[The effects of three nickel-titanium rotary instruments on root canal curvature].
OBJECTIVE
To investigate the effects of three nickel-titanium rotary instruments on root canal curvature and their working efficiency.


METHODS
64 curved mesial canals of extracted lower molars were randomly assigned to four groups: Flexofile, LightSpeed, ProFile, Qantec SC. Root canal preparation was carried out at two stages: first to size 30, then to size 40. The root canal curvatures before and after preparation as well as preparation time were measured.


RESULTS
Preparation with Flexofile resulted in the maximum reduction of root canal curvatures. The differences between three nickel titanium (Ni-Ti) groups and Flexofile were statistically significant from bucco-lingual view (P<0.01). No significant differences were detected between pre- and post-operative curvatures within Ni-Ti groups when preparation was carried out to size 30 (P>0.05). Preparation with ProFile or Quantec SC instruments cost significantly less time than the other two groups P<0.01).


CONCLUSIONS
Preparation with Ni-Ti rotary instruments maintained the root canal curvature to a maximum extent. The techniques were also timesaving.
Wei
X
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Department of Endodontics, Faculty of Stomatology, Sun YatSen University of Medical Sciences, Guangzhou 510055, Guangdong province, China. xi-wei@21cn.com
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