Abstract
Purpose: Recently, composite denture teeth have been commonly used for denture construction, but discoloration has frequently been reported. The purpose of this study was to investigate the discoloration of composite denture teeth. Thisin vivoandin vivostudy examined laboratory procedures for denture fabrication, the oral environment, and the methods of cleaning dentures, to clarify the phenomenon of discoloration.
Methods: Four kinds of composite denture teeth were prepared and immersed in yellow colorant solution, coffee solution, and distilled water for 3, 6, and 12months, respectively. Surface roughness, Vickers hardness, and discoloration of the composite denture teeth were measured at each specified period. During thein vivoinvestigation, the color differences after delivery of the dentures were measured, and examination of saliva was carried out. In addition, 42 patients were monitored regarding their denture cleaning methods.
Results: 1. Severe discoloration was observed on the teeth immersed in the yellow colorant solution, because composite denture teeth surfaces were rougher. In the coffee solution, remarkable discoloration was found on all composite denture teeth. The composite denture teeth with smooth surfaces and great hardness tended to show little discoloration.2.In thein vivoinvestigations, discoloration of the composite denture teeth was observed in 55% of 42 cases after 6-months, and the color differences (ΔE*) were more than 2.There was a high correlation between discoloration and the methods of denture cleaning (the use of dentifrices).
Conclusions: Composite denture teeth with rougher surfaces and lower Vickers hardness tended to show discoloration. Laboratory procedures for denture fabrication might also influence discoloration. To prevent discoloration, it is necessary to improve the mechanical properties of composite denture teeth. Furthermore, instructions to patients regarding proper handling and methods of denture cleaning are very important.
