Role of configuration factor on bond strength of universal adhesives in occlusal cavities: An in vitro study.

Abstract

Introduction: During curing of composite resins, polymerization shrinkage occurs and generates stress. The configuration factor (C-factors) is an important clinical parameter and is related to polymerization shrinkage, bond strength, and durability. High C-factors indicate situations in which the material polymerizes under greater external constraint.

Aim: To evaluate the effect of C-factor on the bond strength of universal dental adhesives to the dentin of the cavity floor and cavity wall in class-I composite restorations using nanohybrid composites.

Materials and methods: Sixty noncarious human molars were randomly divided into four groups (n = 15). Then, each group was subdivided into two subgroups according to the type of adhesive used: Prime and Bond Universal (Dentsply) or Adper Single Bond 2 (3M). After the bonding procedure, nanohybrid composite was applied in 2 mm increments to fill the cavities. The teeth were sectioned into 2 mm² sticks and micro-tensile bond strength (μTBS) was measured at two areas: cavity wall and cavity floor using a universal testing machine. Fracture pattern was analyzed using the stereomicroscope. Results were tabulated and statistical analysis was done using the Analysis of Variance with post hoc Tukey's test.

Results: Prime and Bond Universal had significantly better μTBS (mean = 8.53) as compared to Adper Single Bond 2 at the floor (mean = 6.64) of the cavity. At the wall of the cavity, Prime and Bond Universal was better, but the difference was not statistically significant (P < 0.05). The cohesive mode of fracture was common in all the groups.

Conclusion: To overcome high C-factor in Class I cavities, Prime and Bond universal had better bond strength when measured at the floor and wall of the cavity.