Saturday, August 21, 2010

The Many Faces of the Genetics

Oakley M, Vieira AR: The many faces of the genetics contribution to temporomandibular joint disorder Orthod Craniofac Res 2008;11:125–135.

M. Oakley, Department of Restorative Dentistry ⁄ Comprehensive Care, School of Dental Medicine, University of Pittsburgh, Pittsburgh, PA, USA, A.R. Vieira, Departments of Oral Biology and Pediatric Dentistry and Center for Dental and Craniofacial Genetics, School of Dental Medicine, and Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA.

Chronic pain disorders are estimated to cost approximately $80 billion per year in health care costs and lost productivity in the United
States (1, 2).
Pain in the facial region, including orofacial pain and craniofacial pain (excluding the traditional headache), accounts fora significant proportion of the approximately 10% of the Americans that suffer from chronic pain conditions. Sources of orofacial pain include caries, periodontal diseases, and neuropathic and musculoskeletal conditions (8). Orofacial pain is a major symptom of temporomandibular joint disorders (TMD) (9) and among the orofacial pain disorders, TMD comprise a relevant proportion of the total cases. The current treatments for these conditions could benefit from new approaches (10, 11) however, persistent pain among patients constitutes a public health concern that inflicts especially women between 20 and 40 years of age (2, 11–18). Studies concerning TMD have been limited because of the heterogeneous nature of symptoms leading to difficulties in diagnosis (19–21).

As reported by the National Institute of Dental Craniofacial Research (NIDCR) of the National Institutes of Health (NIH), TMD is known to affect over 10 million people in the USA at any given time. This disorder afflicts both men and women, however, women in their childbearing years constitute approximately 90% of those seeking treatment.

Objectives – Review the literature on candidate genes for temporomandibular joint disorder (TMD).

Setting and Sample Population – Literature review.

Materials and Methods – Two basic approaches were used to obtain literature in any language regarding genes and TMD. First, Medline, Embase, and Science Citation Index databases were searched using the keywords temporomandibular joint disorder and temporomandibular joint dysfunction for studies published from 1966 to 2007. Then, the references list of the studies obtained in the database was also considered.

Results – Candidate genes for TMD include genes for individual variations in pain perception, gender and ethnicity, proinflammatory cytokines, female hormones, breakdown of extracellular matrix, and syndromic forms of TMD.

Conclusion – Most of the studies on genetic variation contributing to TMD are approaching the disease mainly from an immune-inflammatory perspective. Recent investigations of the genetic variables which may predict identifiable levels of pain perception may uncover new approaches to our traditional treatment modalities for the chronic pain patient.

Temporomandibular joint disorder is a collection of symptoms related to the muscles and joints of the masticatory system. They likely comprise a number of etiologically distinct conditions that lead to similar symptoms. As individuals are not equally susceptible to TMD, this condition appears to be the result of the person s unique genetic makeup. For that reason, it has been suggested that a better understanding of the genetics modulating TMD is a necessary step that will lead to innovative therapies related to these conditions.

Wednesday, December 16, 2009

Musculoskeletal Etiology and Therapy of Craniomandibular Pain and Dysfunction

Coy, Richard E., Flocken, John E., Adib, Fray (1991) Musculoskeletal Etiology and Therapy of Craniomandibular Pain and Dysfunction. Cranio Clinics Intl, Williams and Wilkens, Baltimore, pp 163-173.

The investigators sent questionnaires and guidelines for submission of case histories to Fellows of the International College of Craniomandibular Orthopedics, who are geographically dispersed over the United States. The practitioners were requested to supply data and case histories on patients who were treated specifically for Craniomandibular pain or dysfunction. Sixty-eight case histories received from 20 practitioners that met the study guidelines were included.

Electronically derived measurement provides an objective quantitative database for diagnosing the existence and extent of myostatic contracture and skeletal malrelation. Compilation of the electronically derived data, correlated with the subjective evaluations of both patient and therapist, establish the existence of significant skeletal malrelation of the mandible to the cranium and consequent myostatic contracture in the pain and dysfunction population. The data reported in these case histories indicate that a common measurable etiology is responsible for the many ostensibly diverse manifestations of craniomandibular pain and dysfunction. The diagnostic validity and usefulness of the electronically derived quantitative data are supported by the correlative subjective perception by the patient of alleviation of symptoms in response to the correction of skeletal malrelation and the consequent reduction of muscle tension (table 7). The course of treatment provides rapid initial palliation followed by long-term resolution as a result of orthopedic correction of skeletal malrelation.

The data clearly established that in the patient population under study:
1. The average electromyograph activity with the patient at rest decreased substantially in the left and right anterior temporalis and masseter muscles after treatment.
2. The average electromyograph activity with the patient clenching increased substantially in the left and right anterior temporalis and masseter muscles after treatment.
3. Following the orthopedic correction of skeletal malrelation, over half of the patients had complete alleviation of symptoms, with the remaining patients experiencing a substantial reduction in the number of their symptoms.

The continuing positive responses to this noninvasive treatment based on quantitative as well as subjective diagnosis indicate the need in every case of craniomandibular pain or dysfunction to rule in or rule out musculoskeletal dysfunction as the most common underlying etiologic factor in most aspects of craniomandibular pain and dysfunction.

In cases in which the data rule out existing musculoskeletal dysfunction as a possible etiology, the patient may then be referred to other appropriate specialties such as neurology, otolaryngology, orthopedics, or psychiatry with the assurance to that specialty that the etiologic possibility of musculoskeletal dysfunction has been explored and ruled out.

Diagnosis and Treatment of Craniocervical Pain and Headache based on Neuromuscular Parameters

Lynn, Jack M., Mazzocco, Mike W., Miloser, Stephen J., Zullo, Thomas, (1992) Diagnosis and Treatment of Craniocervical Pain and Headache based on Neuromuscular Parameters, American Journal of Pain Management, 2:3, pp 143-151.


There is increasing evidence supporting the premise that hypertonicity within facial muscles is an etiologic factor for some chronic headache patients. This muscular hypertonicity is the result of neuromuscular imbalances within the head and neck. Through the analysis of electromyograph (EMG) data, it is possible to construct an intraoral orthosis which creates neuromuscular balance and subsequently relieves the pain.

This study attempted to identify (i) the relationship of EMG-measured dysfunction to reported craniocervical pain and (ii) the effectiveness of EMG-based orthoses on reversing myospastic conditions. Results of the study (N=203) indicate a significant (p<.0001) decrease in muscular myospasm at rest and a significant (p<.0001) increase in muscular activity during function following treatment with EMG-based orthoses. Reported craniocervical pain was significantly reduced. Results of this study support the hypothesis that creation of a physiologic neurovasomuscular envelope of craniocervical motion allows reduction of muscular hypertonicity resulting in reduction of pain. Furthermore, utilization of electromyography is a valuable tool during assessment and treatment of chronic facial pain patients.

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