Extrasinus zygomatic implant placement in the rehabilitation of the atrophic maxilla: three-dimensional finite element stress analysis

Zygomatic Implants in a Patient With History of Mucormycosis: A Case Report

Exposure to mucor mold can lead to mucormycosis, a rare fungal infection with severe consequences, especially in immunocompromised individuals. The year 2020 highlighted the need for orofacial rehabilitation, presenting challenges in cases of maxillary absence. This case report details zygomatic implants, which offer a promising solution by providing stable support even in the absence of significant bone mass due to surgical excision post-COVID-19 mucormycosis. Zygomatic implants outperform traditional grafting techniques. The atrophic or resected jaws can be effectively restored with a single-piece zygomatic implant, which has the lowest rate of postoperative problems, including bone loss, mucositis, peri-implantitis, and screw loosening or fractures. In this case report, four zygomatic implants were placed in the zygomatic bone, and immediate loading was performed. Restoration of patient aesthetics, phonetics, and functional masticatory efficiency were restored.

Stress Distribution of the Zygomatic Implants in Post-mucormycosis Case: A Finite Element Analysis

Aim

The aim of this study was to assess the stress distribution of the zygomatic implants in maxillectomy cases and to understand the long-term prognosis of this rehabilitation option using finite element analysis.

Materials and Methods

A three-dimensional finite element model was designed using computed tomography of a patient who underwent maxillectomy post-mucormycosis. Zygomatic implants and abutments were designed based on the manufacturer's design. Quad zygomatic implants were placed in the canine and premolar region into the zygomatic bone bilaterally. A prosthesis with an entire complement of teeth extending from the first molar teeth bilaterally was designed and attached to the multiunit abutments and zygomatic implants. Forces were applied to the zygomatic implants at six different locations bilaterally on the prosthesis which included occlusal and laterally directed forces on the central incisor region, canine region, and molar region using von Mises criteria. A three-dimensional finite element analysis was run, and maximum stress distribution was recorded at various loads. Statistical Package for Social Sciences for Windows version 22.0 Released 2013. Armonk, NY: IBM Corp., was used to perform statistical analyses. Kruskal-Wallis test was used to compare the mean stress values. Multiple comparisons of mean difference in stress values between force applications in implant were done using Dunn's post hoc test.

Results

The maximum stress was observed at the distal head of the implant in the models. Minimum stress was observed at the apex of the implant in the models. The mean stress values based on force application in the bone and fixed prosthesis showed less significance when compared to the zygomatic implants which was statistically significant at p = 0.03.