• 대한치과보철학회지
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• 제35권3호
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• pp.517-534
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• 1997

It has been held that excessive mechanical forces to the osseous and soft tissues of the TMJ result in joint dysfunction. Understanding the stress pattern on TMJ is very important in TMJ research. But, it is very difficult to measure directly the biomechanical stress distribution in the TMJ when the mandible is loaded. Therefore, stress distribution in the TMJ during functional movement was studied through animal experiment or mathematical model. It was observed and compared the stress distribution occuring in the working and balancing condyle when lower right canine, lower right first molar and lower right second molar were clenched by the three dimensional finite element analysis. Also, stress distribution in the working and balancing condyles were observed and compared when $20^{\circ}$ forward and buccal bite forces were applied to the first molar. The results were as follows : 1. Stress distribution in the condyles during unilateral clenching of the first molar, second molar, canine showed no difference. In the working condyle, tensile force was concentrated on the lateral aspect of the condylar articular surface and condylar neck. And compressive force was concentrated on the anteromedial and lateral aspect of condyle. In the balancing condyle, tensile and compressive forces were concentrated on the lateral aspect of the condylar articular surface and stress transmission to the temporal bone was not observed. 2. When lateral forces were applied to the first molar, tensile forces were concentrated on the medial aspect of the condylar neck and condylar posterior surface in working and balancing condyle. Compressive force was concentrated on the anteromedial and lateral surface of the condyle and stress transmission to the temporal bone was not observed. 3. During unilateral clenching, stress in the working condyle decreased as the occlusal load moved posteriorly while the stress in the balancing condyle increased. when lateral force was applied to first molar, the incremental amount of stress was greater than vertical load. 4. During unilateral clenching, the average balancing/working condyle stress ratio was 2.52. There was a greater concentration of stress in the balancing condyle. The ratio increased as the occlusal load moved posteriorly and decreased considerably when lateral forces were applied to the first molar.

• 대한치과교정학회지
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• 제21권2호
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• pp.353-366
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• 1991

This study was performed to analyze the effects of forces to the alveolar bone by various molar uprighting spring such as helical uprighting spring. T-loop spring, Modified T-loop spring and open coil spring. The simplified two-dimensional photoelastic model was constructed with a lower left posterior quadrant containing the second molar, the first and second premolars and the canine, with the first molar missing. Several molar uprighting springs were fabricated from 0.017 by 0.022 inch blue Elgiloy and applied to the photoelastic model. Two-dimensional photoelastic stress analysis was performed, and the stress distribution was recorded by photography The results obtained were as follows; 1. In all the kinds of the springs, the center of rotation of the mandibular second molar was oserved at the apical 1/5-1/6 between the alveolar crest and the root apex. 2. In all the kinds of the spring, the stress induced in the mesial root surface of the mandibular second molar was relatively homogeneous but there was some difference in the magnitude of the stress. 3. In the kinds of the springs, the distal crown tipping moment of the second molar was increased in turn as open coil spring, helical uprighting spring, T-loop spring, and modified T-loop spring. 4. The largest extrusive force was occured in the T-loop spring, intrusive force was occured in Modified T-loop spring only, and the largest distal tipping force was occured in open coil spring. 5. In the T-loop spring with activation, the stress induced in the mesial root surface of the second molar was increased gradually from the root apex to the alveolar crest and highly concentrated in the alveolar crest.

• 대한소아치과학회지
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• 제44권2호
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• pp.147-153
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• 2017

본 연구는 5 - 10세 아동에서 상악 제1대구치의 이소맹출과 골격적 부정교합 유형 사이의 연관성을 평가하고자 하였다. 상악 제1대구치의 이소맹출이 있는 93명의 아동을 실험군으로, 이소맹출이 없는 693명의 아동을 대조군으로 분류하였다. 제1대구치가 맹출 전이거나 제2대구치가 맹출을 완료한 경우는 연구대상에서 제외하였다. 측모 두부 방사선 사진 계측을 통해 골격적 부정교합의 유형을 조사, 분석하였다. 실험군의 경우, 골격성 3급 부정교합이 57.0% 이었고, 대조군에 비해 골격성 3급 부정교합의 비율이 유의하게 높았다. SNA, ANB, A to N-perpendicular는 실험군에서 작은 경향을 보였고, A-B plane angle과 APDI는 더 크게 나타났다. 반면, SNB와 mandibular plane angle은 두 군 사이에서 유의한 차이가 없었다. 본 연구를 통해 상악의 열성장이 상악 제1대구치의 이소맹출에 영향을 미칠 수 있음을 확인하였다.

• 대한소아치과학회지
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• 제31권4호
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• pp.598-604
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• 2004

하악 제 1대구치 매복의 발생 빈도는 전체 인구의 0.01%로 드물게 나타난다. 매복의 원인으로는 맹출 공간의 부족, 과잉치, 치성 종양이나 낭과 같은 맹출로상의 장애물, 유전적 요인, 내분비 질환, 외상 등이 있다. 하악 제 1대구치의 매복으로 인해 하안면 고경의 감소, 낭의 형성, 치관 주위염, 인접치의 치근 흡수, 부정 교합 등의 부작용이 생길 수 있으며, 치료 방법으로는 외과적 노출술, 교정적 견인, 외과적 재위치술, 발거 등이 있다. 다음의 두 증례는 하악 제 1대구치의 미맹출을 주소로 내원한 환아에게 외과적 노출술을 시행하여 원심 경사 매복된 하악 제 1대구치의 자발적 맹출을 유도한 증례들이다.

• 대한소아치과학회지
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• 제47권4호
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• pp.389-396
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• 2020

Pyramidal molar는 완전히 융합된 하나의 치근과 근관을 갖는 대구치를 의미한다. 이번 연구의 목적은 청소년들에서 Pyramidal molar의 유병률과 특성을 파악하는 것이다. 이 연구에서는 연세대학교 치과대학병원 소아치과에 내원한 만 13세에서 16세 사이의 1,612명의 파노라마가 분석되었고 총 12,896개의 대구치(제1,2대구치)가 평가되었다. Pyramidal molar의 발생 위치와 성별에 대한 상대적인 유병률을 계산하였고 카이제곱 검정을 사용하여 상관관계를 분석하였다. Pyramidal molar의 유병률은 1.49%였으며 Pyramidal molar가 발견된 24명의 환자 중 남성이 6명, 여성이 18명으로 여성에서 호발하였다. 전체 대구치(제3대구치 제외)에서 Pyramidal molar는 0.31%를 차지하였다. Pyramidal molar 중 88%가 상악에서 발견되었고 모든 Pyramidal molar는 제2대구치에서 나타났다. Pyramidal molar는 일반적인 다근치에 비해 치주적인 예후가 좋지 못하며 치수치료시 구조적 특성에 대한 이해가 중요하다. 임상가들은 pyramidal molar의 해부학적 특성을 이해하고 치료 및 예후 평가에 적용할 수 있어야 한다.

• 대한치과의사협회지
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• 제41권5호통권408호
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• pp.359-361
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• 2003

A cases report is presented describing treatment : of a mandibular first molar in which three canals were located, prepared, and obtained in the mesial root. The incidence of middle mesial canals in mandibular molars is reviewed 물 treatment considerations are described.

• 대한치과교정학회지
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• 제50권4호
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• pp.268-277
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• 2020

This case report demonstrates two different uprighting mechanics separately applied to mesially tipped mandibular first and second molars. The biomechanical considerations for application of these mechanisms are also discussed. For repositioning of the first molar, which was severely tipped and deeply impacted, a novel cantilever mechanics was used. The molar tube was bonded in the buccolingual direction to facilitate insertion of a cantilever from the buccal side. By twisting the distal end of the cantilever, sufficient uprighting moment was generated. The mesial end of the cantilever was hooked over the miniscrew placed between the canine and first premolar, which could prevent exertion of an intrusive force to the anterior portion of the dentition as a side effect. For repositioning of the second molar, an uprighting mechanics using a compression force with two step bends incorporated into a nickel-titanium archwire was employed. This generated an uprighting moment as well as a distal force acting on the tipped second molar to regain the lost space for the first molar and bring it into its normal position. This epoch-making uprighting mechanics could also minimize the extrusion of the molar, thereby preventing occlusal interference by increasing interocclusal clearance between the inferiorly placed two step bends and the antagonist tooth. Consequently, the two step bends could help prevent occlusal interference. After 2 years and 11 months of active treatment, a desirable Class I occlusion was successfully achieved without permanent tooth extraction.

• 대한치과보철학회지
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• 제18권1호
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• pp.99-109
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• 1980

An investigation was made Into 1,357 fixed bridges which had been performed at the Department of Prosthetic Dentistry, Seoul National University Hospital from 1973 to 1979. The purpose of this investigation was to establish a basic reference of the treatment with fixed bridges by obtaining statistical conclusions from the data concerning the patients who had been treated with fixed bridges. The following conclusions were obtained; 1. The ratio of the fixed bridges made on the maxillae to those made on the mandible was 1:1. 2. The cases of fixed bridges with one pontic were the most frequent, i.e., 946 cases out of total 1,357 cases, which were 69.7% of the total. 3. As the number of missing teeth increased, the number of the relevant cases of fixed bridges decreased. 4. The most frequent age group of the patients who had been treated with fixed bridges was the twenties, which was 40.8% of the total. As the age of the patients increased, the number of corresponding cases of fixed bridges decreased. 5. Most of the fixed bridges with more than three pontics were made at the anterior portion samely on the maxilla and on the mandible. 6. As for the retainers, the porcelain fused to metal crown and the partial veneer crown were frequently used at the anterior portion, while the full veneer crown was frequently used and the inlay and the attachment were used in some cases at the posterior portion. The locations of fixed bridges in the order of their frequency were: canine, lateral incisor, second bicuspid, central incisor, second molar, first bicuspid, first molar, and third molar on the maxilla; second bicuspid, second molar, first bicuspid, first molar, canine, third molar, lateral incisor, and central incisor on the mandible.

• Journal of Dental Anesthesia and Pain Medicine
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• 제23권4호
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• pp.213-220
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• 2023

Background: Third molar extraction is the most commonly performed minor oral surgical procedure in outpatient settings and requires regional anesthesia for pain control. Extraction of the maxillary molars commonly requires both posterior superior alveolar nerve block (PSANB) and greater palatine nerve block (GPNB), depending on the nerve innervations of the subject teeth. We aimed to study the effectiveness of PSANB alone in maxillary third molar (MTM) extraction. Methods: A sample size comprising 100 erupted and semi-erupted MTM was selected and subjected to study for extraction. Under strict aseptic conditions, the patients were subjected to the classical local anesthesia technique of PSANB alone with 2% lignocaine hydrochloride and adrenaline 1:80,000. After a latency period of 10 min, objective assessment of the buccal and palatal mucosa was performed. A numerical rating scale and visual analog scale were used. Results: In the post-latency period of 10 min, the depth of anesthesia obtained in our sample on the buccal side extended from the maxillary tuberosity posteriorly to the mesial of the first premolar (15%), second premolar (41%), and first molar (44%). This inferred that anesthesia was effectively high until the first molars and was less effective further anteriorly due to nerve innervation. The depth of anesthesia on the palatal aspect was up to the first molar (33%), second molar (67%), and lateromedially; 6% of the patients received anesthesia only to the alveolar region, whereas 66% received up to 1.5 cm to the mid-palatal raphe. In 5% of the cases, regional anesthesia was re-administered. An additional 1.8 ml PSANB was required in four patients, and another patient was administered a GPNB in addition to the PSANB during the time of extraction and elevation. Conclusion: The results of our study emphasize that PSANB alone is sufficient for the extraction of MTM in most cases, thereby obviating the need for poorly tolerated palatal injections.

• 대한소아치과학회지
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• 제47권3호
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• pp.337-343
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• 2020

Molar-incisor malformation(MIM)은 최근 발견된 새로운 형태의 root anomaly로 제1대구치 및 제2유구치의 짧거나 미약한 치근 발달과 협착된 치수강, 그리고 cemento-enamel junction 높이에 석회화물질의 존재를 특징으로 한다. 이 증례는 MIM 이환 환자에서 유치열 전반에 걸쳐 치수강 내를 거의 가득 채우고 있는 free pulp stone을 방사선학적으로 확인할 수 있었다. 발치된 환자의 하악 제1대구치와 상악 제2유구치를 대상으로 micro-computed tomography(micro-CT) 촬영 및 scanning electron microscope-energy dispersive X-ray spectrometer 분석을 시행하였다. Micro-CT 영상을 통해, 하악 제1대구치의 치관 외부로 연결된 부근관의 존재가 확인되었다. 이것은 MIM 이환 치아에서 근관치료의 불량한 예후의 원인이 될 수 있을 것으로 사료된다.