1、Biomechanics of TMJTongji University.Anatomy of TMJAnatomy of TMJ Mandibular condyle Joint surface of temporal bone Articular disc TMJ capsule.Anatomy of TMJ TMJ capsule.Muscle tissue related to TMJ Lateral pterygoid muscle Upper side & lower side FunctionHEAVY LOAD BUT HYPOPLASIA.BIOMECHANICS OF TM
2、J.BIOMECHANICS OF TMJ What is biomechanics Concepts: viscoelastic body; relaxation; creep Mechanical property of collagen & elastic fiber.conceptcreeprelaxation.FUNCTION MOVEMENT & BIOMECHANICS OF TMJ Opening and holding Important balance:Upper side of lateral pterygoid & upper fiber of bilaminar zo
3、neMovement mechanism of joint disc:Shape of disc & Pressure in joint.FUNCTIONAL MOVEMENT AND BIOMECHANICS OF TMJ Opening and holdingNormal：anterior bevel of condyle & intermediate of disc & posterior bevel of joint node one planeOpeningHoldingRest position.FUNCTIONAL MOVEMENT AND BIOMECHANICS OF TMJ
4、 Chewing processMovement mechanism of joint disc: Shape of disc & Pressure in jointWorking sideBalance side Balance side Working side.BIOMECHANICS OF CARTILAGE IN TMJ.BIOMECHANICS OF CARTILAGE IN TMJStructure of cartilageCartilage basementCartilage cell：0.01-0.1H2OCollagen ：Protein polysaccharide：St
5、ructural glycoprotein.Articular cartilage viscoelastical two phase mixture Theory of solidliquid phase porous viscoelastic bodyUnloadBIOMECHANICS OF CARTILAGE IN TMJNormalLoading.Stress cushioning system of cartilageBIOMECHANICS OF CARTILAGE IN TMJBone substance of condyleShallow levelMiddle levelDe
6、ep levelsynoviapressioncollagen- Protein polysaccharide gel grid structure systemFunction of cartilage: bearing; stress dispersion; stress cushioning; joint lubricationCartilageCartilage.Lubrication of cartilageBIOMECHANICS OF CARTILAGE IN TMJBoundary lubricationFluid film lubrication（weeping / pres
7、sion infiltration ）Hydroaulic static Hydroaulic motive Joint lubrication related tosynovia & structure and mechanics of cartilage & motion state of cartilage .BIOMECHANICS OF DISC AND POSTIOR-DISC TISSUE.BIOMECHANICS OF DISC AND POSTIOR-DISC TISSUEJiont discViscoelastic body:Low permeability & high
8、compression rigidityStress concentration buffer:transfer; stress dispersion; short cushioning.Postior-disc tissueBIOMECHANICS OF DISC AND POSTIOR-DISC TISSUEA High compliance fiberous connective tissueElastic fiber grid systemThin and loosen collagen fiberA; V; N; lymph; fatViscoelasticsObvious rela
9、xationHigh permeabilityLow tension strengthHigh passive deformabilityDisc move forward; multiple perforation in postior area of discCounterbalance to upper side of lateral pterygoid muscle.BIOMECHANICS OF CAPSULE AND LIGAMENT OF TMJ.BIOMECHANICS OF CAPSULE AND LIGAMENT OF TMJLateral position of TMJP
10、ost position of TMJ.BIOMECHANICS OF CAPSULE AND LIGAMENT OF TMJLigament - bearing high tension loadCapsule - adapt to multiway tensile loading; stress dispersion; production and transfer of synoviaTMJ capsuleJoint ligamentStability of TMJassistant. REMODELING OF TMJ.REMODELING OF TMJConceptDevelopme
11、nt of TMJ: 20ys, remodeling in all lifetimeRemodelingRetrograde remodeling : anterior-lateral incline of condyle & posterior-lateral incline of joint nodeProgressive ：hyperplasia - condyleRetrograde ：absorption condyle; disc; node.REMODELING OF HARD TISSUES IN TMJ Slight periodical load progressive
12、remodeling2。 Heavy load & long time remodeling cease retrograde remodeling destroy of structure and function.REMODELING OF SOFT TISSUES IN TMJSoft tissues connective tissue zone; proliferative zone; fibrous cartilage zoneImportant part: soft tissue on condyleRemodeling： load formation of cartilageAi
13、ms: adapt to the needs of function.proliferation and polarization.REMODELING OF JOINT CARTILAGE : abrasion and djdNormal: 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.ThanksThanks.
