• Restorative Dentistry and Endodontics
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• v.43 no.2
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• pp.16.1-16.9
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• 2018

Objectives: Understanding the reason for an unsuccessful non-surgical endodontic treatment outcome, as well as the complex anatomy of the root canal system, is very important. This study examined the cross-sectional root canal structure of mandibular first molars confirmed to have failed non-surgical root canal treatment using digital images obtained during intentional replantation surgery, as well as the causative factors of the failed conventional endodontic treatments. Materials and Methods: This study evaluated 115 mandibular first molars. Digital photographic images of the resected surface were taken at the apical 3 mm level and examined. The discolored dentin area around the root canal was investigated by measuring the total surface area, the treated areas as determined by the endodontic filling material, and the discolored dentin area. Results: Forty 2-rooted teeth showed discolored root dentin in both the mesial and distal roots. Compared to the original filled area, significant expansion of root dentin discoloration was observed. Moreover, the mesial roots were significantly more discolored than the distal roots. Of the 115 molars, 92 had 2 roots. Among the mesial roots of the 2-rooted teeth, 95.7% of the roots had 2 canals and 79.4% had partial/complete isthmuses and/or accessory canals. Conclusions: Dentin discoloration that was not visible on periapical radiographs and cone-beam computed tomography was frequently found in mandibular first molars that failed endodontic treatment. The complex anatomy of the mesial roots of the mandibular first molars is another reason for the failure of conventional endodontic treatment.

• Restorative Dentistry and Endodontics
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• v.23 no.2
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• pp.670-675
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• 1998

Recently electronic apex locators have been used widely in root canal treatment, but, accuracy of electronic apex locators is controversial. The purpose of this study was to evaluate the accuracy of Apex Finder A.F.A(EIE Analytic Technology, U.S.A.) in vivo compared with Root-Zx and radiograph. The root canal lengths were determined with Root-Zx(32 tooth) in before pulp extirpation and after pulp extirpation. Then the radiographs were taken with a file in the canal. The root canal lengths were determined with Apex Finder A.F.A.(21 tooth) in before pulp extirpation and after pulp extirpation and under NaOCl. Then the radiographs were taken with a file in the canal. The results were as follows: 1. There was no significant statistical difference in Root-Zx between before pulp extirpation and after pulp extirpation(p > 0.05). 2. There was no significant statistical difference in Apex Finder A.F.A. between before pulp extirpation and after pulp extirpation(p > 0.05). But, there was significant statistical difference under NaOCl(p < 0.05). 3. There was no significant statistical difference in accuracy between Root-Zx and Apex Finder A.F.A.

• Restorative Dentistry and Endodontics
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• v.32 no.4
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• pp.335-342
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• 2007

C-shaped canals are known to present a complex canal anatomy with numerous fins connecting individual canals, thus requiring supplementary effort to accomplish a successful root canal treatment. This study examined the frequency of the C-shaped mandibular second molars and interrelation between the clinical records and radiographs to recognize them treated in the Department of Conservative Dentistry of the Chosun University Dental Hospital during a six-year period (1998-2004). This study reviewed the clinical records of 227 patients who underwent root canal treatment of the mandibular second molars. After opening the chamber, those cases with C-shaped orifices in the pulpal floor were selected, ana the C-shaped root canal types were classified according to Melton's criteria. Three experienced dentists evaluated the radiographs of the C-shaped mandibular second molar on a viewer using a magnifying glass in order to determine if the root apex was fused or separated, the distal root canal was either centered or mesial shifted in the distal root, and if there was bilateral symmetry in a panorama. In conclusion, there is a high frequency of C-shaped mandibular second molars in Koreans. Simultaneous interpretation of the root shape and distal root canal using the preoperative, working length and post-treatment radiographs is important for diagnosing a C-shaped mandibular second molar.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.8 s.197
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• pp.116-121
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• 2007

The length of root canal has to be measured for endodontic treatment. Several electronic apex locators were developed to measure the length of root canal by other researchers. And their accuracies were verified by X-ray or micrometer method. But these methods did not consider the non-linear bends of pulp and had ${\pm}0.5mm$ error which was large enough to measure the length of root canal. The purpose of this study is the introduction of a new method to measure the length of root canal and the verification of the accuracy of an electronic apex locator using a Micro-CT. The length of root canal of 6 teeth were measured with the electronic apex locator. When the electronic apex locator reads 0.5, 0.6, 0.7, 0.8, 0.9 and 1.0 mm length of the file which was inserted in the hole of the tooth to measure the length of root canal. The average (${\pm}$Standard deviation) length of root canal of 6 teeth measured by the Micro-CT was $0.49{\pm}0.03,\;0.59{\pm}0.04,\;0.68{\pm}0.03,\;0.78{\pm}0.03,\;0.90{\pm}0.04\;and\;1.01{\pm}0.03mm$, respectively. The maximum error of the electronic apex locator was 0.06 mm.

• The Journal of the Korean dental association
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• v.56 no.2
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• pp.84-93
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• 2018

Purpose: This study evaluated the apical root canal system of maxillary second molars, in which conventional endodontic treatment had failed. Materials and Methods: One hundred eighteen extracted endodontically failed maxillary second molars were examined to investigate the root canal morphology using clinical photographs. High-resolution cross-sectional images at the 3mm level from the root apices were taken to evaluate the anatomic variations and canal cleanliness. The incidence of anatomic variations and canals containing debris were evaluated statistically. Results: One (0.85%) maxillary second molar had four separate roots, while 52 (44.07%) had three separate roots. The remaining 65 (55.08%) showed 6 different types of fusion in their roots. As the number of fused roots increased from none to three, the incidence of isthmuses in the cross-sectional images increased significantly from 43.40% to 76.92% in 2-root fusion and 88.46% in 3-root fusion. In addition, the occurrence of less-cleansed canals increased from 22.64% to 38.46% and 53.85%, respectively (p<0.05). Sixty four teeth (54.24%) had 3 canals while 38(32.2%) had additional canals; most of them were located in the MB roots (81.58%). Seventy six (64.41%) had isthmuses in the apical region and 58 out of 76 were located in MB roots. Condlusions: Logistic analysis indicated that the less division of roots was associated significantly with the occurrence of insufficient cleaning during endodontic treatment (OR=1.765, p<0.05), while the presence of an additional canal showed no association.

• Proceedings of the KACD Conference
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• 2001.05a
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• pp.243-244
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• 2001

Root resorption is conventionally divided into internal and external varieties. Internal resorption occurs where there is loss of the internal wall of the root canal. and is usually associated with a localized area of necrotic pulp(Trope '||'&'||' Chivian 1984). External resorption occurs where there is loss of the external surface of the root and the resorption may be either transient or progressive(Tronstad 1988). External inflammatory resorption usually occurs following damage to the periodontal ligament or where there is communication between the periodontal ligament and a necrotic pulp. via open dentinal tubules or accessory canals. This type of resorption is usually progressive until root canal treatment is instituted (Barclay 1993).

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.28 no.2
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• pp.471-489
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• 1998

For the successful endodontic treatment, root canal should be cleaned thoroughly by accurate mechanical and chemical canal preparation and sealed completely with canal filling material without damaging the periapical tissues. The accuracy of the root canal length measurement is a prerequisite for the success of the endodontic treatment, and the root canal length is often determined by the standard periapical radiographs and digital tactile sense. In this study, the accuracy and the clinical usefulness of Digora/sup (R)/, an intraoral digital imaging processor and the conventional standard radiographs were compared by measuring the length from the top of the file to the root apex. 30 single rooted premolars were invested in a uniformly sized blocks and No.25 K-file was inserted into and fixed in each canal. Each block was placed in equal distance and position to satisfy the principle of the bisecting angle and paralleling techniques and Digora/sup (R)/ system's image and standard periapical radiographs were taken. Each radiograph was examined by 3 different observers by measuring the length from top of the file to the root apex and each data was compared and analyzed. The results were as follows; 1. In the bisecting angle technique, the average difference between the Digora/sup (R)/ system and standard periapical radiograph was 0.002 mm and the standard deviation was 0.341 mm which showed no statistically significant difference between the two systems(p>0.05). Also, in the paralleling technique, the average difference between these two system was 0.007 mm and the standard deviation was 0.323 mm which showed no statistically significant difference between the two systems(p>0.05). 2. In Digora/sup (R)/ system, the average difference between the bisecting angle and paralleling technique was -0.336 mm and the standard deviation was 0.472 mm which showed a statistically significant difference between the two techniques(p<0.05). Also, in the standard periapical radiographs, the average difference between the bisecting angle and paralleling technique was 0.328 mm and the standard deviation was 0.517 mm which showed a statistically significant difference between these two techniques(p<0.05). 3. In Digora/sup (R)/ system and the standard periapical radiographs. there was a statistically significant difference between the measurement using the bisecting angle technique and the actual length(p<0.05), But there was no statistically significant difference between the measurement using the paralleling technique and the actuallength(p>0.05). In conclusion. the determination of the root canal length by using the Digora/sup (R)/ system can give us as good an image as the standard periapical radiograph and using the paralleling technique instead of the bisecting angle technique can give a measurement closer to the actual canal length. thereby contributing to a successful result. Also. considering the advantages of the digital imaging processor such as decreasing the amount of exposure to the patient. immediate use of the image. magnification of image size. control of the contrast and brightness and the ability of storing the image can give us good reason to replace the standard periapical radiographs.

• Restorative Dentistry and Endodontics
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• v.45 no.3
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• pp.29.1-29.9
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• 2020

This study describes the clinical steps taken in the treatment of a patient who had an avulsed right upper central incisor that presented with incomplete root development and chronic apical periodontitis. A 7-year-old boy was referred from a private dentist to a dental office specializing in endodontics. The tooth had remained in a dry environment for 20 minutes, and tooth replantation was performed at an emergency appointment. After clinical and radiographic examinations, root canal decontamination was performed, followed by several changes in intracanal calcium hydroxide medication. Blood clot formation was attempted, but bleeding within the root canal was insufficient; therefore, we opted for an intracanal medication change to stimulate mineralized tissue formation in the apical region. Root obturation was performed 45 days after the last change of intracanal medication, and clinical, radiographic, and tomographic follow-up examinations were performed at 3, 6, 18, and 40 months after the endodontic intervention. The increase in thickness and length of the root structure and the absence of root resorption were verified through follow-up examinations. Therefore, it was concluded that the procedures used were successful for tooth replantation.

• Imaging Science in Dentistry
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• v.45 no.2
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• pp.95-101
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• 2015

Purpose: This study used cone-beam computed tomography (CBCT) to characterize mandibular molar root and canal morphology and its variability in Belgian and Chilean population samples. Materials and Methods: We analyzed the CBCT images of 515 mandibular molars (257 from Belgium and 258 from Chile). Molars meeting the inclusion criteria were analyzed to determine (1) the number of roots; (2) the root canal configuration; (3) the presence of a curved canal in the cross-sectional image of the distal root in the mandibular first molar and (4) the presence of a C-shaped canal in the second mandibular molar. A descriptive analysis was performed. The association between national origin and the presence of a curved or C-shaped canal was evaluated using the chi-squared test. Results: The most common configurations in the mesial root of both molars were type V and type III. In the distal root, type I canal configuration was the most common. Curvature in the cross-sectional image was found in 25% of the distal canals of the mandibular first molars in the Belgian population, compared to 11% in the Chilean population. The prevalence of C-shaped canals was 10% or less in both populations. Conclusion: In cases of unclear or complex root and canal morphology in the mandibular molars, CBCT imaging might assist endodontic specialists in making an accurate diagnosis and in treatment planning.

• Restorative Dentistry and Endodontics
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• v.10 no.1
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• pp.169-175
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• 1984

This study was undertaken to obtain the average canal length of upper & lower anterior teeth which was important in canal length measuring procedure of endodontic treatment. It was based upon 827 out-patients who had endodontic treatment on their upper & lower anterior teeth at the Department of Operative Dentistry, Dental Infirmary, Yonsei Medical Center from February, 1978 to June, 1984. The 1249 teeth of these patients were devided into sex and age groups. The root canal length of these teeth were measured. The following results were obtained; 1. The mean root canal length of upper & lower anterior teeth were as follows; Upper central incisors : 21.8mm Upper lateral incisors : 21.0mm Upper canines : 24.1mm Lower central incisors : 18.6mm Lower lateral incisors : 19.9mm Lower canines : 22.6mm 2. There was no significant difference in root canal length between sex. (P > 0.05) 3. There was no significant difference in root canal length between age groups. (p > 0.05) 4. The distribution of upper central incisors showed the highest distribution followed by upper lateral incisors and lower central incisors between 10 to 40 year old age groups, and there was no signigicant difference in the rest of the age groups. There was no significant difference in sex distribution, which was 49.5% for males and 50.4% for females. The number of the upper anterior teeth was 74.3% of all the specimens and the lower anterior 25.7%, and 40.6% of all the specimens were upper central incisors.