Orthodontic treatment of a patient with an impacted maxillary second premolar and odontogenic keratocyst in the maxillary sinus

An eight-year-, four-month-old girl was brought to the orthodontic clinic of Okayama University Medical and Dental Hospital. The patient had an impacted upper left second premolar because of an odontogenic keratocyst and showed a skeletal Class II jaw base relationship. At the age of six years four months, marsupialization of a cyst was performed at the Okayama University Medical and Dental Hospital because the patient had shown a swelling of the left cheek because of the cyst. The upper left second premolar was located in the roof of the maxillary sinus. The cyst was histopathologically diagnosed as an odontogenic keratocyst. At the age of nine years 10 months and after regaining the space for eruption of the premolar, the impacted premolar erupted without traction. At the age of 12 years five months, edgewise treatment was initiated, which continued for three years. After removing the edgewise appliance, an optimum occlusion was achieved. The occlusion was maintained without recurrence of the keratocyst after a retention period of five years.