Effect of Finishing and Polishing on Roughness and Gloss of Lithium Disilicate and Lithium Silicate Zirconia Reinforced Glass Ceramic for CAD/CAM Systems

Objective: To assess the efficacy of dedicated finishing/polishing systems on roughness and gloss of VITA Suprinity and IPS e.max CAD. Method: A total of 24 blocks of Suprinity and 24 of e.max were cut into a wedge shape using an InLab MC-XL milling unit. After crystallization, the 24 Suprinity wedges were divided into four subgroups: group A. 1: Suprinity Polishing Set Clinical used for 30 seconds and group A. 2: for 60 seconds; group A. 3: VITA Akzent Plus Paste; and group A. 4: spray. The 24 e.max wedges (group B) were divided into four subgroups according to the finishing procedure: group B. 1: Optrafine Ceramic Polishing System for 30 seconds and group B. 2: for 60 seconds; group B. 3: IPS e.max CAD Crystall/Glaze paste; and group B. 4: spray. After finishing/polishing, gloss was assessed with a gloss-meter and roughness evaluated with a profilometer. Results were analyzed by applying a two-way analysis of variance for gloss and another for roughness (alpha=0.05). One specimen per each subgroup was observed with a scanning electron microscope. Results: For roughness, materials and surface were significant factors (p < 0.001). Suprinity exhibited significantly lower roughness than e.max. Also the Material-Surface Treatment interaction was statistically significant (p=0.026). For gloss, both material and surface treatment were significant factors (p < 0.001). VITA Suprinity showed significantly higher gloss than e.max. Also the Material-Surface Treatment interaction was statistically significant (p < 0 .001). Conclusions: Manual finishing/polishing for 60 seconds and glazing paste are the most effective procedures in lowering the roughness of CAD/CAM silica-based glass ceramics. Manual finishing/polishing for 60 seconds allows milled silica-based glass ceramics to yield a higher gloss. VITA Suprinity displayed higher polishability than IPS e.max CAD.