• Restorative Dentistry and Endodontics
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• v.23 no.2
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• pp.647-655
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• 1998

심미도재수복시의 와동의 폭과 교두의 capping이 응력의 분포에 미치는 영향을 비교하기 위하여 연속사진 촬영술을 이용하여 상악제1소구치의 3차원 유한요소 모델을 제작하였다. 법랑질, 상아질, 도재 및 복합레진시멘트의 각각의 재질에 대한 물성치를 부여하고, 140N의 하중을 가하여 Super SAP 프로그램으로 해석하여 다음과 같은 결과를 얻었다. 1. 응력은 탄성계수값이 큰 법랑질과 도재를 따라 분포되고, 연질의 상아질에는 적게 발생된다. 2. 와동의 협측치수선각부위에서는 인레이모델의 경우에는 와동폭의 증가에 따른 응력의 증가는 관찰되지 않으나, 온레이모델에서는 응력의 증가가 관찰된다. 3. 온레이모델의 경우에는 근심협측교두를 피개하고 있는 도재부위에 최대주응력이 크게 나타나고, 치은변연부의 도재에서는 교두를 피개하지 않은 인레이모델의 해당되는 법랑질에 비해 응력이 1/2정도로 감소된다. 4. 하중이 증가되면 잔존치질의 파절은 근심와동의 협측치은선각부위에서 협측보다는 치은을 향해 경사지게 일어날 것이다. 5. 교두를 피개하면 교두피개부위에서의 도재의 파절가능성은 증가되고, 치은변연에서는 도재와 하부의 치질의 파절가능성은 감소된다. 6. 도재를 이용하여 교두를 피개할 경우에는 응력을 견딜 수 있는 도재의 두께를 부여할 수 있도록 교두를 충분히 삭제하여야 하고, 충분한 강도를 갖는 도재를 선택하여야 한다.

• Journal of Periodontal and Implant Science
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• v.31 no.4
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• pp.777-785
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• 2001

치주질환이 진행되는 동안이나 치주처치후 치유되는 과정에서 치조골의 변화가 야기되는데 방사선 사진은 치조골 변화를 감지하는 유일한 비외과적인 방법이다. 미묘한 치조골 변화의 진단은 치료시나 유지관리기 환자의 평가시 중요한 바, 최근에는 규격화시킨 디지털 영상을 이용하여 정량적인 골변화 측정이 가능하게 되었다. 본 연구의 목적은 중등도의 치주질환을 지닌 환자에서 국소마취하에 초기 치주처치를 시행한후 참조체와 함께 구내 방사선 사진을 촬영하고 디지털화 한 다음 참조체 당량치를 이용하여 치조골의 밀도변화를 평가하기 위한 것이다. 이 연구를 위하여 치주질환에 이환된 환자 5명(남자 3명, 여자 2명 : 평균 47.4세)에서 탐침깊이가 5㎜ 이상이고 골내낭이 있는 제 $1{\cdot}2$ 소구치, 제 $1{\cdot}2$ 대구치 40개(상악 24개, 하악 16개)를 대상으로 구강위생교육과 치석제거술, 치근면활택술을 시행하였다. 임상지수는 술전과 술후 8주째에 측정하였고, 방사선 사진은 술전, 술후 2주, 4주, 6주, 8주째에 촬영하였고, 구리 스텝웨지를 사용하여 규격화 하였다. 촬영된 영상은 NIH image program(U.S.A)에 의해 분석되어졌고 이들 자료를 통해 다음과 같은 결과를 얻었다. 1. 치조골의 밀도는 초기치료후 2주째 까지는 감소된 양상을 보이다가 4주 이후로는 점차적으로 증가하는 양상을 보였다. 2. 치조골의 밀도는 초기치료전과 비교시 초기치료수 6주째와 8주째에서 유의한 차이를 보였다.(p<0.01) 3. 상하악 간의 치조골 밀도는 유의한 차이를 보이지 않았다(p>0.05). 이상과 같은 결과를 통하여 볼때 초기 치주처치만으로도 치조골의 밀도가 증가됨을 확인할 수 있었다.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.1
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• pp.58-72
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• 2004

Statement of problem : Clinically, maxillary first premolar has a high risk of fracture. This is thought to be caused by the susceptible figure which the maxillary first premolar has In other words, sharp cusp angles of the premolar is thought to influence this situation. Purpose : This study was to know stress distribution of all-ceramic crown according to the cusp angle. Material and Method : It was manufactured a three dimensional finite element model simplified maxillary first premolar, and then analyzed stress distribution when cusp angle was each $80^{\circ}$, $90^{\circ}$, $100^{\circ}$, $110^{\circ}$ and $120^{\circ}$. Results and conclusion : 1. The von Misses stress showed that stress decreases as cusp angle increases in the central groove of the occlusal surface. 2. It showed that maximum principal stress was centered at the region of the central groove of the occlusal surface and a region which the force was inflicted. And also it appeared high on the lingual and buccal side of finish line. 3. The X axis of normal stress was focused in the central groove of the occlusal surface. The Y axis normal stress appeared high in the central groove of the occlusal surface, buccal and lingual side. 4. The Stress near the finish line showed a low value compared with stress in the region of the central groove of the occlusal surface. 5. It shows that the most dangerous angle for tooth fracture was on $80^{\circ}$ of the cusp angle and low on $120^{\circ}$ of its.

• Journal of Periodontal and Implant Science
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• v.24 no.1
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• pp.165-177
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• 1994

To investigate the depth of the root concavity and root surface area of the maxillary first premolar, 40 maxillary first premolars were used. All the teeth which extracted because of advanced periodontal disease and orthodontic treatment procedure, were sectioned every 1.5mm from cementoenameljunction to the apex with hard tissue microtome. Each sectioned root was taken photograph with slide film, and projected for measuring with a calibrated digital Curvi-Meter. The root surface area, percentage of the RSA and the linear variation of the RSA were calibrated for each 1.5mm section. Linear variation of the depth of root concavity was measured on mesial and distal root surface for each section using computer-aided digitizer. The results were as follows. 1. The total mean root length of maxillary first premolar was 13.48mm. Mean buccal root length of 2-rooted tooth was 12.59mm, mean palatal root length was 12.73mm, and mean root length of single rooted tooth was 13.78mm. 2. The total mean root surface area of maxillary first premolar was $194.17mm^2$, mean root surface area for 2-rooted tooth was $205.97mm^2$ and mean root surface area for single rooted tooth was $188.49mm^2$. 3. It was 59.93% of the total root surface area that the area from CEJ to coronal 6mm. And, the coronal half of the root length accounted for approximately 71.76% of the total root surface area. 4. Most deepest concavity of the mesial root surface was 0.65mm at apical 3.0mm, 4.5mm level in maxillary first premolar. And, that of the distal root surface was 0.37mm at apical 4.5mm level. 5. All of the maxillary first premolar had mesial root surface concavity. This mesial root surface concavity appeared to be more pronounced in 2-rooted tooth than single rooted tooth.

• The korean journal of orthodontics
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• v.39 no.1
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• pp.54-65
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• 2009

This paper describes the case of a 50-year-old female with a Class II malocclusion who presented with severe bimaxillary protrusion and generalized alveolar bone loss due to adult periodontitis. The treatment plan consisted of extracting both upper and lower first premolars and periodontal treatment. Anterior segmental osteotomy(ASO) of the mandible and upper anterior segment retraction using compression osteogenesis after peri-segmental corticotomy(Speedy orthodontics) was performed. Correct overbite and overjet, facial balance, and improvement of lip protrusion were obtained. However, a slight root resorption tendency was observed on the lower anterior dentition. The active treatment period was 9 months and the results were stable for 27 months after debonding. This new type of treatment mechanics can be an effective alternative to orthognathic surgery.

• Restorative Dentistry and Endodontics
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• v.28 no.4
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• pp.314-325
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• 2003

이 연구의 목적은 수종 상아질 접착 시스템과 복합 레진 및 resin-modified glass ionomer를 상아질 표면에 접착하여 재료 및 상아질내 위치에 따른 미세전단결합강도를 측정, 비교하는 것이다. 상아질 접착 시스템으로는, 3-step인 Scotchbond Multi-Purpose Plus, 2-step인 Single Bond와 자가 부식형 시스템인 Clearfil SE Bond를, 1-step인 Prompt L-Pop을 사용하였다. 이와 함께 hybrid type의 복합 레진인 Clearfil AP-X와 2250을 사용하였으며 resin-modified glass ionomer로는 Fuji II LC를 사용하였다. 상악 소구치를 치아의 근원심 중앙부를 절단하여 상아질면을 노출시켰다. 5개 실험군으로 분류하고 상아질면을 위치에 따라 치관부의 occlusal $\frac{1}{3}$, middle $\frac{1}{3}$, cervical $\frac{1}{3}$과 치근부로 구분지어 시편을 부착하였다. 미세전단결합강도측정는 Universal testing machine(EZ-test; Shimadzu, Japan)에서 측정하였다. Occlusal 1/3부위에서는 SE가 가장 높은 값을, SM과 SB간에는 유의차가 없었으며, PL, GI순으로, Middle 1/3부위에서는 $SM{\;}{\geq}{\;}SE{\;}{\geq}{\;}SB{\;}{\geq}{\;}PL{\;}{\geq}{\;}GI$순으로, cervical 1/3부위에서는 SM, SE, SB간에 유의차가 없었다. Root dentin에서는 SM이 가장 높은 값을 보였으며 SE, PL, GI간에 유의차가 없었다. SE만이 치관부 상아질에 비해 치근부에서 유의할만한 결합강도의 감소를 나타냈다(p<0.05). GI는 치관부 상아질에서는 다른 군에 비해 유의성 있게 낮은 결합강도를 보였으나 치근부에서는 SE, PL과 유의차가 없었다.

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.4
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• pp.305-310
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• 2012

It is a great challenge for dentists to do prosthetic restorations of a patient with reduced occlusal vertical dimension (OVD). Proper determination of the OVD is significant. An 85-year-old male patient came in with missing right maxillary posterior teeth. After diagnostic wax-up, reversible provisional prostheses were used to evaluate the new OVD in the maxilla and mandible. After that, the patient was evaluated clinically based on the criteria of esthetic, phonetic, and OVD. After 8 weeks, teeth with excessive wear were treated with root canal therapy and fiber post and core and irreversible provisional prostheses were done. After 8 weeks of observation period, final restorations with fixed partial dentures and removable partial dentures were made. Throughout the follow-up period of 6 months, no symptoms related with increased OVD and mechanical complications were observed.

• Journal of Dental Rehabilitation and Applied Science
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• v.19 no.3
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• pp.219-237
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• 2003

he purpose of this study was to compare the fracture resistance of the IPS Empress ceramic crown with 1.0mm width rounded shoulder, which is usually recommended in all ceramic crown, and 0.5mm width chamfer finish lines on the maxillary first premolar. 30 sound maxillary first premolars were selected and then storaged in 5% NaOCl and saline. 15 teeth were performed preparation for each group(1.0mm rounded shoulder, 0.5mm chamfer). After 30 stone dies were made for each group, the IPS Empress ceramic crowns were fabricated and cemented with resin cement(Bistite resin cement, Tokuyama Soda Co. LTD., Japan) on the natural teeth. The cemented crowns were mounted on the positioning jig and the universal testing machine(Zwick Z020, Zwick Co., Germany)was used to measure the fracture strength, with stress loading on the occlusal surface between buccal and lingual cusp. And also, three-dimensional finite element model was used to measure the stress distribution with two types of the finish lines(1.0mm rounded shoulder, 0.5mm chamfer) and two loading conditions(both buccal and lingual cusp inclination, lingual cusp inclination only). The result of the this study were as follows. In the fracture resistance experiment according to the finish line, the mean fracture strength of rounded shoulder(842N) showed higher value than that of the chamfer(590N) (p<0.05). In the three dimensional finite element analysis of all ceramic crown, metal die and natural teeth model did not show any differences in stress distribution between finish lines. Generally, when force was loaded on the occlusal inclination of buccal and lingual cusp, the stress was concentrated on the loading point and the central groove of occlusal surface. When force was loaded only on the occlusal inclination of lingual cusp, the stress was concentrated on the lingual finish line and loading point.

• Journal of the korean academy of Pediatric Dentistry
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• v.50 no.1
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• pp.35-46
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• 2023

Congenitally missing teeth are one of the most prevalent dental anomalies in the oral cavity. In this study, the prevalence, distribution, and symmetry of congenitally missing permanent teeth among 1,865 patients aged 7 to 15 years who visited the Pediatric Dentistry Department of Wonju Severance Christian Hospital from March 2011 to May 2021 and took panoramic radiographs were investigated and analyzed. Most of the patients had one or two congenitally missing teeth, mainly in the second premolars and lateral incisors. Congenitally missing teeth occurred more in the mandible than in the maxilla, and there was no significant difference in prevalence between the left and right sides. Congenitally missing teeth tend to occur symmetrically on the left and right sides and in the maxilla and mandible, depending on the tooth. Early oral examination and radiological examination are required to prevent complications due to congenitally missing teeth, and appropriate interdisciplinary treatment is required.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.2
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• pp.245-252
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• 2009

The congenital missing of teeth is common, which takes place since the proliferation and differentiation are not allowed in that tooth bud fail to start development. The purpose of this study is to research incidence rate, number, and missing part of congenital missing teeth, and to study whether a person who has missing teeth has other abnormality of teeth or not. For this study, 1,520 subjects(aged 2.9$\sim$17) who had visited pediatric dentist department of Chonbuk national university dental hospital within 2 years were examined with an panoramic radiograph; exempting third molar missing state. The obtained results are as follows. 1. 8.88% among total subjects show missing teeth; male 9.05%, female 8.64% 2. The most frequently missing permanent teeth were the mandibular second premolars(22.3%). The most frequently missing primary teeth are mandibular lateral incisors(50%). 3. 43.3% patients have one permanent missing tooth, 34.3% have two, and 10.4% have more than six, respectively. In primary teeth, 86.7% patients have one missing tooth, and 13.3% have two missing teeth. 4. 18 patients(13.3%) have missing teeth as well as hyperdontia, while some patients have microdont, ectopic eruption, and fusion teeth.