A comparison of the effects of two burs on endodontic access in all-ceramic high lucite crowns

OBJECTIVE: The purpose of this study was to examine and compare the effects of diamond and tungsten carbide burs with respect to the preparation of access through all-ceramic crowns. STUDY DESIGN: Thirty extracted maxillary premolars were restored with all-ceramic crowns. Each specimen was assigned to one of two groups: (1) access opening prepared with a round diamond bur; (2) access opening prepared with a carbide fissure bur. Access preparations were scanned by means of scanning electron microscopy; observed were defects categorized as edge chipping, microcracks, and fractures. RESULTS: Edge chipping around the access was universal. Significant chipping (x > or = 0.1 m) was seen in 43% of access peripheries. Eleven percent of the crowns fractured. chi(2) analysis (P <.05) demonstrated no statistical difference between the bur groups. Results of a t test revealed no statistical difference in edge chipping between the two bur types. CONCLUSIONS: All-ceramic crowns bonded to extracted maxillary premolars may experience edge chipping, microcracks, and fractures at equal rates whether access is prepared with a round medium coarse diamond bur or a tungsten carbide fissure bur.