Marginal adaptation of metal crowns: comparison of two production methods

doi:10.3969/j.issn.2095-4344.2014.25.014

Abstract

Abstract:

BACKGROUND: At present, the confrontation of CAD/CAM systems and the lost wax casting method for marginal adaptation has been widely concerned, but the results are controversial.
OBJECTIVE: To compare the marginal adaptation of single cobalt-chromium PFM crowns produced by 3 Shape CAD/CAM systems and the lost wax casting method.
METHODS: A maxillary first premolar was prepared according to the standards. 50 resin-generation models were created by bi-color silicone rubber method and randomly divided into two groups: CAD/CAM group (A1-A25) and cast group (B1-B25). All the models were cast in plaster. In CAD/CAM group, the digital impressions were obtained by optical scanning, then designed through computer and cut directly by NC milling machine. In cast group, metal ceramic crowns were made by the lost wax casting method. When crowns were all seated on the working dies, the marginal gaps were copied with light silicone rubber and then embedded with occlusal silicone rubber. The thickness of crown marginal gap was measured with a stereo microscope.
RESULTS AND CONCLUSION: The average vertical clearance was (34.67±7.48) μm of CAD/CAM group, while (53.70±9.64) μm of the cast group; the difference was statistically significant between two groups (P < 0.05). The average level clearance was (37.61±7.63) μm of CAD/CAM group, while (53.02±10.65) μm of the cast group, and the difference was statistically significant between two groups (P < 0.05). Experimental findings suggest that, the
marginal adaptation of single cobalt-chromium PFM crowns cast produced by 3 Shape CAD/CAM systems is clinical acceptable (< 120 μm), and CAD/CAM systems of metal casting is obviously better than the lost wax casting in building metal based crowns with adaptable margin.

中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程

全文链接：

Key words: dental marginal adaptation, metal ceramic alloys

CLC Number:

R318

Shi Xu-xu, Chang Liang, Zou Gao-feng. Marginal adaptation of metal crowns: comparison of two production methods[J]. Chinese Journal of Tissue Engineering Research, 2014, 18(25): 4014-4019.

Figures/Tables 2

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