Methods: 18 female patients who attended a private practice in Tehran were selected. The mean age of these patients was 10.5 ±0.12 years with ANB value higher than 4, SNB value less than 78, O.J value more than 4 mm and normal mandibular growth pattern. R-Appliance is a tooth and tissue born appliance including buccal and lingual shields, which are connected to each other through occlusal clearance during bite construction. The lingual shield should be fabricated with the least possible amount of undercut relief .The right and left lower lingual shields are connected and reinforced with a heavy round arch wire measuring 1.2mm, in order to withstand load of muscular activity. In addition to the heavy palatal wire for appliance reinforcement, a labial bow from canine to canine with a vertical loop using a 0.7 round wire was constructed. Study Models, X-rays and photographs were taken before and after 18 months of study, and Cephalometric data were observed and analyzed.
Results: Paired T-test and Wilcoxon tests showed that SNB values increased 2+1.7 (p<0.001), while ANB and 1-SN values decreased significantly. Changes in SNA, IMPA and Y- Axis were not significant as is shown in the Graph.
Conclusion: Traditional functional appliances restrain maxillary growth (SNA) and procline mandibular incisors (IMPA), resulting from the action of mandibular retractor muscles. But due to less relief in R-Appliance construction bite and in order to avoid any trauma resulting from lingual tissue impingement, the patient moves the mandible into a forward position and keeps the protractor muscle active in order to counter act the side effects of retractor muscles in traditional functional appliance therapy.
Keywords: New functional appliance, Class II div. 1 malloclusion.