Osteoradionecrosis (ORN) Prevention
Information for Dentists and Oral Surgeons
Hyperbaric Oxygen Therapy for ORN Management is Fully Covered by OHIP
Background on ORN in Dental Patients
Patients diagnosed with head and neck cancers are commonly treated with a combination of radiotherapy and ablative surgery and can often require extensive oral rehabilitation following their cancer treatment. Although it is always ideal to complete as much dental work as possible before radiotherapy, patients will still frequently require dental extractions or implant placement afterwards. In these patients, recovery can be complicated by ORN and delayed wound healing with negative effects on osseointegration and implant survival.
Although ORN can occur spontaneously months to years after the radiotherapy treatment of head and neck cancers, an important precipitating factor is post-radiotherapy dental surgery. Additional risk factors suggested to increase the risk of developing ORN include pre-radiotherapy osteotomy or prior tooth extraction, poor oral hygiene, tobacco smoking, alcohol consumption, radiation dose and tumor-to-bone proximity (1).
Hyperbaric Oxygen Therapy (HBOT) to Reduce the Risk of ORN
HBOT is known to positively affect surgical outcomes in vulnerable tissues as in those affected by radiotherapy. HBOT works to by increasing the oxygen supply in hypoxic tissues leading to fibroblast proliferation and capillary formation which in turn increases tissue vascularity, viability, and healing capacity. On this basis, many protocols support the use of prophylactic and perioperative HBOT to reduce the risk of ORN and improve implant retention in an irradiated mandible.
Update on Current Literature
One of the earlier protocols was by Marx, which through a randomized prospective trial demonstrated that ORN incidence was decreased to 5.4% in the group pretreated with HBOT versus 29.9% in those treated with penicillin alone prior to dental extractions (2). Since then, retrospective reviews have continued to support the role of HBOT in ORN (3,4) including a more recent prospective study that followed 411 patients over 8 years. This study looked at the complete heal rates in patients undergoing ORN surgery and it found that 92% of the 166 patients in the 20 pre-procedure and 10 post-procedure HBOT arm achieved complete healing (5).
Furthermore, a comprehensive 2016 Cochrane review of 14 trials encompassing a total of 753 patients found that HBOT was associated with a 1.3 odds ratio (95% CI: 1.1-1.6 P=0.003) of achieving mucosal coverage in patients at risk of ORN versus standard care alone and this translated to a number needed to treat of 5 to achieve additional benefit in this patient population (6).
A study that has been cited in dental literature by Annane et al (7) did not support the use of HBOT for patients at risk of ORN undergoing dental procedures, however this paper has come under heavy scrutiny over methodologic concerns and interpretability of data.
Firstly, in this study 68 subjects were enrolled from 12 different hospitals making adherence to one standard of care unachievable.
Secondly, HBOT treatment schedules were not provided with one quarter of the treated subjects receiving less than 22 sessions (a subtherapeutic regiment when compared to other studies).
Thirdly, looking at the statistical outcomes and confidence intervals it is evident that the study was underpowered making accurate interpretation of the findings difficult.
Finally, and most concerningly, was how treatment failure was defined. In this study HBOT failure was defined as the need for debridement surgery.
As per USHMS guidelines, HBOT is to be used as an adjunct therapy in patients at risk of ORN needing dental procedures to improve the odds of tissue healing. This means using it in conjunction with surgical debridement and not trying to replace it.
Recommendations for HBOT use for ORN Risk Reduction
At this time, a formal consensus has not been reached regarding a standard protocol for HBOT in patients undergoing dental procedures who are at risk of ORN and additional data is forthcoming. An ongoing randomized trial “Hyperbaric Oxygen for the Prevention of Osteoradionecrosis (HOPON)” will compare patients receiving oral antibiotics and mouthwashes, with and without the use of 20 pre-procedure and 10 post-procedure HBOT sessions (8).
In the interim, HBOT protocols with 20-30 pre-procedure and 10 post-procedure sessions at 2.4 ATA for 90 minutes should be utilized as an important adjunct treatment in this patient population (9,10). This should always be combined with existing standard of care guidelines that include smoking and alcohol cessation, perioperative antibiotics and chlorhexidine mouthwashes, and appropriate surgical timing.