The radiobiological basis for tissue reactions in the oral cavity following therapeutic x-irradiation. A review.

The radiobiological basis for the response of tissues in the oral cavity following therapeutic doses of ionizing radiation has been reviewed. Clinical manifestations of radiation response occur when the functional compartment of the tissue, the parenchymal cells, is depleted to some minimal value. The time course and severity of the response depend on the sensitivity of cellular compartments, the vegetative intermitotic compartment being the most sensitive and the fixed postmitotic cells being the least sensitive. Early responses are therefore seen in rapid cell renewal systems while the chronic effects are closely correlated with damage to the terminal vascular bed, a multipotential connective tissue compartment. Osteonecrosis of bone following irradiation involves a series of events, including a decreased salivary gland function, devitalization of bone, and infection. Carcinogenesis in oral cavity tissues is a very rare late sequela of therapeutic radiation.