What systemic and local biochemical factors can delay bone healing after jaw surgery?

For healthy fusion (bone consolidation) of the cut bone segments after orthognathic surgery, both the overall biochemical balance of the body and local factors must be favorable. Systemically, uncontrolled diabetes, advanced osteoporosis, vitamin D and calcium deficiency, chronic use of corticosteroid drugs, and smoking, which impairs oxygenation in tissues and disrupts capillary development (angiogenesis), severely delay or halt bone fusion (non-union). Locally, insufficient rigid fixation of bone segments with plates, infection at the incision site, and excessive heating and necrosis of the bone during surgical cutting (thermal necrosis) impair the activity of bone cells (osteoblasts) and lead to failure.