This study evaluates, by means of cone beam computed tomography (CBCT), the alterations in the nasal septum and alveolar cleft volume that occur in cleft lip and palate (CLP) patients after rapid maxillary expansion(RME). 40 unilateral CLP patients (mean age, 11.1 ± 2.2 years) with transverse maxillary deficiency that underwent to RME will be evaluated in this investigation. CBCT images were taken prior to RME (T0) and after the removal of the expander (T1), for adequate secondary bone graft surgical planning. The scans will be used to analyze the effects on the nasal septum, anterior and posterior maxillary basal width (MBW) and alveolar cleft volume.

Rapid maxillary expansion (RME) is performed to correct crossbite in CLP patients as part of the orthodontic treatment, being able to improve the maxillary transverse dimension, that is an essential condition for alveolar bone grafting. The primary aim of the secondary graft surgery is to restore the function and structure of the maxillary arch at the cleft side, providing support to arch width, minimizing its transverse collapse. However, since RME exert heavy forces to separate the two maxillary helves, it may significantly widen the alveolar cleft defect, possibly compromising bone graft success.

Moreover, RME has an important impact on the geometry and function of the nasal cavity, providing a lateral displacement of the walls and facilitating the airflow through the upper airways. These effects are very important to CLP patients, since they usually present reduced upper airway dimensions, adenoid hypertrophy, sleep disorders, oral breathing, and a marked nasal septal deviation. The nasal septal deviation is one of the major causes of nasal obstruction in non-cleft patients, and often results in blocking of the nasolacrimal ducts, sinusitis, ear infections and mouth breathing. However, nasal septum deviation in CLP patients commonly persists even after surgical repair of the cleft, leading to a chronic obstruction of the air passage, until the septorhinoplasty, at the age of 14-18 years.

Each expander was cemented with a fluoride releasing cement, and the activation regimen was established at 2 turns/day until the tip of the lingual cusps of the maxillary teeth touched the tips of the buccal cusps of the mandibular teeth. After the 3-month retention period, the expander was removed, and a post-expansion CBCT scanning (T1) was acquired for adequate secondary bone graft surgical planning.

Inclusion Criteria:

• The inclusion criteria comprehended the presence of unilateral cleft lip and palate, rapid maxillary expansion as an initial part of the orthodontic treatment, and absence of previous orthodontic treatment.

Exclusion Criteria:

• The exclusion criteria were absent maxillary permanent first molars, signs of active periodontal disease, and presence of any additional craniofacial syndrome.

40 unilateral cleft lip and palate patients (UCLP) (23 male and 17 female), aging from 8 to 14 years old (mean age of 11.1 years ± 2.2). All subjects were in prepubertal or pubertal stage of maturation based on the cervical vertebrae maturation19 assessed on reconstructed lateral cephalograms generated from CBCT.

Patient's individual data might be available upon a reasonable request