우(牛) 하악골의 천공시 발생하는 마찰열에 관한 실험적 연구

AN EXPERIMENTAL STUDY ON THE FRICTIONAL HEAT GENERATED FROM BOVINE MANDIBLES DRILLING

The removal of cancellous and cortical bone in oral and maxillofacial surgery is frequently accomplished with burs. Heat generated from drilling is due to the friction and the fragmentation of particles of bone at the cutting edge of the drill. The frictional heat has serious consequences leading to hyperemia, fibrosis, osteocytic degeneration and increased osteoclastic-osteoblastic activity, dehydration, dessication, shrinkage, carbonization, and nercrosis. Various techniques applied to reduce or limit frictional heat arising from drilling included slow rotational speeds, intermittent drilling, sharp drilling instruments, external irrigation, internal irrigation with water or saline solution. This study was undertaken to compare frictional heat of the No. 6 round bur to the No. 702 fissure bur under the controlled condition, that is, 4800 rpm, drilling force of 1, 2, or 3㎏, external irrigation with 18℃ 0.9% saline solution, no irrigation, preparation of 5 ㎜ cavity in depth, temperature measurements at 1 ㎜ distance from the experimental cavity, using the bovine mandibles in vitro. The obtained results were as follows. 1. The lowest frictional heat was generated, when the No. 6 round bur was used with iirigation, with drilling force of 1 ㎏. 2. The effect of irrigation was evident, when the No. 6 round bur was used with irrigation, with drilling force of 1㎏ or 3 ㎏. but, unevident in drilling force of 2 ㎏. 3. The frictional heat was independent of the drilling force of 1㎏ or 2㎏, when the No. 702 fissure bur was used with irrigation. 4. There was no temperature variation between the No. 6 round bur and the No. 702 fissure bur, when cavity preparation was done with irrigation, drilling force of 2㎏.