Evaluation of oro-facial function in young subjects with temporomandibular disorders

The aim of this study was to evaluate bite force (BF) and oro-facial functions at different dentition phases (initial-mixed, intermediate-mixed, final-mixed and permanent dentition) in children and adolescents diagnosed with temporomandibular disorders (TMDs). The sample was selected from four public schools in Piracicaba, São Paulo, Brazil. Of the 289 participants recruited, aged 8-14 years old, 46 were placed into the TMD group. TMD was diagnosed using Axis I of the Research Diagnostic Criteria for Temporomandibular Disorders (2011). Oro-facial functions were evaluated using the Nordic Orofacial Test-Screening (NOT-S), which involves both an interview and a clinical examination. BF was measured using a digital gnathodynamometer. Age and body mass index (BMI) were also considered. The data were analysed by the following tests: Kolmogorov-Smirnov test, Student's t-test, Spearman and Pearson coefficients, Qui-square test, Fisher's exact or binomial test, as indicated. Moreover, univariate and multivariable logistic regression were applied. For the TMD group, scores associated with NOT-S interview and NOT-S total were higher than for the control group (P = 0.033 and P = 0.0062, respectively). No differences in BF between genders or groups (P > 0.05) were detected. Variables included in the multivariate logistic regression were BMI and NOT-S total. Based on this analysis, NOT-S total was associated with TMDs. Reported sensory function was the specific domain within NOT-S interview that established the significant difference between the groups (P = 0.021). The TMD group also had a greater number of alterations in the face-at-rest domain of the NOT-S exam (P = 0.007). Concluding, it did not detect an association between TMDs and either dentition phase or BF. Instead, BF correlated with age and BMI. Oro-facial dysfunction was associated with TMD in the studied sample, but this association may be bidirectional, requiring further researches.