Involvement of myofacial muscles in patients with temporomandibular disorders- a clinical study

Objective-To investigate the involvement of myofacial muscles in different diagnostic categories in patients with temporomandibular disorders.
Material and Methods- In this cross-sectional study, 50 consecutive patients (20=males; 30=females) with TMJ disorders were selected with the documented presence of signs and symptoms of TMDs. For each patient, a standardized protocol was followed for history taking and clinical examination and then exploration was carried out according to the RDC/TMD axis I criteria, in accordance with routine clinical practice. All the patients were classified into the diagnostic categories according to the RDC/TMD criterion.All the muscles of mastication were palpated for tenderness and positive findings were noted down.Clinical parameters were compared using paired and unpaired t-tests, and Kruskal-Wallis test.
Results- In this study, masseter was found to be involved more frequently in all the diagnostic categories, (20%- Group Ia; 33%- Group IIa; 27%- Group IIb; 50%- group IIIb), followed by pterygoideus lateralis muscle (16%- Group Ia; 24%- Group IIa; 30%- Group IIb; 0%- group IIIb) and pterygoideus medialis. The least involved was the trapezius muscles (10%- Group Ia; 0%- Group IIa; 03%- Group IIb; 0%- group IIIb).
Conclusions- Within the limitations of this study, we can conclude that the most frequent involved muscle in all the diagnostic categories of temporomandibular disorders was masseter muscle followed by pterygoideus lateralis muscle.