ORN Flashcards
Pathophysiology of ORN
3 theories:
Meyers theory: Radiation, Trauma, Infection
Any form of trauma (surgical trauma, dental extraction, ill fitting dentures) on irradiated bone -> access of bacteria into underlying bone -> irradiation prevents from tissues to resist infection -> necrosis
Marx theory: Hypovascular Hypocellular Hypoxia
-> gradual ischemia -> impair healing -> necrosis
DRIFT (Delanian radiation-induced fibroatrophic theory): Free radicals -> deregulates activity of fibroblasts -> affects osteoblastic/osteoclastic activity -> soft tissue and bone necrosis
3 stages: initial prefibrotic phase, constitutive organized phase, late fibroatrophic phase
Risk factors of ORN
Radiation factor: >60Gy Reradiation Radical/adjuvant RT Combined chemoradiotherapy 2DRT (more general dosage) vs IMRT (concentrate dose to the disease region and subclinical region and can spare the nontumor region to have lower dose)
Tumor factor:
Mandible - primary site, proximity to tumor
Extent/proximity to radiation field
Dental factor: Surgical procedure (biopsy, extraction, implant) Denture - mucosal bearing Periodontal disease Poor OH
Patient factor: Poor nutrition Alcohol/smoking Time >18months after RT higher risk Clinical features of ORN pain soft tissue ulceration exposed bone orocutaneous fistula pathologic fracture
Staging of ORN
Three stages
Stage I - superficial involvement of cortical bone only +/- soft tissue ulceration/necrosis
Stage II - involvement of cortical and medullary bone with sequestrum +/- soft tissue ulceration/necrosis +/- orocutaneous fistula
Stage III - diffuse involvement of cortex and medullary bone, close or involving the mandibular border +/- orocutaneous fistula +/- pathologic fracture
Prevention of ORN
Prior to radiation:
Dental clearance of poor prognosis teeth 2weeks prior to RT
During radiation (7): OHI reinforcement Topical fluoride Protection trays with fluoride Mouth rinsing saline 10x/day, CHX 2x/day Nystatin - antifungal Jaw opening exercise Adequate nutrition- OGT/ NGT feeding
Post irradiation (6): Topical fluoride No mucosa borne dentures Salivary subs for xerostomia Postextraction - antibiotics + soft tissue closure HBO therapy (20:10) pre and post PenTo (400mg bd/1000IU) +/- Clo
How to minimize the risk of ORN during extraction
Suggest for Preop HBO therapy (20dives) Atraumatic technique Avoid LA with adrenaline Antibiotic prophylaxis Pentotoxyfilline (400mg BD) Soft tissue closure Post op AB until soft tissue healed
Tx of Stage I ORN
Local debridement Symptomatic tx Antibiotic long term until soft tissue healing Mouthwash Pen-To-Clo
Tx of Stage II ORN
Local debridement + Sequestrectomy + until bleeding bone + soft tissue closure Symptomatic tx Antibiotic long term Mouthwash Pen-To-Clo HBO therapy
Tx of Stage III ORN
Aggressive surgical extirpation of diseased soft and hard tissues
Resection of necrotic bone with composite flap reconstruction to ensure soft tissue coverage
Longterm A/b therapy
How to treat pathological fracture in ORN mandible
Similar as stage III tx:
Resection with vascularized free tissue transfer using composite flap.
HBO and PenToClo not neccessary.
Radiated patient wants to do Implant. How?
…
AO ORN Pathophysiology
Orn risk factors - >60Gy - reradiation - location of tumor if its close to mandible - trauma (surgery/exo/etc) - poor OH - Concurent chemort - Radical/adjuvant - Type of Rt 2Drt (more general dosage) vs imrt (concentrate the dose to the disease region and subclinical region)(can spare the nontumor organ to have less dosage)
Pathophysiology!!!!
1) Marx theory
-
Endarteritis Obliterans
2) Radiation-induced Fibroatrophic theory
- the main reason for using pentoxyfilline - tocopherol - clodronate
3)….
Constitutive organized phase
Late fibroatrophic phase
Treatment:
evidence not strong enough to recommend HBO -20/10 protocol
No evidence of antibiotic use as well before exo to reduce orn
Pen-To-Clo
