Etiopathogenesis of disk displacement of the temporomandibular joint: a review of the mechanisms.

Disk displacement of the temporomandibular joint (TMJ) is a clinically important condition, showing a high prevalence in both patient and non-patient populations. Despite its clinical importance, there is incomplete understanding of the etiopathogenic mechanisms leading to disk displacement. A number of possible risk factors have been identified. This article analyzes the etiopathogenesis from both the clinical and the biomechanical viewpoints and also reviews the literature on the association between disk displacement and the main risk factors (i.e., trauma, altered disk shape and/or dynamic properties, occlusal abnormalities, steepness of the articular eminence, hyperactivity of the lateral pterygoid muscle, joint hypermobility, etc.). According to our interpretation of available data, an impairment of joint lubrication may be a common finding in cases of disk displacement, thus suggesting the need for future studies addressing both local and systemic neuroendocrine aspects influencing the friction coefficient of the TMJ. A full comprehension of the etiopathogenesis of disk displacement is far from being achieved, and clinicians must take into account this consideration when treating patients with temporomandibular disorders.