• 대한소아치과학회지
• /
• 제37권1호
• /
• pp.130-135
• /
• 2010

이소맹출은 치아가 비정상적인 위치로 맹출하는 경우를 말하며, 주로 상악 제1대구치, 하악 측절치, 상악 견치에서 발생하며 하악 제1대구치에서는 드물게 발생한다. 제1대구치의 이소맹출은 흔히 제2유구치의 비정상적인 치근흡수를 야기하며, 이를 방치하게 되면 제2유구치의 조기상실, 제1대구치의 근심경사 및 회전, 제2소구치의 맹출 공간 부족 및 교합문제 등을 야기하게 되므로 이소맹출로 진단될 경우 조기 치료가 추천된다. 이소맹출은 대개 통상적인 방사선검사를 통해 발견되나, 간혹 제2유구치의 치근흡수가 심할 경우 치수가 감염되어 동통을 야기하는 경우도 있다. 이소맹출의 치료는 제2유구치를 보존하면서 제1대구치의 맹출 방향을 바로 잡아 주는 것으로 크게 치간이개(interproximal wedging)와 원심경사이동(distal tipping)을 이용한 방법을 사용한다. 본 증례들은 하악 제1대구치의 이소맹출을 보이는 환아들로, Humphrey appliance와 Halterman appliance를 이용하여 양호한 치료 결과를 얻었기에 보고하는 바이다.

• Imaging Science in Dentistry
• /
• 제44권4호
• /
• pp.273-278
• /
• 2014

Purpose: This study was performed to investigate the course of the mandibular canal on panoramic radiography and the visibility of this canal on both panoramic radiography and cone-beam computed tomography (CBCT). Materials and Methods: The study consisted of panoramic radiographs and CBCT images from 262 patients. The course of the mandibular canal, as seen in panoramic radiographs, was classified into four types: linear, elliptical, spoon-shaped, and turning curves. The visibility of this canal from the first to the third molar region was evaluated by visually determining whether the mandibular canal was clearly visible, probably visible, or invisible. The visibihlity of the canal on panoramic radiographs was compared with that on CBCT images. Results: Elliptical curves were most frequently observed along the course of the mandibular canal. The percentage of clearly visible mandibular canals was the highest among the spoon-shaped curves and the lowest among the linear curves. On panoramic radiographs, invisible mandibular canals were found in 22.7% of the examined sites in the first molar region, 11.8% in the second molar region, and 1.3% in the third molar region. On CBCT cross-sectional images, the mandibular canal was invisible in 8.2% of the examined sites in the first molar region, 5.7% in the second molar region, and 0.2% in the third molar region. Conclusion: The visibility of this canal was lower in the first molar region than in the third molar region. The mandibular canal presented better visibility on CBCT images than on panoramic radiographs.

• Restorative Dentistry and Endodontics
• /
• 제45권4호
• /
• pp.46.1-46.8
• /
• 2020

Objectives: This study aimed to investigate the incidence and location of the second mesiobuccal root (MB2) canal in maxillary molars with the aid of various measuring points and lines using cone-beam computed tomography (CT). Materials and Methods: A total of 205 images of patients who underwent cone-beam CT examinations between 2011 and 2015 as part of their dental diagnosis and treatment were included. There were 76 images of the maxillary first molar and 135 images of the maxillary second molar. Canal orifices were detected at -1 mm from the top of the pulpal floor on cone-beam CT images. Image assessment was performed by 2 observers in reformatted image planes using software. Assessments included measurement of the distance between the MB1 and MB2 canals, and the angles between the lines connecting the MB1-MB2 and distobuccal (DB)-palatal (P) canals. The data were analyzed using the student's t-test. Results: The prevalence of the MB2 canal was 86.8% in the first molar and 28.9% in the second molar. The angle between the lines connecting the MB1-MB2 and DB-P canals was 2.3° ± 5.7° in the first molar and -3.95° ± 7.73° in the second molar. The distance between the MB1 and MB2 canals was 2.1 ± 0.44 mm in the first molar and 1.98 ± 0.42 mm in the second molar. Conclusions: The angles between the lines connecting the MB1-MB2 and DB-P canals was almost parallel. These findings may aid in the prediction of the location of the MB2 canal orifice.

• 대한치과보철학회지
• /
• 제29권2호
• /
• pp.147-160
• /
• 1991

The purpose of this study was to examine, by the method of finite element analysis, how implant geometry with or without connection between natural tooth and osseointegrated abutments affected the stress distribution in surrounding bone and osseointegrated prosthesis. The mandibular first and second molars were removed and the two osseointegrated implants were placed in the first and second molar sites. Stress analysis induced by prostheses with connection(Model A)or without connection(Model B) between natural tooth(second bicuspid) and two osseointegrated abutments(first molar and second molar) was performed under vertical point load(Load P1) or distributed point load(Load P2). The results were as follows; 1. Under vertical point load, mesial tilting was shown in both Model A and Model B and inferior displacement of Model A was greater than that of Model B in the second bicuspid. 2. Under vortical point load, the first and second molars showed mesial tilting in both Model A and Model B, and inferior displacement of them was similar in Model A and Model B and was less than that of the second bicuspid. 3. Under distributed point load, mesial displacement was shown in Model A and Model B and inferior displacement of Model A was less than that of Model B in the second bicuspid. 4. Under distributed point load, mesial tilting was shown and inferior displacement of Model A was similar to that of Model B in the first and second molars. 5. In Model A under vertical point load, high stress was concentrated in the corneal portion of first molar and distributed throughout the second molar and the second bicuspid, and the stress distribution of the second molar was greater than that of the second bicuspid. 6. In Model B under vertical point load, high stress was concentrated in the coronal and mesio-cervical portion of the first molar. 7. In Model A under distributed point load, high stress was concentrated in the mesio-cervical portion of the first molar and evenly distributed throughout the second molar and the second bicuspid. 8. In Model B under distributed point load, high stress was concentrated in the disto-cervical portion of the second bicuspid and evenly distributed throughout the first and second molars.

• 대한소아치과학회지
• /
• 제36권4호
• /
• pp.556-562
• /
• 2009

이소맹출은 유전적 요인 혹은 여러 가지 국소적 요인에 의해 치아가 비정상적인 위치로 맹출하는 경우를 말한다. 이소맹출이 가장 빈번히 발생하는 치아는 상악 제1대구치로 이를 방치할 경우 인접치의 치근흡수 및 이에 따른 조기탈락으로 영구치 맹출공간 부족을 야기하며, 결과적으로 부정교합을 유발하는 중요한 요인으로 작용한다. 그러나, 치료에 앞서 이소맹출중인 치아가 자발적으로 맹출하기를 기다려볼 것인지 혹은 조기에 치료를 하여 제2유구치의 치근흡수나 탈락을 예방해야 할 것인지에 대한 결정이 선행되어야 한다. 현재 이를 위한 몇몇 진단학적 기준이 제시되고 있으나 학자간 이견이 존재한다. 본 연구에서는 방사선학적 검사를 통해 상악 제1대구치의 이소맹출이 조기 발견된 증례들 중 전방에 위치한 제2유구치의 치근이 흡수되어 비가역적 특징을 보인다고 판단되는 증례에 대해 특별한 처치 없이 주기적인 검진을 통해 자발적으로 해소된 결과를 관찰하였다. 이와 함께 상악 제2유구치 치근흡수의 정도와 상악 제1대구치의 맹출 기울기에 따른 후향적 분석을 통해 상악 제1대구치 이소맹출의 유형을 예측하고자 하였다. 상악 제2유구치의 치근 흡수 정도에 따라 grade I에서 IV로 분류하였고, 파노라마 방사선 사진 상에서 양측 안와의 최하방점을 연결한 수평선과 상악 제1대구치의 근심면을 따라 연결한 수직선을 기준으로 하여 근심각(mesial angle)을 측정하였다. 결과적으로는 상악 제2유구치의 치근 흡수 정도보다 상악 제1대구치의 맹출 기울기가 이소맹출의 유형을 진단하는 데에 있어 더 신뢰할만한 기준이라고 판단할 수 있었다.

• 대한치과교정학회지
• /
• 제35권3호
• /
• pp.227-237
• /
• 2005

하악 제1대구치의 맹출 장애는 매우 드문 편으로 맹출로에 물리적인 장애가 있거나 맹출 과정의 결함으로 인해 생긴다. 하악 제1대구치의 맹출 장애가 있으면 그 원인을 살펴 정확한 치료계획을 세워야 하는데 무엇보다도 조기진단과 조기 치료가 중요하다 일차미맹출(primary retention)된 하악 제1대구치를 치개 절개와 forced eruption을 통해 치료하여 치료결과가 양호하고 성공적으로 유지된 증례를 살펴보고자 한다.

• 대한소아치과학회지
• /
• 제35권1호
• /
• pp.167-174
• /
• 2008

하악 유구치와 제1대구치는 보통 근심과 원심에 하나씩 2개의 치근을 가지나 원심설측에 독립적으로 존재하는 부가치근을 갖는 경우가 발견된다. 발생 빈도는 하악 제1대구치의 경우 백인에서는 3% 정도로 드물게 나타나지만 중국이나 일본, 에스키모, 북미 인디언 등 황인종에서는 20% 내외로 비교적 높다. 유구치의 경우는 제1대구치보다는 적게 발생되고 제1유구치보다는 제2유구치에서 더 많이 발생한다. 하악 유구치에 부가치근이 관찰되면 후방에 있는 유구치와 제1대구치에서도 부가치근이 발생할 가능성이 높으며 부가 치근을 가지는 하악 제1유구치의 치관의 형태는 원심설측에 존재하는 부가치근의 영향으로 삼각형 모양을 나타낼 수 있다. 본 증례는 연세대학교 치과대학병원 소아치과에 내원한 5명의 환아에게서 발생된 하악 유구치와 제1대구치의 부가 치근에 관한 보고로서 부가치근을 가진 유구치는 치근의 수와 치관의 형태 등에 문제가 있으므로 치수치료나 기성금관 수복, 발치 시에 정확한 진단과 치료가 필요할 것으로 사료된다.

• Journal of Korean Dental Science
• /
• 제15권2호
• /
• pp.181-189
• /
• 2022

Molar incisor malformation (MIM) has been introduced as a new type of dental anomaly. Currently, the morphological and histological characteristics of MIM are known; however, its etiology has not been clearly identified. To date, the long-term prognosis of first permanent molars (FPM) affected by MIM has rarely been reported, and few treatment guidelines have been established. The purpose of this case report was to present guidelines for the extraction of FPM affected by MIM, depending on the presence of the third molar. In patients with a third molar, spontaneous mesial shift of the posterior molars might be induced by extracting the FPM at an appropriate time, that is, when the second permanent molar is at an early furcation stage of the tooth. However, it is recommended that FPM be preserved for as long as possible if a third molar does not exist. When an FPM needs to be extracted, it is suggested to consider space maintenance.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제28권5호
• /
• pp.341-347
• /
• 2002

This study was designed to determine the location of the mandibular canal on lower molar areas. Thirty-three patients were examined with multi-planar reformatted CT scan($Dentascan^{(R)}$). Three kinds of measurements were performed. The first was the distances between the upper border of the mandibular canal and the root apices of the first and second molars, the second was the distance between the cortical plate of the mandible and mandibular canal, and the last was the location of the mandibular canal in the buccolingual plane. The obtained results are as follows 1. The distance between the root apices of lower molars and the superior border of mandibular canal was largest at the mesial root of the first molar, and shortest at the distal root of the second molar(p<0.05). 2. The longest distance between the outer surface of the buccal cortical plate of the mandible and mandibular canal was measured from the distal root of the second molar, and this distance decrease gradually mesially(p<0.05). 3. The distance between the mandibular base and inferior border of mandibular canal was longest at the distal root of the second molar, and shortest at the mesial root of the first molar(p<0.05). 4. The location of mandibular canal was lingually positioned in relation to the axis of teeth and alveolar ridge in molar areas.

• Journal of Oral Medicine and Pain
• /
• 제25권2호
• /
• pp.205-214
• /
• 2000

This study was performed to investigate the relationship between mandibular midline shift and anteroposterior first molar occlusal relation, and their effects on the mandibular height and the occlusal plane angle. For this study, 49 patients with temporomandibular disorders were selected. They did not show facial asymmetry and their facial midline coincide with maxillary dental midline. Upper and lower mandibular impression were taken and the casts were fabricated. Amount and direction of the mandibular midline shift and the anteroposterior shift between the two occluding first molars were measured on the casts. Several items related to height such as mandibular height from top of the articular surface of the condyle to curve changing point between antegonial notch and mandibular angle, condylar height which was the vertical distance from the articular surface to retroepicondyle of the condyle, and sigmoid height from the deepest point of sigmoid notch to the curve changing point and the occlusal plane angle were also measured on the panoramic and on the transcranial radiographs. Correlation between midline shift and anteroposterior first molar relation and comparison between right and left mandibular height by the midline shift and the first molar relation were analysed by SPSS windows program. The results of this study were as follows : 1. Mean amount of midline shift in the subjects with midline shift were 2.0mm for both side, respectively. The first molar relation of the ipsilateral side of midline shift showed Angle class II tendency and the contralateral side showed Angle class III tendency, which meant drift of the dentition to the side of the midline shift. 2. The occlusal plane angle on the panoramic radiograph were $13.0^{\circ}$ in right, and $12.5^{\circ}$ in left side, and their were no correlation between occlusal plane angle and mandibular midline shift and the first molar occlusal relation. 3. Angle's classification for both sides of the first molar relation were same in about half of all the subjects. Amount of deviation from class I first molar relation, however, were decreased in the contralateral side of observed side. 4. Mandibular height of the ipsilateral side to which mandibular midline shift showed tendency of lower than that of the contralateral side, and there was a tendency that the height was higher in class III subjects, then class II subjects, and lower in class I subjects. However, condylar height did not show any difference in the subjects with midline shift and also show no difference by the first molar occlusal relation.