Lopes H P, Elias C N, Estrela C, Costa Filho A
Associação Brasileira de Endodontia, Rio de Janeiro, Brasil.
Braz Dent J. 1994;5(2):141-4.
The aim of this study was to determine the variation of the shaft diameter close to the active cutting region and close to the radius of concordance of 28- and 32-mm Gates-Glidden drills and to analyze the diameter influence on the torsion fracture resistance. Seventy-two stainless steel Maillefer drills were studied. The drill diameter varied along the shaft, the smallest diameter occurring close to the radius of concordance. This variation causes stress concentration which leads to complete fracture of the instrument.
本研究的目的是确定28毫米和32毫米Gates-Glidden钻针靠近有效切割区域及靠近一致半径处的杆部直径变化情况，并分析直径对扭转抗折性的影响。研究了72支不锈钢Maillefer钻针。钻针直径沿杆部变化，最小直径出现在靠近一致半径处。这种变化会导致应力集中，从而致使器械完全折断。
