Table 1. Different staging systems of ORN.

Study	Year	Stages
Marx 11 14	1983	Stage I	Exposed alveolar bone without pathological fracture, which responds to HBO therapy
		Stage II	Not responsive to HBO therapy and requires sequestrectomy and saucerization
		Stage III	Most severe and involves full-thickness bone damage or pathological fracture and requires resection and reconstruction with free tissue
Glanzmann and Grätz 16	1995	Stage 1	Bone exposure without signs of infection and persisting for at least 3 mo
		Stage 2	Bone exposure with signs of infection or sequester and without the signs of grades 3–5
		Stage 3	Bone necrosis treated with mandibular resection with a satisfactory result
		Stage 4	Bone necrosis with persisting problems despite mandibular resection
		Stage 5	Death from ORN
Støre and Boysen 17	2000	Stage 0	Mucosal defect only
		Stage 1	Radiological evidence of necrotic bone with intact mucosa
		Stage 2	Positive radiological findings with denuded bone intraorally
		Stage 3	Clinically exposed radionecrotic bone, verified by imaging techniques, along with skin fistulae and infection
Schwartz and Kagan 15	2002	Stage I	Minimal soft tissue ulceration and limited exposed cortical bone; patients are treated with conservative management
		Stage II	Localized involvement of the mandibular cortex and underlying medullary bone
		Stage III	Full-thickness involvement of the bone, including the inferior border; pathological fractures may be present
Notani et al 18	2003	Stage I	ORN confined to the alveolar bone
		Stage II	ORN limited to the alveolar bone and/or mandible above the level of the inferior alveolar canal
		Stage III	ORN involving the mandible below the level of the inferior alveolar canal and/or skin fistula and/or pathological fracture

Abbreviations: HBO, hyperbaric oxygen; ORN, osteoradionecrosis.