Diagnosing mandibular asymmetry using posteroanterior cephalograms in patients with unilateral and bilateral degenerative joint disease

Abstract

Objectives: The purpose of this study was to evaluate the possible differences in facial asymmetry between bilateral degenerative joint disease (BDJD) and unilateral degenerative joint disease (UDJD) when compared to asymptomatic controls. Materials and Methods: Posteroanterior cephalograms of 61 pre-orthodontic treatment patients (21 BDJD, 20 UDJD, and 20 controls) were evaluated (young adults, between 12 and 25 years of age) to investigate the inclination of the frontal occlusal plane (FOP) and frontal mandibular plane (FMP) to determine vertical asymmetry. Mandibular dental midline shift (DMS) and mandibular midline shift (MMS) were studied to determine transverse asymmetry. FOP, FMP, MMS, and DMS were compared pairwise between study groups, with multiple comparisons justified by Tukey–Kramer procedure. Correlation analyses were performed to evaluate the relationship between the measures. Mantel–Haenszel Chi-square test was used to evaluate the association between groups and symptom severity. Results: The findings suggest that severity of the vertical mandibular displacement was associated with significant differences between BDJD and control patients, and between UDJD groups and control patients. However, they were no significant differences found between UDJD and BDJD patients, and this may be attributable to a different pattern of load on the ipsilateral and contralateral sides of the TMJ when they were compared to the controls. Moreover, the higher values of FOP and FMP correlated with the mandibular displacement being notably greater when the asymmetry was >3°. A similar tendency of a higher prevalence of mandibular displacement with a higher value of DMS and MMS was observed. Conclusion: Clinical implications of this study apply to patients with asymmetry in vertical and transverse dimensions. These patients should be evaluated for dental, skeletal (condylar changes), and soft-tissue changes before orthodontic and/or orthognathic treatment planning.