Effect of hyperbaric oxygen on demineralized bone matrix and biphasic calcium phosphate bone substitutes.
OBJECTIVE
The aim of this study was to assess the possible effect of hyperbaric oxygen (HBO) on the healing of critical-sized defects that were grafted with demineralized bone matrix (DBM) combined with Pluronic F127 (F127) to form a gel or putty, or a commercially available biphasic calcium phosphate (BCP), mixed either with blood or F127 to form a putty.


METHODS
Twenty New Zealand White rabbits were randomly divided into 2 groups of 10 animals each. Bilateral 15-mm calvarial defects were created in the parietal bones of each animal, resulting in 40 critical-sized defects. Group I defects were grafted with either DBM putty or DBM gel. Group II defects were grafted with either BCP or BCP putty. Five animals from each group received HBO treatment (100% oxygen, at 2.4 ATA) for 90 minutes per day 5 days a week for 4 weeks. The other 5 animals in each group served as a normobaric (NBO) controls, breathing only room air. All animals were humanely killed at 6 weeks. The calvariae were removed and analyzed by micro computed tomography (mCT) and histomorphometry.


RESULTS
mCT analysis indicated a higher bone mineral content (BMC, P < .05), bone volume fraction (BVF; P < .001), and bone mineral density (BMD; P < .001) of the defects grafted with BCP rather than DBM. Furthermore, the voxels that were counted as bone had a higher tissue mineral density (TMD) in the BCP- than in the DBM-filled defects (P < .001). Histologically complete bony union over the defects was observed in all specimens. Histomorphometric analysis showed that DBM-filled defects had more new bone (P < .007) and marrow (P < .001), and reduced fibrous tissue compared with the BCP defects (P < .001) under NBO conditions. HBO treatment reduced the amount of fibrous tissue in BCP filled defects (P < .05), approaching levels similar to that in matching DBM-filled defects. HBO also resulted in a small but significant increase in new bone in DBM-grafted defects (P < .05).


CONCLUSIONS
Use of DBM or BCP promoted healing in these critical-sized defects. Hyperbaric oxygen therapy resulted in a slight increase in new bone in DBM-grafted defects and much larger reduction in fibrous tissue and matching increases in marrow in BCP-grafted defects, possibly through increased promotion of angiogenesis.
Chief Resident in Oral and Maxillofacial Surgery and Anesthesia, University of Toronto, Toronto, Canada.
Ahmed
A
Jan
George K B
GK
Sándor
Bozidar B M
BB
Brkovic
Sean
S
Peel
Yong Deok
YD
Kim
Wen-Zhi
WZ
Xiao
A Wayne
AW
Evans
Cameron M L
CM
Clokie
D000704:Analysis of Variance; D000818:Animals; D015519:Bone Density; D001857:Bone Matrix / Q000502:physiology / Q000637:transplantation*; D001861:Bone Regeneration / Q000502:physiology*; D018786:Bone Substitutes; D016025:Bone Transplantation / Q000502:physiology; D002130:Calcium Phosphates; D003648:Decalcification Technique; D006931:Hyperbaric Oxygenation; D008297:Male; D018919:Neovascularization, Physiologic; D010294:Parietal Bone / Q000000981:diagnostic imaging / Q000601:surgery; D020442:Poloxamer; D011817:Rabbits; D011897:Random Allocation; D055114:X-Ray Microtomography
D018786:Bone Substitutes; D002130:Calcium Phosphates; D020442:Poloxamer