Maxillary anterior segmental distraction osteogenesis (MASDO) is a rather new surgical orthodontic treatment to produce an ideal maxillary dental arch form in patients with cleft lip and palate. Different from total maxillary advancement by DO, this surgical procedure can solves the problems in the small and retruded maxilla without the risk of deterioration of velopharyngeal function, because the distracted segment is only made at the anterior part of the maxillary bone.
To advance the anterior segment in only a single vector, a single palatal bone-borne distractor or toothborne distractor is effective, but two hybrid type distractors on each side of alveolar process can produce some rotational movements of anterior segment by controlling advancement amount in each side. Therefore, this procedure solves not only the size of maxillary arch but also the shape of deformed dental arch.
As bone height and width at distracted space on alveolar process is enough for fuature alignments of crowding teeth or anterior movement of molars, this treatment is an effective pre-orthodontic surgical treatment for solving discrepancy of maxillary dental arch.