Electromyographic Evaluation of the ‘Vertical’ Dimension: the Learreta TMJ Decompression Test

Abstract

The clinical observation of the incisors overbite is the most common form used to evaluate the occlusal vertical dimension (OVD); however, this technique offers poor information about the compression state of the TMJ. In order to obtain such information, it is necessary to evaluate the electrical activity of the elevator muscles using surface electromyography (EMG). In case of a compressive irritation of the joint receptors, the trigeminal nucleus returns an inhibitory motor response of the elevator muscles that can be measured. The Learreta’s EMG decompression test is done by measuring the EMG response of the masticatory muscles at maximal occlusion in four different OVD positions in such a way that the reduction of the TMJ pressure, and subsequently, relief of the inhibitory motor response can be studied. The aim of this study is to illustrate this technique, its clinical use and its limitations.

Additional information

Notes on contributors

Marcelo Freire Matos

Dr. Marcelo F. Matos is a postgraduate in chronic pain management at UniFacs, the University of Salvador, Brazil. He is a specialist in dentistry and maxillofacial radiology and a member of the ABO-Brazilian Dental Association. He has expertise in TMJ pathology and is a member of the ABCM Cranio Mandibular Brazilian Association.

Andreas C. Durst

Dr. Andreas C. Durst is a graduate of the University of Buenos Aires - Argentina and a member of the SAO Argentinean Society of Orthodontic. He is a professor of orthodontics and also has a private practice in TMD and orthodontics.

Jane Luzia Freire Matos

Dr. Jane Luzia Freire Matos holds a Ph.D. in dental and maxillofacial radiology and is a specialist in radiology. She is on the faculty of radiology, Bahia Federal Dentistry University and also Fundação Bahiana para o Desenvolvimento das Ciencias. Dr. Matos is also the coordinator of the specialty program in dental and maxillofacial radiology, Brazilian Dental Association.

Jorge Alfonso Learreta

Dr. Jorge A. Learreta holds a Ph.D. in odontology and a Masters degree in TMJ from the International College of Craniomandibular Orthopedics. He is an Honorary Diplomate of the American Academy of Craniofacial Pain (AACP) and has a specialty in orthodontics from the Buenos Aires University. Dr. Learreta is the president of AACM Cranio Mandibular Argentinean Association and the director for the Latin American Cranio Mandibular Association.