Experimental Study On Effects Of Root Canal Preparation By FlexMaster Ni-Ti Rotary Instrument

Objective:To evaluate the effects of root canal preparation by FlexMaster Ni-Ti rotary instrument, search for a safe and effective root canal preparation instrument, provide a reference for clinical.Methods:60extracted human single-rooted teeth suffering periodontal disease or orthodontic requirement with root canal curvatures between 20 and 40 degrees.They were divided into three groups randomly:FlexMaster(FM), ProFile(PF), Hero642(H), each group of 20 teeth.The root canals of each group were respectively prepared with FlexMaster,Hero642 and ProFile Ni-Ti rotary instruments, technology to the preparation of crown down. The straightening degree, the root canal transposition score, root canal preparation time, security, the numbers of dentinal tubule openings, the debris and smear layer of root canal wall were observed and comparied by digital radiographs and scanning electron microscopy, the method of software analysis.Result:1,The instruments keep former anatomy form of the curved root canal well, root canal preparation straightening slightly larger degree of group H. no statistically significant difference on the straightening degree between three groups(P>0.05).2,The maximum root canal transposition score was H group, FM group was between the H group and the PF group, and the root canal transposition score of each group were less than 0.2mm, there were no significantly different(P>0.05). 3,The H group has the shortest preparation.There were significant differences in this three groups of root canal preparation time(P<0.05); By visual and microscopic observation, three gtoups of instruments were not found there helicase or helix device encryption, distortion, deformation, cracks and breakage.4,The numbers of dentinal tubule openings of the group FM and H were more than PF in the middle 1/3 of the root canal, there were statistically significant differences(P<0.05); the numbers of the group FM were more than H and PF in the apical 1/3 of the root canal, there were statistically significant differences (P<0.05).5,In the middle and apical 1/3 of root canal, the group FM and H had similar mean debris scores which were less than the group PF. there were significant differences in this there groups(P<0.05); The canal wall of all the groups were cleaned, nearly almost dentinal tubule open, small amount of smear layer were left on the canal wall, there were no significant difference of the smear layer scores between three groups(P>0.05).Conclusion:FlexMaster Ni-Ti instrument keep former anatomy form of the curved root canal well, showed high security and cutting efficiency, with a good shaping and cleaning ability, it could be used widely in clinic.