随着后牙根管治疗的日益增多,扩大针掉入咽喉部,以至落入气管和消化道的事例屡见不鲜。目前采用的预防方法为上橡皮障。但由于上橡皮障需配备良好的吸唾器,而一般的口腔科门诊尚缺乏高吸装备,并且业务繁忙,在实行上存在一定的困难,不易在基层推广。国外有采用安全链来防止扩大针掉入咽喉部的方法。该安全链虽使用方便,但制作工艺复杂。我科在临床工作中研制了改良安全链,在临床大量使用中,效果良好。此法加工简单,容易推广。改良安全链的制法为用一圆形的窗帘环,或钥匙圈,大小以套进手指为宜。再用一根直径为0.8～1.0mm的钢丝,弯成∽状,钢丝圈的大小可较松的插入最粗的扩大针(80~#)。用一根丝绒连接窗帘环和钢 With the increasing number of root canal treatment of the posterior teeth, it is not uncommon to expand the needle into the throat and fall into the trachea and digestive tract. The current prevention method is rubber dam. However, due to the rubber bump need to be equipped with a good saliva saliva, while the general dental clinic is still lack of high suction equipment, and the business is busy, there are some difficulties in the implementation, not easy to promote at the grassroots level. There are foreign countries to adopt the safety chain to prevent the expansion of the needle into the throat method. Although the safety chain easy to use, but the production process is complex. Our department has developed a modified safety chain in clinical work, which is effective in large-scale clinical use. This method is simple to process, easy to promote. Improved safety chain system for the use of a circular curtain ring, or the key ring, the size of the sets into the fingers is appropriate. Re-use a diameter of 0.8 ~ 1.0mm steel wire, bent into a ∽ shape, the size of the traveler can be loosely inserted into the thickest enlarged needle (80 ~ #). Use a velvet to connect the curtain loop and steel