Osteoradionecrosis of the mandible. Comparison of the effects of external beam irradiation and brachytherapy.
OBJECTIVE
To compare the difference in location and severity of osteoradionecrosis (ORN) of the mandible following either external beam irradiation alone or combined with brachytherapy in the management of orofacial cancer.


METHODS
CT was used to evaluate ORN in relation to the radiation source and field and the site of malignancy in 31 patients with orofacial carcinomas. Twenty-three patients received combined radiotherapy and brachytherapy and eight patients only external radiotherapy. The radiation dose distribution to the mandible was calculated retrospectively.


RESULTS
In the combined radiotherapy group all patients had ORN of the lingual cortex, mostly adjacent to the position of previous iridium implants. Lingual defects were also found in the contralateral mandible in 35% of patients. Defects in the buccal cortex were seen in 30%. In the external radiotherapy group, ORN was found in both buccal and lingual cortices and 50% also in the contralateral mandible. When brachytherapy with iridium implants was used the dose to the buccal cortex was about one-third of that to the lingual cortex. There was no dose gradient between the cortices using external beam irradiation alone.


CONCLUSIONS
Evidence of ORN was found in both groups of irradiation regimens. Thus, the entire irradiated mandible should be considered as a compromised tissue at risk of ORN.
Støre
G
G
Department of Maxillofacial Surgery, National Hospital, Oslo, Norway.
Evensen
J
J
Larheim
T A
TA
D000328:Adult; D000368:Aged; D001918:Brachytherapy / Q000009:adverse effects; D016371:Cranial Irradiation / Q000009:adverse effects* / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008336:Mandibular Diseases / Q000000981:diagnostic imaging / Q000209:etiology*; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000532:radiotherapy; D010025:Osteoradionecrosis / Q000000981:diagnostic imaging / Q000209:etiology*; D011879:Radiotherapy Dosage; D011882:Radiotherapy, High-Energy / Q000009:adverse effects; D014057:Tomography, X-Ray Computed