Association between mandibular asymmetry and occlusal asymmetry in young adult males with class III malocclusion

Abstract

Objective. Our aim was to assess the association between mandibular asymmetry and sagittal and transverse occlusal asymmetry in young adult males with class III malocclusion. Our hypotheses were that (1) mandibular asymmetry increases with increasing mandibular length and (2) occlusal asymmetry is correlated with mandibular asymmetry. Material and methods. On lateral cephalograms of 54 subjects, skeletal class and mandibular length were measured. Mandibular asymmetry was evaluated on orthopantomograms as right–left difference between condylar or ramus heights. Occlusal asymmetry was assessed on dental casts by differences between right and left canine and molar relationship, anterior and posterior crossbite as well as midline deviation. Results. Mandibular asymmetry was significantly correlated with sagittal and transverse occlusal asymmetry (p < 0.05), but not with mandibular length (p > 0.05). Condylar asymmetry due to a longer condyle on one side was correlated with asymmetric aggravation of canine and molar class III on the ipsilateral side (r = –0.53 and –0.62, respectively). In contrast, ramus asymmetry was related to contralateral aggravation of canine and molar class III relationships (r = 0.27 and 0.29, respectively). Correlations existed between asymmetry in total height of the condyle and ramus and asymmetric aggravation of anterior crossbite (r = –0.33), posterior crossbite (r = –0.30) and lower midline deviation (r = –0.27) to the contralateral side (p < 0.05). Conclusions. Mandibular asymmetry is associated with occlusal asymmetry, especially in the sagittal plane. Condylar asymmetry had 28% and 38% of variance in common with sagittal canine and molar asymmetry, respectively. Asymmetry in total height of the condyle and ramus was related to transverse occlusal asymmetry.