The Influence of Repairs on the Stress Distribution and Compression Fracture Strength of Denture Bases

Abstract

Purpose : Because of the shape of mandibular complete dentures, stress is the greatest along the midline. These dentures frequently fracture at or near this area. In order to contribute to the database of information available to dental professionals, the present study was undertaken to evaluate the distribution of stress and the fracture strength of denture bases, both before and after repair of a midline fracture.Materials and Methods : Twelve denture bases (each 3 mm thick) were constructed of polymethyl methacrylate acrylic resin. The stress pattern of each base was characterized by measuring changes in thermal emission from the surface of the denture base. The fracture strength of six of the bases was measured by bending them with a compression-bending tester until they fractured.Results : Stress concentration along the midline of the denture bases was observed. The mean fracture strengths of unbroken bases, repaired bases, and bases repaired with both resin and wire were 9.36, 2.28, and 4.34 N, respectively.Conclusion : Greater stress was observed along the midline in bases repaired with autopolymerizing resin only than in unbroken bases. In addition, the fracture strength of the repaired bases was only about 1/4 that of unbroken bases. It was observed that stress was less concentrated along the midline of bases repaired with autopolymerizing resin and a reinforcement wire compared to either repaired bases or unbroken bases.