Evaluation of Stress Distribution in Mandibular Donor Site After Harvesting Bone Grafts of Different Sizes from the Symphysis

Objective: The purpose of this study is to investigate the stress distribution in the mandibular donor site after harvesting bonegrafts of different sizes from the symphysis by applying three different occlusal loads.Methods: First, we constructed 16 experimental mandible models after harvesting the block grafts. We harvested rectangular-shaped and cylindrical block grafts of different sizes, localizations, and depths from the symphysis region. Three different occlusal loads were applied on the models. After the application of three occlusal loads on the models, we analyzed the von Misesstress distribution in the surface of the donor sites in the symphysis.Results: In all the mandible models, the highest von Mises stress values were detected under incisal loads. Under the ipsilateralload of 300 N, the maximum von Mises stress was similar between R1 (unilateral one cylindrical graft) and R2 (unilateral two cylindrical grafts) models, and also between R1+1 (bilateral two cylindrical grafts) and R2+2 (bilateral four cylindrical grafts) models.The maximum von Mises stress under incisal load in the models measuring 20×10×4 mm (width, height, and depth, respectively)and 20×10×6 mm were 2.46 and 2.79 MPa, respectively. Among the unilateral models, the lowest maximum von Mises stress value was found in the R4 model (cylindrical graft: diameter=10 mm, depth=4 mm), and the highest value was found in the modelmeasuring 15×10×6 mm under all the loads.Conclusion: The application of incisal load led to a higher stress as than that of the bilateral and ipsilateral loads. The stress distribution in the symphysis donor site varies according to the localization, shape, and dimensions of the harvested grafts. Cylindricalgrafts led to lower stress than the rectangular grafts.

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