Evaluation of apical canal shapes produced sequentially during instrumentation with stainless steel hand and Ni-Ti rotary instruments using Micro-computed tomography

Article information

Restor Dent Endod. 2011;36(3):231-237

Publication date (electronic) : 2011 May 31

doi : https://doi.org/10.5395/JKACD.2011.36.3.231

Woo-Jin Lee, DDS, MSD ¹, Jeong-Ho Lee, DDS, PhD ¹, Kyung-A Chun, DDS, MSD ², Min-Seock Seo, DDS, MSD ³, Yeon-Jee Yoo, DDS ¹, Seung-Ho Baek, DDS, PhD ¹

¹Department of Conservative Dentistry and Dental Research Institute, College of Dentistry, Seoul National University, Seoul, Korea.

²Department of Conservative Dentistry, Korea University Anam Hospital, Seoul, Korea.

³Hanyang University Seoul Hospital, Seoul, Korea.

Correspondence to Seung-Ho Baek, DDS, PhD. Associate Professor, Department of Conservative Dentistry and Dental Research Institute, Seoul National University College of Dentistry, 28-2 Yeongeon-dong, Jongro-gu, Seoul, Korea 110-749. TEL, +82-2-2072-3951; FAX, +82-2-2072-3850; shbaek@snu.ac.kr

Received 2011 April 11; Revised 2011 April 27; Accepted 2011 April 29.

Abstract

Objectives

The purpose of this study was to determine the optimal master apical file size with minimal transportation and optimal efficiency in removing infected dentin. We evaluated the transportation of the canal center and the change in untouched areas after sequential preparation with a #25 to #40 file using 3 different instruments: stainless steel K-type (SS K-file) hand file, ProFile and LightSpeed using microcomputed tomography (MCT).

Materials and Methods

Thirty extracted human mandibular molars with separated orifices and apical foramens on mesial canals were used. Teeth were randomly divided into three groups: SS K-file, Profile, LightSpeed and the root canals were instrumented using corresponding instruments from #20 to #40. All teeth were scanned with MCT before and after instrumentation. Cross section images were used to evaluate canal transportation and untouched area at 1- , 2- , 3- , and 5- mm level from the apex. Data were statistically analyzed according to' repeated nested design'and Mann-Whitney test (p = 0.05).

Results

In SS K-file group, canal transportation was significantly increased over #30 instrument. In the ProFile group, canal transportation was significantly increased after preparation with the #40 instrument at the 1- and 2- mm levels. LightSpeed group showed better centering ability than ProFile group after preparation with the #40 instrument at the 1 and 2 mm levels.

Conclusions

SS K-file, Profile, and LightSpeed showed differences in the degree of apical transportation depending on the size of the master apical file.

Keywords: LightSpeed; Master apical file; Micro CT, ProFile; Stainless steel K-file; Transportation

Notes

This study was supported by the Seoul National University research fund for new faculty.

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Figure 1

Measuring the distance and the angle between original center and deviated center. a: original center of the canal. b: deviated center after preparation. Canal transportation (by distance) : Distance between a and b. Canal transportation (by degree) : A positive value indicates a movement of the canal center in the outer root surface (purple arrow), while a negative value signifies a shift in the opposite direction (green arrow).

^* Original canal wall was drawn by red line and canal wall after preparation by black line.

Figure 2

Cross sectional images acquired by µCT illustrate the sequential canal deviation by each group of instrument. Profile and Lightspeed group show more round and less deviated canal shapes.

Figure 3

Mean displacement of the canal centers according to the file size and instrument type at each level (µm).

Figure 4

Changes of untouched areas of canal space are demonstrated (%SD).