BACKGROUND: Reconstruction of mandibular defects caused by combat injuries is challenging for clinicians due to soft tissue defects and high complication risk. This study evaluated the outcomes of mandibular continuous defects reconstruction with non-vascularized iliac crest graft (NVICG) in patients with combat injuries.
METHODS: Patients with continuous mandibular defects acquired by high-velocity agents, who received NVICG reconstruction with or without microvascular-free soft tissue or regional flaps, were included in the study. The outcome variable was graft loss due to postoperative complications or full (more than 90 %) resorption. The primary predictor variable was soft tissue defect in the recipient area. The secondary predictor variable was the length of the defect. Variables related to patients, defect site, surgery, and other complications were also evaluated. Statistical analysis was performed with the usage of independent sample t-test, Pearson\'s chi-squared and Fisher\'s exact tests with a significance level of P < 0.05 RESULTS: The study included 24 patients with 27 mandibular defects. Overall, the general success rate of reconstructions was 59.3 %. Soft tissue defects were significantly associated with graft failure and other complications (p < 0.05), which were mostly related to soft tissue defects. The graft success rate was only 14.3 % even in minor soft tissue defects. In turn, in reconstructions with sufficient soft tissue coverage, the graft survived in 75.0 % of the cases. In addition, patients with more delayed reconstruction had significantly fewer graft failures than those with earlier surgery (p < 0.05). No associations were found between defect size and complications.
CONCLUSIONS: The sufficient soft tissue coverage is essential in the reconstruction of mandibular defects caused by combat injuries. Also, minor soft tissue defects should be covered with soft tissue flaps to avoid complications and graft loss in these specific injuries. Even large defects can be reconstructed with NIVICG if the soft tissue coverage is sufficient.

This study developed design criterion for patient-specific reconstructed implants with appearance consideration and structural optimization of various mandibular continuity defects. The different mandible continuity defects include C (from left to right canines), B (from 1st premolar to 3rd molar), and A (from 3rd molar to ramus) segments defined based on the mandible image. The finite element (FE) analysis and weighted topology optimization methods were combined to design internal support beam structures within different reconstructed implants with corresponding occlusal conditions. Five continuity mandibular defects (single B/C/A+B and combination of B+C and B+C+B segments) were restored using additive manufacturing (AM) reconstructed implant and bone plate to confirm reasonable design criterion through biomechanical fatigue testing. The worst mandible strength was filtered based on the material mechanics and results from segmental bone length, thickness, and height statistics from the established database containing mandible images of 105 patients. The weighted optimization analysis results indicated that the sizes and positions of internal supporting beams within the reconstructed C, B, and A+B implants can be defined parametrically through corresponding segmental bone length, width, and height. The FE analysis found that the weight variation percentage between the parametric designed implants and original core solid implants in the C, B, and A+B was reduced by 54.3%, 63.7%, and 69.7%, respectively. The maximum stress values of the reconstructed implant and the remaining bone were not obviously reduced but the stress values were far lower than the material ultimate strength. The biomechanical fatigue testing indicated that all cases using the AM reconstructed implant could pass the 250,000 dynamic load. However, condyle head, bone plate fracture, and bone screw loosening could be found in cases using bone plates. This study developed a design criterion for patient-specific reconstructed implants for various mandibular continuity defects applicable for AM to further clinical use.

OBJECTIVE: The aim of this work was to compare different 12 cases (3 patients * 4 cases = 12 cases) with varying gaps between implant and bone by analyzing the effect of these gaps on implant and screws using FEM.
METHODS: In each patient\'s case 1 using CSOG and in case 2, 3, and 4 without using CSOG tumor cutting was done. Hence in each patient zero gaps at case 1 and overcutting at case 2, 3, and 4 have obtained at different locations.
RESULTS: FEM results reveal that in each patient\'s case 4 (maximum gap) was more susceptible to loosening of the screws due to higher strains (37%) and implant failure due to higher stress (28%) concentration under the same loading conditions when compared with case 1 (zero gap).
CONCLUSIONS: The study reveals that mandibular reconstruction with implant placement using CSOG can significantly enhance the stability and safety of the implant.

OBJECTIVE: Patients with continuous bone defects of the mandible after ablative tumor surgery need bony reconstruction for proper function and aesthetics. Free microvascular reanastomized bone grafts provide a clinically proven option for such patients, yet the optimal source of donor tissue has not yet been established. The aim of this study was to evaluate and compare the bone volume stability of vascularized bone grafts, particularly in the early highly resorptive phase, from the iliac crest (DCIA) and the fibula and to assess the implantologic rehabilitations.
METHODS: Thirty-six patients with mandibular continuity defects due to tumor resection were reconstructed by the use of vascularized bone grafts; 21 patients received DCIA flaps and 15 patients received a composite free fibular flap, depending on the size and location of the defect. Bone resorption was assessed using digital panographs. Radiographs were taken immediately after bone reconstruction, 6 months postoperatively, prior to implant surgery, and at prosthetic loading.
RESULTS: After a mean observation period of 6 months, vertical bone resorption was 6.79% for the patients of the iliac crest group (DCIA), 10.20% after 11 months, and 12.58% after 17 months. Fibular grafts showed a bone resorption of 5.30% after a mean observation time of 6 months, 8.26% after 11 months, and 16.95% after 17 months. Eighteen patients received 71 implants for implant-retained dental reconstructions.
CONCLUSIONS: Microvascular reanastomized bone grafts represent a reliable treatment option for reconstruction in cases of large defects of the mandible, with low graft resorption in the early healing phase. Additionally, the compared grafts provide sufficient bone volume to permit implant rehabilitation.