Tooth-Borne Versus Tooth-Bone-Borne Rapid Maxillary Expanders: A Stereophotogrammetric Evaluation of Soft Tissues

The patients were treated with a expansion appliance containing a Hyrax expansion screw positioned parallel to the second premolars and were used to correct the posterior crossbite. RME activation was performed twice a day for the first week and then once per day. When it was decided that the expansion was sufficient (until the palatal tubercles of the upper molars came into contact with the buccal tubercles of the lower molars), the screw was fixed with the 0.012-inch ligature wire (American Orthodontics) and the appliance was kept in the mouth without being activated for 3 months.

The patients were treated with a Hybrid hyrax RME appliance containing a Hyrax expansion screw positioned parallel to the second premolars and mini-screws. RME activation was performed twice a day for the first week and then once per day. When it was decided that the expansion was sufficient (until the palatal tubercles of the upper molars came into contact with the buccal tubercles of the lower molars), the screw was fixed with the 0.012-inch ligature wire (American Orthodontics) and the appliance was kept in the mouth without being activated for 3 months.