[Experimental study on fabricating Ni-Cr alloy coping with laser rapid forming].

To probe the feasibility of fabricating Ni-Cr alloy coping with laser rapid forming (LRF). The digitalized model of coping was designed using the technology of reverse engineering and computer aided design (CAD) based on the abutment. The Ni-Cr alloy coping was fabricated with LRF. The gaps between the internal surface of coping and the external surface of abutment were measured respectively at the locations of occlusal surface edge, midpoint of axial wall and shoulder edge. The results were compared with the reference of 120 microm which was accepted generally to analyze the adaptation by statistical means. With statistical analysis of the t-test, the mean of gap width of each group, (82.60 +/- 13.58) microm for group A, (45.80 +/- 16.12) microm for group B, and (57.90 +/- 9.04) microm for group C, was less than 120 pm and the differences were statistically significant (t(A) = 8.71, t(B) = 14.56, t(C) =21.72, P <0.05). The Ni-Cr alloy coping with a thickness of 0.8 mm can be fabricated with LRF successfully and the adaptation can meet the reference of 120 microm.