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

Abstract

summary: 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®), heat‐pressing (Empress II®) and CAD/CAM crown‐copings (Cerec inLab®, DCS®, Decim® and Procera®) were seated on 12 dies each. Marginal and internal gap width was measured in the SEM at 120× magnification. Marginal gap of slip‐cast (25 ± 18 μ m) was significantly (P < 0·05) smaller than that of Empress II® (44 ± 23 μ m) copings. Procera® (17 ± 16 μ m) and Decim® (23 ± 17 μ m) did not differ (P > 0·05) from slip‐cast (25 ± 18 μ m) but were smaller (P < 0·001/P < 0·01) than Empress II® (44 ± 23 μ m) and Cerec inLab® (43 ± 23 μ m) (P < 0·001/P < 0·05). DCS® (33 ± 20 μ m) did not differ (P > 0·05) from any of the others. The internal mid‐orobuccal gap width of Procera® (136 ± 68 μ m) was larger (P < 0·001) than that of Decim® (81 ± 30 μ m) and slip‐cast (94 ± 84 μ m) (P < 0·05) while Empress II® (105 ± 53 μ m), DCS (110 ± 79 μ m) and Cerec inLab® (114 ± 58 μ m) did not differ significantly (P > 0·05) from Decim®, Procera® 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.