Purpose: To evaluate and compare the wear of natural enamel against a metal-ceramic and a monolithic zirconia crown, with the null hypothesis that there is no difference in the wear of enamel between antagonist metal-ceramic and monolithic zirconia crowns.
Materials and methods: In 30 subjects (irrespective of sex and within the age range of 18 to 40 years), two bilaterally opposing molars (maxillary/mandibular) were prepared to receive monolithic zirconia or metal-ceramic crowns with feldspathic porcelain veneer. A polyvinyl siloxane impression of the opposing arch was taken at the time of cementation and 1 year after cementation. Casts were poured in type III gypsum and scanned, and the images were superimposed on each other. AutoCAD was used to calculate the difference between two images, which corresponded to the linear wear of the antagonist teeth. Statistical analysis of the data was done using one-way analysis of variance (ANOVA) and post hoc Tukey honest significant difference test for intergroup comparison. The P value obtained by one-way ANOVA was 1.1102e^-16 (< .05), and by post hoc Tukey test was .001 (< .01).
Results: The mean wear of enamel against enamel was 14.8 ± 1.3 μm, enamel against metal-ceramic was 87.1 ± 18.3 μm, and enamel against monolithic zirconia was 59.4 ± 13.6 μm. The P values obtained; ie, 1.1102e^-16 (one-way ANOVA) and 0.001 (post hoc Tukey), indicated that the difference in wear of the antagonist tooth between monolithic zirconia and feldspathic porcelain was significant.
Conclusion: It can be concluded that monolithic zirconia causes less wear of the antagonist tooth than feldspathic porcelain.