An in vitro comparative evaluation of shear bond strengths of veneering porcelain and different core materials

Abstract

Aim: The aim of the present study was to evaluate and compare the bond strengths of different core structures to veneering porcelain. Materials and methods: Sixty specimens were divided into 4 groups of 15 each. Specimen fabrication was done according to the International Organization for Standardization (ISO) specifications 9693:1999. Group 1 comprised core structure made of cast alloy, group 2 from sintered metal, group 3 from milled zirconia and group 4 milled zirconia without liner at the interface. The shear bond strengths were recorded and the values obtained were statistically examined. Results: Highest values were recorded in group 3 and there were significant differences between groups 1 and 3 while groups 3 and 4 were not statistically different. This led us to imply that zirconia as a core structure provided maximum strengths and laser sintered metal came second. The results also pointed out that the role of the zirconia liner is not that crucial to attaining adequate strength. Conclusion: The present study concluded that zirconia and laser sintered metal are excellent core materials and feasible alternatives to cast alloy. We also concluded from our study that a zirconia liner did not affect the bond strength significantly and is not absolutely essential. Clinical significance: This study helps us to understand the role of materials used as core structures in enhancing the shear bond strength to veneer porcelains and also clarifies the role of a zirconia liner in the process.