Temporomandibular disorders: the habitual chewing side syndrome

Background:Temporomandibular disorders are the most common cause of chronic orofacial pain, but, except where theyoccur subsequent to trauma, their cause remains unknown. This cross-sectional study assessed chewing function (habitualchewing side) and the differences of the chewing side and condylar path and lateral anterior guidance angles in participantswith chronic unilateral temporomandibular disorder. This is the preliminary report of a randomized trial that aimed to testthe effect of a new occlusal adjustment therapy.Methods:The masticatory function of 21 randomly selected completely dentate participants with chronic temporoman-dibular disorders (all but one with unilateral symptoms) was assessed by observing them eat almonds, inspecting the lateralhorizontal movement of the jaw, with kinesiography, and by means of interview. The condylar path in the sagittal plane andthe lateral anterior guidance angles with respect to the Frankfort horizontal plane in the frontal plane were measured onboth sides in each individual.Results:Sixteen of 20 participants with unilateral symptoms chewed on the affected side; the concordance (Fisher’s exacttest, P = .003) and the concordance-symmetry level (Kappa coefficientk= 0.689; 95% confidence interval [CI], 0.38 to 0.99;P = .002) were significant. The mean condylar path angle was steeper (53.47(10.88) degrees versus 46.16(7.25) degrees;P = .001), and the mean lateral anterior guidance angle was flatter (41.63(13.35) degrees versus 48.32(9.53) degrees P = .036)on the symptomatic side.Discussion:The results of this study support the use of a new term based on etiology, ‘‘habitual chewing side syndrome’’,instead of the nonspecific symptom-based ‘‘temporomandibular joint disorders’’; this denomination is characterized inadults by a steeper condylar path, flatter lateral anterior guidance, and habitual chewing on the symptomatic sideThis study was financed with a grant PI11/02507 from the Institute of Health Carlos III of the Ministry of Science and Innovation of the Government of Spain. It was completed with the equipment granted by the General Directorate of Universities and Research; Department of Education and University. Xunta de Galicia. Official Journal No. 143 Galicia, July 22, 1996. And the Department of Innovation, Industry and Commerce. Xunta de Galicia, April 30, 2004S

Biomechanical Evaluation of Neuro-occlusal Rehabilitation for Occlusal Imbalance Correction in Children with Facial Asymmetry

Contemporary eating habits may cause malformations in children jaw, that are difficult to evaluate and treat clinically. In this work, a computational methodology for the diagnosis and the treatment of this pathology is proposed. It combines porous-fibrous material models, medical devices and computational models of patients with facial asymmetries from the perspective of neuro-occlusal rehabilitation

Asymmetry of dental or joint anatomy or impaired chewing function contribute to chronic temporomandibular joint disorders

Introduction: The etiologies of most chronic temporomandibular joint disorders are unknown. However, an association between habitual chewing on a particular side and chronic temporomandibular joint disorders has been reported. The aim of this study was to investigate the differences between sides (affected vs unaffected) of biodynamic factors (including lateral dental guidance determined by dental anatomy) or condylar path angles (determined by temporomandibular joint morphology) and chewing function (physiological alternate chewing vs single habitual chewing side). The study scope was to investigate possible etiological factors to improve the understanding of temporomandibular joint disorders. The null hypothesis was that no difference would be found between sides that are or are not affected by chronic temporomandibular joint disorders in chewing function or in levels of dental or temporomandibular joint remodeling. Methods: This cross-sectional, double-blind study involved 24 adults with substantial, chronic, unilateral symptoms diagnosed as temporomandibular joint disorders. Chewing function, temporomandibular joint remodeling (using axiography) and dental anatomy (lateral guidance angles using kinesiography) were assessed. Results: Habitual chewing on one particular side was observed in 17 of 24 participants; significantly more (n = 15) chewed on the affected side than on the unaffected side (P = 0.002 in a two-tailed Fisher’s exact test; risk estimate = 4.5; 95% CI 1.326–15.277). The condylar path (CP) angle was steeper on the affected side than on the unaffected side (mean (standard deviation) = 50.52° (9.98°) versus 45.50° (7.98°); P = 0.002 in a two-tailed t-test). The lateral guidance (LG) angles were flatter on the affected side in all 24 participants. Conclusion: Our results suggest that habitual chewing on one side may be associated with increasing condylar path, with flattening lateral guidance angles, and also with chronic temporomandibular joint disorder on the habitual chewing sideThis study was supported by the Carlos III Institute of Health (Ministry of Science and Innovation of the Government of Spain and the European Development Fund, ‘Una manera de hacer Europa’) (grant no. PI11/02507). The design, management, analysis, and reporting of the study are entirely independent of the Carlos III Institute of HealthS

Remodeling dental anatomy vs sham therapy for chronic temporomandibular disorders. A placebo-controlled randomized clinical trial.

BACKGROUND: Evidence regarding the etiology or effective treatments for chronic orofacial pain, the majority diagnosed as temporomandibular disorder (TMD), is limited. PURPOSE: To investigate whether occlusal equilibration therapy (ET) and decreasing the (higher) angle of the lateral guidance on the nonworking-side leads to a reduction in chronic TMDs intensity. METHODS: It was conducted a randomized, explanatory, single blind with blinded assessment, placebo-controlled trial with strong protection against bias involving patients with chronic TMDs. Participants were randomly assigned to receive equilibration therapy or sham therapy. ET in this study consisted of minimal invasive occlusal remodeling to obtain balanced occlusion with reduction of the steeper angle of lateral mandibular movement with respect to the Frankfort plane. The primary outcome was a change in the pain intensity score (on a 0-10 point scale, with 0 indicating no pain and 10 the worst possible pain) at month 6. Secondary outcomes include maximum unassisted mouth opening and psychological distress. RESULTS: A total of 77 participants underwent randomization, 39 of whom received ET and 38 sham therapy. The trial was stopped early for efficacy, according to preestablished rules when 67 participants (n = 34, n = 33, respectively) had completed the analysis. At month 6, the mean unadjusted pain intensity score was 2.1 in the ET and 3.6 in the sham therapy group (adjusted mean difference, -1.54; 95% confidence interval [CI] -0.5 to -2.6; P = 0.004; ANCOVA model). The mean increase in maximum unassisted mouth opening (main secondary outcome) was significantly higher in the real therapy group (adjusted mean difference 3.1 mm, 95% CI 0.5-5.7, p = 0.02). CONCLUSION: ET significantly reduced the intensity of facial pain associated with chronic TMDs and increased maximum unassisted mouth opening, as compared with sham therapy, over the course of 6 months. There were no serious adverse events. Funded by the Instituto de Salud Carlos III from the Ministry of Science and Innovation of the Government of Spain and European Regional Development Fund, Grant nº PI11/02507; "una manera de hacer Europa"

Temporomandibular disorders: the habitual chewing side syndrome.

BACKGROUND: Temporomandibular disorders are the most common cause of chronic orofacial pain, but, except where they occur subsequent to trauma, their cause remains unknown. This cross-sectional study assessed chewing function (habitual chewing side) and the differences of the chewing side and condylar path and lateral anterior guidance angles in participants with chronic unilateral temporomandibular disorder. This is the preliminary report of a randomized trial that aimed to test the effect of a new occlusal adjustment therapy. METHODS: The masticatory function of 21 randomly selected completely dentate participants with chronic temporomandibular disorders (all but one with unilateral symptoms) was assessed by observing them eat almonds, inspecting the lateral horizontal movement of the jaw, with kinesiography, and by means of interview. The condylar path in the sagittal plane and the lateral anterior guidance angles with respect to the Frankfort horizontal plane in the frontal plane were measured on both sides in each individual. RESULTS: Sixteen of 20 participants with unilateral symptoms chewed on the affected side; the concordance (Fisher's exact test, P = .003) and the concordance-symmetry level (Kappa coefficient κ = 0.689; 95% confidence interval [CI], 0.38 to 0.99; P = .002) were significant. The mean condylar path angle was steeper (53.47(10.88) degrees versus 46.16(7.25) degrees; P = .001), and the mean lateral anterior guidance angle was flatter (41.63(13.35) degrees versus 48.32(9.53) degrees P = .036) on the symptomatic side. DISCUSSION: The results of this study support the use of a new term based on etiology, "habitual chewing side syndrome", instead of the nonspecific symptom-based "temporomandibular joint disorders"; this denomination is characterized in adults by a steeper condylar path, flatter lateral anterior guidance, and habitual chewing on the symptomatic side

Gnathography procedure.

<p>A, The face-bow placed on the patient’s head and the magnet attached to the buccal surface of the mandibular incisors. B, lateral anterior dental guidance tracings and the right angle with respect to the <i>bimeatus</i>-horizontal plane.</p

Axiography procedure: condylar path tracings.

<p>A, the kinematic face-bow attached with silicone putty to mandibular teeth through an occlusal rim; lateral condylar path drawn on the surface of the recording card. B, parasagittal plane of lateral condylar path tracings and their angle with respect to the tragus-infraorbital Frankfort plane.</p

Craniomandibular relationships of a patient with left-side symptoms.

<p>A, Maximal intercuspal position. B, Right lateral jaw motion. C, Left lateral jaw motion. Left lateral jaw motion is more horizontal than right lateral jaw motion (α>α’ and/or β>β’).</p