The Wear Characteristics and Volume Loss of Different CAD/CAM Materials

With the improvement of CAD/CAM technology in its application to dentistry, there has been an increase in use of milled, all-ceramic restorations by clinicians. This study evaluates how these different CAD/CAM materials with different surface textures might affect volume loss after a length of time in function. Utilizing a ball-on-block tribometer and artificial saliva, glazed and glazed then polished samples of zirconia and lithium disilicate were tested. Surface characterization was performed using white-light interferometry and scanning electron microscopy. The volume loss, surface roughness and coefficient of friction of the samples were analyzed. All lithium disilicate samples exhibited increased wear compared to zirconia samples. In addition, lithium disilicate samples were rougher than zirconia samples after wear simulation. Similarly, the coefficient of friction of the lithium disilicate samples was greater than that of the zirconia samples. The glazed then polished zirconia samples showed less volume loss than the glazed zirconia samples. In contrast, the glazed then polished lithium disilicate samples showed more volume loss than the glazed lithium disilicate samples. The differences seen between samples can be best explained by the introduction of three-body wear once previously worn material started to collect on the lithium disilicate samples. This is supported by the SEM imaging taken of the different samples.