EVALUATION OF SHEAR BOND STRENGTH OF HIGH-PERFORMANCE POLYMERS TO ITS RESIN VENEERING AND TO DENTIN (IN VITRO STUDY)

Abstract

INTRODUCTION: : Looking through the wide range of prosthetic options High-performance polymers properties. Needs over layering resin veneer, bonded by a special adhesive, this adds an additional challenge to achieve adequate bond strength, also its bonding to tooth structure remains difficult. OBJECTIVES: To evaluate shear bond strength of CAD/CAM High-performance polymers (BioHPP) with its CAD/CAM veneering composite using two different adhesives, as well as to dentin using two types of cements. MATERIALS AND METHODS: This in vitro study, for Group I, twenty BioHPP discs with their CAD/CAM veneering composite, were milled and divided randomly into two subgroups (n =10) according to the adhesive system used. Subgroup IA: using DTK adhesive (dualhardening adhesive). Subgroup IB: using Combo.lign (dual-hardening adhesive). For Group II, twenty CAD/CAM High-performance polymers (BioHPP) discs were milled and divided into two subgroups according to the different cements used to lute to dentin surface. Subgroup IIA: using: RelyX Unicem resin cement, subgroup IIB: using Fuji Plus GI cement. After water storage, thermocycling (1200 cycles, 5°C/55°C) corresponding to one year of clinical service, all the specimens were subjected to shear force until failure and the results in the various groups were compared and statistically analyzed. Modes of failure were assessed. RESULTS: Mean SBS were as follows: subgroup IA (DTK adhesive 6.238), subgroup IB (combo.lign2.42), subgroup IIA (RelyX Unicem 2.07) and subgroup IIB (Fuji Plus 3.77). Mann-Whitney test demonstrated significant differences between the two subgroups in groups I and II (U= 2.0, P=.001) (U=17, P=.013) respectively. Stereomicroscope revealed that mixed and adhesive failure were the most dominant mode of failure. CONCLUSIONS MDP-Containing Self-adhesive Resin (DTK adhesive) is recommended as efficient adhesive to increase the shear bond strength of the veneering composite to BioHPP. Also Fuji Plus showed better bond strength than RelyX Unicem with BioHPP and dentin.