[The preparation of ceramic restorations with superfine diamond instruments]

Four groups of computer machined (Cerec 64 microns) Vita Mk II porcelain samples with six blocks (12 x 7 x 1.5 mm) each were finished, using super-fine diamond burs (15, 8, 4 microns) and Proxoshape files (15, 8, 4 microns) and additionally polished with standard round and experimental angular cut discs. Surface roughness was measured after each treatment. For control, porcelain surfaces were high-gloss polished with a laboratory polishing machine (LPM). The roughness values R15/8/4 achieved with 15/8/4 microns diamond burs, were significantly different between the diamond grain sizes used: R15 = 1.49 +/- 0.44 > R8 = 0.86 +/- 0.25 (p < 0.05); R8 = 0.86 +/- 0.25 > R4 = 0.56 +/- 0.10 (p < or = 0.055); R4 = 0.56 +/- 0.10 > RLPM = 0.05 +/- 0.01 (p < 0.001). The diamond coated Proxoshape files caused the following roughness values RP15 = 0.53 U +/- 0.17 > RP8 = 0.24 +/- 0.06 (p < 0.01) and the Proxoshape file with 4 microns diamond coating did not achieve lower roughness values. The 8 microns diamond coating of burs and Proxoshape files caused a very fine "pre-polish" surface quality on porcelain. Angular discs had the same polishing ability as standard round discs but were more effectively used in fissures.