铸造力对铸钛全冠完整性的影响

本实验的目的是证实铸造力对铸造钛全冠完整性的影响.在树脂牙上进行全冠牙体预备,颊侧边缘为凹型,舌侧边缘为刃状.将18个全冠蜡型分为6组,用专用钛包埋材包埋,用Ohara钛铸造机铸造.1至6组所上的弹簧圈数分别为5、10、15、20、25和30圈,这样便产生逐渐增加的铸造力.第1组只铸出铸道,第2组铸出铸道和部分冠壁;第3、4组的冠大体铸出,但舌侧边缘圆钝并有小的缺损;第5、6组的冠基本完整,边缘锐利,只是舌侧边缘有少数很小的缺损.实验结果表明:①铸造钛金属时要有足够大的铸造力.②如果铸造技术未得到进一步改进,应避免为铸钛修复体设计刃状边缘.

Effect of Casting Force on Integrity of Cast Titanium Crowns

The aim of the investigation is to get knowledge about the relationship between casting foRce and integrity of cast titanium crowns. Full crown preparation is made on resin teeth with chamfer margin in the buccal and knife margin in the lingual. 18 wax patterns are divided into 6 groups, invested in a special titanium investment material and casted with the OHARA casting machine (Ohara Inc, Osaka, Japan). The rotation of spring for group 1-6 are 5, 10, 15, 20, 25 and 30 respectively, resulting in an increasing centrifugal force (casting pressure). Group 1- no crown is found except for sprue. Group 2: only partial crown is to be seen. Group 3 and 4: all these crowns are basically complete but the margins are a bit round with some small defects. Group 5 and 6: all the crowns are complete. The margins are sharp but the lingual margins are missing integrity. The results indicate that 1 it is. necessary for casting titanium crowns to keep the casting force as high as possibe and 2. it is of advantage to avoid the design of knife margins because of the mould filling problems with cast titanium in the used casting machine.