頁籤選單縮合
題名 | Fracture Resistance and Failure Modes of CEREC Endo-crowns and Conventional Post and Core-supported CEREC Crowns= |
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作者 | Chang, Chia-yu; Kuo, Jau-shing; Lin, Yang-sung; Chang, Yen-hsiang; |
期刊 | Journal of Dental Sciences |
出版日期 | 20090900 |
卷期 | 4:3 2009.09[民98.09] |
頁次 | 頁110-117 |
分類號 | 416.9 |
語文 | eng |
關鍵詞 | CAD-CAM; CEREC; Endo-crown; Failure modes; Fracture resistance; |
英文摘要 | Background/purpose: The purpose of this in vitro study was to compare the fracture resistance and failure modes of CEREC endo-crowns with the CEREC classic designed crown supported with glass fiber-reinforced composite posts and composite cores. The influences of thermal cycling and fatigue loading on both types of restorations were also investigated. Materials and methods: Twenty extracted intact maxillary premolars were randomly divided into two groups (C and E). The crown portion of the specimens was removed junction (CEJ). All specimens were endodontically treated with a nickel-titanium rotary system and obturated with gutta-percha by a vertical compaction technique. In group C (n = 10), teeth were restored with glass fiber-reinforced composite posts and composite cores with a 1.0-mm wide circumferential shoulder margin at the CEJ and a 1.5-mm ferrule. In group E (n = 10), teeth were prepared for fabrication of CEREC endo-crowns. Both types of ceramic crowns were produced from ProCAD ceramic blocks utilizing a CEREC 3D CAD-CAM unit, and these were bonded to the preparations with an adhesive system and composite resin cement. Teeth were thermally cycled (2000 cycles of 5ºC/55ºC with a dwell time of 30 seconds,) and fatigue loaded (20,000 cycles at 5 kg and 3 Hz) in a custom-made fatigue simulator. All specimens were loaded in a universal testing machine with a cross-head speed of 0.5 mm/s until fracture occurred. Fracture resistance and failure modes were statistically evaluated with a t test and χ2 test. Results: The mean fracture resistance ± standard deviation was recorded as follows: 1163.30 ± 163.15 N for group C and 1446.68 ± 200.34 N for group E. A significant difference was found between groups with respect to fracture resistance (P < 0.05). Regarding failure modes, most specimens of both groups exhibited unfavorable fractures, and no significant difference was found between the two groups. Conclusion: The bonded ceramic endo-crowns showed a significantly higher fracture resistance than the classic reinforced and designed group and, therefore, offer a feasible alternative for severely damaged teeth. |
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