Growing patients with Duchenne muscular dystrophy: longitudinal changes in their dentofacial morphology and orofacial functional capacities.

Aim: The aim of this study was to describe the longitudinal changes in facial morphology, dental arch alterations and oral functional capacities that occur in growing patients with Duchenne muscular dystrophy (DMD) in order to identify the effects of the progression of the disease.

Subjects and Methods: Twelve DMD patients (6.5-17.5 years of age) and 12 matched controls were screened on two different occasions (T1 and T2), 2 years apart. Dental casts, lateral cephalometric radiographs, maximal posterior bite force and labial force were measured to determine changes in their functional capacities and dentofacial morphology. Furthermore, the thickness and echogenicity of the masseter muscle were measured during clenching.

Statistical evaluation: Unpaired t-tests were performed to evaluate the differences between the DMD patients and their healthy matched controls; paired t-tests were used to assess the changes that occurred within each group between T1 and T2.

Results: Between T1 and T2 the following changes were observed: widening of the lower dental arch for the DMD patients of 2.6mm (±0.9mm) compared to a slight reduction of -0.1mm (±0.8mm) for the control group (P = 0.001). We found a statistically significant reduction of the sagittal skeletal intermaxillary relationship (ANB-angle) of 2.0° (±2.0°) in the DMD group (P = 0.012). In T1 and T2, the maximal posterior bite force and the labial force were lower for the DMD patients compared to the control group (P = 0.001), who showed an increase during this period.

Conclusion: The results indicate that DMD influences the facial morphology, dental arch dimensions and oral functional capacities. The longitudinal perspective of this study revealed that the worsening of most of the measured parameters is associated with the progression of the disease. Besides the expected deterioration of the functional measurements, we found in all patients, a marked transverse increase of the posterior part of the dental arches, more in the lower than in the upper, resulting in posterior crossbites, as well as a tendency towards a skeletal Class III relationship.