Zygomatic Implants: The Impact of Zygoma Bone Support on Biomechanics
Maxillectomy and severely resorbed maxilla are challenging to restore with provision of removable prostheses. Dental implants are essential to restore esthetics and function and subsequently quality of life in such group of patients. Zygomatic implants reduce the complications associated with bone grafting procedures and simplify the rehabilitation of atrophic maxilla and maxillectomy. The purpose of this study was to compare, by means of 3-dimensional finite element analysis, the impact of different zygomatic bone support (10, 15, and 20 mm) on the biomechanics of zygomatic implants. Results indicated that maximum stresses within the fixture were increased by 3 times when bone support decreased from 20 to 10 mm and were concentrated at the fixture/bone interface. However, stresses within the abutment screw and the abutment itself were not significantly different regardless of the bone support level. Supporting bone at 10 mm sustained double the stresses of 15 and 20 mm. Fixture's deflection was decreased by 2 to 3 times when bone support level increased to 15 mm and 20 mm, respectively. It was concluded that zygomatic bone support should not be less than 15 mm, and abutment screw is not at risk of fracture regardless of the zygomatic bone support.
Figure 1. Three-dimensional finite element model which includes an abutment (blue), abutment screw (green), fixture (pink), and supporting bone (white). Figure 2. A load of 150 N was applied at 45° to the long axis of the implant and bone constrained at the base of supporting bone at all directions.
Figure 3. von Mises stresses within the zygomatic implant and its supporting bone at different bone levels. (a) 10 mm bone level support. (b) 15 mm bone level support. (c) 20 mm bone level support. Figure 4. Displacement of zygomatic implant and its supporting bone at different bone levels; (a) 10 mm bone level support. (b) 15 mm bone level support. (c) 20 mm bone level support.
Figure 5. von Mises stresses (MPa) within the zygomatic implant and its supporting bone at different bone level support. Figure 6. Displacement (mm) within the zygomatic implant and its supporting bone at different bone level support.
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