What are the risk factors for osteoradionecrosis (ORN), in a xerostomic radiation-treated patient, if extractions are required?
This question was submitted to us by a general dentist: If extractions are required, what are the risk factors for osteoradionecrosis (ORN) in a xerostomic patient with rampant decay two years after the successful treatment of their head and neck cancer (radiation, chemotherapy and surgery)?
Dr. Jeff Chadwick, at Princess Margaret Hospital, Dental Oncology, Ocular, and Maxillofacial Prosthetics Group, provided a preliminary response to this question:
With the numerous comorbidities associated with head and neck radiation (oral mucositis, radiodermatitis, dysgeusia, dysphagia/odynophagia, trismus, and xerostomia), arises a critical issue with tooth extraction is the altered biology of the maxilla and mandible due to therapeutic radiation exposure. The treatment results in osseous hypovascularity, hypocellularity, and hypoxemia.
Prior to performing any extractions on radiation-treated patients (head and neck), vital information must be considered, including:
1. General Medical History/Medication History/Social History and other impediments to wound healing
- Diabetes Mellitus
- Renal/Hepatic Failure
- Continued Tobacco Use
- Autoimmune Disease
- Alcohol Abuse
2. Oncology History
- Original diagnosis
- Date of diagnosis and treatment
- Treatment Centre/Radiation Oncologist
- Any ongoing therapy (if applicable)
- Treatment delivered (Radiation/Chemotherapy/Surgery)
- Type of surgery
- Constituents and duration of chemotherapy
- Type and duration/dose of radiation (# of fractions/# Gray [Gy])
3. Clinical history of current dental issues
- Subjective history of pain/swelling/fever/temperature sensitivity/oral fetor
- Clinical examination
- Radiographic examination
If it is determined that the source of infection or rampant decay was in the field of radiation (See Note below), the risk of ORN is significant once the relative dose climbs above 50Gy. It is at this point that the practitioner should consider the following:
1. Refer patient back to the Department of Dentistry at the original treatment site (if possible) for treatment.
2. Place amalgam fillings, if teeth are restorable, wherever possible.
3. Consider endodontic treatment, if certain teeth are beyond restoration, leaving roots in situ and allowing them to passively erupt.
4. If a tooth is not amenable to endodontic therapy (vertically fractured, exceptional canal anatomy), you could consider extraction with attention given to the following:
- Pre-extraction/post-extraction antibiotic prophylaxis
- Conservative surgical approach (avoidance of bone removal/flap elevation)
- Post-operative use of Chlorhexidiene 0.12% rinse twice daily until mucosal coverage is achieved
- Vigilant, frequent, follow-up and monitoring of the healing process
- If multiple teeth require extraction, they should be performed one or two at a time to allow for the completion of the initial stages of healing (this avoids multiple anatomic sites with post-extraction complications)
Ideally, prior to the commencement of a course of head and neck radiation, patients will have been meticulously examined for dental disease by the staff dentists at their respective cancer centres. While there are many conditions that are commonly observed in private practice, any source of infection (including, but not limited to: caries, odontogenic, periodontal) must be treated prior to radiation therapy to reduce peri/post-radiation complications. The conscientious practitioner must identify and prevent dental problems before the patient is faced with the prospect of full-mouth clearance (see Figures 1, 2 and 3).
For dentate patients, a rigorous oral hygiene and maintenance program is mandatory and includes more frequent follow-up, scaling, oral hygiene re-instruction as well as more frequent radiographic surveys. Patients must also be placed on a regimen of 1.1% neutral pH sodium fluoride gel treatment delivered using custom “mouth-guard” type trays on a daily basis for the remainder of their lives to aid in the reduction of post-radiation decay secondary to radiation-induced xerostomia. In virtually all cases, once a patient has completed cancer treatment and the acute effects of radiation have subsided, they will be referred back to their general dentist for regular care.
Note: You can verify if the source of infection or rampant decay is in the field of radiation, if you contact the patient’s radiation oncologist. Then, they may consult their dosimetry report which would show the dose of radiation delivered to the tooth-bearing portions of the maxilla/mandible.
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