Microstructural changes in the irradiated and osteoradionecrotic bone: a SEM study

Area of Science:

• Oral and Maxillofacial Surgery
• Biomaterials Science
• Radiology

Background:

• Radiation therapy for head and neck cancers can negatively impact mandibular bone metabolism and healing.
• Osteoradionecrosis (ORN) is a serious complication of radiotherapy, characterized by bone death and impaired healing.
• Understanding radiotherapy-induced microstructural changes is crucial for managing ORN risk.

Purpose of the Study:

• To investigate the microstructural alterations in human mandibular bone following radiotherapy using scanning electron microscopy (SEM).
• To compare bone microstructural parameters between control, irradiated, and osteoradionecrosis (ORN) patient groups.

Main Methods:

• Mandibular cortical bone biopsies were collected from three groups: control, irradiated, and ORN patients.
• Bone samples underwent preparation for light microscopy and scanning electron microscopy (SEM).
• SEM analysis quantified osteons, Haversian canals (HC), osteon diameter (D.O), HC diameter (D.HC), osteonal wall thickness (O.W.Th), osteocytes, and osteocytic dendrites.

Main Results:

• Irradiated and ORN bone samples showed significant reductions in osteons, D.O, D.HC, O.W.Th, osteocytes, and osteocytic dendrites compared to controls (p < .05).
• A non-significant decrease in Haversian canals (HC) was observed in irradiated and ORN bone.
• Long-term radiation effects (>5 years) demonstrate progressive deterioration of bone quality, structure, cellularity, and vascularity.

Conclusions:

• Radiotherapy induces significant long-term microstructural damage to the human mandible.
• These microscopic changes impair bone quality, cellularity, and vascularity, increasing susceptibility to ORN.
• SEM provides valuable insights into the pathogenesis of radiation-induced bone damage and ORN.