Effect of pre-processing surface treatments of acrylic teeth on bonding to the denture base

The aim of this study was to examine the bond strength between acrylic teeth after various surface treatments and processing with either a heat- or microwave-polymerized denture base material. Specimens were prepared and tested according to the methods described in American National Standard/American Dental Association Specification No.15 (Synthetic Polymer Teeth) using a special assembly. Three brands of acrylic teeth were used with the following treatments: control (no treatment), grinding and grinding plus sandblasting. Treatment groups were further divided into two denture base processing subgroups: heat-polymerized and microwave-polymerized methods. Denture base processing to the acrylic teeth was performed according to the manufacturer's recommendations. Bond strength test was performed using a universal testing machine with five specimens and each specimen is composed of six anterior teeth per experimental group. Data were analysed using a three-way ANOVA and the Scheffe'F-test post hoc pair wise comparison at the 95% significance level. The mean bond strength values ranged from 33.1 +/- 4.1 to 51.6 +/- 2.5 MPa. The bond strength values of sandblasted surfaces were significantly higher than those of the ground surface and the control (P < 0.05). Combined (acrylic tooth and denture base resin) cohesive failures were disclosed in all tested samples. Acrylic tooth surface pre-processed surface treatment with grinding plus sandblasting and processed with a heat-polymerized denture base provided the greatest bond strength between acrylic tooth and denture base.