Chang Ting-Ling, Maruyama Chizuru, White Shane N, Son Seung, Caputo Angelo A
Division of Advanced Prosthodontics, Biomaterials, and Hospital Dentistry, School of Dentistry, University of California at Los Angeles, Los Angeles, CA 90095-1668, USA.
Int J Oral Maxillofac Implants. 2005 Sep-Oct;20(5):720-5.
To compare the dimensional accuracy of implant framework castings from an argon vacuum casting machine with those from a centrifugal casting machine.
Three 4 x 10-mm external hex-type implants (3i/Implant Innovations) were embedded in an acrylic resin block 7 mm apart, with a 2 mm offset of the middle implant. Eight reference points were marked on the implant collars. Twenty implant bar frameworks were waxed with UCLA abutments, invested with a ringless system, and subjected to the same thermal cycle. Ten wax patterns were cast in gold alloy using an oxygen-propane torch and centrifugal casting system; 10 were cast using an argon vacuum casting machine (KDF; Denken). The White 1-screw technique was applied after sequentially tightening the mesial and distal abutment screws to 10 Ncm. Fit of the implant framework castings was evaluated by measuring the marginal opening between the casting and implant at the reference points. These measurements were averaged and statistically compared for differences.
The mean marginal openings at the most distant measuring locations from the tightened retaining screw at location 1 was between 44 to 48 microm for the centrifugal system compared to between 28 to 32 mm for KDF (P < .01). For screws tightened at location 3, the mean marginal openings at the most distant measuring locations were between 40 to 51 mm for the centrifugal system compared to between 27 to 29 microm for KDF (P < .01).
In comparison with the centrifugal casting and oxygen-propane system, the argon vacuum system was more accurate and user friendly and less technique-sensitive.
The argon vacuum casting machine tested produced more accurate, better fitting implant-supported prosthesis frameworks than a conventional centrifugal casting system. The "1-screw" method of evaluating casting fit was most effective when either of the prostheses' end screws were tightened.
比较氩气真空铸造机和离心铸造机制备的种植体支架铸件的尺寸精度。
将三个4×10毫米的外六角型种植体（3i/种植体创新公司）埋入一块丙烯酸树脂块中，彼此相距7毫米，中间的种植体有2毫米的偏移。在种植体颈部标记八个参考点。用加州大学洛杉矶分校基台制作二十个种植体杆支架蜡型，采用无圈包埋系统包埋，并进行相同的热循环。十个蜡型用氧气 - 丙烷喷枪和离心铸造系统铸造金合金；另外十个用氩气真空铸造机（KDF；登肯公司）铸造。依次将近中基台螺钉和远中基台螺钉拧紧至10牛厘米后，采用白色1螺钉技术。通过测量铸件与种植体在参考点处的边缘间隙来评估种植体支架铸件的适合性。对这些测量值进行平均并进行统计学差异比较。
在位置1处，离拧紧的固位螺钉最远的测量位置，离心铸造系统的平均边缘间隙在44至48微米之间，而KDF铸造机的平均边缘间隙在28至32微米之间（P <.01）。对于在位置3处拧紧的螺钉，离心铸造系统在最远测量位置的平均边缘间隙在40至51微米之间，而KDF铸造机的平均边缘间隙在27至29微米之间（P <.01）。
与离心铸造和氧气 - 丙烷系统相比，氩气真空系统更精确、用户友好且技术敏感性更低。
所测试的氩气真空铸造机比传统的离心铸造系统能生产出更精确、更适合的种植体支持修复体支架。当修复体的任何一个端部螺钉拧紧时，“1螺钉”评估铸造适合性的方法最为有效。
