Effect of Different Polishing Systems on the Polishability and Microhardness of an Alkasite Restorative Material

In restorative dentistry, the finishing and polishing of restorative materials are important steps to enhance both the aesthetics and longevity of restorations. The aim of this study was to evaluate the effect of different polishing systems on surface roughness and microhardness of the Cention N alkasite restorative material (Ivoclar Vivadent, Schaan, Liechtenstein) and compare its light-cured versus self-cured specimens.

This experimental in vitro study was conducted at the College of Dentistry, Qassim University, Saudi Arabia, from September 2021 to January 2022. Sixty disc-shaped specimens of Cention N were prepared using custom-made moulds (10 mm diameter × 2 mm thickness). Specimens were randomly allocated into three groups (n = 20): Group 1 (control, Mylar strip finish), Group 2 (three-step Sof-Lex disc system), and Group 3 (one-step PoGo system). Half of each group was light-cured (40 seconds at 400 mW/cm²) while the remainder was self-cured. Surface roughness was measured using profilometry (Perthometer M1; Mahr GmbH, Göttingen, Germany) and microhardness assessed via Vickers hardness test (Vickers hardness number, or VHN). Data were analysed using two-way ANOVA and post hoc Bonferroni tests (p < 0.05).

Significant differences in surface roughness existed between polishing systems (F = 156.731, p < 0.001), with the control group producing the smoothest surface (0.077 ± 0.055 μm), followed by PoGo (0.173 ± 0.039 μm) and Sof-Lex (0.238 ± 0.054 μm). All values remained below the 0.2 μm bacterial adhesion threshold. Significant interaction effects were found for both surface roughness and microhardness (p < 0.001). Light-cured specimens showed significantly higher microhardness than self-cured ones (47.8 ± 0.2 vs. 42.3 ± 0.2 VHN, p < 0.001).

The null hypothesis was rejected. While the Mylar strip finish provided optimal smoothness, all polishing systems maintained clinically acceptable surface roughness. Sof-Lex polishing combined with light curing offers superior microhardness, potentially enhancing restoration longevity.