The Influence of Implant Number on Stress Distribution in the Anterior Region of Mandible Reconstructed with Fibula Bone Graft: A Finite Element Analysis

The goal of this study was to compare the stress distribution of three or four implants in the anterior region of the mandible that was grafted with a free vascularized fibula flap.

Two three-dimensional finite element models were designed based on cone-beam computed tomography of a patient whose anterior region of the mandible was restored with a free vascularized fibula flap. In both three- (G1) and four-implant (G2) models, the fixtures were connected with a fixed suprastructure. Occlusal loads were simulated using 300N.cm vertical and 50 N cm oblique forces. Implant micromotion and von Mises stress (VMS) distribution were measured. Inter-model comparisons were performed.

Regarding vertical forces for G1 and G2, the supporting bone volume at maximum VMS was 2.44 mm³ and 3.04 mm³; the fixture volume undergoing maximum VMS was 160 mm³ and 175 mm³. For oblique forces, in the G1 and G2, respectively, the maximum VMS resulted in 7.09 mm³ and 7.73 mm³, and the fixture volume was 7.23 mm³ and 1.56 mm³. In G1, the most distal and middle implants showed the highest and lowest displacement; whereas in G2, the most distal implant displaced under vertical forces, showing the least micromotion under oblique loads. The inter-model comparison showed G2 had lower micromotion on average.

Employing the three-implant concept in rehabilitating the anterior region of a fibula-reconstructed mandible resulted in less VMS concentration under vertical and oblique forces; however, using four implants would be better for minimizing the fixture displacement. It is suggested new studies compare new scenarios matching different types of bone grafts and dental implants placed in the mandible and maxilla, trying to keep the heterogeneous complexity of the biomaterials to have better mimics and reality, increasing the reliability of the study.