Abstract
Statement of problem
Fundamental crown preparation principles are taught and are highly regarded in dental
education. Whether tooth preparations made by dental students match these principles
is unclear.
Purpose
The purpose of this retrospective study was to report the total occlusal convergence
(TOC) and margin widths of crown preparations clinically prepared by New Zealand predoctoral
dental students between 2013 and mid-2015.
Material and methods
A total of 371 stereolithography files of tooth preparations for metal ceramic crowns
prepared by predoctoral dental students were extracted from the Technical Services
Laboratory database at the University of Otago. The files were put through the preparation
measuring software Preppr, with outputs being TOC angles in faciolingual and mesiodistal
cross sections and margin widths in facial, lingual, distal, and mesial aspects. Means,
standard deviations, 95% confidence intervals, and distributions using box and whisker
graphs were calculated and presented.
Results
The majority of TOC angles fell within an acceptable range of 10 to 20 degrees; however,
the angles ranged from undercuts (<0 degrees) to >60 degrees. The majority of margin
widths were between 0.5 and 1 mm, while the maximum was approximately 2 mm and the
minimum was 0 mm.
Conclusions
Predoctoral dental students in New Zealand are able to produce literature-recommended
TOC angles and margin widths for metal ceramic crowns; however, further attention
and training are needed for excessive tooth preparations, mainly in the form of large
TOC angles.
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Article info
Publication history
Published online: March 01, 2016
Identification
Copyright
Copyright © 2016 by the Editorial Council for The Journal of Prosthetic Dentistry.
