Immediate hyperbaric oxygen after tooth extraction ameliorates bisphosphonate-related osteonecrotic lesion in rats.

BACKGROUND: This study aims to assess whether hyperbaric oxygen (HBO) applied immediately after tooth extraction could ameliorate medication-related osteonecrosis of the jaw in rats. METHODS: To evaluate whether osteonecrosis could be successfully induced, healing of extraction maxillary molars was examined in 40 female Sprague Dawley rats received zoledronic acid (7.5 microg/kg) plus dexamethasone (1 mg/kg). Rats were divided into four groups, receiving zero, two, four, or seven injection(s) for 7 days, respectively. Effect of HBO, pressurized to 2.5 atmospheres absolute (ATA) at rate of 0.15 ATA/min with 100% oxygen for 90 minutes, applied immediately after tooth extraction, on the development of osteonecrosis was evaluated. Lesions among groups were compared by size of ulceration, exact area (mm(2) ) or relative area (%), and by histology. RESULTS: Unhealed ridge was observed in all nine rats in four and seven injection groups, but none of 10 rats in the control (non-injection) group. Immediate HBO significantly reduced the lesions in rats that received four injections, regardless of the distribution and the total/relative areas of lesions (P <0.01). Histological findings showed the lesions were uncovered epithelium and severe tissue inflammation. CONCLUSION: This is the first in vivo study demonstrating the HBO applied immediately after tooth extraction effectively decreases the development of medication-related osteonecrosis.