Effects of synthetic diamond abrasives on the surface quality of CAD-CAM restorative materials

Finishing and polishing protocols can markedly influence the surface quality of computer-aided design-computer-aided manufacturing (CAD-CAM) restorative materials; however, the performance of synthetic diamond abrasives across different microstructures remains unclear.

The purpose of this in vitro study was to evaluate the effects of various finishing and polishing procedures on the surface roughness, gloss, and contact angle of 4 CAD-CAM restorative materials.

Eighty rectangular specimens (15×1.5×1.5 mm) were prepared from a polymer-infiltrated ceramic (Enamic), ceramic-reinforced composite resin (Cerasmart), fiber-reinforced composite resin (Trinia), and feldspathic ceramic (Vita Mark II). After standardized grinding with 600-, 800-, and 1000-grit silicon carbide papers, specimens were assigned to 4 groups (n=5): control (C), rubber-cup polishing (RC), rubber-cup polishing followed by diamond polishing paste (RC+DP), and rubber-cup polishing followed by synthetic diamond abrasives (RC+SD). Surface roughness (Ra), gloss, and contact angle were measured using a contact profilometer, glossmeter, and drop-shape analyzer, respectively. Data were analyzed using 2-way analysis of variance and the Tukey post hoc test (α=.05).

Both polishing procedure and material type significantly affected surface roughness, gloss, and contact angle values (P<.001), with significant interactions between the 2 factors for all parameters. Trinia exhibited the highest roughness and lowest gloss, whereas Cerasmart and Enamic demonstrated smoother surfaces after polishing. The RC+SD protocol generally produced lower Ra values and higher gloss and contact angles compared with RC and RC+DP (P<.001).

Finishing and polishing protocols substantially influence the surface quality of CAD-CAM restorative materials. Synthetic diamond abrasives generally produce smoother surfaces, higher gloss, and increased hydrophobicity. Polishing protocols incorporating synthetic diamond abrasives may be considered a reliable approach across different CAD-CAM restorative materials.