The Effect Of Hyperbaric Oxygen Therapy On Bone Regenerate Ossification During Mandibular Distraction Osteogenesis In Goats

[Objective]The purpose of this study was to evaluate the effect of hyperbaric oxygen therapy on bone regeneration ossification during distraction of goat mandibles.[Methods]Six healthy goats were randomly divided into two groups. The first group (n = 3) did not go through hyperbaric oxygen therapy, the second group (n =3) went through intermittent hyperbaric oxygen therapy. All animals underwent a osteotomy on two sides of mandible and then two distraction devices were placed. Distraction, at a rate of 1 mm/day and a rhythm of 2 turn/day, began after a 5-day latency period for ten days. The second group underwent hyperbaric oxygenation of 1.5 hours daily for fourteen days from second day of latency phase. Twenty-eight days after completion of distraction protocol, all animals were killed and the distracted mandibles were harvested.The appearance of the samples,radiological changes,bone mineral density, mechanical strengths and histology were examined. Moreover, serum alkaline phosphatase was measured before hyperbaric oxygen therapy and every four days thereafter from treatment 3 days through first day after treatment .[Results]1.Clinical observation: All animals survived in the experiment and distraction devices fixed good. When the hauling ended, the goats'lower jaws were forward prominent and the occlusions were disorder. In the experimental group, the surgery region swelling abated quickly; In the control group, an animal's surgery region has had infection. 2.Specimen observation: Every goat had bony Callus, and the experimental group resulted in harder and wider healing bone. 3.X-ray: All specimens showed progressive calcification of distracted area between mandibular segment and the bone cerebral cortex had connected completly except one infected animal;The distracted zone in the experimental group exhibited the higher radiodense opacity. 4. Bone Mineral Density:After the animals were killed, bone density was surveyed with dual-energy x-ray absorptiometry, which showed that the experimental group resulted in denser healing bone (P<0.05). 5.Biomechanical test: Three-point bending test showed that the maximal loading and flexibility loading in the experimental group were higher than the control group (P<0.05),and fracture energy between the two groups showed no significant difference; The maximal strain and flexibility strain in the control group were higher than the experimental group.6.Histology: In the control group ,three zones exhibited the progress of intramembranous ossification. From center to edge of the distracted area there were the zone of fibrouse tissue, zone of extending bone formation and zone of bone remodeling. In the experimental group, the zone of extending bone formation and zone of bone remodeling were broader, in some specimens, the zone of fibrouse tissue tended vanishing and at the edge of the distracted area, the healing bone tends to be mature. 7.Histomorphometric:Statistical analysis of the percentage of bone trabeculae area in the distraction gap revealed that experimental group showed significantly increased compared with the control group (P<0.05).8.Serum alkaline phosphatase:Early after surgery, every animal's serum alkaline phosphatase increased and the experimental group increased more significantly than the control group (P <0.05).[Conclusion]1.Hyperbaric oxygen therapy could enhance anti-infection capacity of the surgery district and accelerate the rate of bone regenerate and ossification. 2.Early in the distraction osteogenesis, hyperbaric oxygen may increase the activity of serum alkaline phosphatase and accelerating new bone mineralization.3. Hyperbaric oxygen therapy could increase mechanical strength of the new bone in distraction osteogenesis.