The effect of radiotherapy in the treatment of retinoblastoma upon the developing dentition.

Two patients who received supervoltage x-ray external beam irradiation for treatment of retinoblastoma by standard techniques showed interference with the root formation of the maxillary deciduous molars and abnormalities of crown and root formation of the permanent maxillary molars. Both patients showed a relative maxillary retrognathism thought to be related to radiation effects on maxillary bone growth. Simulation of lateral radiation portals with subsequent beam shaping using an appropriate block placed in the radiation beam is suggested as a means to eliminate the dental complications of radiation therapy for retinoblastoma.