Wear Resistance of Fully Crystallised Lithium-Disilicate CAD/CAM Material Following Chewing-Simulation

Objectives: Computer-Aided Design and Manufacturing (CAD/CAM) materials are commonly used in restorative dentistry due to their superior strength and predictability. However, the long-term success of restorations depends on how these materials withstand wear forces over time, particularly in occlusal surfaces subjected to chewing forces. This study aim to evaluate the wear performance of fully crystallised Initial LiSi (GC, Japan) CAD/CAM restorative material using a dual-axis chewing simulator.
Methods: CAD/CAM blocks Initial LiSi (GC) were prepared to produce 12.7mm x 14.7 mmx 2.0mm samples (n=8) which were then polished as per manufacture’s instruction with 3 steps polishing wheels DIAPOL TWIST (EVE, Germany) and diamond paste. Sample were then inserted into a 3D printed holder and mounted in a dual-axis chewing simulator (Willytec, SD Mechatronik, Germany). Unrestored human premolar teeth were mounted as the antagonist using universal holder. Samples were subjected to 250,000 cycles of chewing simulation with lateral slide of 0.7mm under 49N at 1-1.6 Hz frequency with distilled water as the immersion medium. Samples were scanned after the chewing simulation using a 3D white-light profilometer (Proscan 2200, Scantron, UK) and volume loss (mm³) was calculated using Proscan software.
Results: Wear tracks were evident after the chewing simulation and the mean volume loss measured was 1.24mm³ (SD 0.77). Wear facets were also visible on the opposing antagonist enamel tooth surface appearing to wear at a similar rate to the restorative material.
Conclusions: Fully crystallised Initial LiSi CAD/CAM restorative material exhibits measurable wear after simulated chewing cycles. The wear observed on both the material and the antagonist tooth enamel highlights the importance of considering material’s impact on the opposing dentition as well the material’s long term survival.