Abstract: The mixed dentition period is one of the most active periods of occlusal and maxillofacial growth and development. It is the period when the problems of malocclusion appear and aggravate in patients with cleft lip and palate, and an important treatment stage in the sequential treatment of cleft lip and palate. Due to congenital malformation, surgical trauma and scarring, patients with cleft lip and palate often suffer from maxillary underdevelopment, which causes abnormal intermaxillary transverse and sagittal relationships, manifesting as anterior and posterior crossbite. Congenital missing teeth and early tooth loss due to poor tooth development and poor oral hygiene further complicate the malocclusion in patients with cleft lip and palate. During the mixed dentition period, orthodontic treatment of abnormal intermaxillary transverse and sagittal relationship and the treatment of the tooth abnormalities in patients with cleft lip and palate can alleviate occlusal and maxillofacial deformities, improve the function of the stomatognathic system, and be beneficial to the occlusal and maxillofacial development. The alveolar bone grafting during the mixed dentition period is vital in the sequential treatment of cleft lip and palate, which lays a good foundation for the subsequent orthodontic treatment of malocclusion. The necessary orthodontic treatment before bone grafting is expected to improve the treatment effect of bone grafting. In this article, we will address the common malocclusion and the corresponding orthodontic treatment in patients with cleft lip and palate during the mixed dentition period.

Key words: cleft lip and palate, mixed dentition, maxillary relationship, malocclusion, orthodontics