Temporomandibular joint

TMJ in dentistry. periodontology

1. TEMPOROMANDIBULAR JOINT Dr Bhaumik Thakkar MDS-Part 1. Dept. Of Periodontology and Implantology .

2. INTRODUCTION The most important functions of the temporomandibular joint (TMJ) are mastication and speech and are of great interest to dentists, orthodontists, clinicians, and radiologists . The TMJ is a ginglymoarthrodial joint, a term that is derived from ginglymus , meaning a hinge joint, allowing motion only backward and forward in one plane, and arthrodia , meaning a joint of which permits a gliding motion of the surfaces.

3. Temporomandibular joint Only mobile joint of skull formed between head of mandible and articular fossa of temporal bone.

4. Peculiarity of TMJ Bilateral diarthrosis – right & left function together Articular surface covered by fibrocartilage - instead of hyaline cartilage Only joint in human body to have a rigid endpoint of closure (that of the teeth making occlusal contact) .

5. In contrast to other diarthrodial joints TMJ is last joint to start develop in- about 7 th week in utero. Develops from two distinct blastema . i ) Temporal. ii) Condylar .

6. Ligaments Fibrous capsule Articular disc Lateral ligament of jaw Sphenomandibular ligament Stylomandibular ligament

7. Fibrous capsule Above to the anterior edge of the preglenoid plane. P osteriorly to the squamotympanic fissure, between these to the edges of the articular fossa . Below to the periphery of the neck of the mandible.

8. Articular disc Fibrocartilaginous disc dividing joint cavity in upper and lower compartment. Shape: Oval Makes articular surface congruent. In sagittal section- a thin intermediate zone and thickened anterior and posterior bands, and its upper surface appears concavo-convex. Posteriorly - Attached to a region of loose vascular and nervous tissue which splits into two laminae , the bilaminar region.

9. Functions of Articular disc S tabilize the TMJ. Makes articular surfaces congruent. R educe wear of TMJ. A id lubrication of the joint.

10. Lateral ligament of Jaw Attached above to the articular tubercle on the root of the zygomatic process of the temporal bone. It extends downwards and backwards at an angle of 45° to the horizontal, to attach to the lateral surface and posterior border of the neck of the condyle , deep to the parotid gland. Function: T o prevent posterior displacement of the resting condyle .

11. Sphenomandibular ligament M edial to, and normally separate from, the capsule. It is a flat, thin band that descends from the spine of the sphenoid . Widens at the lingula of the mandibular foramen. This part is a vestige of the dorsal end of Meckel's cartilage . It is separated from the pharynx by fat and a pharyngeal vein.

12. Stylomandibular ligament A thickened band of deep cervical fascia that stretches from the apex and adjacent anterior aspect of the styloid process to the angle and posterior border of the mandible. Along with sphenomandibular ligament it is responsible for limitation of mandibular movement.

13. Blood supply & Innervation Auriculotemporal nerve maxillary artery Masseteric nerve Superficial temporal artery Arterial supply : Superficial temporal artery laterally and the maxillary artery medially. Nerve supply: Masseteric and auriculotemporal nerves

14. VASCULARIZATION Predominant vessals supplying tmj are : Superficial temporal artery from the posterior Middle meningeal artery from the anterior Internal maxillary artery from the inferior

15. HISTOLOGY OF ARTICULAR SURFACE OF TMJ

16. The Articular zone Dense fibrous connective tissue Poor blood supply Better ability to repair Good adaption to sliding movement Shock absorber Less susceptible to the effect of aging time & breakdown over time.

17. 2. The proliferative zone Mainly cellular zone Undifferentiated mesenchymal cells Proliferation & regeneration throughout life

18. 3. The cartilagenous zone Collagen fibers arranged in criss -cross pattern of bundles Fibrocartilage appears in a random orientation, providing a three-dimensional network that offers resistance against compressive and lateral forces. Offers considerable resistance against compressive & lateral forces But becomes thinner with age.

19. 4. The calcified zone Deepest zone Chondrocytes , chondroblasts & osteoblasts Active site for remodeling activity as bone growth proceeds.

20. Movements of TMJ Rotational / hinge movement in first 20-25mm of mouth opening Translational movement after that when the mouth is excessively opened.

21. Muscles involved in movement. Depression Lateral pterygoid , Digastric , Geniohyoid , Mylohyoid . Elevation Temporalis , Masseter , Medial pterygoid . Protrusion Medial pterygoid , lateral pterygoid . Retraction Posterior fibres of temporalis .

22. Age changes of the TMJ: Condyle: Becomes more flattened Fibrous capsule becomes thicker. Osteoporosis of underlying bone. Thinning or absence of cartilaginous zone. Disk: Becomes thinner. Shows hyalinization and chondroid changes. Synovial fold: Become fibrotic with thick basement membrane. Blood vessels and nerves: Walls of blood vessels thickened. Nerves decrease in number

23. A ge changes lead to: Decrease in the synovial fluid formation Impairment of motion due to decrease in the disc and capsule extensibility Decrease the resilience during mastication due to chondroid changes into collagenous elements Dysfunction in older people

24. Symmetrical opening A ssociated with preparation for incising. At the start, each mandibular condyle rotates in the lower joint compartment inside the annulus of its disc. After a few degrees of opening, the condyle continues rotating inside its disc, and, in addition, both slide forward down the articular eminence of the upper joint compartment. Without this forward slide, it rapidly becomes impossible to continue opening the jaw.

25. Eccentric jaw opening Preparation for power stroke of mastication. Condyle on the non-working side slide back and forth during lateral movements. Temporomandibular and Sphenomandibular ligament keep condyle firmly against articular eminence.

26. Eccentric and symmetrical jaw closing Jaw closing muscles have a component of force that forces joint surfaces together. Joint tissues compressed- ligaments shortened- no constraint on movements. Non-working condyle moves further and is most heavily loaded during power stroke.

27. Temporomandibular J oint Disorder

28. Various terms have been used to describe disturbances of the masticatory system. 1934 James costen described group of symptoms centering around ear and TMJ- Costen syndrome . 1959 Shore introduced TMJ Dysfunction Ash & Ramfjord - functional TMJ disturbances Terminology

29. Limited nature of these terms lead to a broader term- Craniomandibular disorders. Bell coined the term Temporomandibular disorders. Describes both problems associated with the joint & disturbances associated with function of masticatory system.

30. Event Events can be either local or systemic. Local: a change in proprioceptive input e.g improper crown. Can be secondary to trauma- too wide opening of mouth; unaccustomed use- bruxism .

31. Also deep pain input- alters muscle function by way of central excitatory effects. Systemic events; that alter normal function occurs at a systemic level; emotional stress.

32. Physiologic tolerance Influenced by local and systemic factors. Local: orthopedic stability - relation between mandible and maxilla- good stability; mandible closes with the condyles in their most superior and anterior position against posterior slopes of articular eminence- even contact of all possible teeth. Here masticatory system is best able to tolerate local and systemic events.

33. Poor stability: one way by which occlusal condition influences symptoms associated with TMD. Instability can be in occlusion/joints/both. Can be genetic/developmental/iatrogenic. Also related to alterations in normal anatomic form .

34. Systemic: multiple systemic factors influence physiologic tolerance; genetic/gender diet/chronic & acute diseases.

35. Etiologic considerations for TMD . 5 major factors associated with TMD Occlusal condition: Trauma Emotional stress Deep pain input Para-functional activities.

36. Occlusal condition Excessive load on the system due to orthopedic instability may lead to intracapsular disorders. 2 factors that determine it are: degree of instability and amount of loading. Changes can be acute/ sudden or chronic.

37. Trauma Macro and micro Macro: sudden face that can result in structural alterations. Eg blow to face. Micro : small force applied repeatedly to structures over a long periods. Bruxism/ clenching.

38. Deep pain input . Centrally excites a brainstem – produces muscle response- protective co-contraction. Functional disorders of masticatory system 2 symptoms: Pain and dysfunction.

39. In case of presence of pain. Evaluated based on chief complaint Questions asked Chief complaint. Location of pain. Onset of pain. Associated factors. Progression.

40. C . Characterstics of pain Quality Behavior Temporal Duration Localization. 3 . Intensity of pain Concomitant symptoms. Flow of pain.

41. D . Aggrevating and alleviating factors Function and parafunction Physical modalities Medications Emotional stress Sleep disturbances E . Past consulations or treatment II Medical history III. Review of systems

42. Interpretation; 0- no pain or tenderness 1- uncomfortable on palpation 2- definite discomfort 3- eye tearing/ extreme discomfort

43. Tmj palpation : digital palpation of joint with mandible in both static and dynamic positions. Finger tips are placed over the lateral aspects of joint areas- lateral poles of condyles passing downward and forward felt. joint sounds: Clicks / crepitation

44. Click is a single sound of short duration; if relatively loud referred to as POP. Crepitation – multiple gravel like sound – grating and complicated Can be done using digits / stethoscope.

45. TMJ DISLOCATION The mandible can dislocate in the anterior, posterior, lateral, or superior position. Anterior dislocations are the most common These dislocations are classified as acute, chronic recurrent, or chronic TMJ dislocation may occur with trauma, extreme opening of the mouth during yawning, laughing, singing, vomiting, or dental treatment . Symmetric mandibular dislocation is most common, but unilateral dislocation with the jaw deviating to the opposite side also can occur. TMJ dislocation is painful and frightening for the patient.

46. TMJ DISLOCATION….

47. TMJ ANKYLOSIS Ankylosis of the TMJ most often results from trauma or infection. True bilateral congenital ankylosis of the TMJ leads to micrognathia or “bird face”. If ankylosis affects only one side, it produces a lateral deviation of the jaw to the non-affected side, due to the fact that this side continues its growth normally.

48. LAB INVESTIGATIONS 1.Blood tests: ESR, CRP for inflammation. 2.Plain radiographs - show gross bony pathology such as degeneration or trauma. 3.CT or MRI scan of the joint. MRI scan shows the soft tissues and intra- articular disc well. 4.Ultrasound - this is a useful alternative imaging technique for monitoring TMJ disorders. 5.Diagnostic nerve block. 6.Arthroscopy.

49. Management.

50. Conservative reversible therapy . Counsel Exercise Physical therapy Medications Appliances Selective Grinding Non conservative irreversible therapy . High Condylectomy Meniscectomy Disectomy Orthodontic surgery High Condylotomy Hyaluronic acid Reconstruction Arthrocentisis Long term studies for TMD treatment have given 2 kinds of approaches ;

51. Definitive treatment Occlusal conditions - occlusal therapy( occlusal splint) Reversible-stabilization appliance Irreversible – selective grinding, restorative procedures. Emotional Stress: Restrictive use, Voluntary avoidance, Relaxation therapy.

52. Supportive therapy Directed toward the reduction of pain and dysfunction. Pharmacologic or Physical therapy. Pharmacologic : Analgesics NSAIDs Corticosteroids Muscle relaxants Antidepressants.

53. Physical therapy. Group of supportive actions, usually instituted as an adjunct to definitive treatment. 2 types- Modalities & Manual techniques Modalities : Thermotherapy, ultrasound , phonophoresis , iontophoresis , laser Manual techniques : provided by physical therapist; 3 types- soft tissue & joint mobilization, muscle conditioning.

54. Temporomandibular joint surgery: what does it mean to the dental practitioner In March 2011, G Dimitroulis in vincents hospital melbourne assesed why dental practioners should be aware of benefits and risks of TMJ surgeries. They concluded that a ll dental practitioners should be aware of the benefits of TMJ surgery so that patients do not suffer unnecessarily from ongoing non-surgical treatments that ultimately prove to be ineffective in the management of their condition.

55. Temporomandibular joint problems and periodontal condition in rheumatoid arthritis patients In December 2011, Garib BT1 and Qaradaxi SS in College of Dentistry, University of Sulaimani , Kurdistan assesedTemporomandibular joint problems and periodontal condition in rheumatoid arthritis patients in relation to their rheumatologic status. They took plaque index, bleeding index, clinical attachment loss, radiographic bone loss, tooth loss, and TMJ problems were assessed in the 2 groups. They concluded that Patients with advanced RA are more likely to develop more significant periodontal and TMJ problems compared with patients with PD and without RA. There is a great need to instruct patients with RA to consult a dentist to at least decrease PD severity.

56. CONCLUSION It is impossible to comprehend the fine points of occlusion without an in depth awareness of anatomy ,physiology ,and biomechanics of the TMJ . The first requirement for successful occlusal treatment is stable, comfortable TMJ . The jaw joints must be able to accept maximum loading by the elevator muscles with no signs of discomfort . It is only through an understanding of how the normal, healthy TMJ functions that we can make sense out of what is wrong when it isn't functioning comfortably . This understanding of TMJ is foundational to diagnosis and treatment .

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