From genetics to occlusal medicine treatment: A case report on the multidisciplinary management of congenitally missing permanent maxillary canines.

Permanent maxillary canine agenesis is a rare condition caused by genetic, epigenetic, or environmental factors affecting tooth development. It results in malocclusion and adverse physiological changes. We present our orthodontic diagnosis, treatment challenges, and successful outcomes of a case involving a 10-year-old male with Class II/0 malocclusion, mild class III skeletal pattern, anterior crossbite, left mandibular lateral displacement malocclusion, right dental-skeletal crossbite, mild transitional bilateral posterior open bite, moderate lower anterior crowding, mild maxillary spacing, and genetic polymorphisms in MSX1 and PAX9; bilateral permanent maxillary canine agenesis, molar taurodontism, and bilateral mesioangular mandibular permanent second molar impactions. Presumptive mild-to-moderate hypolordosis and phase 2 left adolescent idiopathic scoliosis were also identified. Treatment involved widening the maxilla, replacing maxillary canines with bicuspids, second bicuspid extraction and closing spaces in the mandible, and deimpacting second mandibular molars. Spine follow-up showed indirect effects on head posture. Class I occlusion with normal overjet and overbite was achieved. Cervical spine correction occurred spontaneously years later. The spatiotemporal effects of MSX1 and PAX9 polymorphisms on the patient's phenotype led us to apply age-related orthodontic transverse and sagittal treatment strategies to avoid dental replacements and correct dental relationships and molar impactions. This approach also contributed to adolescent idiopathic scoliosis (AIS) self-correction in adolescence and long-term stability in adulthood.