不同倒凹条件下钴铬和钛合金卡环的加工精度、固位力及永久变形量的研究

Research on processing accuracy,retentive force and permanent deformation of cobalt-chromium and titanium alloy clasp with different undercut conditions

目的以铸造钴铬合金(CoCr)卡环为对照,评估0.25和0.50 mm倒凹设计下选区激光熔化(SLM)CoCr和钛合金(Ti)卡环的加工精度、固位力及永久变形量情况。方法3D软件设计不锈钢代型及0.25 mm/0.50 mm倒凹条件下的卡环数据。树脂3D打印蜡型样本,并将其铸造获得CoCr卡环(铸造CoCr组)。用金属激光打印机获得CoCr(SLM CoCr组)和Ti(SLM Ti组)卡环。所有卡环样本经无损检测后评估加工精度及经10000次循环戴入/取出后的固位力及永久变形量情况。结果0.25 mm或0.50 mm倒凹下3组卡环的内表面精度均无统计学差异(P>0.05),但外表面存在统计学差异(P<0.05)。0.25 mm/0.50 mm倒凹下3种卡环的初始固位力为铸造CoCr(8.13/10.00 N)>SLM CoCr(6.07/7.35 N)>SLM Ti(4.97/7.70 N);最大固位力为铸造CoCr(11.98/13.33N)>SLM CoCr(8.44/11.04 N)>SLM Ti(6.02/9.69 N)。经10000次循环戴入/取出测试后,最终固位力为铸造Co Cr(11.25/11.71 N)>SLM CoCr(7.51/9.55 N)>SLM Ti(5.19/7.97 N);永久变形量为铸造CoCr(49.25/62.24μm)>SLM CoCr(30.01/44.36μm)>SLM Ti(25.79/41.10μm)。所有卡环组未出现折断失效现象。结论0.25 mm/0.50 mm倒凹下的铸造CoCr、SLM CoCr及SLM Ti合金卡环内表面的加工精度一致。经10000次循环戴入/取出测试后,0.25 mm/0.50 mm倒凹下的3种卡环固位力和永久变形量变化均不相同,但这些变化均在临床可接受范围内。

Objective Take the cast cobalt-chromium alloy(CoCr)clasp as a control to evaluate the effect of 0.25 and 0.50 mm undercut designs on the processing accuracy,retentive force and permanent deformation of selective laser melting(SLM)CoCr and titanium alloy clasp.Methods 3D software design stainless steel die and clasp data under 0.25 mm/0.50 mm undercut conditions.First of all,the two kinds of clasp data were imported into the resin 3D printer to obtain the wax sample,and then cast the wax sample to obtain the CoCr clasp(Cast CoCr group).Next,the same two kinds of clasp data were imported into a metal laser printer to obtain CoCr(SLM CoCr group)and titanium alloy(SLM Ti group)clasps.After all the clasp samples were non-destructively tested,the processing accuracy of the three types of clasps was evaluated,and then the retention force and permanent deformation after 10000 cycles of insertion/removal were evaluated.Results There was no statistical difference in the accuracy of the inner surface of the clasp under the undercut of 0.25 mm or 0.50 mm in the three groups(P>0.05),but there were statistical differences in the outer surface(P<0.05).The initial retentive force of clasp was Cast CoCr(8.13/10.00 N)>SLM CoCr(6.07/7.35 N)>SLM Ti(4.97/7.70 N),the maximum retentive force was Cast CoCr(11.98/13.33 N)>SLM CoCr(8.44/11.04 N)>SLM Ti(6.02/9.69 N).After 10000 cycles of insertion/removal tests,the final retentive force was Cast CoCr(11.25/11.71 N)>SLM CoCr(7.51/9.55 N)>SLM Ti(5.19/7.97 N),the permanent deformation was Cast CoCr(49.25/62.24μm)>SLM CoCr(30.01/44.36μm)>SLM Ti(25.79/41.10μm).No fracture failure was observed in all clasp groups.Conclusion There are no differences in the processing accuracy of the inner surface of the Cast CoCr,SLM CoCr and SLM titanium alloy clasp under 0.25 mm/0.50 mm undercuts.However,after 10000 cycles of insertion/removal tests,the changes of the retention and permanent deformation of the three types of clasps under 0.25 mm/0.50 mm undercut conditions are different,but these changes are within the clinically acceptable range.