Biomechanics of TMJ,Tongji University,Anatomy of TMJ,Mandibular condyle Joint surface of temporal bone Articular disc TMJ capsule TMJ ligament,Anatomy of TMJ,Mandibular condyle Joint surface of temporal bone Articular disc TMJ capsule TMJ ligament,Muscle tissue related to TMJ,Lateral pterygoid muscle Upper side & lower side Function,HEAVY LOAD BUT HYPOPLASIA,BIOMECHANICS OF TMJ,BIOMECHANICS OF TMJ,What is biomechanics Concepts: viscoelastic body; relaxation; creep Mechanical property of collagen & elastic fiber,concept,creep,relaxation,FUNCTION MOVEMENT & BIOMECHANICS OF TMJ,Opening and holding,Important balance: Upper side of lateral pterygoid & upper fiber of bilaminar zone,Movement mechanism of joint disc: Shape of disc & Pressure in joint,FUNCTIONAL MOVEMENT AND BIOMECHANICS OF TMJ,Opening and holding,Normal： anterior bevel of condyle & intermediate of disc & posterior bevel of joint node one plane,FUNCTIONAL MOVEMENT AND BIOMECHANICS OF TMJ,Chewing process,Movement mechanism of joint disc: Shape of disc & Pressure in joint,Working side,Balance side,Balance side,Working side,BIOMECHANICS OF CARTILAGE IN TMJ,BIOMECHANICS OF CARTILAGE IN TMJ,Structure of cartilage,Cartilage basementCartilage cell：0.01-0.1,H2O Collagen ： Protein polysaccharide： Structural glycoprotein,Articular cartilage viscoelastical two phase mixture, Theory of solidliquid phase porous viscoelastic body,Unload,BIOMECHANICS OF CARTILAGE IN TMJ,Normal,Loading,Stress cushioning system of cartilage,BIOMECHANICS OF CARTILAGE IN TMJ,Bone substance of condyle,Shallow level,Middle level,Deep level,synovia,pression,collagen- Protein polysaccharide gel grid structure system,Function of cartilage: bearing; stress dispersion; stress cushioning; joint lubrication,Cartilage,Lubrication of cartilage,BIOMECHANICS OF CARTILAGE IN TMJ,Boundary lubricationFluid film lubrication （weeping / pression infiltration ）,Hydroaulic static Hydroaulic motive ,Joint lubrication related to synovia & structure and mechanics of cartilage & motion state of cartilage,BIOMECHANICS OF DISC AND POSTIOR-DISC TISSUE,BIOMECHANICS OF DISC AND POSTIOR-DISC TISSUE,Jiont disc,Viscoelastic body: Low permeability & high compression rigidity,Stress concentration buffer: transfer; stress dispersion; short cushioning,Postior-disc tissue,BIOMECHANICS OF DISC AND POSTIOR-DISC TISSUE,A High compliance fiberous connective tissue,Elastic fiber grid systemThin and loosen collagen fiber A; V; N; lymph; fat,Viscoelastics Obvious relaxation High permeability Low tension strength High passive deformability,Disc move forward; multiple perforation in postior area of disc,Counterbalance to upper side of lateral pterygoid muscle,BIOMECHANICS OF CAPSULE AND LIGAMENT OF TMJ,BIOMECHANICS OF CAPSULE AND LIGAMENT OF TMJ,Lateral position of TMJ,Post position of TMJ,BIOMECHANICS OF CAPSULE AND LIGAMENT OF TMJ,Ligament - bearing high tension load Capsule - adapt to multiway tensile loading; stress dispersion; production and transfer of synovia,TMJ capsule,Joint ligament,Stability of TMJ,assistant,REMODELING OF TMJ,REMODELING OF TMJ,ConceptDevelopment of TMJ: 20ys, remodeling in all lifetimeRemodelingRetrograde remodeling : anterior-lateral incline of condyle & posterior-lateral incline of joint node,Progressive ：hyperplasia - condyleRetrograde ：absorption condyle; disc; node,REMODELING OF HARD TISSUES IN TMJ,Slight periodical load progressive remodeling2。 Heavy load & long time remodeling ceaseretrograde remodeling destroy of structure and function,REMODELING OF SOFT TISSUES IN TMJ,Soft tissues connective tissue zone; proliferative zone; fibrous cartilage zone Important part: soft tissue on condyle Remodeling： loadformation of cartilageAims: adapt to the needs of function.,proliferation and polarization,REMODELING OF JOINT CARTILAGE : abrasion and djd,Normal:Periodical load = swelling pressure(in collagen- Protein polysaccharide- gel grid system)Abnormal load system deformation cytoclasis; destroy of collagen Immunoreaction exposure of bone tissue under cartilage stimulate symptom (pain; spasm etc.) fibrosis rigidity of TMJ,Thanks,