Evaluation of shear bond strength of artificial teeth to heat cure acrylic and high impact heat cure acrylic using autoclave processing method

Abstract

Background: Debonding and fracture of artificial teeth from denture bases are common clinical problem, bondingof artificial teeth to heat cure acrylic and high impact heat cure acrylic denture base materials with autoclaveprocessing method is not well known. The aim of this study was to evaluate the effect of autoclave processingmethod on shear bond of artificial teeth to heat cure denture base material and high impact heat cure denturebase material.Materials and methods: Heat polymerized (Vertex) and high impact acrylic (Vertex) acrylic resins were used. Teethwere processed to each of the denture base materials after the application of different surface treatments. Thesample (which consist of artificial tooth attached to the denture base at 45 degree) are consist of (80) artificial teethfrom the same model of central incisor, they were prepared , treated and bonded to the conventional heat curedand high impact acrylic denture base material then processed.Control group (Group A 40 samples) in which acrylic resins PMMA cured by conventional water- bath processingtechnique (74°C for 1.5 hours then boil for 30 minutes),the group was subdivided to 20 samples heat cure acrylic and20 samples high impact acrylic.Experimentalgroups (Group B 40 samples) in which acrylic resins was cured by autoclave at 121°C, 210KPa. For30min.the group subdivided to 20 samples heat cure acrylic and 20 samples high impact acrylic.For each subgroup, the 20 samples were subdivided according to surface treatment into:1-Five acrylic teeth without any surface treatment (control).2- Five acrylic teeth with diatoric preparation (retention grooves).3- Five acrylic teeth conditioned with thinner.4- Five acrylic teeth with retention grooves and thinner.Results: Statistical analysis revealed that chemical and mechanical treatment of acrylic teeth improved the shearbond with heat cure and high impact acrylicalsoautoclave processing improvedthe shear bond with acrylic teeth inhigh impact acrylic.Conclusion: Autoclave polymerization is suggested as alternative method for processing denture base resins.Autoclave polymerization can be easily performed in laboratory conditions. In High Impact Acrylic, there were highlysignificant differences of autoclave processing technique compared with water bath regarding the shear bondstrength with acrylic teeth