J Korean Acad Conserv Dent JKACD Journal of Korean Academy of Conservative Dentistry 1225-0864 2093-8179 The Korean Academy of Conservative Dentistry 10.5395/JKACD.2008.33.1.066 Original Article Evaluation of the influence of apical sizes on the apical sealing ability of the modified continuous wave technique Ryu Muhyun Jung Ilyoung Lee Seungjong Shin Sujung Kim Euiseong Department of Dentistry, The Graduate School, Yonsei University, Korea. Corresponding Author: Euiseong Kim. Department of Conservative Dentistry, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodamun-Ku, Seoul, 120-752, Korea. Tel: 82-2-2228-8701, Fax: 82-2-313-7575, andyendo@yuhs.ac 01 2008 31 01 2008 33 1 66 75 22 10 2007 11 12 2007 17 01 2008 Copyright © 2008 The Korean Academy of Conservative Dentistry 2008

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.

This study examined the influence of the apical sizes on the sealing ability of a root canal filling.

Thirty-six single rooted teeth with a single canal were divided into 3 groups (n = 12) and instrumented with either the Profile® or LightSpeed® system to achieve three different apical sizes (master apical file [MAF] of #25, #40, or #60). The teeth were filled with gutta percha using a modified continuous wave technique. The level of microleakage was determined by immersing ten teeth from each group into India ink for 1 week followed by clearing with nitric acid, ethyl-alcohol, and methylsalicylate. The microleakage was measured using vernier calipers. The data was analyzed statistically using Kruskal-Wallis one-way ANOVA and a Student-Newman-Keuls Method. Two teeth from each group were sectioned horizontally at 1, 2, 3 and 4 mm from the apex in order to observe a cross section.

The apical size was significantly (p < .05) influenced the level of microleakage. In the Student-Newman-Deuls Method, MAF sizes of #25 and #40; and MAF sizes of #25 and #60, respectively showed a statistically significant difference. There was no significant difference between #40 and #60. In most cross sections, oval-shaped canals were observed, and the irregularity of the internal surface increased with decreasing apical size. There was also an increase in the area of recess, which is the area where the canal space is not filled with either gutta-percha or sealer.

When the root canals are filled using a modified continuous wave technique, canal filling with more consistent and predictable outcome may be expected as the apical preparation size is increased.

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Positive control (left), Negative control (right).

Comparison of dye leakage (× 20).

Stereomicroscopic view of cross-section at 1, 2, 3, 4 mm from the apex (× 83).

Minimum, maximum, mean and standard deviation (S.D) value of apical microleakage (mm)