The effect of notch shape and self-cured acrylic resin repair on the fatigue resistance of an acrylic resin denture base.

This study compares four different notch shapes made on the anterior margin of the palatal plates of heat-cured acrylic resin test specimens as well as the effect of self-cured acrylic resin repair on the fatigue resistance of dentures. The test specimens had the shape of an upper partial denture (n = 25). The fatigue test applied was a constant-force fatigue test at a force of 150 N. The stress concentrations during loading the replicas of the test specimens were determined in the field of a circular polarized light. The results showed that the fatigue resistance of the test specimens decreased dramatically (P = 0.002) when there was a notch at the anterior margin of the palatal plate in the test specimen. A 90 degree notch decreased the fatigue resistance most effectively. The test specimens repaired with self-cured acrylic resin were also weaker than the original unnotched test specimens. Examination of the replicas in the field of polarized light showed that stresses occurred only very close to the notch. The highest stress concentrations were detected in the test specimen with a 90 degree notch, i.e. the test specimens with the lowest fatigue resistance. The results of this study suggest that the shape of the anterior margin of the palatal plate in the acrylic resin-based partial denture plays an important role in the fatigue resistance of the dentures.