Flexural Properties of Chairside CAD/CAM Materials
Background. New blocks for milling crowns using CAD CAM technology were introduced to the profession. It is important to determine mechanical properties of such materials since they are used for the fabrication of crowns used in stress bearing areas. Objectives. This study determined the flexural strength (FS) and the flexural modulus (FM) of 2 glass ceramic and 2 nanoceramic resin composite CAD/CAM blocks used for chair side crown fabrication Material and Methods. Rectangular specimens were cut from 4 different CAD CAM blocks. Specimens were 3 mm wide, 1.2 mm thick 14 mm long. Specimens were subjected to 3 point bending test following ISO guidelines (ISO 6872) at cross head speed of 0.5mm/min. The flexural strength (FS) and the flexural modulus (FM) were calculated and the data statistically analyzed with one way ANOVA and Games Howell multiple comparison tests at 95% confidence interval. Results. Means and SDs of FS (MPa) for VE, LU, E max, E max U, CD, CD U were: 123.97(14.84) 168.07(16.70) 334.10(54.3) 128.90(17.6) 177.32(37.54) and 147.61(26.62) respectively. For FM means and SDs were: 17.18(2.03) 9.75(0.51) 44.8(5.52) 35.14(7.46) 32.96(6.55) and 38.90(8.03) for VE, LU, E max, E max U, CD, CD U, respectively. ANOVA revealed a highly significant difference among group means (p 0.0001) for both FS and FM. E max had significantly highest mean FS and FM values among all groups, while VE showed lowest FS and LU lowest FM means. Firing and or crystallization positively affected both flexural properties of E max, but only FS of CD. Conclusions. A wide variability in mean FS and FM was observed among the tested materials. Generally, glassceramic based materials had superior flexural properties (Dent. Med. Probl. 2016, 53, 2, 230 235)