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Simulated enamel wear during occlusal contact.

PURPOSE
To investigate in vitro rates of wear for human enamel that opposes human enamel by means of two-body and three-body wear tests.


METHODS
Flattened surfaces (1000-grit) of molars and hemi-spherically prepared enamel cusps were perpendicularly opposed and loaded (75.6 N, 1.2 Hz) cyclically 100,000 times in both two- and three-body wear test conditions. Wear depths of flat enamel specimens were measured with a profilometer, and those of stylus enamel specimens were determined by a computer digitizing system at 5, 10, 25, 50, and 100 thousand cycles. Data were statistically analyzed by three-way ANOVA (P < 0.05), and differences between two-body and three-body wear data on flat and stylus enamel specimens were determined by Bonferroni-Dunn test.


RESULTS
The amount of wear after 100,000 cycles in the two-body wear test was 175.6 +/- 144.6 microm for flat enamel specimens and 199.3 +/- 72.7 microm for stylus samples. Flat enamel, three-body specimens wore 4.9 +/- 1.4 microm and the stylus samples wore 4.3 +/- 1.0 microm. The data for both flat and stylus enamel specimens subjected to the two-body test were significantly greater than those of the three-body wear test (P < 0.001).