RESUMO
PURPOSE: Marginal fit is one of the important components for the successful prosthodontic restoration. Poor fitting margin of the restoration causes hypersensitivity, secondary caries, and plaque accumulation, which later result in prosthodontic failure. CAD/CAM zirconia all-ceramic restorations, such as LAVA(R) (3M ESPE, St.Paul, MN) and EVEREST(R) (KaVo Dental GmbH, Biberach, Germany) systems were recently introduced in Korea. It is clinically meaningful to evaluate the changes of the marginal fit of the CAD/CAM zirconia systems before and after build-up. The purposes of this study are to compare the marginal fit of the two CAD/CAM all-ceramic systems with that of the ceramometal restoration, before and after porcelain build-up. MATERIAL AND METHODS: A maxillary first premolar dentiform tooth was prepared with 2.0 mm occlusal reduction, 1.0 mm axial reduction, chamfer margin, and 6 degree taperness in the axial wall. The prepared dentiform die was duplicated into the metal abutment die. The metal die was placed in the dental study model, and the full arch impressions of the model were made. Twenty four copings of 3 groups which were LAVA(R), EVEREST(R), and ceramometal restorations were fabricated. Each coping was cemented on the metal die with color-mixed Fit-checker II(R) (GC Cor., Tokyo, Japan). The marginal opening of each coping was measured with Microhiscope(R) system (HIROX KH-1000 ING-Plus, Seoul, Korea. *300 magnification). After porcelain build-up, the marginal openings of LAVA(R), EVEREST(R),and ceramometal restorations were also evaluated in the same method. Statistical analysis was done with paired t-test and one-way ANOVA test. RESULTS: In coping states, the mean marginal opening for EVEREST(R) restorations was 52.00 +/- 11.94 micrometer, for LAVA(R) restorations 56.97 +/- 10.00 micrometer, and for ceramometal restorations 97.38 +/- 18.54 micrometer. After porcelain build-up, the mean marginal opening for EVEREST(R) restorations was 61.69 +/- 19.33 micrometer, for LAVA(R) restorations 70.81 +/- 12.99 micrometer, and for ceramometal restorations 115.25 +/- 23.86 micrometer. CONCLUSION: 1. LAVA(R) and EVEREST(R) restorations in comparison with ceramometal restorations showed better marginal fit, which had significant differences (P .05). 3. EVEREST(R), LAVA(R) and ceramometal restorations showed a little increased marginal opening after porcelain build-up, but did not show any statistical significance (P > .05).