The effects of various scaling instruments on the surface roughness of monolithic zirconia and lithium disilicate

Purpose This in vitro study aims to evaluate the effects of plastic piezoelectric maintenance tips on the surface roughness of monolithic lithium disilicate and zirconia. Materials and Methods Fifty-four lithium disilicate and 54 zirconia disks were prepared with CAD/CAM. On each material, scaling with a stainless-steel curette or with a piezoelectric device using either a steel or plastic tip was conducted. The surface roughness of the materials before and after the instrumentation was measured with a profilometer. The changes in roughness of the materials according to the scaling methods were analyzed with generalized linear models. Mann-Whitney U with Bonferroni correction was used for between-group comparisons. Results The instruments caused surface alterations on both materials (p=0.001), while the roughness change of lithium disilicate and zirconia specimens did not demonstrate any statistically significant difference with each other (p=0.274). However, the curette was found to cause significantly more (p=0.019) roughness change (0.259 ±0.405) on the specimens than the piezoelectric plastic tip (0.060 ±0.238). Conclusion Piezoelectric scalers with plastic tips cause less deterioration on monolithic zirconia and lithium disilicate surfaces when compared to stainless-steel hand curettes.