Histopathology associated with malposition of the human temporomandibular joint disc.

Scapino, R.P.: Oral Surg Oral Med Oral Pathol 1983; 55:382-97.

ABSTRACT

Anterior displacement of the temporomandibular joint disc is associated with a general remodeling of the joint's soft tissues. The anterior part of the posterior attachment becomes fibrotic. The external shape and the internal architecture of the disc change in characteristic ways. The disc appears to overlie more of the lateral pterygoid muscle than is normal. The capsule connecting the anterior band of the disc to the condyle appears to be elongated.

Effect of Increased Maxillo-mandibular Relationship on Isometric Strength in TMD Patients with Loss of Vertical Dimension of Occlusion

Tariq Abduljabbar, D.D.S., M.S.; Noshir R. Mehta, D.M.D., M.S.; Albert G., Forgione, Ph.D.; R. Ernest Clark, Ph.D.; Joseph H. Kronman, D.M.D., Ph.D.; Theodore L. Munsat, M.D.; Patrick George, B.S.: Effect of Increased Maxillo-mandibular Relationship on Isometric Strength in TMD Patients with Loss of Vertical Dimension of Occlusion.  THE JOURNAL OF CRANIOMANDIBULAR PRACTICE JANUARY 1997, VOL. 15, NO. 1, pp. 57-67.

ABSTRACT:
The effect on isometric strength of the shoulders and limbs while biting in habitual occlusion, on a bite-elevating appliance and on a placebo appliance was analyzed. Twenty female volunteer patients, presenting with temporomandibular pain dysfunction syndrome and obvious loss of vertical dimension, served as subjects. All were weaker to the manual application of the Isometric Deltoid Press (IDP) when biting, as opposed to maintaining the mandible in an unsupported rest position. Two intraoral appliances were fabricated for each subject: a bite-elevating appliance (BEA) set by a functional criterion of peak strength to the IDP and a placebo appliance which did not interfere with occlusion but was “set” with a mock IDP procedure. Testing was carried out by the Neuromuscular Research Testing
Laboratory of the Neurology Department of Tufts New England Medical Center. Testing was independent of the dentist who fabricated and set the appliances. A standard neuromuscular test with the Maximal Voluntary Isometric Contraction apparatus was used to assess strength of right and left shoulder, elbow and knee flexion and extension as is routinely performed with all neuromuscular disease
patients. Twelve strength tests were carried out for each of three conditions: 1. Baseline–biting in habitual occlusion; 2. Elevated–biting on the BEA; and 3. Placebo–biting with the placebo appliance inserted.  The order of conditions 2 and 3 was counterbalanced without knowledge of the subjects. Twelve repeated measures ANOVAs (each subject as their own control) were conducted for each of the 12
strength measures. All F-tests indicated a significant main effect for treatment differences (p<0.0001).  Mean strength biting on the BEA was consistantly greater (p< 0.001) than Baseline or Placebo strength.  Baseline and Placebo condition were equivalent. These findings confirmed previous observations at this TMD Center: individuals with loss of vertical dimension of occlusion respond to a bite raising appliance by increased isometric-strength.

Recombinant AAV-mediated VEGF gene therapy induces mandibular condylar growth

A B M Rabie , J Dai, and R Xu: Recombinant AAV-mediated VEGF gene therapy induces mandibular condylar growth. Gene Therapy 14, 972–980 (1 June 2007).


Abstract
Craniofacial anomalies resulting from impaired growth of mandibular condyles require multidisciplinary interventions, which impose a substantial burden on patients and their families. So far, correcting such deformities with an alternative strategy – gene therapy – is still an uncharted territory. Here, we established an effective in vivo gene delivery system with recombinant adeno-associated virus (rAAV)-mediated vascular endothelial growth factor (VEGF) to enhance mandibular condylar growth. With in situ hybridization, RT-PCR, immunostaining and Western blot, transgene expression was clearly detected in the mandibular condyles during the whole experiment periods. At defined time points, specific osteogenetic markers (alkaline phosphatase and osteocalcin) and chondrogenetic markers (collagen type II and collagen type X) were assessed by means of biochemical analysis and their expression significantly changed from day 30. Proliferation index by proliferating cell nuclear antigen staining showed also a significant increase in cell proliferation. Morphological measurement identified that the size of mandibular condyle significantly increased from day 30. Taken together, rAAV-VEGF was successfully established as an efficient delivery system to induce mandibular condylar growth, which provides the basis for future gene therapy to treat patients with craniofacial deformities. Gene Therapy (2007) 14, 972–980; doi:10.1038/sj.gt.3302943; published online 26 April 2007

Subjective reactions to intervention with artificial interferences in

YRSA LE BELL, PAIVI M. NIEMI, TAPIO JAMSA , MERVI KYLMALA & PENTTI ALANEN: Subjective reactions to intervention with artificial interferences in
subjects with and without a history of temporomandibular disorders. Institute of Dentistry, Department of Teacher Education, and Department of Statistics, University of Turku, Turku, Finland. Acta Odontologica Scandinavica, 2006; 64: 59-63.

Abstract:
In a previous double-blind randomized controlled study, subjects with a history of temporomandibular disorder (TMD) reacted to artificial interference with more signs of TMD than did subjects with no TMD history. In the present study, we analysed the subjective reactions of these individuals on several symptom scales. Every day during the 2-week follow-up period, the subjects rated the intensity of their symptoms on 9 VAS scales (occlusal discomfort, chewing difficulties, tender teeth, fatigue in the jaws, headache, facial pain, opening difficulty, bruxism, ear symptoms). Subjects with a history of TMD and true interferences reported stronger symptoms than subjects with no TMD history and placebo interferences.

The most prominent symptoms were occlusal discomfort and chewing difficulties. The difference in outcome between the groups with and without a TMD history suggests that there are individual differences in vulnerability to occlusal interferences. It is likely that the etiological role of occlusal interferences in TMD has not been correctly addressed in previous studies on artificial interferences.

Functional malocclusion that induces posterior condylar displacement

Purisa Cholasueksa, DDSa; Hiroyuki Warita, DDS, PhDb; Kunimichi Soma, DDS, PhDc.: Alterations of the Rat Temporomandibular Joint in FunctionalvPosterior Displacement of the Mandible. Angle Orthod 2004;74:677–683.

Abstract: Functional malocclusion that induces posterior condylar displacement may affect the remodeling processes of the temporomandibular joint structures. We tested the hypothesis that intermittent posterior condylar displacement due to functional malocclusion traumatizes condylar cartilage and joint innervated nerve fibers. Thirty-nine eight-week-old Wistar rats were used. To induce functional posterior condylar displacement, guiding appliances were attached to maxillary incisors of 24 rats for four, seven, and 14 days. Fifteen normal rats served as controls. Sections were stained with hematoxylin and eosin or processed for immunohistochemistry of protein gene product 9.5 and growth-associated protein-43 (GAP- 43). Functional posterior condylar displacement led to a diminution in proliferative cells, reduction in cartilage width, and re-expression of GAP-43–immunoreactive nerve fibers. These results indicate that intermittent posterior condylar displacement due to functional malocclusion causes dysfunctional remodeling of condylar cartilage and nerve injury.

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