Research progress in effect of chewing-side preference on temporomandibular joint and its relationship with temporo-mandibular disorders. / åä¾§å’€åš¼å¯¹é¢žä¸‹é¢Œå ³èŠ‚ç»“æž„çš„å½±å“åŠå ¶ä¸Žé¢žä¸‹é¢Œå ³èŠ‚ç´Šä¹±çš„å ³ç³».

Chewing-side preference is one of the risk factors for temporomandibular disorders (TMD), and people with chewing-side preference is more prone to have short and displaced condyles, increased articular eminence inclination and glenoid fossa depth. The proportion of TMD patients with chewing-side preference is often higher than that of the normal subjects. Clinical studies have shown a strong correlation between chewing-side preference and TMD symptoms and signs; and animal studies have shown that chewing-side preference can affect the growth, development, damage and repair of the mandible. After long-term unilateral mastication, changes in the stress within the joint cause the imbalance of temporomandibular joint (TMJ) structural reconstruction, the transformation and even destruction of the fiber structure of masticatory muscle, resulting in uncoordinated movement of bilateral muscles. The joint neurogenic diseases caused by the increase of neuropeptide substance P and calcitonin-gene-related-peptide (CGRP) released locally by TMJ may be the mechanism of TMD. This article reviews the research progress of the influence of chewing-side preference on the structure of TMJ, the relationship between chewing-side preference and TMD, and the related mechanisms.

Influence of edentulism on the structure and function of temporomandibular joint.

Background: With the acceleration of the aging process of the population, the number of edentulous patients continuously increased. Edentulism induces the loss of occlusal relationship and cause adverse effects on the stomatognathic system. Temporomandibular joint (TMJ), as a significant component of this system, may also be affected by edentulism in the process of supporting mandibular movement. Purpose: Provide a comprehensive review of the structure and function of TMJ in the edentulous population, as well as the prevalence of temporomandibular joint disorder (TMD) in edentulous group. Study selection: An electronic search was conducted on articles prior to December 2022 to filter all papers relevant to the structure and function of TMJ in edentulous population. The internet databases (PubMed, Cochrane Library, Embase) were searched using various combinations of keywords for "edentulism" or "edentulous" and "TMJ" or "TMD". Results: Firstly, 522 articles were selected from the internet database, and finally, a total of 44 articles met the inclusion and exclusion criteria. The research content of these articles mainly focuses on the structure and function of TMJ in edentulous patients, as well as the clinical signs and symptoms of TMD. Conclusions: Edentulous arch induces the loss of occlusal relationship, which may lead to degenerative changes of TMJ components consisting of changes in morphology and bone mass density of condyle, articular fossa, and articular eminence. In addition, the condyle could be shifted backward and upward, and displacement of the articular disc may occur after dentition loss. And the condyle and the articular disc may be guided back to the normal position after effective prosthodontic treatment. But the conclusions of the study on the function of TMJ and the prevalence of TMD in edentulous people are inconsistent. The condition of TMJ, especially the position of condyle-fossa and the symptoms and signs of TMD should not be ignored. If necessary, radiographic examinations should be performed.