TMD and Orthodontic Treatment

by Gerald Nelson, DDS

There has been some compelling research relative to Temporo-Mandibular Joint Dysfunction (TMD) and orthodontic treatment.  Researchers are now convinced that orthodontic treatment, even when extractions are involved, is not connected to the incidence or onset of TMD.  Researchers are also convinced that orthodontic treatment will not effectively relieve or cure TMD. 

 In the American Journal of Orthodontics and Dento-facial Orthopedics,(AJO-DO) Mar 1991, 'Extraction, orthodontic treatment, and CMD' by Dibbets and van der Weele, could find no association between extraction or non-extraction treatment and TMJ pain, limitation of opening, crepitation, or condylar deformation. 

 In the May 1991 issue of the AJODO, 'Orthodontic treatment and TMJ' by Sadowsky, Theisen and Sakois examined 160 patients before and after fixed orthodontic appliances to record changes in joint sounds.  Slightly fewer patients had joints sounds after treatment.  No difference was detected between extraction and non-extraction patients.

 In the same issue, 'Condylar position and maxillary first premolar extraction, 'Gianelly, Coxxani, and Boffa compared the condylar position in the fossa of 17 controls with 17 patients treated with removal of upper first bicuspids.  Computed tomography was used to evaluate condylar position.  They found that condylar position was unrelated to treatment, bite depth, inter-incisal angle, and maxillary incisor inclination. 

 In the August,1991 issue of the AJODO, 'Premolar extraction therapy', by Kudinger, Austin, Christensen, Donegan, and Ferguson compared 29 controls with 29 upper first bicuspid extraction patients.  They checked joint space with computed tomography, and muscle activity with electro-myograms.  No differences were detected between the two groups. 

 In the January 1992 issue of the AJODO, 'Premolar extraction and mandibular position' by Luecke and Johnston showed that the mandibular position comes slightly forward (0.5mm) in the fossa as a result of orthodontic treatment when extractions are done.  This contradicts claims that orthodontic extraction therapy leads to a distal displacement of the condyle. 

 In the same issue, 'Risk factors for TMD' by Kremenak, Kinser, Harman, Menard, and Jakobssen found no significant differences in TMD risk factors of patients before and after treatment, or between extraction or non-extraction groups. 

 In the same issue, 'Study of signs of TMD', by Hirata, Heft, Hernandez, and King found that the incidence of TMD signs for the treatment group and control group were not significantly different. 

 In the same issue, 'Orthodontic treatment and TMD' by Rendell, Norton, and Gay found no relationship in 451 patients between either the onset of TMJ pain and dysfunction and the course of orthodontic treatment or the change in TMJ pain and dysfunction and the course of orthodontic treatment.

 Given these studies, clinicians can be satisfied that orthodontic treatment does not cure or cause TMD.  This does not detract from the many benefits of good orthodontic care, which must be based on thoughtful functional and esthetic goals.