Influence of denture tooth thickness on fracture mode of thin acrylic resin bases: An experimental and finite element analysis.

STATEMENT OF PROBLEM

The optimum selection of denture teeth for patients with a reduced interarch distance has not been established.

PURPOSE

The purpose of this in vitro study was to investigate the influence of denture tooth material and thickness on the fracture resistance of thin acrylic resin denture bases.

MATERIAL AND METHODS

Acrylic resin (AC), composite resin (CO), or ceramic (CE) molar denture teeth were embedded in denture base blocks (2.0 mm thick). The distance from the central fossa to the tooth base was 0.5, 1.0, 2.0, or 2.5 mm for AC and CO, and 1.0 mm for CE (n=7), with a total thickness of 2.5 mm for all specimens. Each specimen was placed on a 3-point flexural setup with a shorter (8 mm) or longer (12 mm) support span than the tooth width and vertically loaded. A finite element analysis was performed to assess the stress distributions. The effects of tooth thickness and support span were statistically tested with ANOVA, followed by the Tukey honestly significant difference post hoc test (α= .05).

RESULTS

With the shorter support, the mean fracture load was higher in CO than AC, regardless of the tooth thickness. Under the longer support, the mean fracture load with the CO decreased significantly as the tooth thickness increased, with increased maximum stress. Some CO tooth specimens of 2.0 mm or 2.5 mm thickness failed at the tooth-denture base interface at significantly lower loads than those exhibited by tooth fractures. CE showed minor cracks before bulk fracture.

CONCLUSIONS

Higher fracture resistance was indicated with CO; however, the resistance decreased as the thickness of the CO tooth increased.