Confirmation of Leinfelder clinical wear standards.
OBJECTIVE
Accuracy of composite wear studies based on Leinfelder standards has been disputed. There are differences with other well-calibrated systems such as the M-L and Vivadent wear standards. The objective of this study was to reevaluate the margin height at key regions along the restoration margins for each of the 6 Leinfelder standards using laser profiling techniques.


METHODS
The Leinfelder standards were profiled in parallel paths 100 microns apart and measured in x-y-z position every 20 microns along those paths using a laser profilometer.


RESULTS
Rounding of cavosurface enamel margins from intraoral wear greatly increased the uncertainty of the true enamel margin location and step height measurements, precluding unequivocal measurements for standards #2 and #3. Values for other standards for the original report, newly measured means and standard errors, and measured ranges were: #4 (322 microns, 333 +/- 34 microns, 171-507 microns), #5 (382 microns, 459 +/- 44 microns, 202-649 microns), and #6 (493 microns, 584 +/- 91 microns, 315-1022 microns). There were no statistically significant differences (p < or = 0.10) between these and original values. Large standard errors may have obscured small differences that may exist. The Leinfelder cast conversion scale seems to be the correct relative magnitude.


CONCLUSIONS
Differences between Leinfelder casts and other standards may be due to differences in shadow production. Clinical wear may be systematically underestimated by other cast evaluation methods that have well-defined margins. This emphasizes the need for standard casts with margin morphology similar to the clinical casts being evaluated for wear.
Bayne
S C
SC
Department of Operative Dentistry, School of Dentistry, University of North Carolina, Chapel Hill.
Taylor
D F
DF
Rekow
E D
ED
Wilder
A D
AD
Heymann
H O
HO
D001641:Bicuspid; D003188:Composite Resins / Q000592:standards*; D018772:Dental Marginal Adaptation; D003793:Dental Restoration, Permanent / Q000592:standards; D003799:Dental Stress Analysis / Q000295:instrumentation / Q000379:methods*; D005069:Evaluation Studies as Topic; D006244:Hardness; D007834:Lasers; D008422:Materials Testing / Q000379:methods / Q000592:standards; D008855:Microscopy, Electron, Scanning; D008963:Molar; D015203:Reproducibility of Results; D013499:Surface Properties
D003188:Composite Resins