Methods: Case #1 was a 26-year-old female with Class I skeletal and dental relationship, bi-maxillary dento-alveolar protrusion with previous extraction of first upper premolars. Case #2 was a 19-year-old female with Class I skeletal and end to end molar relationship who did not accept to extract her first premolars. The treatment plan included distalization of all maxillary posterior teeth simultaneously. The posterior arms of modified Hyrax appliance were attached to the dentition with bands on first molars and bonding to other posterior teeth. Anterior arms had been formed as eyelets with 2 mm internal diameter and were attached to anterior palate with two mini-screws (2 mm×10 mm, Jeil Medical, Korea) at para-median regions. The vector of expansion of appliance was parallel to mid-palatal suture and occlusal plane. Before and after distalization, lateral cephalograms were used to evaluate the results.
Results: In case #1 3.6-mm and in case #2 3.45-mm distalization of entire maxillary posterior teeth were achieved in five months. Bodily distal movement with no significant unwanted rotations and anchorage loss was seen. The anterior face height did not change significantly.
Conclusions: This technique can be used for en-mass distalization of maxillary posterior teeth. The greatest advantage is reducing the treatment time. Other advantages are skeletally anchorage, patient comfort and no unwanted dental tipping and rotations.