The effect of impurities on the stress distribution at the tooth/denture base resin interface.

The most common cause of teeth detaching from the denture base is the presence of impurities along the tooth denture-base interface. However detachment after a period of wear of the denture probably occurs due to the presence of stress concentrations along the interface from which cracks may initiate. The presence of the impurity will inevitably lower the stress threshold for cracks to propagate thereby increasing the risk of tooth detachment. Although this is obvious, there is no evidence to show the effect of impurities on the stress distribution at this interface. This pilot study utilised the finite element method to examine stresses at the tooth-denture base interface in the presence of simulated impurities interspersed along different positions on the interface. Within the limitations of the two-dimensional model used, it was concluded that the presence of an impurity at the edge of the palatal aspect of the interface has a significant effect on the stress magnitude. However, the presence of impurities elsewhere along the interface had no significant effect on the stress magnitude. This would have important implications during the processing of dentures.