Group 2 treatment will consist of a fixed functional Crossbow appliance. Bands will be fitted in the lower first molars, as well as in the upper first molars. A lingual and a vestibular arch connecting the lower molar bands, as well as a Hyrax type rapid maxillary expansion connecting the upper bands will be made in the laboratory. A Forsus spring will be connected from a molar tube in the upper first molar to lower vestibular arch with adjustable Guerin locks. It is expected that the Xbow treatment will be around 6 to 8 months. Fixed orthodontic appliances (brackets and molar tubes) will be inserted thereafter and the regular orthodontic treatment will be provided with an expected additional completion time of 12 to 16 months. Therefore total treatment time will be in the 24-month range.