Objective To establish,based on new diagnostic criteria for osteoradionecrosis of the jaws(ORNJ),an animal model with a controllable bone defect range and early and mild ORNJ characteristics.Methods A method involving single high-dose irradiation with an electron linear accelerator was applied.According to the irradiation dose,the animals were divided into a group(control group);b group(12 Gy group);and c group(14 Gy group).Six rabbits were randomly assigned to each group,b and c groups were uniformly selected for further radiotherapy of the right mandibular area.After 1 week,all animals were prepared with a standard bone defect at the right mandibular angle.After 4 weeks,the animals were euthanized,and general observations were conducted.CBCT scans and HU values of mandibular specimens,HE staining histological observations,Trap staining histology,and osteoclast counts were compared.And the statistical analysis were carried out.Results 4 weeks after the bone defect was created,the soft tissue in the surgical area of b and c groups showed mild swelling,purple skin,and erosion and ulceration of the oral mucosa,with c group showing the most significant changes.CBCT examination showed that the cortical bone of the irradiated areas in b and c groups was rough,while that of c group had poor continuity.No significant changes were observed in the extent of the bone defect in any group,b and c groups had significantly decreased HU values compared with a group.HE staining and histological observation suggested that the bone continuity of b and c groups had deteriorated;there was a large amount of fibrotic tissue proliferation,an increase in blank bone pits without cells,and an infiltration of inflammatory cells.Trap staining revealed a significant increase in osteoclasts in c group compared with a group.Conclusion By using an electron linear accelerator,a single dose of 14 Gy irradiation was applied to the mandibular angle area to create bone defects with consistent specifications in rabbits.After 4 weeks,an animal model that met the early diagnostic criteria of ORNJ and had controllable consistency in the range and degree of bone defects was established.

Objective To establish,based on new diagnostic criteria for osteoradionecrosis of the jaws(ORNJ),an animal model with a controllable bone defect range and early and mild ORNJ characteristics.Methods A method involving single high-dose irradiation with an electron linear accelerator was applied.According to the irradiation dose,the animals were divided into a group(control group);b group(12 Gy group);and c group(14 Gy group).Six rabbits were randomly assigned to each group,b and c groups were uniformly selected for further radiotherapy of the right mandibular area.After 1 week,all animals were prepared with a standard bone defect at the right mandibular angle.After 4 weeks,the animals were euthanized,and general observations were conducted.CBCT scans and HU values of mandibular specimens,HE staining histological observations,Trap staining histology,and osteoclast counts were compared.And the statistical analysis were carried out.Results 4 weeks after the bone defect was created,the soft tissue in the surgical area of b and c groups showed mild swelling,purple skin,and erosion and ulceration of the oral mucosa,with c group showing the most significant changes.CBCT examination showed that the cortical bone of the irradiated areas in b and c groups was rough,while that of c group had poor continuity.No significant changes were observed in the extent of the bone defect in any group,b and c groups had significantly decreased HU values compared with a group.HE staining and histological observation suggested that the bone continuity of b and c groups had deteriorated;there was a large amount of fibrotic tissue proliferation,an increase in blank bone pits without cells,and an infiltration of inflammatory cells.Trap staining revealed a significant increase in osteoclasts in c group compared with a group.Conclusion By using an electron linear accelerator,a single dose of 14 Gy irradiation was applied to the mandibular angle area to create bone defects with consistent specifications in rabbits.After 4 weeks,an animal model that met the early diagnostic criteria of ORNJ and had controllable consistency in the range and degree of bone defects was established.