Cross-sectional morphology and minimum canal wall widths in C-shaped root of mandibular molars

Byung-Chul Song; Yong-Bum Cho

doi:10.5395/JKACD.2007.32.1.037

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Song and Cho: Cross-sectional morphology and minimum canal wall widths in C-shaped root of mandibular molars

Original Article

Journal of Korean Academy of Conservative Dentistry

Journal of Korean Academy of Conservative Dentistry 2007; 32(1): 37-46.

Published online: 31 January 2007

DOI: https://doi.org/10.5395/JKACD.2007.32.1.037

Cross-sectional morphology and minimum canal wall widths in C-shaped root of mandibular molars

Byung-Chul Song, Yong-Bum Cho

Department of Conservative Dentistry, College of Dentistry, Dankook University, Korea.

Corresponding Author: Yong-Bum Cho. Department of Conservative Dentistry, College of Dentistry, Dankook University, 7-1 Shinbu-dong, Cheonan, Korea. Tel: 82-41-550-1966, Fax: 82-41-550-1963, raindrop@dku.edu

Received 23 January 2007 Revised 25 January 2007 Accepted 27 January 2007

(open-access):

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The C-shaped canal system is an anatomical variation mostly seen in mandibular second molars, although it can also occur in maxillary and other mandibular molars. The main anatomical feature of C-shaped canals is the presence of fins or web connecting the individual root canals. The complexity of C-shaped canals prevents these canals from being cleaned, shaped, and obturated effectively during root canal therapy, and sometimes it leads to an iatrogenic perforation from the extravagant preparation.

The purpose of this study was to provide further knowledge of the anatomical configuration and the minimal thickness of dentinal wall according to the level of the root.

Thirty extracted mandibular second molars with fused roots and longitudinal grooves on lingual or buccal surface of the root were collected from a native Korean population. The photo images and radiographs from buccal, lingual, apical direction were taken. After access cavity was prepared, teeth were placed in 5.25% sodium hypochlorite solution for 2 hours to dissolve the organic tissue of the root surface and from the root canal system. After bench dried and all the teeth were embedded in a self-curing resin. Each block was sectioned using a microtome (Accutom-50, Struers, Denmark) at interval of 1 mm. The sectioned surface photograph was taken using a digital camera (Coolpix 995, Nikon, Japan) connected to the microscope. 197 images were evaluated for canal configurations and the minimal thickness of dentinal wall between canal and external wall using' Root Thickness Gauge Program' designed with Visual Basic.

The results were as follows:

1. At the orifice level of all teeth, the most frequent observed configuration was Melton's Type C I (73%), however the patterns were changed to type C II and C III when the sections were observed at the apical third. On the other hand, the type C III was observed at the orifice level of only 2 teeth but this type could be seen at apical region of the rest of the teeth.

2. The C-shaped canal showed continuous and semi-colon shape at the orifice level, but at the apical portion of the canal there was high possibility of having 2 or 3 canals.

3. Lingual wall was thinner than buccal wall at coronal, middle, apical thirds of root but there was no statistical differences.

Keywords: C-shaped Canal, Morphology, Mandibular Molar, Canal Wall Width, Configuration

Figures and Tables

Figure 1

Classification of the canal configuration.

Figure 2

Computer program, measuring minimum wall thickness.

Figure 3

The transfiguration of the canal.

Table 1

The transfiguration of canals at different levels

Table 2

Number of specific canal type at different levels

Table 3

Tooth without any change of configuration

Table 4

Minimum wall thickness at buccal side (mm)

Table 5

Minimum wall thickness at lingual side (mm)

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