Yi Y Cheng1, Wai L Cheung, Tak W Chow. 1. Honorary Research Associate, Faculty of Dentistry, University of Hong Kong, Hong Kong. yycheng@hku.hk <yycheng@hku.hk>
Abstract
STATEMENT OF PROBLEM: The fracture of maxillary complete dentures has been reported as the most common prosthesis failure. PURPOSE: The purpose of this study was to evaluate strain distribution in dentures during application of occlusal load with 3-dimensional (3-D) finite element analysis (FEA). MATERIAL AND METHODS: A maxillary complete denture was converted into a 3-D numerical model by an advanced topometric sensor digitizer (ATOS). The denture surfaces were scanned with fringes. Ten measurements were made for each scan of the denture in top, left, right, back, and front orientations by tilting the scanning table. The individual scans were merged by the digitizing software into a single image. A haptic device with a freeform system (PHANTOM) was used to create the mucosa in contact with the intaglio surface of the denture model. Supporting bone was then constructed from the mucosa model. The posterior teeth were loaded with an occlusal force of 230 N, and the basal bone was constrained for performing FEA. RESULTS: The highest tensile and compressive strains were found at the incisal and labial frenal notches, respectively. Strains on the intaglio surface of the denture were primarily compressive. The buccal flange exhibited tensile strains in the horizontal direction but compressive strains in the vertical direction. The labial flange showed compressive strains in both directions. The posterior border of the denture flexed away from the mucosa during occlusal loading. CONCLUSIONS: Three-dimensional FEA provided different views of strain distribution in the denture and indicated that denture failure was unlikely to occur at the shallow labial frenal notch because the strain is compressive. The high tensile strain concentration at the incisal notch is likely to be the cause of denture fracture during clinical service.
STATEMENT OF PROBLEM: The fracture of maxillary complete dentures has been reported as the most common prosthesis failure. PURPOSE: The purpose of this study was to evaluate strain distribution in dentures during application of occlusal load with 3-dimensional (3-D) finite element analysis (FEA). MATERIAL AND METHODS: A maxillary complete denture was converted into a 3-D numerical model by an advanced topometric sensor digitizer (ATOS). The denture surfaces were scanned with fringes. Ten measurements were made for each scan of the denture in top, left, right, back, and front orientations by tilting the scanning table. The individual scans were merged by the digitizing software into a single image. A haptic device with a freeform system (PHANTOM) was used to create the mucosa in contact with the intaglio surface of the denture model. Supporting bone was then constructed from the mucosa model. The posterior teeth were loaded with an occlusal force of 230 N, and the basal bone was constrained for performing FEA. RESULTS: The highest tensile and compressive strains were found at the incisal and labial frenal notches, respectively. Strains on the intaglio surface of the denture were primarily compressive. The buccal flange exhibited tensile strains in the horizontal direction but compressive strains in the vertical direction. The labial flange showed compressive strains in both directions. The posterior border of the denture flexed away from the mucosa during occlusal loading. CONCLUSIONS: Three-dimensional FEA provided different views of strain distribution in the denture and indicated that denture failure was unlikely to occur at the shallow labial frenal notch because the strain is compressive. The high tensile strain concentration at the incisal notch is likely to be the cause of denture fracture during clinical service.
Authors: Cíntia de Souza Silva; Ana Lucia Machado; Carolina de Andrade Lima Chaves; Ana Cláudia Pavarina; Carlos Eduardo Vergani Journal: J Appl Oral Sci Date: 2013 Impact factor: 2.698