CAD/CAM diamond tool wear.

Objective: This study evaluated the wear of computer-aided design/computer-assisted manufacture (CAD/CAM) burs and the morphologic changes after a number of millings.

Method And Materials: Diamond burs (cylinder and step-bur) were divided into four milling groups: zero millings (G0); 15 millings (G1); 25 millings (G2); and 35 millings (G3). Seventy-five premolar crowns were milled using the Cerec Compact Milling unit and VitaBlock Mark II. Surface roughness, three-dimensional profile, and SEM were used for wear and surface damage evaluation.

Results: Two-way ANOVA and Tukey test (α = .05) showed that G3 produced statistically different values compared to G0 and G2, but not G1. The cylinder burs showed higher roughness values than step-burs for all groups. SEM showed similar diamond particle damage for cylinder burs and step-burs, and signs of surface damage, cracks, and particle losses for G3.

Conclusion: Both cylinder burs and step-burs were able to sustain a larger number of milling procedures than indicated by the manufacturer.