[The strength of ceramic and polymer after CAD/CIM treatment and in a bond with dentin]

The flexural strength of bar samples (2 x 4 x 12 mm) of Vita Mark II, Dicor MGC Dark & Light and CR-Polymer was examined after machining with the Cerec E-Drive unit using grinding wheels coated with coarse (126 microns) and fine (46 microns) diamonds. The flexural strengths of both Vita MK II (98.5-112.4 MPa) and Dicor MGC Dark (135.1-205.3 MPa) were significantly (p < 0.01) different after machining with the coarse and fine discs respectively. The flexural strengths of both Dicor-MGC Light (192.6-220.1 MPa) and of CR-Polymer (103.9-104.3 MPa) were not significantly changed by machining with coarse or fine diamonds, respectively. Bonded sandwich samples (2 x 4 x 12 mm) were made from parts (1.45 x 4 x 12 mm) of Vita MK II, MGC D&L and CR-Polymer and of parts (0.45 x 4 x 12 mm) of bovine dentin using a dentin adhesive and a 100 microns layer of fine hybrid composite resin. The flexural strengths of the samples machined from porcelain and glass ceramic (2 x 4 x 12 mm) and the sandwich samples composed of ceramic (1.45 x 4 x 12 mm) and bovine dentin (0.45 x 4 x 12 mm), respectively, did not differ significantly (p > 0.001): Vita MK II 106.4 +/- 12.2/98.5 +/- 25.8 MPa. Dicor MGC Dark 195.6 +/- 34.6/145.6 +/- 31.2 MPa. Dicor MGC Light 204.1 +/- 29.1/171.5 +/- 18.2 MPa.(ABSTRACT TRUNCATED AT 250 WORDS)