Evaluation of the Bond Strength between the Acrylic Teeth and Reinforced or Non-reinforced Complete Denture Base

Objective: The aim of this study was to examine whether the method of surface treatment of the acrylic teeth and reinforcement of the denture base (carbon fibers) affect the reduction of stress concentration for gap initiation at the interface of acrylic teeth and denture base as a measure of bond strength. Materials and methods: Samples of cross-sections of acrylic teeth and denture base were isolated from four pairs of complete acrylic dentures (with and without reinforcement of the denture base) and were subsequently subjected to compressive loading in a universal testing machine simulating two different occlusions. Selected groups of acrylic teeth (central incisors, first premolars, and first molars) from complete dentures were treated in various ways (untreated, mechanical, chemical, and mechanical-chemical). The gap size at the interface of acrylic tooth and denture base was measured using a light inverted microscope on selected acrylic teeth of individual quadrants. The oneway analysis of variance was used to investigate the influence of denture base reinforcement and different methods of surface treatment of the acrylic tooth on bond strength at the level of statistical significance of p s 0.001. Results: Microscopic analysis of gap size measured at five selected points at the interface between the acrylic teeth and the base of the complete denture ranged from 40 to 144 micrometers. The one-way analysis of variance showed a statistically significant difference between the arithmetic means of the measured gap sizes concerning different methods of surface treatment of the acrylic teeth. Conclusion: The fracture strength, or load-bearing capacity, of complete dentures reinforced with carbon fibers was increased compared to complete dentures with non-reinforced bases. Reduction in gap size at the interface between the acrylic teeth and the base of complete dentures was influenced by the mechanical-chemical treatment of the lower surface of acrylic teeth, while reinforcement of the complete denture base with carbon fibers had no effect on the bond strength.