Background: The temporomandibular joint is a unique bi-condylar joint involved in mastication and speech. Temporomandibular joint disorders (TMD) have a range of symptoms, including aural symptoms, and are present in approximately 75% of normal populations. The present study examined the relationship between signs and symptoms of TMD and mouth opening, gender, joint and aural symptoms, and hearing loss.
Methods: The study involved 464 healthy Greek university students (156 men and 308 women) with a mean age of 19.6 years. Age, gender and maximum mouth opening was recorded. Mouth opening was measured using Vernier calipers. An anamnestic questionnaire was used to stratify the subjects into four groups based on TMD severity. Aural symptoms and an audiogram were recorded for each subject too. Data were analyzed using multifactor ANOVA, chi-square, t-test, Mann-Whitney and Kruskal-Wallis tests.
Results: The overall incidence of TMD signs and symptoms was 73.3%. The incidence and severity was greater in females than males (p-value 0.0001 < 0.05). The number of aural symptoms was associated to the TMD severity (p-value 0.0001 < 0.05) as well as maximum mouth opening (p-value 0.004 < 0.05). Audiometry showed that moderate and severe TMD was associated with hearing loss of median and low tones respectively (p-value 0.0001 < 0.05). TMJ pain (p-value 0.0001 < 0.05), TMJ ankylosis (p-value 0.0001 < 0.05), bruxism (p-value 0.0001 < 0.05) and ear itching (p-value 0.0001 < 0.05) were also found to be statistically different between TMD and non-TMD subjects.
Conclusions: TMD signs and symptoms were more common and severe in females than males. TMD severity is correlated with the degree of mouth opening and the number of aural symptoms. The absence or presence of mild TMD are associated with normal audiograms while moderate and severe TMD are related to hearing loss in median and low tones respectively. Bruxism, joint ankylosis, joint pain and ear itching were more common in TMD than non-TMD patients.