• 대한치주과학회:학술대회논문집
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• 2002.11a
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• pp.103-104
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• 2002

• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.1
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• pp.35-44
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• 2022

The aim of this study is to evaluate the development of the left mandibular third-molar development with modified Demirjian method and its relation to chronological age. A total of 1653 digital panoramic radiographs of healthy individuals aged between 7 and 23 years who visited Yonsei University Dental hospital were selected. The developmental status of the left mandibular third molars was assessed using dental maturity scoring proposed by Demirjian et al. The mean age of the first appearance of mineralization, complete crown formation, and complete root formation were around 9, 14, 21 years respectively. Statistically significant differences between males and females in the development stage of D and G were revealed that crown formation and root length completion were attained earlier in males than in females. There was significant positive relationship between age and third molar development in both sexes, and new formula was presented to estimate age of children and adolescents based on their developmental stages of third molars. In this study, the use of left mandibular third molar as a developmental marker is appropriate, and age estimation can be attained with dental maturity stage.

• Journal of the korean academy of Pediatric Dentistry
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• v.39 no.4
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• pp.404-411
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• 2012

Tooth impaction is defined as a failure of tooth eruption resulting from the physical obstacles in the eruption path or the abnormal position of the tooth germ. Impaction of mandibular second molar is relatively rare, and it may incite pathologic conditions such as dental caries, periodontitis, or root resorption of adjacent first molar. Thus, early diagnosis and treatment is recommended. In the first case, a 10-year-old male patient, was treated by brass wire to separate the bilaterally impacted mandibular second molars. In the second case, a 12-year-old female patient, was treated with Humphrey appliance for impacted mandibular left second molar, which was detected during a periodical dental examination. In the third case, a 17-year-old female patient with impacted mandibular right second molar, was treated by uprighting spring with mini-implant anchorage around premolar area. In the last case, an 18-year-old male patient, was treated with mini-implant placed on the ramus of mandible connected to the orthodontic buttons bonded on impacted mandibular left second molar by elastic thread.

• The korean journal of orthodontics
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• v.34 no.2 s.103
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• pp.109-119
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• 2004

This study aimed at investigating the skeletal, dentoalveolar, and soft tissue changes of Class III malocclusion cases treated by second molar extraction. The lateral cephalograms of 15 subjects with moderate Class III malocclusion by average ANB $-1.4^{\circ}\;and\;IMPA\;85^{\circ}$ were traced and the computerized superimposition of average craniofacial change was made. The data was gathered and statistically analyzed. The results were as follows: 1 Lower anterior facial height/anterior facial height increased by 0.6%(P<0.01), mandibular plane increased by $1.5^{\circ}$(P<0.05). 2. There was a slightly downward & backward rotation of the mandible. 3. Lower first molar tipped distally by 4.nm(P<0.001), lower anterior teeth lingually tipped by $3.2^{\circ}$(P<0.05). 4. Retracted lower lip improved facial profile. This study may suggest that second molar extraction could be effective for a moderate Class III malocclusion to make distalization of the lower first molar easier and avoid severe lingual tipping of the lower incisor, if the lower third molar has a normal shape, good direction of eruption and adequate time for lower second molar extraction

• The korean journal of orthodontics
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• v.26 no.1 s.54
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• pp.105-111
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• 1996

Most of orthodontic cases are treated with extraction of certain teeth, which influence the pre-eruptive movement of the lower third molar The purpose of this study was to evaluate the positional change of lower third molar following orthodontic treatment. Pre- and post-treatment pantomograms of 163 orthodontic patients (77 nonextraction group, 78 first premolar- extraction group, 8 second molar- extraction group) were analyzed in terms of the mesiodistal and buccolingual angles of lower third molar. The results were as follows. 1. The change of the mesiodistal angle of lower third molar by orthodontic treatment was significant in second molar-extraction group. 2. The mesiodistal angle of lower third molar in pre-treatment was significantly correlated to the mesiodistal angle in post-treatment and/or the change of the mesiodistal angle by treatment. 3. The change of the buccolingual angle of lower third molar by orthodontic treatment was significant in non -extraction group or first premolar-extrction group. 4. The change of the buccolingual angle of lower third molar by treatment was significantly correlated to the mesiodistal angle in post-treatment, the change of the mesiodistal angle by treatment, the buccolingual angle in pre-treatment or the buccolingual angle in post-treatment.

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.3
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• pp.415-430
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• 1996

The purpose of this study was to evaluate the stress distributions in the surrounding tissues of the teeth seated by indirect retainers in three different teeth of unilateral distal extension partial denture when the dislodging forces were applied on denture bases. Three dimensional photoelastic models were made. The teeth on which indirect retainers were seated were mandibular left lateral incisor (Model I), canine (Model II), and first premolar (Model III). The dislodging force with 860mg at $45^{\circ}$ angulation to occlusal plane was applied to each model. Three dimensional photoelastic stress analysis was done, and the records were diagramed and analysed. The results were as follows : The compressive stresses were shown the most on neck portions of buccal, mesial, and distal sides in all three models. Slight tensile stresses were shown on neck portions of lingual sides in all three models. The compressive stresses on buccal side were shown in strength in such order as model I, model II, and model III. The compressive stresses were shown on neck portion of mesial and distal sides of model I and mode II, with model I more than Model II. The compressive stresses were shown only on neck portion of mesial side on Model III. The general overall magnitude of compressive stresses were shown in strength in such order as Model I, Model II, and Model III.

• Journal of dental hygiene science
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• v.9 no.3
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• pp.257-263
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• 2009

The objective of this study is to establish the number of erupted $1^{st}$ molar, the age. sex and somatic measures of weight and height in population of Chungcheongnam-do, South Korea based cross sectional study. The consistent and complete data were obtained from 441 children with age of six. SPSS 12.0 was used for various statistical analyses including descriptive, cross tabulation, correlation and regression. Results demonstrates that variation of the number of the erupted $1^{st}$ molar was explained by age($x^2$(df)=117.68), height($x^2$(df=59.74) and weight($x^2$(df)=31.69) of children (P<.001). The study also showed the strong correlation among erupted $1^{st}$ molar rate, age, height and weight (p<.01). Numerical values of correlation among those are following: r = .45 between Erupted $1^{st}$ molar rate and age; r = .31 between erupted $1^{st}$ molar rate and height; r = .24 between erupted $1^{st}$ molar rate and weight; r = .40 between age and weight; r = .24 between age and height; r = .54 between height and weight. It was concluded that above variables influences one another and the age of the children is the greatest variable that influences the number of erupted $1^{st}$ molar, followed by height and weight of the children.

• The korean journal of orthodontics
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• v.35 no.3 s.110
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• pp.227-237
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• 2005

Eruptive disturbance of the permanent lower first molar is an uncommon condition caused by physical barriers on the eruption path or failure of the eruptive mechanism. Once eruptive disturbance of the permanent lower first molar is diagnosed. treatment should be started as soon as possible to establish a normal eruption pathway and to avoid any detrimental effects on the developing occlusion A case of primary retention of the mandibular first permanent molar treated with operculectomy and forced eruption which showed good treatment results and stability is described

• Journal of the Korean Academy of Esthetic Dentistry
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• v.29 no.1
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• pp.13-24
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• 2020

Autotransplantation is the surgical repositioning of an autogenous erupted or unerupted tooth from one site to another in the same individual. This treatment is indicated in traumatic tooth loss, teeth with severe caries, congenitally missing teeth, teeth with bad prognosis and in case of developmental anomalies of teeth. The following 2 cases describe the potential to utilize autotransplantation to replace hopeless teeth with sound wisdom teeth.

• Journal of Periodontal and Implant Science
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• v.28 no.1
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• pp.161-175
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• 1998

치주상태의 진단은 일반적으로 치주탐침과 같은 임상적 검사와 보조적으로 방사선 검사를 이용한다. 방사선학적인 검사가 치주조직의 파괴정도와 골 흡수를 진단하는데 유용하지만 실제적인 골 흡수를 정확하게 나타나는데는 한계가 있다고 하였다. 그리고 임상적 측정과 방사선 사진을 비교연구하여 이들간의 관계를 알아보고자 하는 노력이 있었다. 방사선이 임상에서 참고사항으로는 중요하지만 절대적 신뢰를 주는데는 문제가 있는 것으로 생각되어왔다. 방사선학적 측정과 임상지수 측정간의 상관관계에대하여 계속적인 연구를 통해 규명하는 것이 중요하다고 생각되어 저자는 연세대학교 치과 대학병원 치주과를 내원한환자중 연령 및 성별에 관계없이 전신질환이 없는 환자 130명을 대상으로 소구치의 원.근심부, 대구치의 원.중.근심부에서 치주낭의 깊이와 (P.D), 부착상실 (A.L)을 측정하였다. 방사선 사진상의 원.근심부에서 백악 법랑질 경계부에서 치조골능 상부까지의 치조골 수준 (Rx.B.L)을 측정하였고 이개부 부위에서는 이개부의 천정으로부터 나타나는 골 흡수의 방사선 투과상을 측정하였다. 이를 기초로 임상지수와 방사선학적 측정간에 상관관계를 연구하여 다음과 같은 결론을 얻었다. 1. 원·근심부의 P.D와 Rx.B.L을 비교 했을 때 상관관계는 모든 치아에서 높게 나타났다(r=0.897$\sim$r=0.725, p<0.01). 2. 원·근심부의 A.L와 Rx.B.L을 비교 했을 때 상관관계는 모든 치아에서 높게 나타났다 (r=0.915$\sim$r=0.732, p<0.01 ). 3. 대구치 769개가 실험 대상인었다. 상악 대구치중(356개) 40%가 이개부 병소를 나타냈고 (146개), 하악 대구치중(413개) 41%가 이개부 병소를 나타냈다(170개). 4. 대구치의 이개부 병소의 중앙부에서 측정한 P.D와 Rx.B.L을 비교 하였을 때 상관관계는 상악 제1대구치를 제외한 모든 치아에서 높게 나타 났다(r=0.811$\sim$r=0.435, p<0.01). 5. 대구치의 이개부 병소의 중앙부에서 측정한 A.L와 Rx.B.L을 비교 하였을 때 상관관계는 상악 제1대구치를 제외한 모든 치아에서 높게 나타 났다(r=0.906$\sim$r=0.479, p<0.01). 이상의 결과를 종합하여 볼 때 임상지수와 방사선학적 측정을 비교한 바, 이들의 상관관계는 모든 치아에서 밀접하게 나타났다. 따라서 방사선학적 측정은 임상지수와 더불어 치주질환의 진단과 치료계획에 크게 기여할 수 있을 것으로 사료된다.