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Consistency of Labial Finish Line Preparation for Metal Ceramic Crowns: An Investigation of a New Bur
Author(s) -
Seymour Kevin G.,
Cherukara George P.,
Samarawickrama Dayananda Y.D.,
Zou Lifong
Publication year - 2008
Publication title -
journal of prosthodontics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.902
H-Index - 60
eISSN - 1532-849X
pISSN - 1059-941X
DOI - 10.1111/j.1532-849x.2007.00238.x
Subject(s) - chamfer (geometry) , crown (dentistry) , materials science , dentistry , orthodontics , bevel , medicine , composite material , mathematics , engineering , geometry , structural engineering
Purpose: Previous studies have reported on the difficulties inherent in preparing the labial aspect of teeth for metal ceramic crowns with consistency and also the implications for the definitive restoration of underprepared and overangled finish lines. In this study, a bur designed to prepare a 1.2‐mm deep chamfer was tested and compared with two other bur kits. Materials and Methods: Seventy‐two teeth were prepared to receive metal ceramic crowns in vitro by students using one of the two bur kits or the new bur. Using a coordinate measuring machine (CMM), replicas of the prepared teeth were scanned in the mid‐labial plane, and shoulder width and cavosurface angles were measured. Results: The new bur produced preparations with a mean shoulder width and cavosurface angle of 1.146 ± 0.241 mm and 108 ± 11°, respectively, compared with 0.626 ± 0.234 mm and 128 ± 14° produced by a commercially available standardized crown cutting bur system and 0.626 ± 0.218 mm and 124 ± 15° produced by the bur kit in use at our center at the time of the study. These differences were statistically significant at the 5% level, using Tukey's comparison of means. Conclusions: Teeth prepared by the new bur had wider shoulders and lower cavosurface angles than teeth prepared either with a standardized crown cutting system or locally selected bur kit. The quality of labial preparations produced by the new bur in terms of closeness to the postulated “ideal” width and angulation warrants further investigation.