• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.3
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• pp.529-533
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• 2006

Supernumerary teeth are defined as an excess in the number of teeth when compared to the normal dental formula. They are more prevalent in the permanent dentition than the primary dentition. Supernumerary teeth can occur in the maxilla, mandible, or both. But the majority are found in the maxilla and most of it is found in the premaxilla region The present cases documents about the uncommon cases of supernumarary teeth on maxillarty premolar area and mandibular incisal area.

• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.3
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• pp.340-347
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• 2022

Distal displacement of the tooth germ of the mandibular second premolar (MnP2) leads to its impaction and obturation of the eruption path of the mandibular first molar delaying its eruption. The present case report describes the treatment of 2 cases of eruption guidance for distally displaced developing MnP2 that caused delayed eruption of the mandibular first molar. Intentional extraction of primary predecessor results in the mesial shift of the displaced MnP2. However, unfavorable distal ectopic eruption of the mandibular first premolar after the premature loss of primary second molar has been previously reported. Hemisection and sequential extraction of the mandibular primary second molar were performed to mesially shift the distally displaced MnP2, while preventing unfavorable distal ectopic eruption of the mandibular first premolar.

• The korean journal of orthodontics
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• v.31 no.1 s.84
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• pp.1-13
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• 2001

The extraction lot orthodontic treatment can be adopted for aligning crowded dentition, improving facial esthetics and solving a skeletal discrepancy as alternative for a surgical option. Mandibular second premolar extraction was often selected as treatment plan when there we very little or no space shortage in lower arch or limited retraction of the lower incisors was required. The primary object of this study was evaluate a pretreatment condition and examine the amount of tooth movement ior a mandibular second premolar extraction in growing patients. Pretreatment and posttreatment lateral cephalograms of 14 cases that had their four first premolar extracted (4/4 group), 15 cases with upper first and lower second premolar extraction (4/5 group) were selected. Structural method superimposition was conducted to evaluate a difference of dental change between 4/4 and 4/5 group. The results were as follows, 1. Pretreatment factor for 4/4 extraction or 4/5 extraction choice included maxillary incisor axis to occlusal plane, Class II molar relationship, IMPA and interincisal angle. 2. The amount of molar anterior movement in 4/5 group was greater than that of 4/4 group(p<0.05). 3. There was no significant difference between 4/4 group and 4/5 group in aspects of maxillary tooth movement(p<0.05).

• The korean journal of orthodontics
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• v.26 no.1 s.54
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• pp.113-124
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• 1996

The purpose of this report is to present the successful improvement of occlusal relationship and facial estherics in Class II div.1 malocclusion by orthodontic treatment with upper first premolars and lower second premolars extracted. Before treatment, the patients showed Class II div. 1 relation with severe overjet. deep overbite, large ANB angle, retrusive mandible and a convex soft tissue profile. After treatment, normal canine and molar relationships were obtained. Facial esthetics were improved. There were no mesial tipping of lower first molars and root resorptions. With the adequate diagnosis and treatment plan and biomechanics, the application of upper first and lower second premolar extraction may be one of good strategies in some Class II cases treatment.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.4
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• pp.324-328
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• 2014

Aberrant anatomy of mandibular premolars is very rare in Korean, but aberration can contribute the endodontic failure as it makes difficult to remove the irritants during cleaning and shaping procedure. This case report describes the successful root canal treatment of a rare mandibular first premolar with C-shaped root canal as using a cone-beam computed tomography to understand the internal shape of root canal system and a dental operating microscope to improve the magnification and illumination.

• Journal of Oral Medicine and Pain
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• v.16 no.1
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• pp.73-84
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• 1991

저자는 연령을 추정하기 위한 기본자료를 얻기 위하여 상하악의 대구치, 소구치의 발육정도를 평가하였다. Orthopantomograph를 촬영한 722명의 3,464개 치아를 대상으로 crown-root ratio를 측정하여 발육정도를 평가하였으며, 다음과 같은 결론을 얻었다. 1. 완전히 형성된 치아의 crown-root ration에는 남녀간에 유의한 차이가 없었다. 2. 발육중인 치아의 crown-root ratio에는 좌우측간에 유의한 차이가 없었다. 3. 각 치아의 crown-root ratio를 이용한 연령추정의 회귀방정식은 다음과 같다. 남자: 여자 : 하악좌측 제 2대구치 : Y=4.599X+7.832(r=0.8337) 하악 좌측 제 2대구치 : Y=4.857X+7.429(r=0.8975) 제 1대구치 : Y=5.179X+2.324(r=0.7948) 제 1대구치 : Y=5.919X+2.018(r=0.8144) 제 2소구치 : Y=3.863X+7.432(r=0.8638) 제 2소구치 : Y=3.679X+7.275(r=0.8819) 제 1소구치 : Y=3.472X+7.120(r=0.8352) 제 1소구치 : Y=4.001X+6.544(r=0.9024) 하악우측 제 2대구치 : Y=4.447X+7.938(r=0.8045) 하악 우측 제 2대구치 : Y=4.653X+7.365(r=0.8598) 제 1대구치 : Y=5.954X+1.495(r=0.7777) 제 1대구치 : Y=5.449X+2.012(r=0.7553) 제 2소구치 : Y=3.894X+7.253(r=0.8689) 제 2소구치 : Y=3.772X+7.025(r=0.8719) 제 1소구치 : Y=4.189X+6.717(r=0.8370) 제 1소구치 : Y=4.327X+6.193(r=0.8524) 상악좌측 제 2대구치 : Y=4.430X+7.722(r=0.7538) 상악 좌측 제 2대구치 : Y=4.876X+7.606(r=0.8311) 제 1대구치 : Y=4.645X+2.886(r=0.6894) 제 1대구치 : Y=6.754X+1.891(r=0.5378) 제 2소구치 : Y=4.391X+6.686(r=0.7700) 제 2소구치 : Y=1.245X+10.575(r=0.1908) 제 1소구치 : Y=5.564X+6.037(r=0.9032) 제 1소구치 : - 상악우측 제 2대구치 : Y=4.587X+7.966(r=0.7882) 상악 우측 제 2대구치 : Y=4.454X+7.803(r=0.8443) 제 1대구치 : Y=4.047X+4.124(r=0.6352) 제 1대구치 : Y=6.336X+2.911(r=0.4688) 제 2소구치 : Y=2.920X+8.089(r=0.7277) 제 2소구치 : Y=3.105X+8.082(r=0.6381) 제 1소구치 : Y=3.264X+6.970(r=0.7292) 제 1소구치 : - 4. Orthopantomograph상의 crown-root ratio를 이용한 연령의 추정에는 상악치아들 보다 하악치아들이 더 정확하게 사용될 수 있다.

• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.4
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• pp.484-491
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• 2018

Tooth agenesis is a common human dental anomaly and the agenesis of mandibular second premolars has been proven to be the most frequently observed. The aim of this study is to investigate tooth agenesis and delayed tooth development in patients with agenesis of mandibular second premolars. This study reviewed 9 to 15 year-old patients with agenesis of mandibular second premolars who visited the department of pediatric dentistry of Yonsei University Dental Hospital and took panoramic radiographs from January 2014 to December 2016. On panoramic radiographs, agenesis of teeth was observed and developmental delay of teeth was evaluated by the Nolla method. Among 125 patients with agenesis of mandibular second premolars, 58 patients (46.4%) showed agenesis of other teeth and 38 patients (30.4%) showed delayed tooth development. In this study, patients with agenesis of mandibular second premolars were more likely to have tooth agenesis or delayed eruption of other teeth.

• Restorative Dentistry and Endodontics
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• v.35 no.4
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• pp.302-305
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• 2010

Mandibular premolars show a wide variety of root canal anatomy. Especially, the occurrence of three canals with three separate foramina in mandibular second premolars is very rare. This case report describes the root canal treatment of an unusual morphological configuration of the root canal system and supplements previous reports of the existence of such configuration in mandibular second premolar.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.1
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• pp.115-124
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• 2002

The purpose of this study was to establish regression equations and probability charts for predicting the sum of mesiodistal crown diameters of unerupted unilateral canine and premolars from the sum of mesiodistal crown diameters of four mandibular incisors in Korean male and female. The plaster casts of 162 children(75 boys and 87 girls) among the contestees in 1994-2001 Healthy Dentition Contest in Seoul were measured. Sex differences are compared and the following results were obtained: 1. Bilateral comparison of sum of widths of permanent canine and premolars showed no significant differences for either sex(p>0.05). Sum of widths of permanent canine and premolars of male were significantly larger than that of female(p<0.01). 2. Regression equations for the prediction of sum of widths of permanent canine and premolars in each sex were as follows Male ${\Sigma}Maxillary$ 345 y= 10.45+0.53x Male ${\Sigma}Mandibular$ 345 : y= 10.07+0.51x Female ${\Sigma}Maxillary$ 345 : y=12.65+0.42x Female ${\Sigma}Mandibular$ 345 : y=11.70+0.42x Male+female ${\Sigma}Maxillary$ 345 y=11.01+0.50x Male+female ${\Sigma}Mandibular$ 345 : y=9.87+0.51x

• Journal of the korean academy of Pediatric Dentistry
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• v.42 no.1
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• pp.22-29
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• 2015

The purpose of this study was to evaluate the eruption patterns of mandibular premolars associated with dentigerous cysts after marsupialization regarding the depth, angulation and root development of impacted teeth. Spontaneous eruption was found in 93% of mandibular premolars after marsupialization. Eruption speed and rate of angulation change were greater in mandibular premolars associated with a cyst than those on the non-cyst side. The group with less matured roots tended to have greater eruption speed and angulation change. The eruption speed and angulation change declined rapidly during the first 6 months after marsupialization. Based on the results of this study, it might be possible to predict the eruption pattern of mandibular premolars associated with a cyst after marsupialization, which would be useful for treatment planning.