Abstract
Introduction: The purpose of the study was to investigate the impact of root canal preparation with different sizes and tapers on fracture strength of roots.
Methods: A total of 42 freshly extracted intact human permanent mandibular premolars. Teeth were randomly divided into 7 groups I-VII (n =6): un-instrumented root canals (control), 25/0.04, 25/0.06, 30/0.04, 30/0.06, 35/0.04and 35/0.06 respectively. K3XF rotary files (Kerr Endodontics, Orange, CA) were used for canal instrumentation with distilled water irrigation. Fracture strength was tested using a universal test machine.
Results: Group I (control) had the highest statistically significant mean compared with the experimental groups II-VII. The means and standard deviation for groups I-VII were 1022.08±87.61, 819.29±97.11, 691.63±82.39, 719.14±102.58, 668.60±185.20, 669.32±130.63 and 669.32±130.63, respectively.
Conclusion: Under the conditions of the present study, we can conclude that increasing preparation size and taper up to 35/0.06 did not affect the fracture strength of roots. Instrumentation of mandibular premolars up to 35/0.06 did not affect their fracture strength.