Micro-computed tomographic comparison of nickel-titanium rotary versus traditional instruments in C-shaped root canal system

By Yin X, Cheung G, Zhang C, Masuda Y, Kimura Y, and Matsumoto K,

Date: 01/2010
Journal: JOE


Purpose:  to assess the morphologic changes of the C-shaped canal system before and after instrumentation using a NiTi rotary system or traditional stainless steel instruments

N= 24 mandibular molars with C-shaped canals. (selected according to the type of pulp floor, 3D configuration, and number of main canals and apical foramina)

 Inclusion criteria: teeth with completed root formation without visible apical resorption.


•The teeth with C shaped canals were selected in pairs and sorted equally into 2 groups. (n=12/Group).

•The 1st group was instrumented with a crown-down approach using the ProTaper rotary instruments and the 2nd group was instrumented with the step-down technique by K-files and Gates-Glidden burs.

•Three dimensional images were constructed by micro-CT (pre-instrumentation and post-instrumentation).

•The volume of dentin removed, un-instrumented canal area, time taken for instrumentation, and iatrogenic error of instrumentation were investigated.

Most highlighted Results: 


Clinical significance: 

The importance of chemical cleaning of C-shaped canals because of the large percentages of untouched areas after preparation of both types of instruments. To reduce procedural errors and reach larger areas of the walls of c shaped canals, a combination of rotary and hand instruments may be used.

Strengths: matching pairs of C-shaped canals to decrease the confounding variables between the 2 groups.

weakness: all the procedures performed by a single operator.