• 구강회복응용과학지
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• 제21권2호
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• pp.153-167
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• 2005

The purpose of this study was to compare the v-shape thread with the square shape thread of fixture in the view of stress distribution pattern using finite element stress analysis. The finite element model was designed with the parallel placement of two standard fixtures(4.0 mm diameter ${\times}$ 11.5 mm length) on the region of mandibular 1st and 2nd molars. Three dimensional finite element model was created with the components of the implant and surrounding bone. This study simulated loads of 200 N at the central fossa in a axial direction (load A), 200 N at the buccal offset load that is 2 mm apart from central fossa in a axial direction (load B), 200 N at the buccal offset load that was 4 mm apart from central fossa in a axial direction (load C). These forces of load A',B',C' were applied to a $15^{\circ}$ inward oblique direction at that same site with 200 N. Von Mises stress values were recorded and compared in the supporting bone, fixture, and abutment screw. The following results have been made based on this study : 1. The highest stress concentration occurred at the cervical region of the implant fixture. 2. Von Mises stress value of off-site region was higher than that of central fossa region. 3. Square shape thread type showed more even stress distribution in the vertical and oblique force than V-shape thread type. 4. Stress distribution was the most effective in the case of buccal offset load (2, 4 mm distance from central fossa) in the square shape thread type. 5. V-shape thread type revealed higher von Mises stress value than square shape thread type in all environmental condition. The results from numerical analyses concluded that square shape thread type had the lower destructive stress and more stress distribution between the fixture and bone interface than V-shape thread type. Therefore, square shape thread type was regarded as optimal thread configuration in biomechanical concepts.

• Journal of Periodontal and Implant Science
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• 제29권1호
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• pp.233-249
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• 1999

Primary fixation is one of the most important factor in establishing adequate osseointegration between implant and bone. To evaluate the initial healing response of bone around implants without primary bone contact, this study was designed to create considerable space between implant and bone in 5 mongrel dogs, about 1-year old. After 3 holes of 6.0mm in diameter were prepared at the femur neck of the dogs, commercially pure titanium thread type implants(STERI-$OSS^{(R)}$), 8mm in length and 3.8mm, 5.0mm and 6.0mm in diameter, were inserted. Implants were supported by only nonresorbable membrane($Teflon^{(R)}$), and the penetration of upper soft tissue into the gap was inhibited by it. The each implant was positioned in the center of the drilled hole. 9 implants with different diameters were inserted in 3 dogs for histologic observation, and 12 were inserted in 2 dogs for mobility test and removal torque test.Fluorescent dyes were injected in order of Doxycycline, Alizarin Red S, and Calcein at intervals of 2 weeks. At 4-, 8-, and 12-week after placement, 3 dogs were sacrificed for histologic observation, and at 8- and 12-week after placement, 2 dogs were sacrificed for mobility test using $Periotest^{(R)}$ (Simens AG, Bensheim, Germany) and torque test using Autograph AGS-1000D $series^{(R)}$(Japan). The result were as follows: 1. The wider the gap between bone and implant was, the less bone maturity was, and the later osseointegration was occurred. Trabecular direction of new bone around implant was changed from parallel to perpendicular to the implant, and the gap was filled with new bone, over time. 2. There was a decreasing tendency over time in the mobility of all implants, but the wider gap between bone and implant was, the smaller decrease of the mobility was. 3. There was a increasing tendency over time in the removal torque gauge of all implants, and the wider gap was, the smaller increase of the removal torque gauge was. The results suggest that osseointegration in case of implant without primary bone contact may be obtained by guided bone regeneration technique with prolonged healing period, but the time of second surgery should be considered carefully.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제30권4호
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• pp.331-338
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• 2004

Stress transfer to the surrounding tissues is one of the factors involved in the design of dental implants. Unfortunately, insufficient data are available for stress transfer within the regenerated bone surrounding dental implants. The purpose of this study was to investigate the concentration of stresses within the regenerated bone surrounding the implant using three-dimensional finite element stress analysis method. Stress magnitude and contours within the regenerated bone were calculated. The $3.75{\times}10-mm$ implant (3i, USA) was used for this study and was assumed to be 100% osseointegrated, and was placed in mandibular bone and restored with a cast gold crown. Using ANSYS software revision 6.0, a program was written to generate a model simulating a cylindrical block section of the mandible 20 mm in height and 10 mm in diameter. The present study used a fine grid model incorporating elements between 165,148 and 253,604 and nodal points between 31,616 and 48,877. This study was simulated loads of 200N at the central fossa (A), at the outside point of the central fossa with resin filling into screw hole (B), and at the buccal cusp (C), in a vertical and $30^{\circ}$ lateral loading, respectively. The results were as follows; 1. In case the regenerated bone (bone quality type IV) was surrounded by bone quality type I and II, stresses were increased from loading point A to C in vertical loading. And stresses according to the depth of regenerated bone were distributed along the implant evenly in loading point A, concentrated on the top of the cylindrical collar loading point B and C in vertical loading. And, In case the regenerated bone (bone quality type IV) was surrounded by bone quality type III, stresses were increase from loading point A to C in vertical loading. And stresses according to the depth of regenerated bone were distributed along the implant evenly in loading point A, B and C in vertical loading. 2. In case the regenerated bone (bone quality type IV) was surrounded by bone quality type I and II, stresses were decreased from loading point A to C in lateral loading. Stresses according to the depth of regenerated bone were concentrated on the top of the cylindrical collar in loading point A and B, distributed along the implant evenly in loading point C in lateral loading. And, In case the regenerated bone (bone quality type IV) was surrounded by bone quality type III, stresses were decreased from loading point A to C in lateral loading. And stresses according to the depth of regenerated bone were distributed along the implant evenly in loading point A, B and C in lateral loading. In summary, these data indicate that both bone quality surrounding the regenerated bone adjacent to implant fixture and load direction applied on the prosthesis could influence concentration of stress within the regenerated bone surrounding the cylindrical type implant fixture.

• 대한치과보철학회지
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• 제61권1호
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• pp.63-72
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• 2023

완전 무치악에서 전악 임플란트 고정성 수복물로 구강회복 치료를 진행할 경우, 해당 악궁의 해부학적 상황과 대합치와의 관계를 고려하여 최종 보철물의 형태와 위치를 결정하는 과정과 이에 따라 다수의 임플란트를 계획된 방향과 각도로 식립하는 과정은 매우 중요하다. 본 증례는 기존 의치의 불편감으로 내원한 상악 무치악 환자를 computer-guided surgery를 통해 상부 보철물에 기반하여 이상적으로 계획된 위치에 임플란트를 식립하였다. 이를 통해 상악 전악 임플란트 고정성 보철물을 제작하여 구강 회복을 진행한 치료로 환자와 술자 모두 기능 및 심미적으로 만족할만한 결과를 얻었기에 이를 보고하고자 한다.

• 대한치과보철학회지
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• 제47권4호
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• pp.365-375
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• 2009

연구목적: 임플란트 보철물의 유지형태 중 나사 및 시멘트 혼합 유지형의 경우 나사 풀림력 등에 영향을 주는 임플란트 구성 성분의 응력에 관한 연구가 부족하였다. 임플란트 상부 보철물의 유지형태, 즉, 시멘트 유지와 나사 유지, 그리고 이 두 가지 유지형태가 서로 연결된 혼합형의 임플란트 보철물의 응력분산의 특징들을 3차원 유한요소분석법을 이용하여 비교하고자 하였다. 연구재료 및 방법: 하악골에서 제1소구치 부위와 제1대구치 부위에 2개의 임플란트 (SS II, Osstem Co. Ltd., Seoul, Korea)를 식립한 가상의 3본 계속가공의치를 모델화하였다. 지대주 종류와 그 위치에 따라, 4가지 모형 군으로 나누어 실험하였다. 모형 1은제1대구치와 제1소구치 각각의 고정체에 모두 동일한 시멘트 유지형 지대주인 Comocta abutment (Osstem Co. Ltd) 를 장착하여 3본 계속가공의치를 합착시킨 경우이고, 모형 2는 제1대구치와 제1소구치 각각의 고정체에 모두 나사 유지형 지대주인 Octa abutment (Osstem Co. Ltd) 를 장착하여 3본 계속가공의치를 나사로 고정시킨 경우이며, 모형 3은 제1대구치의 고정체에는 시멘트 유지형 지대주인 Comocta abutment를 장착하고, 제1소구치에는 나사 유지형 지대주인 Octa abutment를 장착한 후 3본 계속가공의치를 각각 시멘트 합착 및 나사로 고정시킨 경우이다. 그리고 모형 4는 모형 3에서 각각 제1대구치 및 제1소구치의 지대주를 맞바꾼 후 3본 계속가공의치를 나사 및 시멘트로 고정시킨 경우로 나누었다. 평균저작압인 하중을 대구치 565 N과 소구치 288 N의 힘으로 설정하고 수직방향으로 중심와와 협측 교두정에, 그리고 $30^{\circ}$ 경사 하중을 협측 교두정 부위에 준 다음 골, 고정체, 지대주, 그리고 지대주 나사 등에 나타나는 von-Mises stress 양상을 평가하였다. 결과: 네 가지 모형 중 나사 유지형 지대주인 Octa abutment를 제1대구치와 제1소구치 부위에 사용한 모형 2가 전반적으로 가장 낮은 안정적인 응력 분포를 보였다. 네 가지 모형 모두 피질골 및 고정체에 미치는 응력 크기 및 분포는 거의 유사하며, 치조골에 작용하는 응력은 하중의 종류와 상관없이 주로 피질골에 집중되었다. 지대주, 지대주 나사, 그리고 보철물 나사 등에 미치는 응력 크기나 분포는 모형에 관계없이 나사 유지형인 경우가 시멘트 유지형인 경우에 비해 낮은 안정적인 값을 보였다. 제1대구치와 제1소구치의 상부 구조물의 차이에 의한 교호작용 (reciprocal action)은 상대적으로 약하였다. 모든 부위에서 중앙 수 직하중, 교두정 수직하중, 그리고 교두정 경사하중의 순으로 응력값이 증가하였다. 결론: 본 유한 요소실험의 한계내에서 나사 및 시멘트 혼합 유지형의 임플란트 보철물은 시멘트 유지형만 사용하는 경우와 비교하여 주위에 더 큰 응력을 나타내지는 않았다. 이상적인 passive fit의 가정하에서 나사 유지형의 임플란트 보철물이 본체와 주위에 가장 작은 응력을 나타내었다.

• Journal of Periodontal and Implant Science
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• 제49권6호
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• pp.346-354
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• 2019

Maxillary implants are inserted in the upward direction, meaning that they oppose gravity, and achieving stable support is difficult if the alveolar bone facing the maxillary sinus is thin. Correspondingly, several sinus-lifting procedures conducted with or without bone graft materials have been used to place implants in the posterior area of the maxilla. Even with these procedures available, it has been reported that in about 5% of cases, complications occurred after implantation, including acute and chronic sinusitis, penetration of the sinus by the implant, implant dislocation, oroantral fistula formation, infection, bone graft dislocation, foreign-body reaction, Schneiderian membrane perforation, and ostium plugging by a dislodged bone graft. This review summarizes common maxillary sinus pathologies related to implants and suggests an appropriate management plan for patients requiring dental implantation.

• 구강회복응용과학지
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• 제26권2호
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• pp.179-195
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• 2010

임플란트 보철물에 저작력 등 외부 하중이 작용하면 내부 반응으로 응력이 발생되는데 지지골에 나타난 응력은 골재생 및 흡수 파괴, 임플란트에 나타난 응력은 임플란트 자체의 파절이나 나사의 풀림현상 및 파절, 상부 구조물에 나타난 응력은 보철물의 파절 등을 예견하는 지침이 될 수 있을 것이다. 지대주의 형상과 재질에 따라 연결방법과 보철방법이 달라지고 임플란트 내부의 하중전달 기전이 변하게 되고 이에 따라 악골에 발생하는 응력분포 역시 달라질 수 있다. 본 연구에서는 하악 제 1대구치 부위에 이중나사 구조를 갖고 원추형 내측연결 임플란트 시스템인 GSII$^{(R)}$ (Osstem, Korea)임플란트를 이용해 지대주의 종류를 티타늄 소재의 2-piece Transfer$^{TM}$ abutment (GST), 금합금 소재의 2-piece GoldCast$^{TM}$ abutment(GSG), 외부 연결형태를 가진 3-piece Convertible$^{TM}$ abutment (GSC) 로 분류하여 이에 따른 응력분포 양상을 비교 분석하여 보았다. 결과 하중조건에 관계없이 응력은 주로 지대주와 고정체가 접촉하는 경부에 집중되었다. 또한 하중조건에 관계없이 임플란트의 고정체 상부와 접촉하는 치밀골에 높은 응력이 나타나고 해면골에는 아주 작은 응력이 나타났다. 축하중보다는 중심축을 벗어난 하중조건에서 더 높은 응력이 발생되었고 수직하중보다 경사하중에서 더 높은 응력이 발생되었다. 전체에 걸친 최대응력은 GSG에서는 지대주, 치관 및 고정체에 고르게 분포되었고 GST는 주로 고정체와 지대주 나사에, GSC는 고정체와 지대주에 집중되었다. 세 지대주 간 골내의 최대응력에는 유의한 차이가 없었고 GSG가 전체 구성부의 응력분포에 있어 유리한 것으로 나타났다.

• 대한치과보철학회지
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• 제41권2호
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• pp.182-206
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• 2003

Statement of problem : Successful osseointegration of endosseous threaded implants is dependent on many factors. These may include the surface characteristics and gross geometry of implants, the quality and quantity of bone where implants are placed, and the magnitude and direction of stress in functional occlusion. Therefore clinical quantitative measurement of primary stability at placement and functional state of implant may play a role in prediction of possible clinical symptoms and the renovation of implant geometry, types and surface characteristic according to each patients conditions. Ultimately, it may increase success rate of implants. Purpose : Many available non-invasive techniques used for the clinical measurement of implant stability and osseointegration include percussion, radiography, the $Periotest^{(R)}$, Dental Fine $Tester^{(R)}$ and so on. There is, however, relatively little research undertaken to standardize quantitative measurement of stability of implant and osseointegration due to the various clinical applications performed by each individual operator. Therefore, in order to develop non-invasive experimental method to measure stability of implant quantitatively, the resonance frequency analyzer to measure the natural frequency of specific substance was developed in the procedure of this study. Material & method : To test the stability of the resonance frequency analyzer developed in this study, following methods and materials were used : 1) In-vitro study: the implant was placed in both epoxy resin of which physical properties are similar to the bone stiffness of human and fresh cow rib bone specimen. Then the resonance frequency values of them were measured and analyzed. In an attempt to test the reliability of the data gathered with the resonance frequency analyzer, comparative analysis with the data from the Periotest was conducted. 2) In-vivo study: the implants were inserted into the tibiae of 10 New Zealand rabbits and the resonance frequency value of them with connected abutments at healing time are measured immediately after insertion and gauged every 4 weeks for 16 weeks. Results : Results from these studies were such as follows : The same length implants placed in Hot Melt showed the repetitive resonance frequency values. As the length of abutment increased, the resonance frequency value changed significantly (p<0.01). As the thickness of transducer increased in order of 0.5, 1.0 and 2.0 mm, the resonance frequency value significantly increased (p<0.05). The implants placed in PL-2 and epoxy resin with different exposure degree resulted in the increase of resonance frequency value as the exposure degree of implants and the length of abutment decreased. In comparative experiment based on physical properties, as the thickness of transducer increased, the resonance frequency value increased significantly(p<0.01). As the stiffness of substances where implants were placed increased, and the effective length of implants decreased, the resonance frequencies value increased significantly (p<0.05). In the experiment with cow rib bone specimen, the increase of the length of abutment resulted in significant difference between the results from resonance frequency analyzer and the $Periotest^{(R)}$. There was no difference with significant meaning in the comparison based on the direction of measurement between the resonance frequency value and the $Periotest^{(R)}$ value (p<0.05). In-vivo experiment resulted in repetitive patternes of resonance frequency. As the time elapsed, the resonance frequency value increased significantly with the exception of 4th and 8th week (p<0.05). Conclusion : The development of resonance frequency analyzer is an attempt to standardize the quantitative measurement of stability of implant and osseointegration and compensate for the reliability of data from other non-invasive measuring devices It is considered that further research is needed to improve the efficiency of clinical application of resonance frequency analyzer. In addition, further investigation is warranted on the standardized quantitative analysis of the stability of implant.

• 대한치과보철학회지
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• 제45권4호
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• pp.506-521
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• 2007

Statement of problem: The cumulative success rate of wide implant is still controversial. Some previous reports have shown high success rate, and some other reports shown high failure rate. Purpose: The aim of this study was to analyze, and compare the biomechanics in wide implant system embeded in different width of crestal bone under different occlusal forces by finite element approach. Material and methods: Three-dimensional finite element models were created based on tracing of CT image of second premolar section of mandible with one implant embedded. One standard model (6mm-crestal bone width, 4.0mm implant diameter central position) was created. Varied crestal dimension(4, 6, 8 mm), different diameter of implants(3.3, 4.0, 5.5, 6.0mm), and buccal position implant models were generated. A 100-N vertical(L1) and 30 degree oblique load from lingual(L2) and buccal(L3) direction were applied to the occlusal surface of the crown. The analysis was performed for each load by means of the ANSYS V.9.0 program. Conclusion: 1. In all cases, maximum equivalent stress that applied $30^{\circ}$ oblique load around the alveolar bone crest was larger than that of the vertical load. Especially the equivalent stress that loaded obliquely in buccal side was larger. 2. In study of implant fixture diameter, stress around alveolar bone was decreased with the increase of implant diameter. In the vertical load, as the diameter of implant increased the equivalent stress decreased, but equivalent stress increased in case of the wide implant that have a little cortical bone in the buccal side. In the lateral oblique loading condition, the diameter of implant increased the equivalent stress decreased, but in the buccal oblique load, there was not significant difference between the 5.5mm and 6.0mm as the wide diameter implant. 3. In study of alveolar bone width, equivalent stress was decreased with the increase of alveolar bone width. In the vertical and oblique loading condition, the width of alveolar bone increased 6.0mm the equivalent stress decreased. But in the oblique loading condition, there was not a difference equivalent stress at more than 6.0mm of alveolar bone width. 4. In study of insertion position of implant fixture, even though the insertion position of implant fixture move there was not a difference equivalent stress, but in the case of little cortical bone in the buccal side, value of the equivalent stress was most unfavorable. 5. In all cases, it showed high stress around the top of fixture that contact cortical bone, but there was not a portion on the bottom of fixture that concentrate highly stress and play the role of stress dispersion. These results demonstrated that obtaining the more contact from the bucco-lingual cortical bone by installing wide diameter implant plays an important role in biomechanics.

• Journal of Periodontal and Implant Science
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• 제32권2호
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• pp.379-388
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• 2002

임플랜트의 성공을 위해서 정확한 방사선학적 검사는 가용골의 높이와 하악관의 위치를 평가하고 중요구조물의 손상을 방지하는데 있어 필수적이다. CT촬영법 중 영상재구성법을 이용한 방법(CT/MPR)은 하악관의 위치를 잘 보여준다. 치아에 평행한 협설 단면 (cross-sectional plane)을 얻기 위해서는 횡단면(axial plane)이 교합면과 평행하도록 해야 한다. 횡단면(axial plane)이 교합면과 평행하지 않으면 재구성된 협설 단면(cross-sectional plane)은 계획된 fixture의 방향과 각을 이루게 되어 그 fixture의 실제 dimension을 보여주지 못하게 된다. 협설단면(cross-sectional view)에서 측정한 가용골 높이가 실제 가용골 높이보다 너무 큰 경우, 수술시 하악관을 침범할 가능성이 있게 된다. 이 연구의 목적은 하악 임플랜트 CT 촬영시 횡단면이 임플란트를 위한 가용골 높이의 측정에 미치는 영향을 알아보는 것이다. 하악 대구치 부위의 임플랜트를 계획하고 radiographic stent를 만든 후 치과 방사사선과에서 하악 임플랜트 CT를 촬영한 40명의 환자, 45개 부위를 선택하였다. 임플랜트 CT의 central panoramic view에서 치조정과 하악관, stent를 tracing한 후, 치조정과 하악관간의 거리(available bone height, ABH)를 재구성된 협설단면상에서 측정하였다(uncorrected ABH). 다음으로, .stent 방향으로 그은 직선상에서 측정하였다(corrected ABH). 두 거리사이의 각을 측정하였다. 두 거리로부터 각각 fixture의 길이를 결정하였다. 연구 결과, 두 가용골의 높이간에는 제 1 대구치와 제 2 대구치에서 모두 유의성있는 차이를 보였다 (p<0.001). 차이가 1 mm 이상인 경우는 제 1 대구치에서 8.7%, 제 2 대구치에서 15.5% 였다. 차이가 2 mm 이상인 경우는 제 1 대구치에서 2.0%, 제 2 대구치에서 6.6%였다. 최대값은 제 1 대구치에서 2.5 mm, 제 2 대구치에서 2.2 mm 였다. 두 가용골의 높이차와 각과의 상관 관계는 제 1 대구치와 제 2 대구치에서 모두 양의 상관관계를 보였다. 상관 계수는 제 1 대구치에서 0.534, 제 2 대구치에서 0.728 였다. 제 2 대구치가 더 강한 양의 상관관계를 보였다. 두 가용골의 높이로부터 결정한 fixture의 길이가 일치하지 않는 경우는 제 1 대구치에서는 24.4%, 제 2 대구치에서는 28.9%였다.