Evaluation of the artificial tooth and polymer-base bond in removable dentures

Abstract

Introduction: The most commonly used materials for prosthetic denture base are acrylic resins - polymethyl methacrylate, which has all the important physical and chemical properties. The bond between a denture base and an acrylic tooth has a significant functional value. Aim: To evaluate the influence of various procedures on bonding quality between the denture base and the artificial tooth, the measurement of gaps when connecting the tooth and the denture base using an optical or electron microscope, and evaluating the mechanical properties by compressive testing. Materials and methods: Forty eight acrylic models with bonds between acrylic teeth and prosthetic denturebases, and 12 models for compressive testing were created as the materials in this in vitro study. The acrylic models were allocated to four groups (with 12 samples) for microscopy, and three groups for compressive testing. The samples for microscopy contained denture bases with fixed, unprocessed acrylic teeth, mechanically processed acrylic teeth, chemically processed acrylic teeth, and mechanically and chemically processed acrylic teeth, respectively. The acrylic models had the same dimensions, and the surface of each model was prepared using a slow speed saw, abrasive diamond paste, and special paper grinders. A special metal cast was created for compressive testing with internal dimensions of 20 x 9 mm. The size of a gap was measured on the light inverse microscope (Nikon Epiphot 300) and pressure testing was performed on a Zwick/Roell Z010 pressure machine. Results: The average value of the gap on mechanically and chemically treated samples was 68.250 μm, which was significantly lower than the gap on the untreated samples with the average value of 103.75 μm. The compressive strength was 3200 N/mm2 on untreated samples and above 6000 N/mm2 on the mechanically and chemically treated ones. Conclusions: It can be concluded that surfaces which come into contact must be mechanically and chemically processed. Although in practice prostheses are made using mechanical tooth-base retention, larger gaps occur when compared to mechanically and chemically processed surfaces.

Keywords

• bond
• acrylic tooth
• polymer base
• removable denture