An investigation of the variables which may affect the bond between plastic teeth and denture base resin

Abstract

Objectives: The failure of the bond between acrylic resin denture base material and resin teeth remains a significant problem. This study evaluated the tensile bond strength of specimens produced by commonly employed tooth preparation and processing methods as used in dental laboratories. Methods: Twenty-two experimental groups, each consisting of 36 specimens, were investigated by subjecting the tooth–resin bond to tensile loading. The groups were allocated to one of five experimental sets to investigate: (a) effect of resin dough time, (b) effect of tooth surface condition, (c) effect of processing variables, (d) effect of monomer cementing, and (e) effect of acrylic resin cement. The results were analysed statistically using a one factor anova and a Student t test. Results: A significantly stronger bond was obtained when the resin was packed late in the dough stage, and a superior bond, in all cases, when high-impact resin was used. Tooth surface modification by grinding or grooving made no significant difference when compared with unmodified surfaces. Wax-contaminated surfaces produced highly significant weaker bonds. Time of introduction and duration of water-bath processing had no significant effect on bond strength. Monomer cementing of the tooth surface, especially with high-impact monomer, significantly improved the bond strength. The application of resin cements was found to produce the most significant increase in denture tooth bond strength. Conclusions: The important steps in obtaining a consistently high value denture tooth bond are thorough dewaxing of the tooth surface followed by the application of a suitable resin cement.