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Biomechanics of TMJ Tongji University. Anatomy of TMJ  Mandibular condyle  Joint surface of temporal bone  Articular disc  TMJ capsule  TMJ ligament.

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Presentation on theme: "Biomechanics of TMJ Tongji University. Anatomy of TMJ  Mandibular condyle  Joint surface of temporal bone  Articular disc  TMJ capsule  TMJ ligament."— Presentation transcript:

1 Biomechanics of TMJ Tongji University

2 Anatomy of TMJ  Mandibular condyle  Joint surface of temporal bone  Articular disc  TMJ capsule  TMJ ligament

3 Anatomy of TMJ  Mandibular condyle  Joint surface of temporal bone  Articular disc  TMJ capsule  TMJ ligament

4 Muscle tissue related to TMJ  Lateral pterygoid muscle  Upper side & lower side  Function HEAVY LOAD BUT HYPOPLASIA

5 BIOMECHANICS OF TMJ

6  What is biomechanics  Concepts: viscoelastic body; relaxation; creep  Mechanical property of collagen & elastic fiber

7 concept creep relaxation

8 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

9 FUNCTIONAL MOVEMENT AND BIOMECHANICS OF TMJ  Opening and holding Normal : anterior bevel of condyle & intermediate of disc & posterior bevel of joint node — one plane Opening Holding Rest position

10 FUNCTIONAL MOVEMENT AND BIOMECHANICS OF TMJ  Chewing process Movement mechanism of joint disc: Shape of disc & Pressure in joint Working side Balance side Working side

11 BIOMECHANICS OF CARTILAGE IN TMJ

12  Structure of cartilage Cartilage basement Cartilage cell : % H 2 O Collagen : Protein polysaccharide : Structural glycoprotein

13 Articular cartilage - viscoelastical two phase mixture ★ Theory of solid - liquid phase porous viscoelastic body Unload BIOMECHANICS OF CARTILAGE IN TMJ NormalLoading

14  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

15  Lubrication of cartilage BIOMECHANICS OF CARTILAGE IN TMJ Boundary lubrication Fluid film lubrication ( weeping~ / pression infiltration ~ ) Hydroaulic static ~ Hydroaulic motive ~ Joint lubrication related to synovia & structure and mechanics of cartilage & motion state of cartilage

16 BIOMECHANICS OF DISC AND POSTIOR-DISC TISSUE

17  Jiont disc Viscoelastic body: Low permeability & high compression rigidity Stress concentration buffer: transfer; stress dispersion; short cushioning

18  Postior-disc tissue BIOMECHANICS OF DISC AND POSTIOR-DISC TISSUE A High compliance fiberous connective tissue Elastic fiber grid system Thin 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 ×

19 BIOMECHANICS OF CAPSULE AND LIGAMENT OF TMJ

20 Lateral position of TMJ Post position of TMJ

21 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 capsuleJoint ligament Stability of TMJ assistant

22 REMODELING OF TMJ

23  Concept  Development of TMJ: 20ys, remodeling in all lifetime  Remodeling  Retrograde remodeling : anterior-lateral incline of condyle & posterior-lateral incline of joint node Progressive ~ : hyperplasia - condyle Retrograde ~ : absorption – condyle; disc; node

24 REMODELING OF HARD TISSUES IN TMJ 1. Slight periodical load progressive remodeling 2 。 Heavy load & long time remodeling cease retrograde remodeling destroy of structure and function

25 REMODELING OF SOFT TISSUES IN TMJ  Soft tissues - connective tissue zone; proliferative zone; fibrous cartilage zone  Important part: soft tissue on condyle  Remodeling : load formation of cartilage  Aims: adapt to the needs of function. proliferation and polarization

26 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

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