抄録
Purpose: The aim of this article is to standardize the designs of zirconia copings and abutments from the viewpoint of fracture mechanics, by using a 3-D finite element method.
Materials and methods: 3-D finite element models were created in which single standing screw implants were placed in the alveolar bone, having zirconia coping crowns and zirconia abutments. Three zirconia copings were designed and designated as follows: RP0, no porcelain support; RP1, 1 mm porcelain support; RP2, 2 mm porcelain support. Similarly, three abutments were designed: RP0, having a regular diameter neck (as 4 mm implant platform); NP0, having a narrow concave curved neck; and WP0, having a wide 5 mm diameter abutment neck. Oblique static loading 100 N (30-degree buccolingal direction) was applied, and the maximum principal stress was analyzed under the different coping and abutment designed models to estimate the structural integrity of their designs.
Results: Maximum principal stress of zirconia copings was measured in RP0 as 60.2 MPa; in RP1 as 14.1 MPa; and in RP2 as 3.8 MPa. Wider porcelain support models tended to decrease principal stress. The maximum principal stress of zirconia abutments was measured in NP0 as 189 MPa;in RP0 as 94.7 MPa;and in WP0 as 91.0 MPa. The maximum principal stress in NP0 was twice that of RP0 and WP0.
Conclusion: It is suggested that a zirconia coping design having a wide porcelain support would be effective to reduce stress in the implant crown. However, a narrow concave curved neck zirconia abutment might be unfavorable from the viewpoint of fracture mechanics.
