RESUMEN
OBJECTIVES: To evaluate dento-skeletal effects of the Pendulum Hygienic Distalizer (P.H.D), utilized on expansion of the maxillary arch and distalizing of maxillary first molars. MATERIAL AND METHODS: Ten patients were selected from the outpatient clinic of Department of Orthodontics, Faculty of Dentistry, Mansoura University having: (1) Skeletal Class I with moderate maxillary crowding; (2) Angle Class II molars relation; (3) Constricted maxillary arch (posterior crossbite); (4) Ages ranged from 11 to 14 years with an average age of 12 years and 2 months. The changes that, brought by the appliance were evaluated from the lateral cephalometric, postero-anterior radiographs and study cast model taken before and after appliance application by means of a paired t-test. RESULTS: Significant amounts of maxillary expansion, molar distalization, molar distal tipping and anchorage loss were observed. The amount of maxillary expansion was 4.35 ± 072 mm. The mean maxillary first molar distal movement was 2.27 ± 0.52 mm with a distal tipping of 1.71 ± 0.74 degrees in 3.19 ± 0.53 months. The rate ofdistal movement was 0.70 mm per month. Reciprocal mesial movement of the first premolars was 1.73 ± 0.92 mm with a mesial tipping of 2.60 ± 1.02 degrees. Maxillary incisors moved 1.80 ± 0.85 mm and tipped 2.02 ± 1.43 degrees mesially. CONCLUSIONS: It was concluded that the Pendulum Hygienic Distalizer works well with the treatment philosophy of Class II malocclusion with posterior cross-bite by expansion the maxillary arch and distalizing of maxillary molars.