• 대한치과교정학회지
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• 제25권3호
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• pp.299-310
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• 1995

이 연구의 목적은 교정치료시 제2대구치의 위치변화를 알아보기 위함이다. 이를 위하여 제1대구치까지 banding하여 교정치료를 완료한 성인환자 64명을 Class I 발치군 15명, Class I 비발치군 12명, Class II 13명, Class III 14명으로 4개의 군으로 분류하고 치료전후의 두부방사선 계측사진을 분석하였다. 이 연구로부터 얻어진 결과는 다음과 같다. 1. Class I 발치군에서 하악 제2대구치는 제1대구치보다 적은 정출과 더 많은 원심경사를 보였고, 상악 제2대구치는 제1대구치와 유사한 정출과 근심경사를 보였다. 2. Class I 발치군에서 하악 제2대구치는 제1대구치에 비해 함입되고 유사한 원심경사를 보였으며, 상악 제2대구치는 제1대구치와 비슷하게 정출되었다. 3. Class II군에서 하악 제2대구치는 제1대구치에 비해 적은 정출을 보였고, 상악 제2대구치는 제1대구치보다 많은 정출을 보였다. 4. Class III군에서 하악 제2대구치는 제1대구치와 유사한 정출과 더 많은 원심경사를 보였으며, 상악 제2대구치는 제1대구치에 비해 적은 정출을 보였다. 5. 제2대구치 위치변화에 대한 각 군간의 비교시 FH plane에서 상악 제2대구치 치근 분기점까지 거리 변화는 Class I 발치군과 Class II, Class I 발치군과 Class III군에서 차이를 보였으며, 구개평면과 교합평면에 대한 상악 제2대구치의 각도 변화는 Class I 발치군과 Class III군에서 차이를 보였으며, 하악평면에 하악 제2대구치 치근분기점까지 거리변화는 Class I 발치군과 비발치군, Class I 비발치군과 Class II군, Class I 비발치군과 Class III군에서 차이를 보였으며, 하악 평면과 교합평면에 대한 하악 제2대구치의 각도 변화는 각 군간에 차이를 보이지 않았다.

• 대한소아치과학회지
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• 제36권4호
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• pp.556-562
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• 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.

• Journal of Periodontal and Implant Science
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• 제37권2호
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• pp.165-180
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• 2007

Dental Implants have been proved to be successful prosthetic modality in edentulous patients for 10 years. However, there are few reports on the survival of implant according to location in molar regions. The purpose of this study was to evaluate the $4{\sim}5$ years' cumulative survival rate and the cause of failure of dental implants in different locations for maxillary and mandibular molars. Among the implants placed in molar regions in Gwangju Mir Dental Hospital from Jan. 2001 to Jun. 2002, 473 implants from 166 patients(age range; $26{\sim}75$) were followed and evaluated retrospectively for the causes of failure. We included 417 implants in 126 periodontally compromised patients, 56 implants in 40 periodontal healthy patients, and 205 maxillary and 268 mandibular molar implants. Implant survival rates by various subject factors, surgical factors, fixture factors, and prosthetic factors at each location were compared using Chi-square test and Kaplan-Meier cumulative survival analysis was done for follow-up(FU) periods. The overall failure rate at 5 years was 1O.2%(subject level) and 5.5%(implant level). The overall survival rates of implants during the FU periods were 94.5% with 91.3% in maxillary first molar, 91.1% in maxillary second molar, 99.2% in mandibular first molar and 94,8% in mandibular second molar regions. The survival rates differed significantly between both jaws and among different implant locations(p<0.05), whereas the survival rates of functionally loaded implants were similar in different locations. The survival rates were not different according to gender, age, previous periodontal status, surgery stage, bone graft type, or the prosthetic type. The overall survival rate was low in dental implant of too wide diameter(${\geq}5.75$ mm) and the survival rate was significantly lower for wider implant diameter(p

• 대한소아치과학회지
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• 제25권2호
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• pp.383-399
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• 1998

Tooth development is usually described in four stages such as bud stage, cap stage, bell stage and crown stage. Exact time of appearance of tooth primordia is different among reports, and up to now there is no timetable regarding initial tooth development. To understand the congenital malformations and other disorders of the orofacial region, there is a need to establish a standard timetable on early tooth development. Till now, studies on the tooth development were mainly on later fetuses, and only few reports on early stage. Also, there were no reports on the time when bud stage turns to cap stage, and cap stage to bell stage. In this study, external morphology of face and the early development of the tooth, and transition of bud stage to cap stage, cap stage to bell stage were studied using 27 staged human embryos and 9 serially sectioned human fetuses. The results are as follows: 1. Mandibular region was formed by union of both mandibular arch at stage 15, and maxillary region by union of maxillary arch, medial nasal prominence, and intermaxillary segment at stage 19. 2. Ectodermal thickening which represents the primordia of tooth appeared in mandibular region at stage 13, and maxillary region at stage 15. 3. Bud stage began from mandibular primary central incisor at stage 17, and maxillary primary central incisor at stage 18. And the sequence of appearance was in the mandibular primary lateral incisor at stage 19, maxillary primary lateral incisor at stage 20, mandibular primary canine at stage 22, maxillary primary canine and primary first molar at stage 23, madibular primary first molar and maxillary primary second molar at 9th week, and mandibular primary second molar at 10th week of development. 4. Cap stage began from the primary anterior teeth at 9th week, and primary second molar still had the characteristics of cap stage at 12th week of development. 5. Transition to bell stage started from the primary anterior teeth at 12th week, and primary second molar started at 16th week of development. 6. Trnasition to crown stage started from primary anterior teeth at 16th week, and primary second molar at 26th week of development.

• Restorative Dentistry and Endodontics
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• 제37권3호
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• pp.175-179
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• 2012

The aim of this study was to present a method for endodontic management of a maxillary first molar with unusual C-shaped morphology of the buccal root verified by cone-beam computed tomography (CBCT) images. This rare anatomical variation was confirmed using CBCT, and nonsurgical endodontic treatment was performed by meticulous evaluation of the pulpal floor. Posttreatment image revealed 3 independent canals in the buccal root obturated efficiently to the accepted lengths in all 3 canals. Our study describes a unique C-shaped variation of the root canal system in a maxillary first molar, involving the 3 buccal canals. In addition, our study highlights the usefulness of CBCT imaging for accurate diagnosis and management of this unusual canal morphology.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제16권2호
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• pp.167-170
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• 1994

The surgical removal of the wisdom teeth is obligate when forceps extraction fails or when the wisdom teeth are impacted. The surgical removal of impacted maxillary third molars is a commonly performed procedure usually associated with few complications & little morbidity. The most frequent complications are tooth root fracture, maxillary tuberosity fracture, tooth displacement into the maxillary sinus & oroantral fistula formation. A rarely reported complication is the displacement of a tooth into the infratemporal fossa. The method of prevention of this complication is by the placement of either a finger or periosteal elevator posterior to the tooth during extraction. To remove the displaced upper third molar is very difficult & has many complications, e.g., persistent bleeding & nerve damage. When the wisdom teeth is displaced, it is initially necessary to gain access to bone by developing a mucoperiosteal path of delivery is developed by additional bone removal or, preferably planned sectioning of the tooth. There are many approaching techniques to remove the displaced upper third molar. This following report describes the surgical technique of displaced upper third molar in the pterygopalatine fassa by the midpalatal ＆transpharyngeal approach.

• Restorative Dentistry and Endodontics
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• 제40권3호
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• pp.241-248
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• 2015

Variation in root canal morphology, especially in maxillary first molar presents a constant challenge for a clinician in their detection and management. This case report describes the successful root canal treatment of a three rooted right maxillary first molar presenting with three canals each in the mesiobuccal and distobuccal roots and one canal in the palatal root. The clinical detection of this morphologic aberration was made using a dental operating microscope, and the canal configuration was established after correlating and computing the clinical, radiographic and cone-beam computed tomography (CBCT) scan findings. CBCT images confirmed the configuration of the canals in the mesiobuccal and distobuccal roots to be Al-Qudah and Awawdeh type (3-2) and type (3-2-1), respectively, whereas the palatal root had a Vertucci type I canal pattern. This report reaffirms the importance of careful examination of the floor of the pulp chamber with a dental operating microscope and the use of multiangled preoperative radiographs along with advanced diagnostic aids such as CBCT in identification and successful management of aberrant canal morphologies.

• 대한치과교정학회지
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• 제43권5호
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• pp.218-224
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• 2013

Objective: To examine the effect of bite force on the displacement and stress distribution of orthodontic mini-implants (OMIs) in the molar region according to placement site, insertion angle, and loading direction. Methods: Five finite element models were created using micro-computed tomography (microCT) images of the maxilla and mandible. OMIs were placed at one maxillary and two mandibular positions: between the maxillary second premolar and first molar, between the mandibular second premolar and first molar, and between the mandibular first and second molars. The OMIs were inserted at angles of $45^{\circ}$ and $90^{\circ}$ to the buccal surface of the cortical bone. A bite force of 25 kg was applied to the 10 occlusal contact points of the second premolar, first molar, and second molar. The loading directions were $0^{\circ}$, $5^{\circ}$, and $10^{\circ}$ to the long axis of the tooth. Results: With regard to placement site, the displacement and stress were greatest for the OMI placed between the mandibular first molar and second molar, and smallest for the OMI placed between the maxillary second premolar and first molar. In the mandibular molar region, the angled OMI showed slightly less displacement than the OMI placed at $90^{\circ}$. The maximum Von Mises stress increased with the inclination of the loading direction. Conclusions: These results suggest that placement of OMIs between the second premolar and first molar at $45^{\circ}$ to the cortical bone reduces the effect of bite force on OMIs.

• Imaging Science in Dentistry
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• 제39권2호
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• pp.69-73
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• 2009

Purpose: This study compared panoramic radiography and cone beam computed tomography (CBCT) for evaluating the relationship between the maxillary sinus floor and the roots of maxillary molars. Materials and Methods: Paired panoramic radiographs and CBCT images from 97 subjects were analysed. This analysis classified 388 maxillary molars according to their relationship to the maxillary sinus floor on panoramic radiograph and CBCT. Correlations between these two radiographic techniques were examined. Results: Maxillary molar roots that were separate from the sinus floor showed the same classification in 100% of the cases when using these two imaging techniques. The corresponding percentage for such roots that were in contact with the sinus floor was 75%. When roots overlapped the maxillary sinus floor on panoramic radiographs, only 26.4% of maxillary first molars and 60.0% of second molars showed protrusion of roots into the sinus with CBCT. Conclusion : The results of the study suggest that roots projecting into the sinus on panoramic radiographs require a three-dimensional image in order to analyze the proximity of their apex to the sinus floor. (Korean J Oral Maxillofac Radiol2009; 39 : 69-73)

• Restorative Dentistry and Endodontics
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• 제38권3호
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• pp.172-177
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• 2013

The mesiobuccal root of the maxillary molars is well known to pose a hindrance during endodontic therapy. Presented here is a case of a maxillary left second molar where three canals were located in its mesiobuccal root with the use of visual and diagnostic aids. Difficulties encountered during the process of unveiling the tooth's internal anatomy were discussed. The dilemmas encountered pertained to the root canal configuration, the nomenclature of the extra canals, and the justification for the presence of a third canal. The root canal configuration of 3-2-1 was confirmed for the mesiobuccal root using information gained from clinical, radiographic, and multidetector computed tomography (MDCT) scan findings. This case demonstrates the need for efforts to locate extra canals in the mesiobuccal root of the maxillary molars as their internal anatomy remains a mystery.