ABSTRACT
Objective: To study the effect of the modified preparation method with root canal flushing of different solutions on the anti-fracture properties of mechanical nickel-titanium filings. Methods: A transparent resin model of root canal was established. ProTaper Universal (PTU F1) instrument was used to prepare the root canals. The number of prepared root canals by each PTU F1 with the various solutions(n = 20) was recorded and compared among groups. Results: 6. 13 ± 3. 52 root canals were prepared in distilled water group, 6. 25 ± 1. 76 in 0. 9％saline group, 6. 27 ± 2. 07 of 0. 2％ chlorhexidine group, 6. 88 ± 3. 21 in 1％ sodium hypochlorite group, 4. 31 ± 2. 34 in 5％ sodium hypochlorite group and 3. 26 ± 2. 08 in dry drilling group. The number between each 2 of distilled water, 0. 9％saline group, 0. 2％chlorhexidine group and 1％ sodium hypochlorite group, and the number between 5％ sodium hypochlorite group and dry drilling group was not statistically significant(P＞ 0. 05). The number of prepared root canals in the first 4 groups was more than that in the latter 2 groups(P＜ 0. 05). Conclusion: Distilled water, 0. 9％ saline, 0. 2％ chlorhexidine or 1％ sodium hypochlorite for root canal irrigation can improve mechanical nickel-titanium instrument for fatigue resistance in root canal preparation, but 5％ sodium hypochlorite and dry drilling can not.