J Korean Assoc Oral Maxillofac Surg 2016; 42(1): 20~30
Investigation of a pre-clinical mandibular bone notch defect model  in miniature pigs: clinical computed tomography,  micro-computed tomography, and histological evaluation
Patricia L. Carlisle1, Teja Guda1,2, David T. Silliman1, Wen Lien1, Robert G. Hale1, Pamela R. Brown Baer1
1Department of Craniomaxillofacial Regenerative Medicine, The United States Army Dental and Trauma Research Detachment, Fort Sam Houston, 2Department of Biomedical Engineering, The University of Texas at San Antonio, San Antonio, TX, USA
Teja Guda
Department of Biomedical Engineering, The University of Texas at San Antonio, One UTSA Circle, AET 1.356, San Antonio, TX 78249, USA
TEL: +1-210-458-8529   FAX: +1-210-458-7007E-mail: teja.guda@utsa.edu
ORCID: http://orcid.org/0000-0002-3218-2916
Received October 15, 2015; Revised December 22, 2015; Accepted December 29, 2015.; Published online February 29, 2016.
© Korean Association of Oral and Maxillofacial Surgeons. All rights reserved.

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Objectives: To validate a critical-size mandibular bone defect model in miniature pigs.Materials and Methods: Bilateral notch defects were produced in the mandible of dentally mature miniature pigs. The right mandibular defect remained untreated while the left defect received an autograft. Bone healing was evaluated by computed tomography (CT) at 4 and 16 weeks, and by micro-CT and non-decalcified histology at 16 weeks.Results: In both the untreated and autograft treated groups, mineralized tissue volume was reduced significantly at 4 weeks post-surgery, but was comparable to the pre-surgery levels after 16 weeks. After 16 weeks, CT analysis indicated that significantly greater bone was regenerated in the autograft treated defect than in the untreated defect (P=0.013). Regardless of the treatment, the cortical bone was superior to the defect remodeled over 16 weeks to compensate for the notch defect.Conclusion: The presence of considerable bone healing in both treated and untreated groups suggests that this model is inadequate as a critical-size defect. Despite healing and adaptation, the original bone geometry and quality of the pre-injured mandible was not obtained. On the other hand, this model is justified for evaluating accelerated healing and mitigating the bone remodeling response, which are both important considerations for dental implant restorations.
Keywords: Mandible, Autografts, Bone regeneration, Porcine, Critical-size defect
Fig. 1. A. Schematic diagram of the mandibular bone notch defect study design. B, C. Surgical images of the bilateral bone defects in pigs(n=5). The removed bone (D-F) was morselized, hydrated with sterile saline (G-I) and packed into the left side defect, serving as autograft (J), whereas the right side received no treatment (K); both hemi-mandibles were fixed with plates.

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