Objective: To determine whether orthodontically treated patients with cleft lip and palate (CLP) possess a different masticatory function than those of untreated patients with normal occlusion.
Design: Occlusal contact area, occlusal force, as well as masseter and anterior temporal muscular activity were measured during maximum voluntary clenching (MVC) tests. Mandibular left and right lateral movements during mastication were also assessed. To further elucidate the nature of masticatory function, especially to determine the rate of abnormal jaw movement patterns, a parametric error index (EI) was set. Finally, masticatory efficiency was evaluated with a glucose sensitive measuring device.
Participants: Fifteen patients with CLP who had previously completed the orthodontic treatments required to achieve an acceptable and more harmonious occlusion accepted to volunteer in this study along with 21 untreated patients who already possessed a normal occlusion.
Results: Patients with CLP showed a significantly lower occlusal force, reduced occlusal contact area, and decreased masticatory efficiency as well as significantly higher EI value when compared with controls. However, there was no significant difference when analyzing muscle activity, although masticatory efficiency was significantly different between the 2 groups. Despite this result, the scores obtained by the patients with CLP in the masticatory efficiency tests were still in the normal range.
Conclusions: Orthodontic treatment for adult patients with CLP provides a satisfactory result for the patients' masticatory ability albeit significantly less ideal compared with untreated patients with normal occlusion.
Keywords: dental occlusion; muscle function; orthodontics.