TMD and Malocclusion

1. 1 Temporomandibular joint dysfunction Temporomandibular joint dysfunction and malocclusion and malocclusion Prepared by: Prepared by: Dr Mohammed Alruby Dr Mohammed Alruby TMD and Malocclusion TMD and Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

2. 2 The effect of malocclusion on TMJ has been a matter of controversy since many years, the problem is often related to the path of mandibular closure from the initial contact to centric occlusion It has been noted that, the path of mandibular closure from rest position to initial contact is essentially normal in most pt, the most of difference occurs from the point of initial contact to centric occlusion In normal individual, the rest position, centric relation, initial contact and centric occlusion should be coincident. However, malocclusion may provide a change in the initial contact position because of the premature points of contact and teeth guidance problems, the mandible may be shift from the ideal acclusal to the usual occlusal position. Arc of closure: = the mandible usually closes with lower incisors follow an arc in upward and forward direction. This arc of closure is abruptly disturbed at the point of initial contact of prematurity or teeth guidance problem exist. This arc of closure may become vertical, upward and backward or lateral shift depending on the type of tooth guidance. Since, the articular disc is held in its position by the external pterygoid muscle which prevent it from being further retruded. In some cases, such as Class II divi 2 when the mandible closed, it will be guided backward by the effect of retroclined maxillary incisors. The condyle forced upward and backward, and may rides the posterior tip of articular disc and in some instances become imping on the post articular connective tissues. Initiation of the opening movement may result in: 1-The articular disc pulled forward by contraction of external pterygoid muscle and the condyles snap over the disc periphery against the post articular connective tissue. Then the condyle starting late but moving forward rapidly, riding over the posterior margin of the disc into more normal position. 2-The posteriorly displaced condyle, move forward riding over the posterior lip of the disc In all instances, snap or pop sensation is felt by the patient, pain or limitation of movement may or may not occur depending upon the type of disharmony and resistance of patient Definition: TMD: disorders with common signs and symptoms affecting the joint, facial muscles or both : limited opening of mandible < 40mm in males and <45mm in females : Joint noise and pain, tender muscle of mastication, popping or tinnitus of the ears, and headaches Etiology: -Multifactorial -Inflammatory -Degenerative -Dysfunction -Idiopathic TMD and Malocclusion TMD and Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

3. 3 Clinical studies: == studies suggesting positive correlation: Moteg et al 1992 keeling 1994 Tanne et al Brand et al 1995 Tanne et al reported the incidence of TMD in his untreated sample was 19%, however no other epidemiologic studies were available to support this finding It was found that, the incidence of TMD increase as the age of the patient increase, however Keeling et al found no such age difference in their sample (3742) pt It was evident from the results of the previous studies that, certain type of malocclusion may induce TMD more frequently than other type, and not all types of malocclusion should be considered responsible for the occurrence of TMD. TMD according to the previous studies was found to be associated with one or more of the following occlusal features: 1-Increase in anterior dimension of the face and skeletal open bites (Pullinger et al, Tann et al) however Keeling et al found no significant correlation between increase LAFH and TMD 2-Over jet more than 6 mm ----- Pullinger et al, Tann et al 3-Occlusal slide more than 2mm Pullinger et al 4-Extracted no restored posterior tooth Pullinger et al 5-Unilateral posterior cross bite Pullinger et al, Tanne et al 6-Increase maximum opening Keeling et al 7-Skeletal deep bite Tanne et al, Keeling wt al 8-Crowding Keeling wt al 9-Decrease maxillary and Mand Corpus length Brand et al 10-Edge to edge bite 11-Mandibular prognathism Tanne et al 12-Class II div 2 and postural Class III Mac Namara et al in their review article, concluded that, the relationship of malocclusion to TMD is minor but, the major question is how to investigate this minor contribution in TMD pt == Studies found no correlation between malocclusion and TMD: = On the other hand, De-Boever et al and Tankineshita et al found no significant correlation between malocclusion and TMD. They found a wide range of variation in the occlusal characteristic in both TMD and TMD free groups No one in occlusal factor in TMD group could be correlated to the condition, these finding indicated the higher power of adaptation of TMJ to various occlusal changes. = Sadowsky concluded that, these finding should not be surprising for 2 reasons: 1-TMD is multifactorial 2-TMJ have a higher power of adaptation to various occlusal changes TMD and Malocclusion TMD and Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

4. 4 Effect of different forms of malocclusion on TMJ 1-Unilateral cross bite ----- interfere with lateral movement------- abnormal distribution of biomechanical stresses with TMJ, the funcyional adaptation to unilateral cross bite comes on the expenses of articular dis derangement 2-Centric occlusion- centric relation slide: the slide from the point of initial contact to centric occlusion------ malposition of condyle dis assembly --------- stress the joint --------- internal derangement which may progress to arthrosis. 3-Excessive over jet ------ dual bite ----- stress the muscle of mastication and load the TMJ ligament 4-Crowding -------- many occlusal interference + occlusal slides from the initial contact to centric occlusion. 5-Open bite -------- loss of anterior guidance to protrusive movement ------- increase the range of border movement ------- stress the TMJ 6-Anterior cross bite ---------- loss of anterior guidance 7-Edge to edge bite ------------ little effect 8-Deep bite ---------------- mandibular over closure forcing the condyle into more retruded position TMD and orthodontic treatment: Roth’s 1973 work demonstrating that, the symptoms of TMD from 9 cases post treatment resolved once they were equilibrated using positioning splints TMD and extraction treatment: Bowbeer 1987: the functional orthodontist believe that extraction cause the condyle to be displaced distally as the incisors are retracted into extraction spaces TMD and orthodontic treatment: Proffit believes that orthodontic treatment reduces TMD symptoms Sadwsky 1980; TMD reduced in patient have functional appliances and this is not statistically significant Kermanak 1992: TMD reduced in patient with functional appliances with small statistically significant TMD and orthognathic surgery: Egermark et al 2000: orthognathic surgery does not necessarily increase or decrease the signs / symptoms of TMD. 5 years follow post-surgery found that signs / symptoms decrease in some patient and remain the same in others Condyle position and TMD: = Bowbeer 1987: there should be 3mm of joint space behind condyle, they believe that extraction force the condyle distally and trap the disc anteriorly -------- TMD = Johnston 1992, Pluinger et al 1987: orthodontic treatment does not force condyle distally infect it moves temporarily forward 0.7mm in 70% AND: 25% of a symptomatic individual with Class I occlusion have posteriorly positioned condyles. TMD and Malocclusion TMD and Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby

5. 5 How to investigate the TMJ and functional occlusion? 1-Clinical examination; = assessment of joint sound during occlusion and at different jaw movement = assessment of masticatory muscles and related muscles for pain and tenderness = assessment of joint pain and tenderness by palpation = assessment of jaw movement, range of motion and maximum pain free opening. 2-Radiographic examination: Panorama, CT, TMJ view, lateral transcranial view, MRI, and electronic thermography 3-Examination of functional occlusion: Any deviation during function should be detected a-Interference from initial contact to centric occlusion b-Balancing side interference c-Loss of incisal guidance d-Deviation in path of mandibular closure from maximum opening to initial contact should be detected The mandible deviates toward the side of derangement N: B: Loss of incisal guidance: =The movement of lower incisors from occlusion to incision to protrusion, provide a firm basis for a functional deviation =An acute V shaped pattern indicate incisor interference, this observation should be coordinated with the clinical observation of labially inclined pattern of attrition on lower incisors and lingual wear of upper incisors. = The upper incisors may also demonstrate palpable mobility on closure = Straight line pattern of incisors movement downward and forward from full closure indicate molar interference, the normal path was observed to be a more V pattern between two extremities Balancing side interference: = From centric occlusion, the patient in instructed to perform first left and right lateral excursion to cusp to cusp position = Functional occlusal contact was recorded as being present or absent, using one thickness of articulating ribbon on working side and two thickness of ribbon on non-working side (balancing) = The presence or absence of posterior contact on protrusion was similarly recorded with two thickness of articulating ribbon. TMD and Malocclusion TMD and Malocclusion Dr. Mohammed Alruby Dr. Mohammed Alruby