下颌骨三维有限元模型的建立及体部骨折坚固内固定的有限元法分析
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摘要
目的：下颌骨骨折是最常见的颌面部损伤。坚固内固定技术已成为治疗下颌骨骨折的常用手段。建立生物相似性和力学相似性较高的下颌骨三维有限元模型及右侧下颌骨体部骨折坚固内固定三维有限元模型，并进一步分析下颌骨功能状态下及坚固内固定时的应力分布，探讨可能发生的应力遮挡作用，为下颌骨骨折的发生、诊断、治疗及防护提供参考。
方法：以正常咬合的青年女性尸头为标本，用螺旋CT断层扫描技术、图形数字化仪、ANSYS6.0有限元软件等方法在计算机上建立下颌骨三维有限元模型，对下颌骨体部骨折在骨愈合的不同时期及采用不同的内固定方法固定时的应力分布进行分析，并以应力遮挡率表示应力遮挡作用的大小。
结果：1、建立了包括下颌骨皮质骨、松质骨及牙齿的下颌骨三维有限元模型，共有节点13320个，单元59932个；并进一步建立了右侧下颌骨体部骨折坚固内固定三维有限元模型，共有节点14256个，单元63758个；2、正中咬合时，下颌骨髁状突颈部、磨牙区、颏孔区、颏联合处以及下颌角是Von-Mises应力较大的区域。其中，髁状突颈部的Von-Mises应力最大，在皮质骨为8.333Mpa，松质骨为15.627 Mpa；3、小型接骨板坚固内固定，在骨折愈合的早期，单、双钢板固定时的应力遮挡率分别为98.90％、99.63％，钛板为98.65％、99.58％；在骨折愈合的中期，单、双钢板固定时的应力遮挡率分别为6.8％、22.96％，钛板为5.12％、20.99％；在骨折愈合的后期，单、双钢板固定时的应力遮挡率分别为5.73％、14.14％，钛板为4.47％、13.71％。
结论：1、在螺旋CT扫描及三维重建的基础上建立的下颌骨三维有限元模型具有较好的相似性，可用于各种工况的有限元分析，可作为今后深入研究的原始模型；2、功能状态下，下颌骨髁状突颈部、磨牙区、颏孔区、颏联
天津医科大学
硕士研究生学位论文
合处以及下领角是下领骨应力较为集中的区域;3、小型接骨板用于下领骨体
部骨折坚固内固定时，在骨折愈合的各个时期均存在明显的应力遮挡作用;
双板固定时的应力遮挡作用大于单板固定:接骨板材料的选择对应力遮挡作
用有影响，钢板的应力遮挡作用大于钦板;接骨板固定位置的选择对骨断层
的应力分布有重要的影响，本试验模拟的两种固定方法中，以双板固定下领
骨上下缘的临床效果较好。建议下领骨颊孔区体部骨折，以双板固定。
Object: Mandibular fractures are the most common injuries in
maxillofacial trauma,The use of rigid internal fixation for mandibular fractures had become progressively more popular in past thirty years.The purpose of this study was to establish a three-dimensional finite element model(3-D FEM) of dentulous mandible with better similarity for the research on stress distribution during clenching and rigid internal fixation (RIF) of mandibular fractures.The stress shielding effects were also evaluated so as to provide reference optimizing rigid internal fixation design.
Methods: A young female skull with normal occlusion was adopted for
CT scanned transverse section and then modern computer image processing system and the finite element software (Ansys 6.0) were used to take and analyse the data to establish the 3-D FEM of mandible.The clenching task in the intercuspal position were modeled. The regularity of stress distribution of mandibular body fracture under different conditions were then analysed during different period of bone healing. The value of stress shielding rate was used to represent the level of stress shielding effects.
Result: 1) A 3D-FEM of mandible including cortical bone,cancellous
bone and dentition was established, which consisted of 13,320 nodes and 59,932 elements.Then ,a 3D-FEM of rigid internal fixation for mandibular body fracture was also established, which consisted of 14,256 nodes and 63,758 elements. 2) There were higher Von-Mises stress at the neck of condyle, molar region,mental foramen region ,symphsis region and angle in the intercuspal position.In these sites,the Von-Mises stress at the neck of condyle was largest,which is 8.333Mpa
for cortical bone and 15.627 Mpa for cancellous bone; 3) When single and double steel miniplates were fixed respectively,the stress shielding rate were 98.90% , 99.63% and titanium miniplate 98.65% , 99.58% respectively during the earlier period of bone healing; the stress shielding rate of single and double steel miniplates were 6.8% , 22.96% and titanium miniplate 5.12% , 20.99% respectively during the middle period of bone healing; the stress shielding rate of single and double steel miniplates were 5.73% , 14.14% and titanium miniplate 4.47% , 13.71% respectively during the later period of bone healing.
Conclusion: 1) The above mentioned methods were proved to be
feasible in the Establishement of 3D-FEM of the dentulous mandible and could improve the biomechanical similarity of FEM of mandible effectively. The 3D-FEM could analyse the regularity of stress distribution of madibular fracture by using internal rigid fixation . 2) There were higher Von-Mises stress at the neck of condyle, molar region,mental foramen region ,symphsis region and angle under functional status. 3) The stress shielding effects definitely existed when miniplate rigid internal fixation system was chosen to treat mandibular body fractures. Stress shielding effects in the double-plated mandible were larger than that in the single-plated mandible in all time periods.The material of plate affected stress shilding effects. Stress shielding effects in the titanium-plated mandible were lower than that in the steel-plated mandible. The position of the plate also affected stress distribution of bone transverse section. In the two method of this trial ,the clinical effects were better when two miniplate
were fixed in superior border and inferior border. We suggest that two miniplate were used for mandibular body fracture.
方法：以正常咬合的青年女性尸头为标本，用螺旋CT断层扫描技术、图形数字化仪、ANSYS6.0有限元软件等方法在计算机上建立下颌骨三维有限元模型，对下颌骨体部骨折在骨愈合的不同时期及采用不同的内固定方法固定时的应力分布进行分析，并以应力遮挡率表示应力遮挡作用的大小。
结果：1、建立了包括下颌骨皮质骨、松质骨及牙齿的下颌骨三维有限元模型，共有节点13320个，单元59932个；并进一步建立了右侧下颌骨体部骨折坚固内固定三维有限元模型，共有节点14256个，单元63758个；2、正中咬合时，下颌骨髁状突颈部、磨牙区、颏孔区、颏联合处以及下颌角是Von-Mises应力较大的区域。其中，髁状突颈部的Von-Mises应力最大，在皮质骨为8.333Mpa，松质骨为15.627 Mpa；3、小型接骨板坚固内固定，在骨折愈合的早期，单、双钢板固定时的应力遮挡率分别为98.90％、99.63％，钛板为98.65％、99.58％；在骨折愈合的中期，单、双钢板固定时的应力遮挡率分别为6.8％、22.96％，钛板为5.12％、20.99％；在骨折愈合的后期，单、双钢板固定时的应力遮挡率分别为5.73％、14.14％，钛板为4.47％、13.71％。
结论：1、在螺旋CT扫描及三维重建的基础上建立的下颌骨三维有限元模型具有较好的相似性，可用于各种工况的有限元分析，可作为今后深入研究的原始模型；2、功能状态下，下颌骨髁状突颈部、磨牙区、颏孔区、颏联
天津医科大学
硕士研究生学位论文
合处以及下领角是下领骨应力较为集中的区域;3、小型接骨板用于下领骨体
部骨折坚固内固定时，在骨折愈合的各个时期均存在明显的应力遮挡作用;
双板固定时的应力遮挡作用大于单板固定:接骨板材料的选择对应力遮挡作
用有影响，钢板的应力遮挡作用大于钦板;接骨板固定位置的选择对骨断层
的应力分布有重要的影响，本试验模拟的两种固定方法中，以双板固定下领
骨上下缘的临床效果较好。建议下领骨颊孔区体部骨折，以双板固定。
Object: Mandibular fractures are the most common injuries in
maxillofacial trauma,The use of rigid internal fixation for mandibular fractures had become progressively more popular in past thirty years.The purpose of this study was to establish a three-dimensional finite element model(3-D FEM) of dentulous mandible with better similarity for the research on stress distribution during clenching and rigid internal fixation (RIF) of mandibular fractures.The stress shielding effects were also evaluated so as to provide reference optimizing rigid internal fixation design.
Methods: A young female skull with normal occlusion was adopted for
CT scanned transverse section and then modern computer image processing system and the finite element software (Ansys 6.0) were used to take and analyse the data to establish the 3-D FEM of mandible.The clenching task in the intercuspal position were modeled. The regularity of stress distribution of mandibular body fracture under different conditions were then analysed during different period of bone healing. The value of stress shielding rate was used to represent the level of stress shielding effects.
Result: 1) A 3D-FEM of mandible including cortical bone,cancellous
bone and dentition was established, which consisted of 13,320 nodes and 59,932 elements.Then ,a 3D-FEM of rigid internal fixation for mandibular body fracture was also established, which consisted of 14,256 nodes and 63,758 elements. 2) There were higher Von-Mises stress at the neck of condyle, molar region,mental foramen region ,symphsis region and angle in the intercuspal position.In these sites,the Von-Mises stress at the neck of condyle was largest,which is 8.333Mpa
for cortical bone and 15.627 Mpa for cancellous bone; 3) When single and double steel miniplates were fixed respectively,the stress shielding rate were 98.90% , 99.63% and titanium miniplate 98.65% , 99.58% respectively during the earlier period of bone healing; the stress shielding rate of single and double steel miniplates were 6.8% , 22.96% and titanium miniplate 5.12% , 20.99% respectively during the middle period of bone healing; the stress shielding rate of single and double steel miniplates were 5.73% , 14.14% and titanium miniplate 4.47% , 13.71% respectively during the later period of bone healing.
Conclusion: 1) The above mentioned methods were proved to be
feasible in the Establishement of 3D-FEM of the dentulous mandible and could improve the biomechanical similarity of FEM of mandible effectively. The 3D-FEM could analyse the regularity of stress distribution of madibular fracture by using internal rigid fixation . 2) There were higher Von-Mises stress at the neck of condyle, molar region,mental foramen region ,symphsis region and angle under functional status. 3) The stress shielding effects definitely existed when miniplate rigid internal fixation system was chosen to treat mandibular body fractures. Stress shielding effects in the double-plated mandible were larger than that in the single-plated mandible in all time periods.The material of plate affected stress shilding effects. Stress shielding effects in the titanium-plated mandible were lower than that in the steel-plated mandible. The position of the plate also affected stress distribution of bone transverse section. In the two method of this trial ,the clinical effects were better when two miniplate
were fixed in superior border and inferior border. We suggest that two miniplate were used for mandibular body fracture.
引文
1．张益，顾晓明．我国口腔颌面创伤外科的现状与展望．中华口腔医学杂志．2001，36(2)：88
2. Ferre JC, et al. The application of modern engineering methods to anatomical research. Anat Clin. 1982;4:189
3. Ferre JC, et al. A physicomathematical approach to the structure of the mandible. Anat Clin. 1984;6:45
4．徐勇忠，刘春丽，刘寒冰，等．人体下颌骨骨折的三维有限元分析．口腔医学纵横．1991，7(2)：100
5．薄斌，周树夏，曹建广，等．下颌骨在撞击作用下的力学响应特点．中华创伤杂志．1994，15(2)：93
6．薄斌，周树夏，曹建广，等．下颌骨在撞击载荷作用下的应力分布．第四军医大学学报．1999，20(2)：119
7．薄斌，周树夏，曹建广，等．撞击部位对下颌骨不同结构受力三维有限元分析．华西口腔医学杂志．2000，18(1)：67
8．周树夏，顾晓明．现代颌面创伤救治的基本原则．中华口腔医学杂志．2001，36(2)：85
9. Ikemura K. Osteosynthesis in facial bone fracture using miniplates:clinical and experimental studies. J Oral Maxillofac Surg. 1988;46:10
10. Kennady MC. Histomophometric evaluation of stress shielding in mandibular continuity defects treated with rigid fixation and bone grafts. J Oral Surg. 1989;18:170
11. Kennady MC. Stress shielding effect of rigid interal fixation
plates on mandibular bone grafts. Int J Oral Maxillofac Surg. 1989;18:307
12. Fernandez JR, Gallas M, Burguera M, et al.A three-dimensional numerical simulation of mandible fracture reduction with screwed miniplates. J Biomech. 2003;36(3):329
13．沈金根，吴曹宝，徐小明，等．人类下颌骨的力学模型．解剖学报．1987，18(1)：1
14. Faulkner G, Hatcher D, Hay A. A three dimensional investigation of TMJ loading.J Biomechanics. 1987;20:99
15．李凤和 梁建术，王永海，等．下颌骨应力分布的三维有限元分析，现代口腔医学杂志．1998，12(1)：30
16．卢军，斯方杰，李明，等．下颌骨坚固内固定应力遮挡作用的有限元分析．口腔颌面外科杂志．1995，5(1)：23
17．胡凯，周续林，洪民，等．建立模拟功能状态下的下颌骨三维有限元模型．中华颌面外科杂志．1997，7(3)：183
18. Korioth TW, Romilly DP, Hannam AG. Three-dimensional finite element stress analysis of the dentate human mandible. Am J Phy Anthropol. 1992; 88(1): 69
19. Korioth TW, Hannam AG. Mandible forces during simulated tooth clenching. J Orofac Pain. 1994; 8(2):178
20. Korioth TW, Hannam AG. Deformation of the human mandible during simulated tooth clening. J Dent Res. 1994 ;73(1):56
21．周学军，赵志河，赵美英，等．下颌骨三维有限元模型的边界约束设计．华西口腔医学杂志．1999，17(1)：29
22. RuddermanRH, Mullen RL. Biomechanics of the facial skeleton. Clin Plast Surg. 1992;19:11
23. Wagner A, Krach W, Schicho K, et al. A 3-dimensional finite-element
analysis investigating the biomechanical behavior of the mandible and plate osteosynthesis in cases of fractures of the condylar process. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2002:94(6):678
24．向喜林，张永福，刘路平，等．下颌骨体部骨折坚固内固定的三维有限元分析．中华口腔医学杂志．1995，30(2)：95
25. Maurer P, Schubert J, Holweg S. Finite element analysis of a tandem screw configuration in sagittal split osteotomy using biodegradable osteosynthesis screws. Int J Adult Orthodon Orthognath Surg. 2001;16(4):300
26. Maurer P, Holweg S, Knoll WD, et al. Study by finite element method of the mechanical stress of selected biodegradable osteosynthesis screws in sagittal ramus osteotomy. Br J Oral Maxillofac Surg. 2002;40(1):76
27. Jones JK. Rigid fixation :a review of concepts and treatment of fracture. J Oral Surg. 1988;65:13
28．林野，王兴，尹彪，等．下颌骨骨折的小型钛板坚固内固定技术．中华口腔医学杂志．2000，35(2)：85
29. Hart RT, Hennebel VV, Thongpreda N, et al. Modeling the biomechanics of the mandible:a three-dimensional finite element study. J Biomech. 1992;25(3):261
30. Batenberg RH, Raghoebar GM, et al. Madibular overdentures supported by two or four endosteal implant. A prospective, comparative study. Int J Oral-Maxillo-fac Surg. 1998:27(6):435
31. Rieger MR, Fareed K, Adams WK et al. Bone stress distribution for three endussous implant. J Prosthet Dent. 1989; 61:223
32．陈治清．口腔材料学．人民卫生出版社．1995，174-175
33．赵云凤主编．口腔生物力学．北京：北京医科大学-中国协和医科大学联合出版社．1996，58
34．皮昕．口腔解剖生理学，第四版．人民卫生出版社．1999，193
35. Osborn JW, Baragar FA. Predicted pattern of human muscle activity during clenching derived from a computer assisted model:Symmetric bite force. J Biomechanics. 1985;18:599
36．刘路平，由敬舜，徐剑青，等．五种咬合情况下颞下颌关节负荷的三维有限元分析．中华口腔医学杂志．1994，29：368
37．程杰等．股骨-接骨板系统对外载荷反应的力学分析．生物医学工程学杂志．1986，3：86
38．袁旬华等．接骨板内固定的三维有限元分析．生物力学研究和应用．华南理工大学出版社．1990，396
39. Tanne K, Tanaka E, Sakuda M. Stress distribution in the TMJ during clenching in patients with vertical discrepancies of the craniofacial complex. J Orofacial Pain. 1995;9:153
40．徐剑青，由敬舜．下颌骨骨折的有限元分析．上海生物医学工程．1994，3：8
41．张益．下颌骨骨折治疗．北京医科大学-中国协和医科大学联合出版社．1993，76
42. Yerit KC, Enislidis G, Schopper C et al. Fixation of mandibular fractures with biodegradable plates and screws. Oral Surg Oral Med Oral Pathol Oral Radiol Endod .2002;94(3):294
43. Tomita N, Kutsuna T, Tamai S et al. Mechanical effects of a cushioned plate on bone fixation. Biomed Mater Eng 1991:1(4):243
44. Patel MF, Langdon JD. Titanium mesh (TiMesh) osteosynthesis: a fast and adaptable method of semi-rigid fixation. Br J Oral Maxillofac Surg. 1991;29(5):316
45． Thaller SR,Huang V,Tesluk H.Use of biodegradable plates and screws in a rabbit model.J Craniofac Surg.1992;2(4) :168
46． Islamoglu K,Coskunfirat OK,Tetik G,et al.Complications and removal rates of miniplates and screws used for maxillofacial fractures.Ann Plast Surg.2002:48(3) :265
2. Ferre JC, et al. The application of modern engineering methods to anatomical research. Anat Clin. 1982;4:189
3. Ferre JC, et al. A physicomathematical approach to the structure of the mandible. Anat Clin. 1984;6:45
4．徐勇忠，刘春丽，刘寒冰，等．人体下颌骨骨折的三维有限元分析．口腔医学纵横．1991，7(2)：100
5．薄斌，周树夏，曹建广，等．下颌骨在撞击作用下的力学响应特点．中华创伤杂志．1994，15(2)：93
6．薄斌，周树夏，曹建广，等．下颌骨在撞击载荷作用下的应力分布．第四军医大学学报．1999，20(2)：119
7．薄斌，周树夏，曹建广，等．撞击部位对下颌骨不同结构受力三维有限元分析．华西口腔医学杂志．2000，18(1)：67
8．周树夏，顾晓明．现代颌面创伤救治的基本原则．中华口腔医学杂志．2001，36(2)：85
9. Ikemura K. Osteosynthesis in facial bone fracture using miniplates:clinical and experimental studies. J Oral Maxillofac Surg. 1988;46:10
10. Kennady MC. Histomophometric evaluation of stress shielding in mandibular continuity defects treated with rigid fixation and bone grafts. J Oral Surg. 1989;18:170
11. Kennady MC. Stress shielding effect of rigid interal fixation
plates on mandibular bone grafts. Int J Oral Maxillofac Surg. 1989;18:307
12. Fernandez JR, Gallas M, Burguera M, et al.A three-dimensional numerical simulation of mandible fracture reduction with screwed miniplates. J Biomech. 2003;36(3):329
13．沈金根，吴曹宝，徐小明，等．人类下颌骨的力学模型．解剖学报．1987，18(1)：1
14. Faulkner G, Hatcher D, Hay A. A three dimensional investigation of TMJ loading.J Biomechanics. 1987;20:99
15．李凤和 梁建术，王永海，等．下颌骨应力分布的三维有限元分析，现代口腔医学杂志．1998，12(1)：30
16．卢军，斯方杰，李明，等．下颌骨坚固内固定应力遮挡作用的有限元分析．口腔颌面外科杂志．1995，5(1)：23
17．胡凯，周续林，洪民，等．建立模拟功能状态下的下颌骨三维有限元模型．中华颌面外科杂志．1997，7(3)：183
18. Korioth TW, Romilly DP, Hannam AG. Three-dimensional finite element stress analysis of the dentate human mandible. Am J Phy Anthropol. 1992; 88(1): 69
19. Korioth TW, Hannam AG. Mandible forces during simulated tooth clenching. J Orofac Pain. 1994; 8(2):178
20. Korioth TW, Hannam AG. Deformation of the human mandible during simulated tooth clening. J Dent Res. 1994 ;73(1):56
21．周学军，赵志河，赵美英，等．下颌骨三维有限元模型的边界约束设计．华西口腔医学杂志．1999，17(1)：29
22. RuddermanRH, Mullen RL. Biomechanics of the facial skeleton. Clin Plast Surg. 1992;19:11
23. Wagner A, Krach W, Schicho K, et al. A 3-dimensional finite-element
analysis investigating the biomechanical behavior of the mandible and plate osteosynthesis in cases of fractures of the condylar process. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2002:94(6):678
24．向喜林，张永福，刘路平，等．下颌骨体部骨折坚固内固定的三维有限元分析．中华口腔医学杂志．1995，30(2)：95
25. Maurer P, Schubert J, Holweg S. Finite element analysis of a tandem screw configuration in sagittal split osteotomy using biodegradable osteosynthesis screws. Int J Adult Orthodon Orthognath Surg. 2001;16(4):300
26. Maurer P, Holweg S, Knoll WD, et al. Study by finite element method of the mechanical stress of selected biodegradable osteosynthesis screws in sagittal ramus osteotomy. Br J Oral Maxillofac Surg. 2002;40(1):76
27. Jones JK. Rigid fixation :a review of concepts and treatment of fracture. J Oral Surg. 1988;65:13
28．林野，王兴，尹彪，等．下颌骨骨折的小型钛板坚固内固定技术．中华口腔医学杂志．2000，35(2)：85
29. Hart RT, Hennebel VV, Thongpreda N, et al. Modeling the biomechanics of the mandible:a three-dimensional finite element study. J Biomech. 1992;25(3):261
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