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.


METHODS
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.
Haselton
D R
DR
University of Iowa, Department of Family Dentistry, College of Dentistry, Iowa City, IA 52242-1001, USA.
Lloyd
P M
PM
Johnson
W T
WT
D001641:Bicuspid; D002516:Ceramics; D016009:Chi-Square Distribution; D003442:Crowns / Q000706:statistics & numerical data; D003722:Dental Alloys; D018130:Diamond; D006801:Humans; D066298:In Vitro Techniques; D008437:Maxilla; D008855:Microscopy, Electron, Scanning; D019904:Polymethyl Methacrylate; D011897:Random Allocation; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000706:statistics & numerical data; D013499:Surface Properties; D017973:Tungsten Compounds
D003722:Dental Alloys; D017973:Tungsten Compounds; C002802:tungsten carbide; D018130:Diamond; D019904:Polymethyl Methacrylate