• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.1
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• pp.1-12
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• 2010

The purpose of this study was to compare the strain on the alveolar ridge in the centric, eccentric and protrusive position according to the occlusal scheme (bilateral balanced occlusion with 33 degree anatomical teeth, group B; monoplane occlusion with non-anatomical teeth, group M; lingualized occlusion with 33 degree anatomical teeth and non-anatomical teeth, group L; of complete dentures. Experimental dentures were set bilateral balanced occlusion, lingualized occlusion and monoplane occlusion. They are analysed through T-Scan II(Tekscan, Boston, U.S.A) and 1.5mm thick layer was removed from the denture-supporting surface of resin model and then replaced with silicone to simulate resilient edentulous ridge mucosa. A $4{\times}6$ linear strain gauge is attached to the $1^{st}$ premolar and $1^{st}$ molar area. The strain values are recorded according to the occlusal scheme in the centric, eccentric and protrusive position after uniformly applying 50 N and 150 N force through a Universal Testing Machine(instron$^{(R)}$ 5567, Bluehill 2.0 software ,U.S.A.) with the models mounted in the articulator. When performing centric and protrusive occlusion, the three groups of occlusal scheme were compared in the anterior region and in the posterior region. The strains of each group were also compared in the working side and in the non-working side during eccentric excursion. It was observed that the strain in the bilateral balanced occlusion showed a higher value than the lingualized occlusion and monoplane occlusion in every position except the non-working side. However, during the eccentric movement the strain value in the non-working side showed the lowest value in the bilaterally balanced occlusion. The strain change amount from the working side or centric occlusion to non-working side and also the strain variation rate within the non-working side showed the highest value in bilateral balanced occlusion.

• Restorative Dentistry and Endodontics
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• v.31 no.6
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• pp.427-436
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• 2006

The objective of this study was to investigate the effects of various occlusal loads on the stress distribution of the buccal cervical region of a normal maxillary second premolar, using a three dimensional fnite element analysis (3D FEA). After 3D FE modeling of maxillary second premolar, a static load of 500N of three load cases was applied. Stress analysis was performed using ANSYS (Swanson Analysis Systems, Inc., Houston, USA). The maximum principal stresses and minimum principal stresses were sampled at thirteen nodal points in the buccal cervical enamel for each four horizontal planes, 1.0 mm above CEJ, 0.5 mm above CEJ, CEJ, 0.5 mm under CEJ. The results were as follows 1. The peak stress was seen at the cervical enamel surface of the mesiobuccal line angle area, asymmetrically. 2. The values of compressive stresses were within the range of the failure stress of enamel. But the values of tensile stresses exceeded the range of the failure stress of enamel. 3. The tensile stresses from the perpendicular load at the buccal incline of palatal cusp may be shown to be the primary etiological factors of the NCCLs.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.4
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• pp.309-315
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• 2016

Recently, finite element analysis technique has been widely used for structural and mechanical understandings of human body in the dentistry field. This research proposed an effective finite element modeling method based on CT images, and parametric studies were performed for the occlusal simulation. The analyses were performed considering linear material behaviors and nonlinear geometrical effect, and validated with the experimental results. In addition, the skull models with two different molar relations such as Class I and full-CUSP Class II were generated and the analyses were performed using the proposed analytical method. As results, the relationships between the mandibular movement and occlusal force of both two models showed similar tendency in human occlusal force. However, stress was evenly distributed from teeth to facial bone in the skull model with Class I, while stress concentration was appeared in the model with full-CUSP Class II due to the changes of occlusal surfaces of the model.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.4
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• pp.317-324
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• 2008

The objective of this study was to test effects of (1) where the occlusal contact points locate on a full veneer crown, and (2) which direction the contact forces are directed to, on the stresses within the luting cement layer that might suffer microfracture. A total of 27 finite element models were created for a mandibular first molar, combining 9 different locations of the occlusal contact points and 3 different loading directions. Type 3 gold alloy was used for crown material with a chamfer margin, and the luting cement material was glass ionomer cements in uniform thickness of $75{\mu}m$. Modeled crowns were loaded at 100 N. Different patterns in the cement stress were observed in the vicinity of the buccal and lingual margins. Whereas, the peak stress in buccal margin occurred approximately 0.5 mm away from the external surface, the highest stress in lingual margin was observed at approximately 1 mm. Significantly different distribution of stresses was recorded as a function either of the location of the occlusal contact points or of the loading direction. Higher stresses were produced by more obliquely acting load, and when the loaded point was in the vicinity of the cusp tip.

• 대한치과보철학회:학술대회논문집
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• 1996.11a
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• pp.106-107
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• 1996

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.2
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• pp.269-288
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• 1999

현재 골 유착성 임플랜트는 안전하고 유용한 보철 수복 분야의 하나로 자리잡아 가고있다. 과거 완전 무치악 환자에게 있어서 저작 기능의 회복이란 면에 중점을 두었던 경향에서 현재 골유착 임플랜트의 높은 성공률에 의해 부문 무치악, 단일치 수복에 까지 다양하게 사용되고 있다. 특히 심미성과 인접치의 손상을 가하지 않는다는 면에서 단일치 수복에서 골유착 임플랜트 치료에 관심이 모아지고 있다. 단일치 수복에 있어서 심미성이 중요한 문제로 대두되면서 이런 수복에 사용될 수 있는 다양한 계통의 임플랜트들이 개발되어 사용되고 있다. 이중 가장 기본적인 Branemark 계통의 CeraOne 지대주, 최근에 개발된 전부도재 지대주인 CerAdapt 전부주조 지대주인 UCLA 계통등은 높은 성공률을 보이며 많이 사용되고 있다. 임상가들에 의해 나사유지형 보철물이 착탈성이란 관점에서 선호되고 있다. 시멘트유지형 보철물에서는 나사공이 없는 온전한 교합면을 유지한다는 면과 교합력을 받는 면적에 있어서 더 넓은 면을 가진다는 점등 더 많은 장점을 가진다고 주장하는 사람도 있다. 임상가들의 기호에 의해 선택되어지는 나사 유지형과 시멘트 유지형에 있어서 교합력이 야기하는 하중하에서 각각의 응력 분포를 분석할 필요성이 요구되었다. 이 연구는 단일치 수복에 사용되는 CeraOne, CerAdapt UCLA 계통에서 각각의 나사 유지형과 시멘트유지형에서의 응력분포를 삼차원 유한요소법으로 분석하고 상부 구조물에 가해지는 수직하중, 수평 하중, 경사 하중에 의해 야기되는 응력을 비교 분석한 것이다. 본 연구의 연구 결과는 다음과 같다. 1. CeraOne, CerAdapt, UCLA 지대주 모두 시멘트유지형보다 나사유지형에서 응력집중이 컸다. 2. CeraOne 시멘트유지형인 1번 모델에서 응력분산이 유리하였고, UCLA 나사 유지형인 6번 모델에서 가장 불리하였다. 3. 모든 모델에서 고정체 경부에서 가장 큰 응력 집중이 있었고 이것은 UCLA 지대주에서 가장 컸다. 4. 상부 구조물에서 주된 응력의 집중은 교합면에서 일어났다. 5. 골은 상부 피질골, 즉 고정체경부와 만나는 부위에서 가장 큰 응력의 집중이 일어났으며 수평, 경사 하중시 응력집중 양상은 힘을 가한 쪽의 반대쪽 고정체 경부에 응력이 집중되는 양상을 보였다. 6. 전체 모델과 골, 고정체 모두에서 수평 하중과 경사 하중시 보다는 수직 하중시 더 적은 응력값을 보였다.

• Restorative Dentistry and Endodontics
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• v.31 no.5
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• pp.359-370
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• 2006

The objective of this study was to investigate the effect of excessive occlusal loading on stress distribution on four type of cervical lesion, using a three dimensional finite element analysis (3D FEA). The extracted maxillary second premolar was scanned serially with Micro-CT. The 3D images were processed by 3D-DOCTOR. ANSYS was used to mesh and analyze 3D FE model. Four different lesion configurations representative of the various types observed clinically for teeth were studied. A static point load of 500N was applied to the buccal and lingual cusp (Load A and B). The principal stresses in lesion apex, and vertical sectioned margin of cervical wall were analyzed. The results were as follows 1. The patterns of stress distribution were similar but the magnitude was different in four types of lesion 2. The peak stress was observed at mesial corner and also stresses concentrated at lesion apex. 3. The compressive stress under load A and the tensile stress under load B were dominant stress. 4. Under the load, lesion can be increased and harmful to tooth structure unless restored.

• The Journal of Korean Academy of Prosthodontics
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• v.25 no.1
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• pp.281-302
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• 1987

의치상 재료 종류에 따라 의치, 점막 및 하악골에 발생되는 변위 및 응력을 연구하기 위하여 컴퓨터를 이용한 수치적 해석인 2차원 유한 요소법을 이용하였다. 2차원 유한 요소 모형으로선 표준 크기의 하악골 및 의치를 고려하여 231개의 사변형 요소 및 268개의 절점으로 분할한 후 각 구성 성분의 물리적 성질인 탄성률 및 프와송비를 대입시켰다. 사용된 의치로서는 일반 합성수지의치, 2mm후경의 탄성재를 의치상 하부에 이장한 합성수지의치, 2mm후경의 탄성재를 치아와 의치상 중앙에 삽입한 합성수지의치 및 0.5mm후경의 금속상의치의 4종류였으며, 하중시에 하악의 고정 부위로선 생체와 동일 조건을 부여하기 위하여 교근, 내측익돌근, 측두근등의 하악 폐구근이 부착되는 하악각 부위 및 하악 근돌기 부위의 16절점을 고정점으로 하였다. 하중 조건으로선 하악 제1대구치의 일점에 10kg의 수직 집중하중, 하악 중절치의 일점에 7kg의 수직 집중하중 및 하악 제 1소구치로 부터 하악 제2대구치까지의 교합면에 10kg의 수직 분산하중을 부여하여 분석한 결과는 다음과 같다. 1. 하중이 의치 교합면위의 가해진 부위에 따라 다양한 의치 회전 및 강하 현상을 보였으며, 탄성재를 이장 및 삽입한 합성 수지 의치의 변위가 일반 합성수지의치 및 금속상 의치의 변위보다 더 컸다. 2. 주응력을 고려할때 점막 부위에는 주로 압축 응력이 작용하였으며 치조제 부위는 압축응력과 인장 응력이 함께 작용하였다. 3. 탄성재를 삽입한 합성수지의치에 최고 등가 응력이 집중되었으며 그 다음은 탄성재를 이장한 합성수지의치, 일반 합성수지의치의 순이였으며 금속상의 경우는 금속을 따라서 높은 등가 응력이 넓게 분산되었다. 4. 의치상 종류에 관계없이 동일 하중 조건하에선 점막에 나타나는 등가 응력의 크기 및 분산양태는 유사하였다. 5. 하악골에서 등가 응력은 의치지지 부위에만 국한되지 않고 넓게 분산 되었으며 의치상 종류 및 하중 조건에 관계없이 치조제 후방 및 하악연의 후방 부위에 특히 높은 등가응력이 집중되었다. 6. 하악 중절치의 일점에 수직 하중을 가한 경우가 다른 하중 조건에 비하여 지지점과의 거리차이로 인하여 하악골에 가장 높은 등가 응력을 유발하였다. 7. 의치상 재료에 따른 하악 골에 발생되는 응력의 크기 및 분산에는 큰 차이가 없으나 금속상의 경우가 교합압을 분산하는데는 효과적이었다.

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.2
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• pp.112-120
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• 2020

Purpose: The purpose of this study was to compare the biomechanical outcome in the mandibular posterior region between two different loading conditions by finite element analysis. Materials and Methods: The mandibular posterior teeth model and the implant model were generated for the study. And 2 different types of loading conditions were provided: Arbitrary occlusion and natural occlusion obtained from the digital occlusal analyzer, Accura (Accura, Dmetec Co. Ltd., Seoul, Korea). Total load of 100 N was evenly distributed over arbitrary occlusion points, and 100 N load was differentially distributed over natural occlusion points according to Accura data. The biomechanical outcome was evaluated by the finite element analysis software. Results: The result of finite element analysis showed considerable difference in both von Mises stress pattern and displacement under different loading conditions. Conclusion: In finite element analysis, it is recommended to simulate a realistic occlusal loading pattern that is based on accurate measurement.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.4
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• pp.297-305
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• 2018

Purpose: This study aimed to analyze stress distribution and maximum von Mises stress generated in intracoronal restorations and in tooth structures of mandibular molars with various types of cavity designs and materials. Materials and Methods: Three-dimensional solid models of mandible molar such as O inlay cavity with composite and gold (OR-C, OG-C), MO inlay cavity with composite and gold (MR-C, MG-C), and minimal invasive cavity on occlusal and proximal surfaces (OR-M, MR-M) were designed. To simulate masticatory force, static axial load with total force of 200 N was applied on the tooth at 10 occlusal contact points. A finite element analysis was performed to predict stress distribution generated by occlusal loading. Results: Restorations with minimal cavity design generated significantly lower values of von Mises stress (OR-M model: 26.8 MPa; MR-M model: 72.7 MPa) compared to those with conventional cavity design (341.9 MPa to 397.2 MPa). In tooth structure, magnitudes of maximum von Mises stresses were similar among models with conventional design (372.8 - 412.9 MPa) and models with minimal cavity design (361.1 - 384.4 MPa). Conclusion: Minimal invasive models generated smaller maximum von Mises stresses within restorations. Within the enamel, similar maximum von Mises stresses were observed for models with minimal cavity design and those with conventional design.