SA3 - Evaluation of Non-Vascularized Autogenous vs. Allogeneic Grafts for Mandibular Reconstruction

Abstract: Mandibular reconstruction remains a fundamental challenge in oral and maxillofacial surgery. Recent literature highlights the potential versatility of allogeneic grafting through bioengineering techniques, even for large and complex defects. However, there is a notable lack of studies directly comparing this approach to the traditionally accepted gold standard – non-vascularized autogenous grafting. This study aims to evaluate the equivalence of allogeneic grafting versus non-vascularized autogenous grafting for large mandibular defects.

This is an in-vivo retrospective study of patients undergoing mandibular resection and reconstruction. Inclusion criteria consisted of patients who had mandibular resection due to benign or infectious pathology. Patients with malignant pathology, poorly controlled systemic disease, a history of radiation therapy, or follow-up of less than 6 months were excluded. The primary outcome assessed was the percentage of mandibular volume restored six months after ablation. Primary predictor variables included Vivigen bone matrix, bone marrow aspirate concentrate (BMAC), and recombinant human bone morphogenetic protein-2 (rhBMP-2) with or without non-vascularized autogenous grafting using femur reamer bone graft or anterior iliac crest graft. Secondary predictor variable was defect size.

Stereolithography (STL) files from the virtual surgical plan (VSP) of the excised lesion were used to determine the pre-ablative mandibular volume in Materialise Mimics (Materialise NV., Leuven, Belgium). Postoperative CBCT DICOM files were segmented at the same anatomical boundaries as the excised lesion, with metal plates subtracted to accurately measure the regenerative volume. The percent of regeneration was determined by comparing the pre ablative mandible volume with the post ablative mandible volume at follow up for both allogeneic and autogenous study groups. Statistical analysis was performed with SASv9.4 (SAS Institute Inc, Cary, NC.). Two one-sided t-tests were used at a 0.10 level to determine if the average difference in the volume restored between the two methods was equivalent within 10%.

A total of 12 subjects were enrolled in the study, with 6 current results in an ongoing study. The averaged percent of mandibular volume restored was 90.99 (SD = 0.77) for allograft compared to 80.85 (SD = 9.42) for the autograft group. The variance was significantly different between the two groups, with autografts associated with significantly greater variability than allograft (P value = .0134). The average difference in the volume restored between the two methods was 10.14 and was not equivalent within 10% of volume restored (90% equivalence bounds: -5.65 to 25.92%). Average size of defects was 15.6 cm³ for allograft subjects and 13.3 cm³ for autograft subjects.

Both non-vascularized autogenous and allogeneic bioengineered bone grafting proved effective in restoring large mandibular defects. While autogenous grafting may offer a more robust restoration, the clinical significance of this difference was not evaluated in this study. Further research and expansion of this study are ongoing.


References:

Dastgir R, Coffey J, Quereshy H, Baur DA, Quereshy FA. Nonvascularized bone grafts: how successful are they in reconstruction of segmental mandibular defects? Oral Surg Oral Med Oral Pathol Oral Radiol. 2024 May;137(5):e63-e72. doi: 10.1016/j.oooo.2023.10.010. Epub 2023 Oct 29. PMID: 38155011.

Melville JC, Tran HQ, Bhatti AK, Manon V, Young S, Wong ME. Is Reconstruction of Large Mandibular Defects Using Bioengineering Materials Effective? J Oral Maxillofac Surg. 2020 Apr;78(4):661.e1-661.e29. doi: 10.1016/j.joms.2019.11.024. Epub 2019 Dec 2. PMID: 31883442.
Figure 1. Radiographic and clinical depiction of the mandibular reconstructive process for the A. autogenous group and B. allogeneic group Figure 2. Data collection protocol carried out in Materialise Mimics Figure 3. Autografts were associated with significantly greater variability than allografts