The purpose of this investigation was to study the effects of the Treatment with the MA.R.S. appliance (Mandibular Advancing Repositioning Splint) by a comparative evaluation of treated and untreated skeletal class II division I malocclusion cases. Twenty of the cases (8 girls, 72 boys) were treated with MA.R.S. appliance and other twenty cases (8 girls, 12 boys) constituted the control grup. At the end of the six month treatment, statistically significant treatment changes can be summarized as follows: intermaxillary relationship was improved as a result of mandibular growth stimulation. Reduction of the ANB angle was due 10 changes in the position of the mandible. SNB angle, total mandibular length (Ar-Pg) ramus height were increased and N-S-Ar and N-S-Gn angle were decreased. Total anterior and posterior facial height were increased due to increkenl of the ramus height and anterior lower facial height. Tipping of the upper and lower incisiors were observed. This study showed that fixed appliance in conjuction with functional appliance is not adequate in the controlling the of incisors inclination.

Keywords: M.A.R.S. appliance, cephalometric changes, class II treatment