HDR brachytherapy irradiation of the jaw - as a new experimental model of radiogenic bone damage.
BACKGROUND
Hitherto, no suitable experimental model exists to test new treatments for radiogenic bone damage, such as new step from knowledge about bone growth factors or angiogenesis factors. The goal of this investigation was to establish such a standardised experimental model.


METHODS
Twenty-four rats were used in this study. In 12 rats a plastic tube was implanted along the right half of the mandible and treated with a single dose of 20 Gy at a high-dose-rate (HDR) using an afterloading machine, the remainder served as control (n=12). One hundred days after irradiation both sides of the mandible were examined using paraffin embedding and non-decalcified histology.


RESULTS
All HDR irradiated rats developed localised alopecia within 2 weeks of radiotherapy. In the irradiated group, a clear growth reduction of the ipsilateral incisor was observed. Paraffin histology revealed minimal damage of the bone structure with slightly increased signs of regeneration. The bone apposition rate was significantly reduced on the irradiated right side, compared with the left side (p=0.028). The average diameter of the mandibular condyles on the irradiated right sides was significantly reduced when compared with the left sides (p=0.023).


CONCLUSIONS
It is possible to induce radiogenic damage of the mandible by using HDR brachytherapy with a single dose of 20 Gy comparable to 45 x 2 Gy of conventional irradiation. This new model is easy and predictable and appears to be suitable for the testing of new treatment modalities. It is advantageous for the testing of bone growth and angiogenesis factors that the contralateral side exhibits completely normal bone apposition characteristics enabling a split-mouth design for future experiments.
Niehoff
Peter
P
Department of Radiotherapy (Radiooncology), University of Kiel, Germany. niehoff@onco.uni-kiel.de
Springer
Ingo N
IN
Açil
Yahya
Y
Lange
Andre
A
Marget
Matthias
M
Roldán
J Camilo
JC
Köppe
Klaas
K
Warnke
Patrick H
PH
Kimmig
Bernhard
B
Wiltfang
Jörg
J
D000505:Alopecia / Q000209:etiology; D000818:Animals; D001861:Bone Regeneration / Q000528:radiation effects*; D001918:Brachytherapy / Q000009:adverse effects*; D016371:Cranial Irradiation / Q000009:adverse effects*; D004307:Dose-Response Relationship, Radiation; D008297:Male; D008334:Mandible / Q000528:radiation effects*; D023421:Models, Animal; D010025:Osteoradionecrosis / Q000503:physiopathology; D011882:Radiotherapy, High-Energy / Q000009:adverse effects; D051381:Rats; D011916:Rats, Inbred F344; D011917:Rats, Inbred Lew; D011921:Rats, Inbred WKY; D018709:Statistics, Nonparametric; D014070:Tooth / Q000528:radiation effects