NGHIÊN CỨU IN VITRO KHẢO SÁT TÌNH TRẠNG GÃY DỤNG CỤ TRONG SỬA SOẠN ỐNG TỦY Ở HỆ THỐNG TRÂM PROTAPER QUAY TAY

Abstract

Objective: This study aimed to investigate the instrument fracture in preparing root canalswith manual Protaper system. Materials and methods: This in vitro study was carried out on 50 proximal canals (including the buccal-mesial and lingual-mesial canals) of the mesial root of lower molars in adults; the rootswere intact and apically closed, with canal curving in the range 10º-40º according to the Schneider 1971 method. Mesial canals were prepared to the F3 instrument. Each protaper set would be manipulated until the tool in the working set broke down. The number of canals manipulated in each set would be recorded. Tooth containing the fracture were analyzed through Cone Beam Computed Tomography Scan (CBCT) to determine the length of the fracture, and also to investigate the correlation of the fracture with the tip and the canal entrance dimension. Result: The maximum number of prepared canals was 10 ± 2.7 canals. The average fracture length was 2.13 ± 1.26mm. The average distance from the top of the fragment to the tip of the tooth was 3.09 ± 1.60mm. The average distance from the tip of the fragment to the entrance of the canal was 5.97 ± 1.84mm. The instrument with the highest fracture rate was file S1. Conclusions: The possibility of fracture in the manual Protaper file system occurs  when  the instrument  has compiled 10 ± 2.7canals. No tools were broken during first preparation. The instrument with the highest fracture rate is file S1. When tool breakage occurs, the average fracture length is 2.13 ± 1.26mm. The fracture tends to be closer to the tip of the tooth than towards the entrance of the canal.