CONFIRMATION OF LEINFELDER CLINICAL WEAR STANDARDS

Objectives. 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 mu m apart and measured in x-y-z position every 20 mu m 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 mu m, 333 +/- 34 mu m, 171-507 mu m), #5 (382 mu m, 459 +/- 44 mu m, 202-649 mu m), and #6 (493 mu m, 584 +/- 91 mu m, 315-1022 mu m). There were no statistically significant differences (p less than or equal to 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. Significance. 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.