[Evaluation of mandibular propulsion appliances in children. A study of 18 cases]

Mandibular propulsion appliances are used currently in the treatment of class II malocclusion. The purpose of this study was to evaluate their effects on facial development to formulate specific indications.

Eighteen children (mean age 9-12) treated with a propulsion device for a class II division 1 malocclusion with a minimum of 4 mm overjet were included in a retrospective study over a 4 year period. We compared maxillomandibular and dentoalveolar position before and after treatment using Delaire computer software cephalometric analysis and superpositions.

Statistically significant effects on molar discrepancy (p = 0.0002), overjet (p = 0.0003), sagittal mandibular position (p = 0.0040 for FM-Me/theoretical and p = 0.0010 for NP-FM-Me), mandibular length (p = 0.004 for FM-Me/theoretical), mandibular corpus length (p = 0.0286 for Go-Me/theoretical), upper incisors palatal version (p = 0.0002), and on lower incisors lip version (p = 0.0436) were assessed. No action on maxillary growth (p = 0.7274 for FM-NP/theoretical), ramus length (p = 0.9651 for Cp-Go/theoritecal), lower facial height (p = 0.7045 for ENA-Me/theoretical) or translation of the alveolar arches (p = 0.9571 for A-Pti'/ENA-Pti and p = 0.1564 for B-Pa'/B-Pa) could be confirmed.

An increase in mandibular corpus development and no effect on alveolar arches suggests a basal mandibular action for this device. This concludes that retromandibular position and brachycorpus with upper incisor lip version, without lower incisors lip version are the best indications for mandibular propulsion appliances. Prospective studies should be carried out to confirm this hypothesis.