J Korean Assoc Oral Maxillofac Surg.  2019 Apr;45(2):97-107. 10.5125/jkaoms.2019.45.2.97.

Are critical size bone notch defects possible in the rabbit mandible?

Affiliations
  • 1Department of Craniomaxillofacial Regenerative Medicine, Dental and Trauma Research Detachment, Fort Sam Houston, TX, USA.
  • 2Department of Biomedical Engineering, University of Texas at San Antonio, San Antonio, TX, USA. teja.guda@utsa.edu

Abstract


OBJECTIVES
Small animal maxillofacial models, such as non-segmental critical size defects (CSDs) in the rabbit mandible, need to be standardized for use as preclinical models of bone regeneration to mimic clinical conditions such as maxillofacial trauma. The objective of this study is the establishment of a mechanically competent CSD model in the rabbit mandible to allow standardized evaluation of bone regeneration therapies.
MATERIALS AND METHODS
Three sizes of bony defect were generated in the mandibular body of rabbit hemi-mandibles: 12 mm×5 mm, 12 mm×8 mm, and 15 mm×10 mm. The hemi-mandibles were tested to failure in 3-point flexure. The 12 mm×5 mm defect was then chosen for the defect size created in the mandibles of 26 rabbits with or without cautery of the defect margins and bone regeneration was assessed after 6 and 12 weeks. Regenerated bone density and volume were evaluated using radiography, micro-computed tomography, and histology.
RESULTS
Flexural strength of the 12 mm×5 mm defect was similar to its contralateral; whereas the 12 mm×8 mm and 15 mm×10 mm groups carried significantly less load than their respective contralaterals (P<0.05). This demonstrated that the 12 mm×5 mm defect did not significantly compromise mandibular mechanical integrity. Significantly less (P<0.05) bone was regenerated at 6 weeks in cauterized defect margins compared to controls without cautery. After 12 weeks, the bone volume of the group with cautery increased to that of the control without cautery after 6 weeks.
CONCLUSION
An empty defect size of 12 mm×5 mm in the rabbit mandibular model maintains sufficient mechanical stability to not require additional stabilization. However, this defect size allows for bone regeneration across the defect. Cautery of the defect only delays regeneration by 6 weeks suggesting that the performance of bone graft materials in mandibular defects of this size should be considered with caution.

Keyword

Bone regeneration; Rabbit; Mandible; Micro-computed tomography; Cautery

MeSH Terms

Animals
Bone Density
Bone Regeneration
Cautery
Mandible*
Rabbits
Radiography
Regeneration
Transplants
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