• Restorative Dentistry and Endodontics
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• v.33 no.6
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• pp.570-579
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• 2008

The purpose of this study was to investigate the distribution of tensile stress of canal obturated maxillary second premolar with access cavity and notch-shaped class V cavity restored with composite resin using a 3D finite element analysis. The tested groups were classified as 8 situations by only access cavity or access cavity with notch-shaped class V cavity (S or N), loading condition (L1 or L2), and with or without glass ionomer cement base (R1 or R2). A static load of 500 N was applied at buccal and palatal cusps. Notch-shaped cavity and access cavity were filled microhybrid composite resin (Z100) with or without GIC base (Fuji II LC). The tensile stresses presented in the buccal cervical area, palatal cervical area and occlusal surface were analyzed using ANSYS. Tensile stress distributions were similar regardless of base. When the load was applied on the buccal cusp, excessive high tensile stress was concentrated around the loading point and along the central groove of occlusal surface. The tensile stress values of the tooth with class Ⅴ cavity were slightly higher than that of the tooth without class V cavity. When the load was applied the palatal cusp, excessive high tensile stress was concentrated around the loading point and along the central groove of occlusal surface. The tensile stress values of the tooth without class V cavity were slightly higher than that of the tooth with class V cavity.

• The korean journal of orthodontics
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• v.26 no.5 s.58
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• pp.535-546
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• 1996

The purpose of this study was to classify mandibular dental arch forms based on Raberin's method, and to compare Raberin's arch forms with that of the Korean's, and to designate arch form of bracket level according to distance between cusp tip and buccal surface of bracket level. The sample consisted of 159 mandibular dental casts showing normal occlusion which was taken from 62 males and 97 females of the Korean, aging from 13 to 25 years. The model was taken by X-ray. The landmarks were cusp points which expressed the mandibular dental arch line of cusp tips and buccal points which were measured from cusp tips to buccal surfaces of bracket level. The landmarks on the film were digitized, and measurements and statistics were performed. The results were as follows; 1. The models were classified as type 1, type 2, type 3, type 4 and type 5 by the author, and polynomial functions of the six degree and R-square values were calculated using statistical method, and each calculated equations explained each group with the least R-square value of 0.97, and each arch forms' were plotted. 2. The distribution of type 1 was $17.6\%$, type 2 $20.8\%$, type 3 $20.8\%$, type 4 $16.3\%$ and type 5 $24.5\%$. 3. The Korean arch form was characterized by larger width, smaller height compared to the French arch form. 4. The designated arch form of bracket level, viz the distance between cusp point and buccal point was calculated. The distance between cusp point and buccal point of incisor was 1mm, canine 1.9mm, first premolar 2.5mm, second premolar 2.6mm, first molar 2.7mm and second molar 2.7mm.

• Journal of Dental Rehabilitation and Applied Science
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• v.35 no.2
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• pp.90-97
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• 2019

Purpose: Previous studies related with occlusal contact area were limited that interocclusal thickness level or the method of measurement has not been accurate in measuring. The purpose of this study was to investigate the relation between head posture and occlusal contact area using photo occlusion analysis. Materials and Methods: 54 subjects with complete dentition (44 men, 10 women / 23 to 33 years of age) were included. To identify the relationship between head posture and occlusal contact area, subjects took interocclusal record in maximal intercuspal position with three different positions(supine position ($0^{\circ}$) / inclined position ($45^{\circ}$) / upright position ($90^{\circ}$)) on the dental unit chair. Occlusal contact area was analyzed using photo occlusion analysis. Statistical analyses were performed with SPSS ver.25.0 at 95% confidence interval. Results: Head posture has no significant effect on the changes of occlusal contact area (P > 0.05). Conclusion: When interocclusal relation is stable, head posture does not change a interocclusal record because head posture has no significant effect on occlusal contact area. Analysis of occlusal contact area using photo occlsion analysis device is useful due to its material property and simplicity.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10b
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• pp.598-600
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• 1999

본 논문은 수공으로 이루어지는 치과 치료 및 보철물 제작을 3차원 컴퓨터 모델링을 하여 좀 더 정확하고 빠른 시간에 처리할 수 있는 시스템을 소개한다. 이 시스템은 기존 2차원 기반이 아닌 3차원 기반으로 설계되었으며, 구강의 석고 모형을 3차원으로 컴퓨터에 모델링한 후, 모델링 정보로부터 능선(ridge), 교두(crusp), 피트(pit), 열구(fissure), 변연(margin) 등과 같은 치아 특성 정보추출과 교합면 생성을 통하여 보철물, 예를 들어 Conus 내관과 외관을 제작한다. 해부학적으로 무수히 많은 변수를 갖고 있는 구강 구조에 대해 본 논문에서는 이들 일련의 과정에서 요구되는 컴퓨터 모델링의 주요 기술들을 제시한다.

• 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 Dental Rehabilitation and Applied Science
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• v.37 no.4
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• pp.268-273
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• 2021

Paramolar tubercle is a rare developmental dental anomaly defined as an additional cusp occurring on the buccal or lingual surfaces of the molar. Permanent molar fused with paramolar tubercles can be a cause of difficulty in root canal treatment. Therefore, proper understanding of these variations is important in order to ensure successful endodontic treatment. Cone beam computed tomography (CBCT) can be helpful to understand anatomy of complicated cases. This case report describes nonsurgical endodontic treatment of maxillary second premolar fused with paramolar tubercle.

• The korean journal of orthodontics
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• v.40 no.6
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• pp.373-382
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• 2010

Objective: The purpose of this study was to assess the dentoalveolar compensation in facial asymmetry individuals using an integration of a CBCT image and a laser scanned dental cast image. Methods: The subjects consisted of 30 adults with asymmetric mandibles and 20 adults with symmetric mandibles. The CBCT and laser scanned dental cast images were integrated with a registration technique. Canine and first molar position and angulation were assessed from reference coordinates. The differences between deviated and non-deviated sides were analyzed with the paired t-test. The differences shown according to menton deviation were also statistically analyzed using Pearson correlation analysis. Results: The experimental group showed deviated and non-deviated side differences (dev.-ndev.) in the position and angle of the canine and first molars. Menton deviation showed positive correlation with the deviation side (dev.-ndev.) for the maxillary and mandibular 1st molar angles, negative correlation with the deviation side for the vertical position of the maxillary 1st molars, transverse position of the mandibular canine, transverse position and vertical position of the mesio-lingual cusp of the mandibular 1st molars. Conclusions: The upper and lower canine and first molars of facial asymmetry individuals were compensated, so the transverse position, vertical position, and angle showed differences between the deviated/non-deviated sides.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.3
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• pp.234-238
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• 2016

Purpose: Increasing use of computer aided design-computer aided manufacturing (CAD-CAM) system and number of design software made design of restoration easy and quick. Outcome of restoration has been dependent on dental technician's wax up proficiency, dentists can design restoration for themselves now. This study aims to investigate the outcome of restoration designs, according to handling skill of CAD-CAM design tool. Materials and methods: A patient's mandibular right 1st molar was prepared. After taking impression, stone model was made, scanned the stone model with 3 shape intra-oral scanner, stereolithography (STL) file was extracted. With 3shape dental designer, one dental technician with more than 5 years work experience (designer 0) and three dental technicians with less than 2years work experience (designer 1, 2, 3-group DT) and 4 1st year residents (designer 4, 5, 6, 7-group RT) designed gold crown on the same STL file. Designed crown's MD (mesio-distal) and BL (bucco-lingual) diameter, height of crown, inter-cuspal distance, number of occlusal contact points were compared. Statistical analysis was carried out, test of normality within each group, using independent t-test. Number of contact points were compared, using Wilcoxon signed-rank test. Results: There was no significant difference between group DT and group RT. Number of contact points also resulted in no significant difference. Conclusion: The outcome of each designed crowns showed no statistical differences, in values which can be expressed as numbers. Subjective factors were different. With increasing proficiency in handling designing software, fabrication of restorations according to each designer's occlusal concept can be made easy.

• The korean journal of orthodontics
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• v.38 no.3
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• pp.175-186
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• 2008

Objective: To evaluate the discrepancies between initial STO and final STO in Class III malocclusions and to find which factors are related to the discrepancies. Methods: Twenty patients were selected for the extraction group and 20 patients for the non-extraction group. They were diagnosed as skeletal Class III and received presurgical orthodontic treatment and mandibular set-back surgery at Pusan National University Hospital. The lateral cephalograms were analyzed for initial STO (T1s) at pretreatment and final STO (T2s) after presurgical orthodontic treatment, and specified the landmarks 3s coordinates of the X and V axes. Results: Differences in hard tissue points (T1s-T2s) in the X coordinates of upper central incisor edge, upper first molar mesial end surface, lower central incisor apex, lower first molar mesial end surface and mesio-buccal cusp and Y coordinates of upper central incisor edge, upper central incisor apex, upper first molar mesio-buccal cusp were statistically significant in the extraction group. Differences in hard tissue points (T1s-T2s) in the X coordinates of upper central incisor edge, lower central incisor apex, lower first molar mesial end surface and Y coordinates of lower central incisor apex were statistically significant in the non-extraction group. In the extraction group, the upper arch length discrepancy (UALD) had a statistically significant effect on maxillary incisor and first molar estimation. Lower arch length discrepancy and IMPA had statistically significant effects on mandibular incisor estimation in both groups. Conclusions: Discrepancies between initial STO and final STO and factors contributing to the accuracy of initial STO must be considered in treatment planning of Class III surgical patients to increase the accuracy of prediction.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.2
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• pp.357-366
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• 2008

Posterior cross-bite is a relatively frequent malocclusion in primary and early mixed dentition and the reported prevalence of posterior cross-bite varies from 7% to 23%. It has been defined as a transverse discrepancy in arch relationship which the palatal cusp of the upper posterior teeth do not occlude in the central fossa of the opposing lower teeth, and can be manifested in a single tooth or in a group of teeth. Posterior cross-bite does not often self-correct and therefore immediate treatment is recommended. Occlusal adjustment to eliminate premature contact that causes mandibular deviation, expansion of narrow maxillary arch, arrangement of the individual teeth to treat asymmetry within the dental arch are the methods of treating cross-bite. In the present case, functional posterior cross-bite was observed in the primary and the early mixed dentition children. The children were treated by the slow maxillary expansion and occlusal adjustment. The outcome of periodic examinations after the correction of cross-bite was favorable.