Marginal and internal fit of all-ceramic CAD/CAM crown-copings on chamfer preparations

Evaluation of the marginal and internal fit of all-ceramic molar crown-copings hypothesizing that Computer Aided Design/Computer Aided Manufacturing (CAD/CAM) fabrication shows the same accuracy of fit as conventional techniques. A set of six individual crown preparations was duplicated 12 times yielding 72 plaster dies. Slip-cast (In-Ceram Zirconia(R)), heat-pressing (Empress II(R)) and CAD/CAM crown-copings (Cerec inLab(R), DCS(R), Decim(R) and Procera(R)) were seated on 12 dies each. Marginal and internal gap width was measured in the SEM at 120x magnification. Marginal gap of slip-cast (25 +/- 18 mu m) was significantly (P < 0.05) smaller than that of Empress II(R) (44 +/- 23 mu m) copings. Procera(R) (17 +/- 16 mu m) and Decim(R) (23 +/- 17 mu m) did not differ (P > 0.05) from slip-cast (25 +/- 18 mu m) but were smaller (P < 0.001/P < 0.01) than Empress II(R) (44 +/- 23 mu m) and Cerec inLab(R) (43 +/- 23 mu m) (P < 0.001/P < 0.05). DCS(R) (33 +/- 20 mu m) did not differ (P > 0.05) from any of the others. The internal mid-orobuccal gap width of Procera(R) (136 +/- 68 mu m) was larger (P < 0.001) than that of Decim(R) (81 +/- 30 mu m) and slip-cast (94 +/- 84 mu m) (P < 0.05) while Empress II(R) (105 +/- 53 mu m), DCS (110 +/- 79 mu m) and Cerec inLab(R) (114 +/- 58 mu m) did not differ significantly (P > 0.05) from Decim(R), Procera(R) and slip-cast. Internal mesiodistal gap width was similar. The fit of conventional and CAD/CAM all-ceramic molar crown-copings covered the same range of gap width confirming the assumed hypothesis.