Objectives: To examine the effect of two ferrule widths on the fracture resistance of endodontically-treated maxillary anterior teeth with a ferrule height of 1.5mm. Methods: 12 extracted human maxillary anterior teeth were randomly divided into 2 groups (n=6). The teeth were selected on the basis of absence of cracks, fractures or caries in the cervical area or root. They were endodontically treated and prepared to receive cast post-cores, keeping the ferrule height constant at 1.5mm. The ferrule width was prepared to either 0.5mm or 1.0mm, depending on the group. To ensure standardization of the ferrule width, measurements were made at 4 points on the buccal, palatal, mesial and distal surfaces of the ferrule. Cast post-cores were waxed, cast, fitted and cemented with zinc phosphate cement (ZPC). After cementation, the specimens were finished to a preparation height of 6mm. Complete gold crowns were waxed, cast, fitted and then cemented with ZPC. A fatigue load of 6kg was applied at an angle of 135degrees to the long axis of each tooth-crown specimen. Preliminary failure was defined as the propagation of a crack in or around the crown luting cement layer. The number of cycles to preliminary failure was determined. The data were subjected to an independent T-test and analyzed using statistical software (SPSS 18.0; SPSS Inc, Chicago, Ill).
Results: Results showed that teeth with 0.5mm ferrule widths did not differ significantly in cycles to preliminary failure when compared to teeth with 1.0mm ferrule widths.
Conclusion: This pilot study showed that there was no significant difference in fracture resistance of endodontically-treated teeth with 0.5mm or 1.0mm ferrule width. Future studies involving a wider range of ferrule width need to be done to determine whether an effective ferrule width exists for optimal resistance against fracture.
This study was supported by NUS Research Grant #R-224-000-027-112.