相對於其他口腔位置之人工牙根植入，下顎臼齒區人工植牙造成植入失敗的可能性較高，而人工牙根的過度負荷一直是造成植入失敗的主要原因之一。 臨床上，牙科醫師運用植體設計與植入設計，期望降低臼齒區人工植牙因為過度負荷所造成的損害，然而何種植體設計與植入設計具有最佳之植入效果，目前仍無具體之研究可證明，並針對臼齒區之人工植牙治療，提供一個整體的分析與建議。 本研究之主要目的在於，探討不同之植體設計與植入設計對臼齒區人工植牙的影響，並找出最佳之植體與植入設計，提供給臨床醫師作為臼齒區人工植牙的參考。
　　本研究運用有限元素模擬分析-不同的植體設計(包含無螺紋以及不同螺紋形狀、階梯狀牙根植體與錐體狀牙根植體的設計)、不同支持結構的牙根(包含標準尺寸、大直徑人工牙根與雙人工牙根)、局部缺牙修復之人工牙根的假牙相連或不相連、局部缺牙修復之人工牙根的排列型態(包含直線與非直線之排列)等參數。結合電腦斷層掃描影像與CAD系統等三維模型建構之技術，所分析的模型具有精確之解剖幾何外形，並使用非等向性之骨質材料性質與p-element之收斂性分析，在兩種負荷模式(多咬合力與單點咬合力)下，進行參數間的比較與分析，此外，本研究亦透過應變規實驗驗證有限元素模擬的合理性。
　　在結果方面，有限元素模擬與應變規實驗分析在應變數值上雖有差異，但兩者具有相當高之相關係數(r2=0.97)，此高的相關係數驗證了有限元素模擬的合理性；在人工牙根設計之結果方面，螺紋結構與階梯狀之植體設計雖無法降低緻密骨質頂端的最高應力值，但在螺紋的凹端與階梯狀植體之不同直徑相接的位置，具有降低人工牙根與骨質間之表面應力的能力。錐體狀植體的設計具有降低緻密骨與疏鬆骨之最高應力值，可有助於降低在人工牙根周圍骨質流失的可能性。
在標準直徑(3.75釐米)、大直徑人工牙根(5釐米)與雙人工牙根的比較方面，發現在臼齒區種植大直徑人工牙根或雙人工牙根，與標準尺寸的人工牙根相比，可大幅降低人工牙根周圍骨質的應力，其原因則是大直徑的人工牙根或雙人工牙根皆有效增加人工牙根與骨質的界面面積。在假牙相連與不相連的探討方面，結果發現，使用相同直徑之人工牙根的植入，其兩者之應力值並沒有明顯差異，但是在假牙相連，且在大臼齒位置種植結構較強的人工牙根(大直徑的人工牙根或雙人工牙根)之情況下，卻有明顯降低小臼齒位置之周圍骨質應力值的效果。在局部臼齒缺牙區，進行以三根人工牙根之直線與非直線排列的比較，發現使用非直線的排列方式，雖然可以降低人工牙根本身的應力值; 然而，在骨質的應力值方面，非直線的種植方式並無法明顯降低應力值，並會在某些人工牙根周圍骨質產生高應力，增加人工牙根植入失敗的危險性。

　Implant-supported molar restoration raises the risk of implant failure because of the possibility of occlusal overloading. In order to provide better clinical performance for implant, many fixture designs and treatment strategies are suggested; nevertheless, most of those suggestions showed controversy results in the clinical studies and research reports. Therefore, the aim of this study is to investigate the biomechanical effects of various implant designs including the fixture designs and treatment strategies on a single and partial molar edentulous restoration.
　Finite element (FE) analysis was used to estimate the implant and bone’s stresses of various implant design parameters including the fixture designs (the threaded characteristics, stepped body and tapered body of fixture), supporting structures of implants (standard, wide-diameter and two implants), splinted and non-splinted crowns, and arrangement of implants (in-line and offset placements). Combing the computer tomography (CT) images and computer-aided design (CAD) system, the finite element models with an accurate anatomic geometry were created. The anisotropic material properties of bone were employed, and two loading conditions (multiple forces and single force) were applied in the models with p-element to ensure the convergence criteria. The experimental strain gauge verification (ESGV) was also performed to validate the finite element simulation. The strains in FE simulation showed a high correlation with the measured strains of ESGV, and therefore the validation of FE simulation was confirmed.
For the results of fixture designs, the threaded characteristic and stepped body of fixture could not reduce the peak bone stresses, but provided the ability to dissipate the interfacial bone stress along the bone/implant interface especially near the valley of the thread and the areas of diameter change in stepped regions. The tapered body of fixture design showed the advantage of decreasing the peak stress in both cortical and trabecular bone and might reduce the risk of the crestal cortical and endostreal trabecular bone loss.
　In the comparison of standard, wider and two implants with using splinted or non-splinted prosthetic crowns, the wide-diameter implant and two implants showed lower bone stresses than that in the standard implant. The stress sharing effect in splinted prosthesis was suggested in the treatment design of splinting crowns with one standard implant and one wider implant (or two implants) simultaneously. The evidence of bone stress decreasing around the standard implant was noticed with this arrangement. For the comparison results of in-line and offset placements, using offset placements could decrease the implant stresses. However, the offset placements showed no benefit in bone stress decreasing over the in-line placement, and further, it might increase the bone stresses around some implants result in the risk of implant's instability.

Adell R, Lekholm U, Rockler B, Brånemark P I. A 15-year study of osseointergration implants in treatment of the edentulous jaw, International Journal of Oral and Maxillofacial Surgery 1981;10:387-416.
Akca K, Iplikciogiu H. Finite element stress analysis of the influence of staggered versus straight placement of dental implants. International Journal of Oral and Maxillofacial Implants 2001;16:722-730.
Akca K, Cehreli MC, Iplikcioglu H. Evaluation of the mechanical characteristics of the implant-abutment complex of a reduced-diameter morse-taper implant. A nonlinear finite element stress analysis. Clinical Oral Implants Research 2003;14:444-454.
Attard NJ, Zarb GA. Implant prosthodontic management of partially edentulous patients missing posterior teeth: The Toronto experience. Journal of Prosthetic Dentistry 2003;89: 352-359.
Bahat O, Handelsman M. Use of wide implants and two implants in the posterior jaw: A clinical report. International Journal of Oral and Maxillofacial Implants 1996;11: 379-386.
Balshi TJ, Hernandez RE, Pryszlak MC, Rangert B. A comparative study of one implant versus two replacing a single molar. International Journal of Oral and Maxillofacial Implants 1996;11:372-378.
Balshi TJ, Wolfinger G.J. Two-implant-supported single molar replacement: interdental space requirements and comparison to alternative options. International Journal of Periodontics Restorative Dentistry 1997;17: 427-435.
Barbier L, Vander Sloten J, Krzesinski G, Schepers E, Van Der Perre G. Finite element analysis of non-axial versus axial loading of oral implants in the mandible of the dog”, Journal of Oral Rehabilitation 1998;25:847-58.
Bolind PK, Johansson CB, Becker W, Langer L, Severtz Jr EB, Albrektsson TO. A descriptive study on retrieved non-threaded and threaded implant designs. Clinical Oral Implants Research 2005;16:447-455.
Brunski JB. In vivo bone response to biomechanical loading at the bone/dental-implant interface. Advances in Dental Research 1999;13:99-119.
Chang CH. Computer aided analysis of femoral stem prosthesis. Ph.D. Dissertation 1990; Rice University, USA
Chun HJ, Cheong SY, Han JH, Heo SJ, Chung JP, Rhyu IC, Choi YC, Baik HK, Ku Y, Kim MH. Evaluation of design parameters of osseointegrated dental implants using finite element analysis. Journal of oral rehabilitation 2002;29:565-574.
Chavez H, Ortman LF, DeFranco RL, Medige J. Assessment of oral implant mobility. Journal of Prosthetic Dentistry 1993;7:345-353.
Ciftci, Y.& Canay, S. The effect of veneering materials on stress distribution in implant-supported fixed prosthetic restorations. International Journal of Oral and Maxillofacial Implants 2000;15:571-582.
Daellenbach K, Hurley E, Brunski JB. Biomechanics of in-line vs. offset implants supporting a partial prosthesis. Journal of Dental Research 1996;75:183.
Davarpanah M, Martines H, Kebir M, Etienne D, Tecucianu JF. Wide-diameter implants: new concepts. International Journal of Periodontics Restorative Dentistry 2001;21: 149-159.
Davarpanah M, Martinez H, Etienne D, Zabalegui I, Mattout P, Chiche F, Michel JF. A Prospective Multicenter Evaluation of 1,583 3i Implants: 1- to 5-year Data International Journal of Oral and Maxillofacial Implants 2002;17:820-828.
Donath K, Hassell T, Jovanovic S, Richter j. Peri-implant pathology. In: Klaus HR, Herbert EW (eds). Color Atlas of Dental Medicine-Implantology, New York: Thieme Medical Publishers Inc., 1995:p318-319
Eskitascioglu G, Usumez A, Sevimay M, Soykan E, Unsal E. The influence of occlusal loading location on stresses transferred to implant-supported prostheses and supporting bone: A three-dimensional finite element study Journal of Prosthetic Dentistry 2004;91:144-150.
Fanuscu MI, Vu HV, Poncelet B. Implant biomechanics in grafted sinus: a finite element analysis. The Journal of Oral Implantology 2004;30:59-68.
Geng JP, Tan KBC, Liu GR. Application of finite element analysis in implant dentistry: A review of the literature. Journal of Prosthetic Dentistry 2001;85:585-598.
Guichet DL, Yoshinobu D, Caputo AA. Effect of splinting and interproximal contact tightness on load transfer by implant restorations. Journal of Prosthetic Dentistry 2002;87:528-535.
Hansson S. The implant neck: smooth or provided with retention elements. A biomechanical approach. Clinical Oral Implants Research 1999;10:394-405.
Hansson S. A conical implant–abutment interface at the level of the marginal bone improves the distribution of stresses in the supporting bone. Clinical oral implants research, 2003;14: 286-293.
Henry PJ, Laney WR, Jemt T, Harris D, Krogh PHJ, Polizzi G, Zarb GA, Herrmann I. Osseointegrated implants for single-tooth replacement: a prospective 5-year multicenter study. International Journal of Oral and Maxillofacial Implants 1996;11: 450-455.
Herbst D, Nel JC, Driessen CH, Becker PJ. Evaluation of impression accuracy for osseointegrated implant-supported superstructure. Journal of Prosthetic Dentistry 2000;83: 555-561.
Holmgren EP, Seckinger RJ, Kilgren LM, Mante F. Evaluating parameters of osseointegrated dental implants using finite element analysis- A two-dimensional comparative study examining the effects of implant diameter, implant shape, and load direction. The Journal of Oral Implantology 1998;24:80-88.
Huiskes R, Weinans H, van Rietbergen B. The relationship between stress shielding and bone resorption around total hip stems and the effects of flexible materials. Clinical Orthopaedics and Related Research 1992;274:124-134.
Iseri H, Tekkaya E, Oztan O, Bilgic S. Biomechanical effects of rapid maxillary expansion on the craniofacial skeleton, studied by the finite element method. European Journal of Orthodontics 1998;20:347-356.
Ishigaki S, Nakano T, Yamada S, Nakamura T, Takashima F. Biomechanical stress in bone surrounding an implant under simulated chewing. Clinical Oral Implants Research 2003;14:97-102.
Isidor F. Loss of osseointergration caused by osslusal load of oral implant. A clinical and radiographic study in monkeys. Clinical Oral Implants Research 1996;8:143-52.
Itoh H, Caputo AA, Kuroe T, Nakahara H. Biomechanical comparison of straight and staggered implant placement configurations. The International Journal of Periodontics & Restorative Dentistry 2004;24:47-55.
Ivanoff CJ, Sennerby L, Johansson C, Rangert B, Lekholm U. Influence of implant diameters on the integration of screw implants. An experimental study in rabbits. International Journal of Oral and Maxillofacial Surgery 1997;26:141-148.
Ivanoff CJ, Grondahl K, Sennerby L, Bergstrom C, Lekholm U. Influence of variations in implant diameters: a 3- to 5-year retrospective clinical report. International Journal of Oral and Maxillofacial Implants 1999;14:173-180.
Jeffcoat MK, McGlumphy EA, Reddy MS, Geurs NC, Proskin HM. A Comparison of hydroxyapatite (HA) –coated threaded, HA-coated cylindric, and titanium threaded endosseous dental implants International Journal of Oral and Maxillofacial Implants2003;18:406-410.
Jemt T, Book K. Prosthesis misfit and marginal bone loss in edentulous implant patients. International Journal of Oral and Maxillofacial Implants 1996;11:620-625.
Ko CC, Douglas WH, DeLong R, Rohrer MD, Swift JQ, Hodges JS, An KN, Ritman EL. Effects of implant healing time on crestal bone loss of a controlled-load dental implant. Journal of Dental Research 2003;82:585-591.
Langer B, Langer L, Herrmann I, Jorneus L. The wide fixture: A solution for special bone and a rescue for the compromised implant. Part 1. International Journal of Oral and Maxillofacial Implants 1993;8:400-408.
Lari N. Convergence requirements. In: Rao SS(eds). The finite element method in engineering, ed2. New York, U.S.A, 1989:123-125.
Maiorana C, Santoro F. Maxillary and mandibular bone reconstruction with hip grafts and implants using Frialit-2 implants. International journal of periodontics & restorative dentistry 2002;22:221-229
Mellal A, Wiskott AWA, Botsis J, Scherrer SS, Belser UC. Simulating effect of implant loading on surrounding bone. Comparison of three numerical models and validated by in-vitro data. Clinical Oral Implants Research 2004;15:239-248.
Misch CE. Clinical Biomechanics. In: Misch CE (eds). Contemporary Implant Dentistry: St Louis: Mosby, 1993; p.298-300
Misch CE. Implant Terminology In: Misch CE (eds). Contemporary Implant Dentistry, St Louis: Mosby, 1999:p21
Miyata T, Kobayashi Y, Araki H. The influence of controlled occlusal overload on peri-implant tissue. Part 3: a histologic study in monkeys. International Journal of Oral and Maxillofacial Implants 2000;15:425-431.
Morris HF, Winkler S, Ochi S, Kanaan A. A new implant design to maximize contact with trabecular bone: Survival to 18 months. Journal of Oral Implantology 2001;27:164-173.
Morris HF, Ochi S,Crum P, IOrenstein IH, Winkler S. AICRG, part I: A 6-year multicentered, multidisciplinary clinical study of a new and innovative implant design. The Journal of Oral Implantology 2004;30:125-133.
Naert I, Koutsikakis G., Duyck J, Quirynen M, Jacobs R, van Steenberghe D. Biologic outcome of implant-supported restoration in the treatment of partial edentulism. Part 1. A longitudinal clinical evaluation. Clinical Oral Implants Research 2002;13: 381-389.
O’Mahony AM, Williams JL, Spencer P. Anisotropic elasticity of cortical and concellous bone in the posterior mandible increases peri-implant stress and strain under oblique loading. Clinical Oral Implants Research 2001;12:648-657.
Pilliar RM, Deporter DA, Watson PA, Valiquette N. Dental implant design – effect on bone remodelling. Journal of Biomedical Materials Research 1991;25: 467–483.
Quirynen M, Naert I, van Steenberghe D. Fixture design and overload influence marginal bone loss and implant success in the Brånemark system. Clinical Oral Implants Research 1992;9:345-360.
Rangert B, Jemt T, Jörmeus L. Forces and moments on Brånemark implants. International Journal of Oral and Maxillofacial Implants 1989;4:241-247.
Rangert B, Krogh PHJ , Langer B, Roekel NV. Bending overload and implant fracture: A retrospective clinical analysis. International Journal of Oral and Maxillofacial Implants 1995;10: 326-334.
Rangert B, Sullivan RM, Jemt TM. Load factor control for implants in the posterior partially edentulous segment. International Journal of Oral and Maxillofacial Implants 1997;12:360-379.
Rangert B, Sennerby L, Meredith N. Design, Maintenance and biomechanical considerations in implant placement. Implantology 1997;24:416-420.
Sato Y, Shindoi N, Hosokawa R, Tsuga K, Akagawa Y. A biomechanical effect of wide implant placement and offset placement of three implants in the posterior partially edentulous region. Journal of Oral Rehabilitation 2000;27:15-21.
Sertgoz A, Guvener S. Finite element analysis of the effect of cantilever and implant length on stress distribution in an implant-supported fixed prosthesis. Journal of Prosthetic Dentistry 1996;76:165-169.
Shulman LB, Driskell TD. Dental implant: A historical perspective. In: Block MS, Kent JN, Guerra LR (eds). Implants in dentistry, Philadelphia: W.B. Saunders co.., 1997:p4-7
Simunek A, Vokurkova J, Kopecka D, Celko M, Mounajjed R, Krulichova I, Skrabkova Z. Evaluation of stability of titanium and hydroxyapatite-coated osseointegrated dental implants: A pilot study. Clinical Oral Implants Research 2002;13: 75-79.
Spiekermann H. Peri-implant pathology. In: Rateitschak KH, Wolf HF (eds). Implantology, New York: Thieme Medical, 1995:p318
Stegaroiu R, Sato T, Kusakari H. Influence of restoration type on stress distribution in bone around implants: A three-dimensional finite element analysis. International Journal of Oral and Maxillofacial Implants 1998;13: 82-90.
Sykaras R, Iacopino AM, Marker VA, Triplett RG, Woody RD. Implant materials, designs, and surface topographies: Their effect on osseointegration. A literature review. International Journal of Oral and Maxillofacial Implants 2000;15:675-690.
Tada S, Stegaroiu R, Kitamura E, Miyakawa O, Kusakari H. Influence of implant design and bone quality on stress/strain distribution in bone around implants: A 3-dimensional finite element analysis. International Journal of Oral and Maxillofacial Implants 2003;18:357-368.
Tanne K, Miyasaka J, Yamagata Y, Sachdeva R, Tsutsumi S, Sakuda M. Three-dimensional model of the human craniofacial skeleton: method and preliminary results using finite element analysis. Journal of Biomedical Engineering 1988;10:246-252
Taylor TD. What is a dental implant? In: Peppers LG. (eds). Dental implants: Are they for me?, Iowa: Quintessence, 1990:p6-7
Ugural AC. Stresses in beams. In: Corrigan JJ, Bradley JW (eds). Mechanics of Materials, Singapore: McGraw-Hill, 1991; p.175-182
van Steenberghe D. Outcomes and their measurement in clinical trials of endosseous oral implants. Annuals of Periodontology 1997;2: 291-298.
Wang TM, Leu LJ, Wang JS, Lin LD. Effects of prosthesis materials and prosthesis splinting on peri-implant bone stress around implants in poor-quality bone: a numeric analysis. International Journal of Oral and Maxillofacial Implants 2003;17:231-237.
Weinberg LA. The biomechanics of force distribution in implant-supported prostheses. International Journal of Oral and Maxillofacial Implants 1993;8:19-31
Weinberg LA, Kurger B. An evaluation of torque (moment) on implant/prosthesis with staggered buccal and lingual off-set. International Journal of Oral and Maxillofacial Implants 1996;16:253-257.