Introduction:

Internal derangements (IDs) of the temporomandibular joint (TMJ) constitute the most common clinical joint condition in patients with temporomandibular disorders (TMDs). Present in up to 80-90 % of symptomatic cases, it is not known why, its presence in asymptomatic subjects does not cause pain or dysfunction. In contrast, a normal position of the disc has been described in 16-23 % of symptomatic patients.

Objectives:

To analyze the prevalence of IDs of the TMJ in asymptomatic voluntary subjects and what clinical-radiological characteristics could favor their presence or development.

Material and methods:

A descriptive, observational, cross-sectional study was designed. Forty-three subjects from a population of 253 residents who performed their training program were selected. The study was carried out in several phases. Phase I: Anamnesis and clinical examination. Use of the Fricton Cranio-mandibular Index (CMI); Phase II: Acquisition and evaluation of Magnetic Resonance Imaging (MRI). The images were processed in DICOM 4.0 format and evaluated by two external examiners. Phase III: Morpho-structural analysis of the TMJs. The MRI were analyzed using the Osirix® V 3.5.1 Software.

Results:

Seventy-two joints (belonging to 36 subjects) were finally analyzed. The mean age was 28.39 ± 3.70 years with a distribution by sex of 47.2% men and 52.8 % women. The inferential analysis showed statistically significant results in relation to the variables sex (p = 0.021), joint click (p = 0.007), CMI value (p = 0.000296), disc morphology (p = 1.032x10-8), condylar morphology (p = 2.116x10-8) and condylar position inside the TMJ ((posterior and superior lengths, p = 5.385x10-9; p = 0.000245, respectively) and morphology of the joint fossa (p = 0.024).

Conclusions:

A high prevalence of IDs in asymptomatic subjects is present in our study. Certain clinical (joint clicking) and radiological criteria (an elongated or bent disc morphology, a flattened condyle and fossa and a more posterior and cranial position of the mandibular condyle) could be considered as predictors or be related to the presence of disc displacement. The CMI could be a useful tool in the diagnosis of joint pathology of the TMJ.

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