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

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.