Randomized controlled clinical trial of wear characteristics of CAD/CAM lithium silicate versus monolithic zirconia crowns

Objectives This clinical study aims to compare the wear characteristics of lithium silicate to monolithic zirconia crowns after a year of cementation.
Methodology Twenty-eight patients were randomized to receive either monolithic zirconia crowns (STML zirconia) or CAD/CAM lithium silicate crowns (Obsidian) for first molars that were opposed by natural antagonistic teeth. Impressions of Vinyl polysiloxane were made after cementation and poured into type IV dental stone. Patients were recalled for re-impressions after one year, replica stone casts were made. The replicas were scanned and digitally superimposed (at baseline and after one year) to assess the wear of the crowns and their antagonist’s enamel. All of the data was assembled, checked twice, revised, and entered into a computer. The data was statistically analyzed using an independent t-test.
Results Following a year of clinical use, the amount of enamel wear against monolithic zirconia crowns was mean ±SD (0.0655 ± 0.0116 mm), which was significantly higher than the amount of enamel wear against lithium silicate crowns mean ±SD (0.0457± 0.0099 mm), p < 0.05. Wear testing of STML zirconia crowns produced a result of mean ±SD (0.0203 ± 0.0049 mm), which was significantly less than the amount of wear of lithium silicate crowns mean ±SD (0.0310 ± 0.0031 mm) p < 0.05.
Conclusions Within the limitations of the current research, monolithic zirconia crowns exhibit more enamel wear than Lithium silicate crowns. Monolithic zirconia ceramic material, on the other hand, showed less wear than lithium silicate glass-ceramics.

Clinical significance The usage of lithium silicate crowns in the posterior region shows less opposing enamel attrition than monolithic zirconia crowns, making this study clinically significant.