44 - Time-Lapse for Cutting Different Zirconia Thicknesses for Removal Purposes

Abstract

To determine time and heat produced during cutting off through yttria-stabilized zirconia (YSZ) ceramic slices of varying thicknesses. Four groups (6 samples per group) of 0.5, 1, 2, and 3 mm YSZ sintered slices (e.max ZirCAD, Ivoclar Vivadent) were cut off completely using coarse diamond burs on a high-speed handpiece under irrigation. A type K thermocouple was placed under the YSZ slice during the cutting-off procedure, lined up with the position of the diamond bur so that the temperature could be accurately recorded. Each sample was held in place in a customized device. Cutting off total time, base temperature, and final maximum temperature during the cutting process was recorded for each group sample. Interaction effects, temperature, and cut-off time were analyzed using one-way ANOVA. Data is shown in the Figure. There was no significant difference in temperature among the different YSZ thicknesses during the cutting-off process. However, there was a significant difference in time (p < 0.001). The thickest samples took around 120 min to slice through fully. Thicker YSZ restorations take a longer time to cut through than thinner YSZ restorations; however, regardless of the time spent during the cutting-off process, the temperature through the ceramic remains similar. Time plays an important role in clinical practice, therefore is important to reconsider if rotary mechanical instrumentation is the best route clinician could take to remove high-strength ceramic structures.