• 대한치과의사협회지
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• 제10권7호
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• pp.413-415
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• 1972

The author had a case report of right maxillary molar tooth root apex cyst involving maxillary sinus, which was misdiagnosed maxillary sinusitis or some cancer. Right maxillary 2nd premolar, 1st molar, & 2nd molar tooth involved root apex cyst was extracted and curetted.

• 대한치과의사협회지
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• 제48권4호
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• pp.297-307
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• 2010

Noncarious cervical lesions(NCCLs) are characterized as structural defects found on the tooth surface of the cement-enamel junction. Loss of tooth structure through noncarious mechanisms may vary in etiology and clinical presentation for each individual but presently many clinician now classify this as tooth failure of abfraction due to the stress applied in the cervical area of the tooth under oral physiological and pathological loads. In the current study, we investigated the stress distribution of maxillary premolar with NCCL using simulated 3D finite element analysis. The results were as follows: 1. In the sound maxillary premolar, the stresses were highly concentrated at cervical enamel surface of the mesiobuccal line angle, asymmetrically. 2. Once the lesion has been formed, the highest stress concentration was observed around the apex of the wedge shaped lesion. 3. In four types of NCCL, the patterns of stress distribution were similar and the peak stress was observed at mesial corner and also stresses concentrated at lesion apex. 4. Lesion cavity modification of rounding apex, reduced stress of lesion apex. 5. When restoring the notch-shaped lesion, material with high elastic modulus worked well at the lesion apex and material with low elastic modulus worked well at the cervical cavosurface margin.

• 치과방사선
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• 제2권1호
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• pp.47-51
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• 1972

The author measured the distance from mental foramen to the occusal plane and classified the positional frequency of mental foramen to the tooth site using topography. The results were obtained as follow; 1. Of 964 mental foramen taken, the common site was in 2nd premolar region showing 64.08 per cent in right and 57.17 per cent in left site. 2. The average distance from occlusal plane to the upper border of premolar region was 23.20㎜. and lower border was 25.07㎜. 3. The positional variation of mental foramen was 4.77 per cent were located above the apex of the nearest tooth, and 50.42 per cent were located at the apex of the nearest tooth and 44.81 per cent were located below the apex of the nearest tooth.

• Restorative Dentistry and Endodontics
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• 제23권2호
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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.

• Journal of Korean Dental Science
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• 제13권2호
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• pp.52-58
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• 2020

Purpose: Using two types of electronic apex locators, this study aimed to investigate the differences in accuracy according to the evaluator and equipment. Materials and Methods: Artificial teeth of the lower first premolars and two mandibular acrylic models (A and B) were used in this study. In the artificial teeth, the pulp chamber was opened and the access cavity was prepared. Using calibrated digital Vernier calipers, the distance from the top of the cavity and the root apex was measured to assess the actual distance between two artificial teeth. The evaluation was conducted by 20 dentists, and each evaluator repeated measurements for each electronic apex locator five times. The difference between the actual distance from the top of the cavity to the root apex and the distance measured using electronic measuring equipment was compared. For statistical analysis, the Friedman test the Mann-Whitney U-test were conducted and the differences between groups were analyzed (α=0.05). Result: As for the accuracy of measurement according to the two types of electronic apex locators, the value of the measurement error was 0.4753 mm in Dentaport ZX and 0.3321 mm in E-Cube Plus. Moreover, electronic apex locators Dentaport ZX and E-Cube Plus showed statistically significant differences (P<0.05). As for the difference in the accuracy of the two types of electronic apex locators according to the evaluator, the resulting values differed depending on the evaluator and showed a statistically significant difference (P<0.001). Conclusion: Electronic apex locator E-Cube Plus showed higher accuracy than did Dentaport ZX. Nevertheless, both types of electronic apex locators showed 100% accuracy in finding the region within root apex ±0.5 mm zone. Furthermore, according to the evaluator, the two electronic apex locators showed different resulting values.

• 대한치과보철학회지
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• 제31권3호
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• pp.303-316
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• 1993

The purpose of this study was to analysis the stress distribution induced by three unit PFM bridges and various cantilever bridges replacing maxillary latersal incisor. The simplified two-dimensional photoelastic models used for this study was contructed in the folio- wing way. CR/R ratio was designed to be 1 : 1, 1 : 1.25 and 1 : 1.5. The pontics of cantilever bridge supported by maxillary canines consisted of wrap-around type, rest-extension type, and simple type. 3-unit PFM bridge was constructed with traditional method. 1kg vertical static load was applied on the center of the incisal edge of the pontic. The stress pattern was examined and recorded by photography. The results obtained were as follows ; 1. The magnitude of stress on the abutment root apex area of a traditional 3-unit bridge was the lowest. 2. The model of cantilevered pontic with a rest showed the relatively well distributed stress around the abutment tooth. The model with simple pontic generated the greatest stress concentration in the supporting structure of the abutment tooth. 3. As the height of bone level reduced, the rotational and vertical force increased around the abutment tooth. 4. The stress concentration of the 3-unit bridges occured on the root apex and stress concentration of the cantilever briage occured on the root apex and cervix area, 5. In the case of the cantilever bridge, stress concentrated distally on the root apex area of the abutment tooth and additional stress was observed mesially on the upper part of the root. Especially in the case of the simple pontic, was phenomenon was more apparent than the others. 6. Force applied to cantilevered pontic was transmitted to the adjacent central incisor through the contact surface. Stress was markedly observed on the mesial cervix area in the case of simple pontic and on the root apex area in the case of wrap-around type and rest-extension type.

• Restorative Dentistry and Endodontics
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• 제41권3호
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• pp.182-188
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• 2016

Objectives: The purpose of this study was to evaluate the proximity of the mandibular molar apex to the buccal bone surface in order to provide anatomic information for apical surgery. Materials and Methods: Cone-beam computed tomography (CBCT) images of 127 mandibular first molars and 153 mandibular second molars were analyzed from 160 patients' records. The distance was measured from the buccal bone surface to the root apex and the apical 3.0 mm on the cross-sectional view of CBCT. Results: The second molar apex and apical 3 mm were located significantly deeper relative to the buccal bone surface compared with the first molar (p < 0.01). For the mandibular second molars, the distance from the buccal bone surface to the root apex was significantly shorter in patients over 70 years of age (p < 0.05). Furthermore, this distance was significantly shorter when the first molar was missing compared to nonmissing cases (p < 0.05). For the mandibular first molars, the distance to the distal root apex of one distal-rooted tooth was significantly greater than the distance to the disto-buccal root apex (p < 0.01). In mandibular second molar, the distance to the apex of C-shaped roots was significantly greater than the distance to the mesial root apex of non-C-shaped roots (p < 0.01). Conclusions: For apical surgery in mandibular molars, the distance from the buccal bone surface to the apex and apical 3 mm is significantly affected by the location, patient age, an adjacent missing anterior tooth, and root configuration.

• 대한치과보철학회지
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• 제52권3호
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• pp.202-210
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• 2014

목적: 이 연구의 목적은 abfraction병소가 있는 금속도재관수복 치아를 수복하거나 하지 않을 때 나타나는 응력집중과 분포를 유한요소분석으로 평가하는 것이다. 재료 및 방법: 상악 제1 소구치를 선정하여 총 10개의 유한요소모델을 만들었다. 모델 1은 자연치; 모델 2는 협측과구개측 백악법랑경계 상방 2 mm에 변연이 위치한 금속도재관; 모델 3은 협측과구개측 백악법랑경계에 변연이 위치한 금속도재관; 모델 4는 abfraction병소를 가진 자연치; 모델 5와 6은 다른 조건은 각각 모델 2와 3과 동일하면서 abfraction병소를 가진 치아; 모델 7은 abfraction병소를 가지고 composite resin으로 수복된 자연치;모델 8과 9는 각각 모델 5와 6과 동일한 모델에 abfraction병소를 composite resin으로 수복한 후 금속도재관 장착한 치아; 모델 10은 composite resin으로 abfraction lesion을 수복하고 금속도재관의변연을 abfraction병소보다 하방에 위치시킨 치아였다. 위치를 서로 달리한 하중 load A와 load B를 가하여, 각 기준점에서의 von Mises stress값들을 측정하여 비교하였다. 결과: Abfraction병소가 있는 치아에 load A 또는 load B를 주었을 때, 응력은 lesion의 apex에 집중되었다. 반면, abfraction병소를 composite resin으로 충전한 치아에 load A 또는 load B를 주었을 때 응력값은 apex에서 감소하였다. 결론: Abfraction이 있는 치아는 복합 레진으로 수복해주는 것이 응력의 집중을 줄여서 병소의 예후에 유리한 것으로 나타났으며, Abfraction이 발생된 치아를 금속 도재관으로 수복할 경우 협측변연을 법랑질 상에 위치시키는 것이 유리하였다.

• Restorative Dentistry and Endodontics
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• 제33권1호
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• pp.20-27
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• 2008

정확한 근관장 측정은 성공적인 근관치료를 위해 필수적이다. Kuttler는 근관협착부는 주근단공에서 0.5 mm 상방에 위치한다고 하였고 Lee는 상아백악질 경계점부위보다 주근단공이 재현성이 높고 임상적으로 관찰하기 용이하다고 보고하였다. 본 연구는 alginate model상에서 2개의 전자근관장측정기를 사용하여 얻은 측정치의 정확성(accuracy)을 평가하고 각각 0.5 mark와 Apex mark 중에서 어느 지점에서 더 일관성(consistency)을 보이는지를 비교하고 또한 근관장을 측정할 때 파일을 전진시키면서 Apex mark를 측정한 값과 치근단부위를 지나친 후 다시 후퇴하면서 측정한 값의 차이를 비교하고자 하였다. 52개의 발거된 건전한 제 1, 2소구치를 대상으로 하였으며 Root ZX와 E-Magic Finder Deluxe를 이용하여 각각 26개중 13개는 파일을 전진하면서 0.5 mark에서 근관장을 측정하고 Apex mark에서 근관장을 측정한 후 0.5 mark에서 고정하였다. 나머지 13개는 0.5 mark에서 근관장을 측정한 후 Apex mark에서 근관장을 측정하고 다시 치근단 부위를 넘어선 후 후퇴하면서 Apex mark에서 근관장을 측정하고 고정한 후 치근단부 4 mm를 삭제하여 현미경상에서 파일 끝부터 주근단공까지의 거리를 측정하였다. 그 결과 Root ZX와 E-Magic Finder 모두, 실험군 100%에서 주근단공과 file tip간의 거리가 임상적 허용범위인 ${\pm}0.5\;mm$내에 있었으며 0.5 mark보다 Apex mark에서 더 높은 일관성을 보였다. 주근단공에서 fie tip사이의 거리는 Root ZX의 0.5 mark에서 -0.18 mm, Apex mark에서 -0.07 mm이고 E-Magic Finder의 0.5 mark에서 -0.25 mm, Apex mark에서 -0.02 mm를 나타내었다. Apex hand는 0.04 mm였다. 따라서 Alginate model을 사용한 본 실험조건에서는 Apex mark에서 근관장을 측정한 결과 거의 주근단공과 일치하고 다른 여러 연구에서 주근단공에서 0.5 mm상방에 근관협착부가 위치한다고 보고하였으므로 임상적인 측면에서 Apex mark에서 측정한 근관장에서 0.5 mm를 빼서 근관장으로 사용하는 것이 임상적으로 더 좋으리라고 사료된다.

• 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.