The histological and histomorphometric changes in the mandible after radiotherapy: An animal model.
OBJECTIVE
Approximately 5% of irradiated head and neck cancer patients develop osteoradionecrosis of the mandible. The current non-surgical treatment options for osteoradionecrosis have limited effects and are based on a small number of studies. Therefore, we aimed to enhance the understanding of the pathophysiology of osteoradionecrosis by investigating changes induced by external irradiation in mini-pigs.


METHODS
Sixteen Göttingen mini-pigs were divided into four groups for the application in two fractions with total equivalent radiation dosages of 25, 50, 70 Gray, and one group served as control. Thirteen weeks after irradiation, the left lateral teeth the mandible were removed and implants were placed. The pigs were sacrificed twenty-six weeks after irradiation, and the bone samples were stained with Masson's trichrome.


RESULTS
The amount of fibrosis, resorption lacunae, necrosis, and the woven/lamellar bone ratios were increased after higher radiation dosages. The diameter of the lumen of the inferior alveolar artery was reduced depending on the irradiation dosages. The rate of bone remodeling decreased after irradiation.


CONCLUSIONS
Both surgery and increasing irradiation dosages cause architectural bone changes and damage the vascularization. This might result in a chronic hypoxic state of the mandibular bone. In general, the bone formation rate was markedly decreased after radiotherapy.
Department of Cranio-Maxillofacial Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands; GROW School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands. Electronic address: l.poort@mumc.nl.
Lucas J
LJ
Poort
Department of Cranio-Maxillofacial Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands; GROW School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands.
Johan H B
JHB
Ludlage
Department of Cranio-Maxillofacial Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands; GROW School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands.
Nienke
N
Lie
Department of Cranio-Maxillofacial Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands; GROW School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands.
Roland A
RA
Böckmann
Laboratory of Experimental Orthopaedics, Department of Orthopaedic Surgery, CAPHRI School for Public Health and Primary Care, Maastricht University, The Netherlands.
Jim C E
JCE
Odekerken
Department of Radiation Oncology (MAASTRO), Maastricht University Medical Centre, Maastricht, The Netherlands; GROW School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands.
Frank J
FJ
Hoebers
Department of Cranio-Maxillofacial Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands; GROW School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands.
Peter A W H
PAWH
Kessler
D000818:Animals; D004195:Disease Models, Animal; D004307:Dose-Response Relationship, Radiation; D005260:Female; D008334:Mandible / Q000473:pathology / Q000528:radiation effects*; D008336:Mandibular Diseases / Q000473:pathology* / Q000503:physiopathology; D010025:Osteoradionecrosis / Q000473:pathology* / Q000503:physiopathology; D013552:Swine; D013556:Swine, Miniature
Animal model; Histological changes; Irradiation; Mandible; Osteoradionecrosis