IN-VITRO COMPARATIVE STUDY OF COMPRESSIVE STRENGTH IN CAD/CAM DENTAL MATERIALS

Aim of the study was to investigate comparatively the compressive strength for three computeraided design/computer-aided manufacturing (CAD/CAM) dental materials: glass ceramic IPS Empress CAD (Ivoclar Vivadent), hybrid ceramic Cerasmart (GC) and polymer-reinforced graphene G-CAM (Graphenano Dental). Material and methods 45 samples consisted of the single-unit molar crowns fabricated by three CAD/CAM materials were cemented adhesively on 3D printed abutments (Asiga Dental Resin). The samples were divided into 3 groups (n=15) according to the crowns thickness; group 1 under the cusps/cervical margins - 0.6 mm/0.4 mm, group 2 - 1 mm/0.7 mm respectively, and group 3 - 1.5 mm/1 mm. Additionally, 20 cylindrical specimens fabricated by the three crowns and abutments material (n=5) were prepared by CAD/CAM technique. All samples and specimens were subjected to an axial compressive load by using a universal testing machine (Instron 3366-10kN, USA) until fracture. Results The compressive strength values were 1258 MPa for Empress CAD, 501.3 MPa for Cerasmart, 435 MPa for G-CAM and 360 MPa Asiga resin. G-CAM crowns exhibited a higher maximum compressive load (1701.5-2011.8N) than both Cerasmart (1295.4-1642.9N) and Empress CAD (494.3-597.5N). Conclusions The CAD/CAM crown materials presented different mechanical behavior; Empress CAD and Cerasmart presented a fragile behavior, with a high compressive strength when compared to G-CAM and Asiga resins.