• 대한소아치과학회지
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• 제8권1호
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• pp.21-24
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• 1981

The author observed a case of ectopic erupted maxillary second premolars and impacted mandibular second premolars due to premature loss of the primary second molars. The treatments were done as follows: 1. In the maxilla, the teeth arrangement problem was corrected with removal of the ectopic erupted second premolars. 2. In the mandible, normal dentition was established with surgical removal of the left second premolar and removal of the permanent first molar in right side combined by orthodontic therapy.

• Journal of Periodontal and Implant Science
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• 제31권3호
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• pp.573-579
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• 2001

The purpose of this study was to investigate the characteristiss of korean multi-rooted teeth extracted by periodontal disease. A total of 182 extracted multi-rooted teeth were examined. The distance from the cementoenamel junction(CEJ) to the root groove and from the CEJ to the root division was measured. The frequency of the root grooves were calculated. The results are as follows : 1. Distances from CEJ to the root groove were $1.53{\cdot}1.60mm$ for maxillary first premolars mesial${\cdot}$distal sides, $1.26{\cdot}1.38{\cdot}1.75mm$ for maxillary first molars buccal${\cdot}$mesial${\cdot}$distal sides, $1.38{\cdot}1.71{\cdot}1.41mm$ for maxillary second molars buccal${\cdot}$mesial${\cdot}$distal sides, $0.98{\cdot}0.99mm$ for mandibular first molars buccal${\cdot}$lingual sides and $1.28{\cdot}1.35mm$ for mandibular second molars buccal${\cdot}$lingual sides. 2. The frequency of the root grooves were $17.4{\cdot}30.4%$ for maxillary first premolars mesial${\cdot}$distal sides, $44.4{\cdot}84.1{\cdot}67.5%$ for maxillary first molars buccal${\cdot}$mesial${\cdot}$distal sides, $100{\cdot}90.3{\cdot}90.3%$ for maxillary second molars buccal${\cdot}$mesial${\cdot}$distal sides, $42.9{\cdot}77.8%$ for mandibular first molars buccal${\cdot}$lingual sides and 90.6% for mandibular second molars buccal${\cdot}$lingual sides. 3. Distances from CEJ to the root division were $6.8{\cdot}7.2mm$ for maxillary first premolars mesial${\cdot}$distal sides, $3.3{\cdot}4.38{\cdot}4.34mm$ for maxillary first molars buccal${\cdot}$mesial${\cdot}$distal sides, $3.67{\cdot}4.8{\cdot}4.07mm$ for maxillary second molars buccal${\cdot}$mesial${\cdot}$distal sides, $3.1{\cdot}3.89mm$ for mandibular first molars buccal${\cdot}$lingual sides and $3.2{\cdot}4.06mm$ for mandibular second molars buccal${\cdot}$lingual sides.

• 치과방사선
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• 제23권1호
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• pp.19-25
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• 1993

저자들은 평행촬영법으로 촬영된 총 6,082명(남자 2,918명, 여자 3,164명)의 구내전악 표준방사선사진을 판독하여 하악 제1대구치와 소구치에서 과잉치근이 발생된 경우를 조사하고 성별, 발생률, 발생부위를 분석하여 다음의 결과를 얻었다. 1. 하악 제1대구치에서 과잉치근의 발생은 9.32%였으며, 남성은 11.35%, 여성은 7.46%으로서 여성에 비해 남성에서의 발생률이 더 높았다. 양측성으로 발생된 경우는 4.26%이었다. 2. 하악 소구치에서 과잉치근의 발생은 3.57%이었으며, 남성은 4.28%, 여성은 2.91%으로서 여성에 비해 남성에서의 발생률이 더 높았다. 제1소구치에서 양측성으로 발생된 경우는 1.53%이었다.

• 대한치과보존학회:학술대회논문집
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• 대한치과보존학회 2006년도 Spring Scientific Meeting(the 125th) of Korean Academy of Conservative Dentistry
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• pp.229-229
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• 2006

• 대한치과교정학회지
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• 제26권1호
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• pp.33-41
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• 1996

소구치 발치 직후 일정기간 동안 고정식 장치를 이용한 치료를 의도적으로 연기함으로써 의외의 좋은 결과를 얻었다는 연구결과가 발표되었고 이러한 연구결과를 입증하는 임상경험을 교정의들도 가끔 하게 된다. 소구치 발치 후 하악치열의 생리적 치아이동현상을 연구한 논문에 의하면 이를 생리적 치아이동(driftodontics)이라 명명하였다. Driftodontics의 개념이 교정학 영역에서 조심스럽게 소개되고 있는 이유는 driftodontics의 성질과 이동되는 양에 대해서는 아직 조사가 미흡한 실정이며 이러한 치아이동을 이용하기 위한 지침서가 거의 소개되어있지 않기 때문이다. 따라서 본 연구의 대상은 제 I급 부정교합자 중 이전에 교정치료를 받은 경험이 없고, 상, 하악 치열궁에 crowding이 있어 상, 하악 제1소구치를 발치하기로 한 57명 (남자 16명, 여자 41명)을 대상으로 하였다. 연령에 따라 두 군으로 나누어 제1군은 26명으로, 평균연령은 13.5세(12.7-14.9세)였으며 제2군은 31명의 환자로 평균연령 21.3(18-22.1)세였다. 두 군 모두에서 소구치 발치 후 약7개월 정도의 driftodontics기간을 유지한 후 측모 두부방사선사진 및 석고모형 계측을 통하여 얻어진 결과는 다음과 같다. 1. 2군(18세-22세)에서는 주로 하악 전치 및 견치의 후방이동이 일어났으며 하악구치는 상대적으로 이동이 미약한 정도로 나타났다. 2. 1군(12세-15세)에서는 전치부 변화 비율이 2군에 비해 더욱 많이 일어났으며, 구치변화는 2군과 유사한 것으로 나타났지만 그 양은 조금 컸다. 3. 하악 전치부의 생리적 이동으로 불규칙지수(irregularity index)가 감소하고 crowding양이 감소하였다.

• Imaging Science in Dentistry
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• 제44권3호
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• pp.221-227
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• 2014

Purpose: This study aimed to investigate the clinical anatomy of lower premolar roots in a Spanish population by using cone-beam computed tomography (CBCT), correlating findings with patient gender and tooth type. Materials and Methods: Using 70 CBCT images, we evaluated 126 healthy, untreated, well-developed lower premolars. The number and morphology of roots and root canals, and the foramina number were assessed. Results for gender and tooth type were compared using the chi-squared and ANOVA tests. Results: The average length of teeth and roots was significantly higher in men (p=0.00). All 126 premolars had a single root. One canal was found in 83.3% of the premolars, with no gender or tooth type differences; Vertucci configuration types I and V were the most prevalent. The first premolars showed significantly greater variability than the second premolars (p=0.03). A single apical foramen was found in 89.7% of the premolars, with no differences by tooth type. Women had a significantly higher prevalence of two apical foramina than men (p=0.04). Some degree of curvature was observed in 65% of the premolars, with no differences by gender or tooth type. A root angle of more than $20^{\circ}$ was found in 12.98% of the premolars, without any differences by gender or tooth. Conclusion: All premolars were single-rooted. One canal had the most prevalent morphology. More variability in canal anatomy was found in the first premolars. Curvatures greater than $20^{\circ}$ were found at less than 5 mm from the apex.

• 한국임상수의학회지
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• 제35권4호
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• pp.137-140
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• 2018

A five-month-old toy poodle was referred for treatment of bilateral mandibular fractures. Preoperative skull and dental radiographs showed rostral mandibular fractures and permanent teeth that had not yet erupted. In addition to providing stability for the healing of fractures, it is very important to focus on restoring normal occlusion. The mandibular fractures were repaired using interdental wiring in a dentate area where the deciduous canines and fourth premolars were stable and could be used to anchor the interdental fixation. In the absence of an erupted permanent mandibular first molar, the modified Risdon wiring was performed using the deciduous mandibular fourth premolars as anchor teeth. An intraoral splint was placed on the mandibular teeth using self-curing composite resin. Five months after surgery, the patient had experienced no complications, and the permanent teeth had erupted normally. In this case, which involves a small-breed puppy with deciduous dentition, treatment with a wire-reinforced interdental splint using intact deciduous fourth premolar teeth as anchor teeth can be considered as a suitable method for rostral mandibular fracture restoration.

• 대한치과교정학회지
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• 제45권4호
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• pp.180-189
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• 2015

Objective: To compare the positions of the mandibular premolars in Angle Class I subjects according to vertical facial type. The results will provide a theoretical basis for predicting effective tooth movement in orthodontic treatment. Methods: Cephalometric parameters were determined using cone-beam computed tomography in 120 Angle Class I subjects. Subjects were categorized as short, normal, and long face types according to the Frankfort mandibular angle. Parameters indicating the position of the mandibular right premolars and the mandible were also measured. Results: The angle between the mandibular first premolar axis and buccal cortex, the distance between the root apex and buccal cortex, angle of vestibularization, arc of vestibularization, and root apex maximum movable distance were significantly greater in the short face type than in the long and norm face types. The angle between the mandibular second premolar axis and buccal cortex, the distance from root apex to buccal cortex, and the arc of vestibularization were significantly greater in the short face type than in the normal face type. Conclusions: There are significant differences in the mandibular premolar positions in Class I subjects according to vertical facial type.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제34권3호
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• pp.293-299
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• 2008

Bite force is created by the force of adjacent teeth accompanied with tension of masticatory muscle. The bite force value is greater in male than in female and ha maximum value at first molar. Masseter muscle is associated with bite force and during muscle contraction the electric signal is expressed in EMG form. The aim of the study is to assess recovery time for masseter muscle activity and according to each part of bite force after open reduction with internal fixation when mandibular angle fracture and subcondyle fracture occurred. And to determine the appropriate period for mandibular fracture patients to have normal masticatory activity. 30 patients with normal bite condition was selected for control group and from April, 2007 to September, 2007, 20 patients who visited our department of oral and maxillofacial surgery of Dankook University, were selected for the study and were diagnosed as mandibular angle fracture and subcondyle fracture. For control group, the bite force for incisors, canine, premolars and molars and activity of the masseter muscle was measured and compared for 1, 2, 3, 4, 6 and 8 weeks. That was divided as fracture side and normal side. Mann-Whitney U test was performed for significant difference and the following result was obtained. 1. The maximum voluntary bite force for incisors, canine, premolars and molars portion were 0.113 kN, 0.182kN, 0.295kN and 0.486kN and the masseter muscle activity was 0.192 volts in the control group. 2. The maximum bite force at fracture side was recovered by 4th weeks for incisors, 6th weeks for canine and premolars and 8th weeks for molars and the masseter muscle activity was recovered by 6th weeks in the experimental group. 2. The maximum bite force at normal side was recovered by 4th weeks for incisors, 6th weeks for canine, premolars and molars and the masseter muscle activity was recovered by 3rd weeks in the experimental group. 3. The method for internal fixation by 2.0mm miniplates at both superior and inferior border had no complications according for twenty patients and had a satisfactory recovery. According to the result, patient with mandibular angle fracture and subcondyle fracture, 8 weeks was required for bite force recovery. Therefore, patients with open reduction and internal fixation under general anesthesis, it can be assumed that 8 weeks was needed after operation in order to have normal bite force and masseter muscle recovery.

• 대한치과교정학회지
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• 제52권5호
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• pp.354-361
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• 2022

Objective: To analyze the overall treatment effects in terms of the amount of uprighting with changes in the three-dimensional positions of the mandibular posterior teeth after applying the biocreative reverse curve (BRC) system. Methods: Thirty-four patients (mean age, 20.5 ± 8.56 years) were treated using the BRC system (mean period, 8.17 ± 2.19 months). Cone-beam computed tomography was performed before treatment and after treatment with the BRC system. The three-dimensional movement of each tooth was analyzed in the coordinate system at points on the crown and root apex. A paired t-test was used to analyze the treatment effects of the BRC system. Results: The application of the BRC system spanning from the first premolar to the second molar resulted not only in buccal and distal uprighting, but also in increased buccal and distal tipping of the teeth. The premolars and the first molar were extruded, and the second molar was intruded. Conclusions: When the BRC system is applied, simultaneous distal and buccal uprighting of the premolars and molars can be achieved bilaterally using a temporary skeletal anchorage device without unnecessary movement of the anterior teeth.