An investigation on the influence of tin foil substitute contamination on bond strength between resin denture teeth and the denture base: an in vitro study.

STATEMENT OF PROBLEM: The problem of acrylic resin denture teeth separating from their denture base remains a major problem in prosthodontic practice and is frustrating to the patients as well as the dentists.

PURPOSE: This study investigated the influence of tin foil substitute contamination on bond strength between acrylic resin denture teeth and their denture base.

MATERIALS AND METHODS: A total of 80 modified acrylic resin maxillary left central incisors were processed to their denture base material. The 80 specimens were divided into two groups of 40 specimens each: the experimental group and the control group. The experimental group had the denture tooth ridge lap area contaminated with tin foil substitute.The 40 specimens in the control group were not contaminated. After 7 days of storage at room temperature, the bond strengths of the two groups were tested with a universal testing machine.The nature of failure was noted as adhesive (interface) or cohesive (in tooth or denture base material). The Welch test and z-test were performed to identify significant differences.

RESULTS: The uncontaminated specimens (group I) showed superior bond strength as compared to the contaminated specimens (group II); the difference in bond strength between the groups was highly significant (P<0.0001). Also the contaminated specimens exhibited predominantly adhesive failure (89.74%), whereas the uncontaminated specimens exhibited 55% adhesive failure and 45% cohesive failure.

CONCLUSION: Tin foil substitute contamination of the ridge laps of acrylic resin denture teeth greatly reduced the bond strength.