Effect of hyperbaric oxygen on demineralized bone matrix and biphasic calcium phosphate bone substitutes

Received 9 March 2009; accepted 2 July 2009. published online 21 October 2009.

Objectives

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.

Study design

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).

Conclusion

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.

a Chief Resident in Oral and Maxillofacial Surgery and Anesthesia, University of Toronto, Toronto, Canada

b Professor and Head of Oral and Maxillofacial Surgery, University of Toronto; Coordinator, Pediatric Oral and Maxillofacial Surgery, The Hospital for Sick Children and Bloorview Kids Rehab, Toronto, Canada; Professor, Regea Institute for Regenerative Medicine, University of Tampere, Tampere, Finland; Dosent, University of Oulu, Oulu, Finland

c Former Stoneman Fellow in Pediatric Oral and Maxillofacial Surgery, The Hospital for Sick Children, University of Toronto, Toronto, Canada; Assistant Professor, Clinic of Oral Surgery, University of Belgrade, Belgrade, Serbia

d Adjunct Professor, Orthobiologics Group, University of Toronto, Toronto, Canada

e Stoneman Fellow in Pediatric Oral and Maxillofacial Surgery, The Hospital for Sick Children, University of Toronto, Toronto, Canada; Assistant Professor, Pusan National University, South Korea

f Assistant Professor, Second Hospital Yuannan Province, Kun Ming, China

g Assistant Professor, Hyperbaric Medicine Unit, Department of Anesthesia, Faculty of Medicine, University of Toronto, Toronto, Canada

h Professor, Oral and Maxillofacial Surgery, Director, Orthobiologics Group, University of Toronto, Toronto, Canada

Reprint requests: George K.B. Sándor, MD, DDS, PhD, FRCDC, FRCSC, FACS, The Hospital for Sick Children, S-525, 555 University Avenue, Toronto, Ontario, Canada M5G 1X8

This study was generously funded by grants from The Canadian Association of Oral and Maxillofacial Surgeons Foundation for Continuing Education and Research; The Oral and Maxillofacial Surgery Foundation of Canada; and Straumann, Canada.

PII: S1079-2104(09)00487-9

doi:10.1016/j.tripleo.2009.07.036

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