• Restorative Dentistry and Endodontics
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• 제38권3호
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• pp.167-171
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• 2013

Biomechanical preparation of root canals with accentuated curvature is challenging. New rotatory systems, such as Reciproc, require a shorter period of time to prepare curved canals, and became a viable alternative for endodontic treatment of teeth with root dilaceration. Thus, this study aimed to report a clinical case of endodontic therapy of root with accentuated dilaceration using Reciproc single-file system. Mandibular right second molar was diagnosed as asymptomatic irreversible pulpitis. Pulp chamber access was performed, and glide path was created with #10 K-file (Dentsply Maillefer) and PathFile #13, #16 and #19 (Dentsply Maillefer) up to the temporary working length. The working length measured corresponded to 20 mm in the mesio-buccal and mesio-lingual canals, and 22 mm in the distal canal. The R25 file (VDW GmbH) was used in all the canals for instrumentation and final preparation, followed by filling with Reciproc gutta-percha cones (VDW GmbH) and AH Plus sealer (Dentsply Maillefer), using thermal compaction technique. The case has been receiving follow-up for 6 mon and no painful symptomatology or periapical lesions have been found. Despite the difficulties, the treatment could be performed in a shorter period of time than the conventional methods.

• 대한치과교정학회지
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• 제51권4호
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• pp.250-259
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• 2021

Objective: The aim of this study was to compare the differences in mandibular posterior anatomic limit (MPAL) distances stratified by vertical patterns in patients with skeletal Class III malocclusion by using cone-beam computed tomography (CBCT). Methods: CBCT images of 48 patients with skeletal Class III malocclusion (mean age, 22.8 ± 3.1 years) categorized according to the vertical patterns (hypodivergent, normodivergent, and hyperdivergent; n = 16 per group) were analyzed. While parallel to the posterior occlusal line, the shortest linear distances from the distal root of the mandibular second molar to the inner cortex of the mandibular body were measured at depths of 4, 6, and 8 mm from the cementoenamel junction. MPAL distances were compared between the three groups, and their correlations were analyzed. Results: The mean ages, sex distribution, asymmetry, and crowding in the three groups showed no significant differences. MPAL distance was significantly longer in male (3.8 ± 2.6 mm) than in female (1.8 ± 1.2 mm) at the 8-mm root level. At all root levels, MPAL distances were significantly different in the hypodivergent and hyperdivergent groups (p < 0.001) and between the normodivergent and hyperdivergent groups (p < 0.01). MPAL distances were the shortest in the hyperdivergent group. The mandibular plane angle highly correlated with MPAL distances at all root levels (p < 0.01). Conclusions: MPAL distances were the shortest in patients with hyperdivergent patterns and showed a decreasing tendency as the mandibular plane angle increased. MPAL distances were significantly shorter (~3.16 mm) at the 8-mm root level.

• Imaging Science in Dentistry
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• 제53권1호
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• pp.77-82
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• 2023

Purpose: This study evaluated anatomical variations in the root canals of the lower premolars and molars in a Brazilian sub-population using cone-beam computed tomography (CBCT). Materials and Methods: In total, 121 CBCT images of patients were selected from a database. All images contained lower first and second premolars and molars on both sides of the arch, fully developed roots, and no treatment, resorption, or calcifications. In each image, the root canals of the lower premolars and molars were evaluated according to the Vertucci classification in On-Demand 3D software in the multiplanar reconstruction with dynamic navigation. Twenty-five percent of the images were re-assessed to analyze intraobserver confidence with the kappa test. Data were statistically evaluated with linear regression to evaluate the correlations of anatomic variations with age and sex, and the Wilcoxon test to analyze the laterality of variations, with a significance level of 5%. Results: The intraobserver agreement (0.94) was excellent. In general, the root canals of lower premolars and molars showed a higher prevalence of type I than other Vertucci classification types, followed by type V in premolars and type II in molars. When the molar roots were evaluated separately, type II was more frequent in mesial roots and type I in distal roots. Although age showed no correlations with the results, sex and laterality showed correlations with tooth 45 and the lower second premolars, respectively. Conclusion: The lower premolars and molars of a Brazilian sub-population showed a wide range of root canal anatomic variations.

• Restorative Dentistry and Endodontics
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• 제47권2호
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• pp.19.1-19.15
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• 2022

Objectives: The aim of this study was to evaluate and compare the apical constriction (AC) and apical canal morphology of maxillary first and second molars, using micro-computed tomography (micro-CT). Materials and Methods: The anatomical features of 313 root canals from 41 maxillary first molars and 57 maxillary second molars of patients with known age and sex were evaluated using micro-CT, with a resolution of 26.7 ㎛. The factors evaluated were the presence or absence of AC, the morphotypes, bucco-lingual dimension, mesio-distal dimension, and the profile (shape) of AC and the apical root canal. The apical root canal dimensions, location of the apical foramen (AF), AC to AF distance, and presence of accessory canals in the apical 5 mm were also assessed. Descriptive and analytical statistics were used for data evaluation. Results: AC was present in all 313 root canals. Patients' age and sex did not significantly impact either AC or the apical canal dimensions. The most common AC morphotype detected was the traditional (single) constriction (52%), followed by the parallel (29%) morphotype. The mean AC dimensions in maxillary first molars were not significantly different from those in maxillary second molars. Sixty percent of AF were located within 0.5 mm from the anatomic apex. Conclusions: The most common morphotype of AC detected was the traditional constriction. Neither patients' age nor sex had a significant impact on the dimensions of the AC or the apical root canal. The majority of AF (60%) were located within 0.5 mm from the anatomic apex.

• Restorative Dentistry and Endodontics
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• 제47권2호
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• pp.24.1-24.15
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• 2022

Objectives: Regenerative endodontic treatment is a clinical procedure aimed at biologically regenerating damaged root canal tissue of immature permanent teeth. This study aimed to report the outcomes of regenerative endodontic treatment performed by endodontic postgraduate students. Materials and Methods: Clinical and radiographic data of 27 patients, aged 10-22 years, who underwent regenerative treatment of immature permanent teeth from 2015 to 2019 were followed up, wherein clinical and radiographic examinations were performed for each patient. Postoperative success rate and tooth survival were analyzed, and the postoperative radiographic root area changes were quantified. Results: A total of 23 patients attended the dental appointments, showing that all teeth survived and were asymptomatic. Specifically, 7 periapical pathosis cases were completely healed, 12 were incompletely healed, and 4 cases failed. Moreover, significant differences were found between discolored and non-discolored teeth, and between the presence or absence of periapical radiolucency. Additionally, 3 anterior teeth showed complete closure of the apical foramen, while the apical foramen width was reduced in 17 teeth and failed in 3 teeth. Root length was also found to have been increased in 7 anterior and 4 posterior teeth, and the average length ranged from 4.00-0.63 mm in the anterior teeth, 2.85-1.48 mm of the mesial root, and 2.73-2.16 mm of the molar teeth distal root. Furthermore, calcified tissue deposition was observed in 7 teeth. Conclusions: A favorable outcome of regenerative endodontic treatment of immature permanent teeth with necrotic pulp was achieved with a high survival rate.

• 한국동물학회지
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• 제33권4호
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• pp.454-460
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• 1990

Acrylamide의 신경독성에 대해 조사하기 위하여 초기운동실조증이 유도된 생쥐의 신경계에 대한 Acrylamide의 영향을 관찰한 결과, 중추 및 말초신경조직에 있어서의 손상이 보여 척수의 전반적 공포현상, 신경원 및 신경교의 세포손상 그리고 말초신경섬유의 퇴행현상들이 보였다. 또한 이들에 대한 미세구조적 관찰에 의하여 신경원에서의 비정상적 미토콘드리아 및 척수전근 섬유에서의 수초의 균혈화 현상등이 야기됨을 알았으며 좌골신경에서의 수초의 부분적 붕괴 및 축삭형질내의 퇴행현상들도 보였다. 위와 같은 실험결과는 Acrylamide로 인한 중독의 영향이 말초신경장애의 증상으로 나타나나 최초의 신경독성효과는 중추 및 말초신경계에 대해 거의 유사한 시기에 작용함을 시사한다.

• Journal of Korean Neurosurgical Society
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• 제51권1호
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• pp.59-61
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• 2012

Although the mechanism of hemifacial spasm (HFS) is not yet well established, vascular compression of the facial nerve root exit zone and hyperexcitability of the facial nucleus have been suggested. We report a case of HFS in the setting of coinciding intracranial hemorrhage (ICH) of the pons and proximal ligation of the contralateral vertebral artery (VA) for the treatment of a fusiform aneurysm of the distal VA and discuss the possible etiologies of HFS in this patient. A 51-year-old male with an ICH of the pons was admitted to our hospital. Neuroimaging studies revealed an incidental fusiform aneurysm of the right VA distal to the origin of the posterior inferior cerebellar artery. Eight months after proximal ligation of the VA the patient presented with intermittent spasm of the left side of his face. Pre- and post-ligation magnetic resonance angiography revealed an enlarged diameter of the VA. The spasm completely disappeared after microvascular decompression.

• Restorative Dentistry and Endodontics
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• 제30권6호
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• pp.461-469
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• 2005

한 개의 치근을 가진 상, 하악 소구치의 방사선 사진 상의 근관계와 동일치아의 투명표본 상의 근관계를 각각 관찰한 다음 상호 비교하기 위해 총 142개의 소구치를 선택한 후, 구내 치과용 표준 방사선 필름을 이용하여 근원심과 협설측으로 방사선을 채득하였다. 동일하게 교육받은 4명의 판독자가 방사전 사진을 판독하여 근관계의 형태를 분류하였다. 동일한 치아에 근판와동을 형성한 후 $5\%$ 질산용액에 48시간 동안 담가 치수조직을 용해시키고 인디안 잉크를 치수강 내로 주입하여 치수조직을 염색하였다. $5\%$ 질산용액에 48시간 동안 담가 탈회시킨 후 메틸 살리실레이트로 투명화시키고 입체현미경하에서 20배의 크기로 근관계의 형태를 평가하여 다음과 같은 결과를 얻었다. 방사선과 입체현미경 소견간에는 판독자 간에 통계학적으로 유의한 차이를 나타냈다 (p<0.05). 따라서 동일한 방사선 사진을 판독할 경우 판독자 간에 근관의 형태에 있어서 차이가 있을 수 있다. 그러므로 임상가는 방사전 사진을 주의깊은 판독과 예견된 근관의 형태에 따라 난이도를 고려하여 근관치료를 시행해야 할 것으로 사료된다.

• Applied Microscopy
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• 제26권1호
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• pp.79-93
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• 1996

The differentiation of nail matrix and fine structure of matrix cells were studied with light and electron microscope using specimens from nails of thumb finger in Korean fetuses 14 to 24 weeks old. Fetal nail matrix consisted of two horizontal layers, thicker ventral and thinner dorsal matrices, originating from invagination of epidermis in proximal nail field. Matrix being generally thicker in its distal region than the apex became gradually thickened with increase of the fetal age. Each matrix consisted of single layer of basal cells and multiple layers of squamous cells which are arranged close to and parallel to the central axis of the nail mairix. The process of keratinization of fetal nail matrix was noted to be occured concurrently in the ventral and dorsal matrices along the central axis of matrix toward distal and dorsal direction. Squamous cells became matured with accumulation of tonofilaments, increase of keratohyalin granules, discharge of membrane coating granules, and narrowing of intercellular spaces, thickening of plasma membrane and finally being transformed into horny cells of nail plate. Horny cells of nail plate filled with fibrous elements in the electron dense amorphous substance. These findings of keratinization process of fetal nail matrix appeared to be similar to those of keratinization in epidermis and inner root sheath of the hair. In the nail matrix, however, corresponding region to the keratogenous zone of growing hair follicle was not observed. Vacuolated squamous cells of nail matrix seen on light microscopy was considered to be artefactual product, but squamous cells with condensed small nuclei rarely found adjacent nail plate was considered to be one of the squamous cells with unknown function. Proximal end of nail plate was observed on dorsal surface of nail field distal to the proximal nail fold at 14 and 16 weeks old human embryos. Proximal prolongation of the proximal end of nail plate was occured with advancing fetal age and afterward 21 weeks nail plate invaded into nail matrix. Melanin granule containing cells and Merkel cells were present only on the basal layer of dorsal nail matirx.

• Restorative Dentistry and Endodontics
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• 제37권3호
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• pp.136-141
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• 2012

Objectives: The maintenance of the healthy periodontal ligament cells of the root surface of donor tooth and intimate surface contact between the donor tooth and the recipient bone are the key factors for successful tooth transplantation. In order to achieve these purposes, a duplicated donor tooth model can be utilized to reduce the extra-oral time using the computer-aided rapid prototyping (CARP) technique. Materials and Methods: Briefly, a three-dimensional digital imaging and communication in medicine (DICOM) image with the real dimensions of the donor tooth was obtained from a computed tomography (CT), and a life-sized resin tooth model was fabricated. Dimensional errors between real tooth, 3D CT image model and CARP model were calculated. And extra-oral time was recorded during the autotransplantation of the teeth. Results: The average extra-oral time was 7 min 25 sec with the range of immediate to 25 min in cases which extra-oral root canal treatments were not performed while it was 9 min 15 sec when extra-oral root canal treatments were performed. The average radiographic distance between the root surface and the alveolar bone was 1.17 mm and 1.35 mm at mesial cervix and apex; they were 0.98 mm and 1.26 mm at the distal cervix and apex. When the dimensional errors between real tooth, 3D CT image model and CARP model were measured in cadavers, the average of absolute error was 0.291 mm between real teeth and CARP model. Conclusions: These data indicate that CARP may be of value in minimizing the extra-oral time and the gap between the donor tooth and the recipient alveolar bone in tooth transplantation.