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.