Evaluation of Maxillary Expansion Using Clear Aligners' Therapy in Patients With Cleft Lip and Palate at the Mixed Dentition Stage: A Pilot Study

Cleft lip and palate (CLP) is the most prevalent among all craniofacial anomalies, affecting one in every 700 births and disturbing the quality of life of more than 7 million people around the world.

Cleft lip and palate are defined as malformations characterized by the non-union of the upper lip and/or palate, either separately or in conjunction with another syndrome. Its etiology is rather complex and definitely multifactorial, where complex interplay between genetic and environmental factors play a significant role in the incidence and cause of cleft.

Cleft lips can be unilateral or bilateral, and may involve the alveolus or palate. Unilateral cleft lip shows a 2:1 left predominance.

Lip and palate surgical repairs are performed in the first months and years of life respectively. As a consequence, the growth and development of the maxillary segments are compromised by scar tissues, presenting a significant maxillary transverse deficiency with medially collapsed cleft segments accompanied with anterior crossbite or both anterior and posterior crossbites. Most CLP patients present a narrower anterior than posterior maxillary arch frequently showing a crossbite in both canine and premolar areas and a normal occlusal transverse molar relationship.

Maxillary expansion is usually performed before the secondary alveolar bone grafting procedure. Expansion improves the maxillary arch morphology and causes the segmental alignment creating appropriate conditions for bone grafting surgery as well as correcting the posterior crossbites.