Inclusion Criteria:  Medically free male or female patients Patients that necessitated maxillary expansion due to constricted maxillary arch shown by a unilateral or bilateral posterior crossbite. The patient should have no missing teeth except third molars. Age ranged from 12 to 18 years old. The patient should have a good gingival condition. The patient should have a good periodontal condition.  Exclusion Criteria:  1-hisory of previous orthodontic treatment. 2- Lack of cooperation. 3- Mental problems. 4- Skeletal open bite. 5- TMJ problem.  -