Exploration of safe clinical use court of using ProTaper rotary nickel-titanium instruments during root canal preparation

Objective To increase clinical use times of ProTaper rotary nickel-titanium instruments by improvement of root canal preparation,which ensuring clinical effect at the same time.Methods A total of 162 human teeth including 23 front teeth,28 premolars and 111 molars were mainly managed with ProTaper rotary instruments followed by the sequence of root canal exploration,working length measurement,root canal dredging with hand file,coronal preflaring on the third of root canal with GG rotary files.Lateral condensation was used for root canal obturation.The effect of preparation and obturation were analyzed with radiographs before,during and after operation.Results ProTaper rotary instruments kept original shape of root canal very well,and endodontic flare-up seldom occurred.The most,lest and average root canal numbers prepared by all 9 series of ProTaper rotary instruments were 51,35 and 41 respectively.Type SX,S1,S2,F1,F2,F3 had been used to 19.4,43.3,43.3,43.2,38.3,6.7 root canals respectively.Finally,two series were broken,tip ends of two series were distorted and another five series showed aging differently on file blade and handle.Conclusions Improvement of root canal preparation,skillful practice,particular records and well-done storage guaranteed the increasement of clinical use count of ProTaper rotary nickel-titanium instruments.The suggestion is that no more than 35 root canals involving anterior and posterior teeth be prepared with ProTaper rotary instruments.