ABSTRACT
Objective:To evaluate the fracture resistance of roots instrumented with Reciproc,WaveOne,ProTaper and BLX respectively.Methods:50 extracted maxillary and 50 extracted mandibular anterior teeth were selected and randomly divided into 5 groups respectively(n =10).The teeth in the 4 experimental groups were instrumented by 4 the instruments respectively and the teeth in the control group were not treated.A vertical load was applied to the roots and the fracture load for each sample was recorded.The data were analyzed with SPSS 19.0 software.Results:After preparition the fracture load of the experimental groups was lower than that of the control (P ＜ 0.05),between the Reciproc and WaveOne groups (P ＞ 0.05),between ProTaper and BLX groups for maxi teeth (P ＞0.05),for mandibular teeth(P ＜ 0.05).The fracture load of Reciproc and WaveOne was higher than that of ProTaper and BLX(P ＜0.05).After making same taper shape using same root canal instrument,the mandibular anterior teeth had lower fracture resistances than the maxillary anterior teeth (P ＜ 0.05).Conclusion:Single-file reciprocating systems groups may decrease less fracture resistance than full-sequence rotary systems.with or without instrumentation,maxillary anterior teeth have higher fracture resistance than mandibular anterior teeth.