > 0.05) in all groups. However, resin composite EverX bulk-fill (GC) has a higher fracture resistance (882.94 ± 64.41 N) compared to other groups, Sonicfill bulk-fill (Kerr) (856.48 ± 101.35 N), and Filtek bulk-fill (3M) (812.15 ± 66.89 N). Conclusion: The use of different bulk-fill resin composites did not yield significant effects in terms of fracture resistance in the restoration of class II MOD cavity on upper premolars (p > 0.05). However, bulk-fill resin composite did offer advantages in clinical applications due to the simplified restoration process and reduced working time.