RESISTANCE TO FRACTURE OF TEETH WITH VARIOUS PREPARATIONS FOR AMALGAM

Objectives: Advances in dental instrumentation and materials have allo wed for increasingly conservative preparations when treating teeth for dental caries. Research has shown that some materials, properly used, can restore teeth to their pre-prepared strength. At the present time , the longevity of these materials is unknown, requiring clinicians to remain committed to conservative methods of tooth preparation. The pu rpose of this study is to compare the resistance to fracture of teeth prepared with occlusal, mesio-occlusal-distal (MOD) and mesial/distal slot preparations against unprepared control teeth. Methods: Thirty-tw o non-carious, non-restored human maxillary premolar teeth were divide d into three experimental groups and a control group with eight teeth in each. After preparation, the teeth were loaded to fracture on an In stron Universal Testing Machine, and the results were compared using a n Analysis of Variance (ANOVA) followed by Tukey's Studentized Range T est (P < 0.05). Fracture patterns were compared by chi-square analysis at the 0.1 level of probability. Results: There was no significant di fference in fracture resistance among the experimental groups, but all were less resistant to fracture than the unprepared control group. Th e MOD and occlusal groups demonstrated a tendency towards vertical fra cture while the mesial-distal slot and unprepared groups tended to a m ore limited fracture of a single cusp. Conclusion: Any preparation app ears to decrease a tooth's resistance to fracture. Conservative prepar ation design may affect fracture pattern and enhance options for subse quent restoration. Published by Elsevier Science Ltd.