Design and optimization of a novel patient-specific subperiosteal implant additively manufactured in yttria-stabilized zirconia

Design and Optimization of a Novel Patient-Specific Subperiosteal Implant Additively Manufactured in Yttria-Stabilized Zirconia

1. Scientific Reference

• Study Title: Design and Optimization of a Novel Patient-Specific Subperiosteal Implant Additively Manufactured in Yttria-Stabilized Zirconia
• Authors: Gunpreet Oberoi, Erik Kornfellner, Daniel Alexander Aigner, Ewald Unger, Martin Schwentenwein, Daniel Bomze, Christoph Staudigl, Dieter Pahr, Francesco Moscato
• Journal: Dental Materials
• Year of Publication: 2024
• DOI: 10.1016/j.dental.2024.07.008

2. Scientific Background

The rehabilitation of severely resorbed edentulous maxillae remains one of the most demanding challenges in modern implant dentistry. In advanced alveolar bone atrophy, conventional implant placement may become difficult or impossible without extensive reconstructive procedures. As a result, patient-specific subperiosteal implants have regained interest as an alternative solution for complex cases where traditional endosseous implant therapy may be limited.

Recent developments in digital workflows, three-dimensional imaging, computer-aided design, and additive manufacturing have significantly expanded the possibilities for customized implant rehabilitation. At the same time, zirconia-based biomaterials have attracted growing attention because of their favorable mechanical behavior, esthetic characteristics, and biological compatibility.

Within this evolving landscape, the combination of topology optimization, finite element analysis, and ceramic 3D printing offers a promising approach for developing highly customized implant solutions tailored to individual anatomical conditions while potentially enhancing biomechanical performance and tissue integration.

3. Study Objective

The primary objective of this study was to design and optimize a patient-specific maxillary subperiosteal implant manufactured from 3 mol% yttria-stabilized zirconia (3YSZ).

The investigators aimed to evaluate whether topology optimization could identify regions of the implant where bulk ceramic material could be replaced by a lattice structure while maintaining mechanical integrity under simulated physiological and pathological occlusal loading conditions. The study also explored the potential of such a design strategy to increase implant surface area and support osseointegration.

4. Methodology

This investigation was conducted as a preclinical engineering and computational study.

An anonymized computed tomography dataset of a patient with a severely atrophic maxilla was used to generate a three-dimensional anatomical model. A customized subperiosteal implant was subsequently designed using digital planning software.

Finite element analysis (FEA) was performed to assess implant behavior under different occlusal loading scenarios, including right molar, incisor, and left molar loading conditions. Topology optimization algorithms were then applied to identify areas subjected to lower mechanical stresses that could be transformed into porous lattice regions.

The optimized implant design underwent additional computational testing using the same loading conditions. Finally, the implant was manufactured through lithography-based ceramic manufacturing (LCM) using 3YSZ and subsequently sintered to obtain its final mechanical properties.

No clinical patient treatment was included within the scope of the presented study.

5. Main Results

The proposed workflow generated two patient-specific implant configurations: a conventional bulk ceramic design and a topology-optimized lattice-enhanced design.

Mechanical simulations demonstrated a Young’s modulus of 205 GPa for the bulk zirconia structure and 83.3 GPa for the lattice component. Maximum principal stresses reached 61.14 MPa in the bulk implant and 278.63 MPa within the lattice structure under the most demanding loading conditions.

According to the authors, these stress values remained substantially below the reported ultimate strength of the zirconia material used in the study, indicating that both configurations could tolerate simulated occlusal forces ranging from 125 to 250 N per abutment.

Topology optimization resulted in a 13.08% reduction in implant mass while increasing the available surface area by 208.71%. The optimized design was successfully manufactured using ceramic additive manufacturing technology and subsequently processed through sintering.

6. Clinical Analysis

The significance of this study lies less in immediate clinical validation and more in its demonstration of an advanced digital workflow for personalized implant development. The work illustrates how patient-specific imaging, biomechanical simulation, topology optimization, and ceramic additive manufacturing can be integrated into a single design process.

One of the most noteworthy aspects is the use of topology optimization to identify mechanically less critical regions within the implant. Rather than simply reducing material volume, the approach creates opportunities for incorporating porous lattice structures while preserving structural stability. This may be particularly relevant in the context of severe maxillary atrophy, where maximizing the implant-bone interface could be advantageous.

The substantial increase in surface area achieved through the lattice design suggests a theoretical potential for improved biological interaction with surrounding tissues. However, the present study does not directly demonstrate enhanced osseointegration, and such assumptions require validation through biological and clinical investigations.

From a biomechanical perspective, the simulations indicate that the optimized zirconia design can withstand the tested loading conditions. Nevertheless, computational models cannot fully reproduce the complexity of the oral environment, long-term fatigue behavior, or biological remodeling processes.

Consequently, these findings should be viewed as an encouraging proof of concept rather than definitive evidence supporting routine clinical implementation.

7. Clinical Applications

The concepts explored in this study may be relevant for several areas of advanced implant rehabilitation, including:

• Severe maxillary bone atrophy.
• Complex edentulous patient rehabilitation.
• Patient-specific implant design.
• Digital implant planning workflows.
• CAD/CAM-guided reconstruction procedures.
• Additive manufacturing of implantable ceramic devices.
• Maxillofacial reconstruction requiring customized solutions.
• Development of surface architectures intended to promote bone integration.

The study does not provide sufficient evidence to establish superiority over existing implant treatment options.

8. Level of Evidence, Limitations and Transparency

This publication represents a preclinical engineering study based primarily on digital design, finite element simulations, and additive manufacturing processes.

Accordingly, the level of clinical evidence remains limited. No prospective clinical evaluation, survival analysis, or long-term follow-up data were reported.

The authors acknowledge several methodological limitations. These include the absence of a mesh convergence study, simplifications in bone modeling assumptions, and the need for experimental validation through physical mechanical testing. More sophisticated loading scenarios and biological evaluations were also identified as areas for future investigation.

Regarding transparency, several authors are affiliated with Lithoz GmbH, the manufacturer of the ceramic printing technology and materials used in the study. This affiliation should be considered when interpreting the findings, although no evidence of scientific misconduct is reported.

The research received funding from the European Commission Horizon H2020 Industrial Leadership Programme through the INKplant project.

9. Key Study Points

• Study Type: Preclinical engineering and computational investigation.
• Level of Evidence: Low to moderate.
• Population or Dataset: One anonymized patient-derived anatomical model.
• Number of Patients or Implants: One patient-specific implant design.
• Follow-up Duration: Not specified in the provided data.
• Primary Outcome: Mechanical performance and topology optimization of a zirconia subperiosteal implant.
• Main Result: 13.08% mass reduction and 208.71% increase in surface area while maintaining acceptable simulated stress levels.
• Scientific Conclusion: Topology optimization can identify low-stress regions suitable for integrating osseoconductive lattice structures without compromising implant stability.
• Potential Limitations: Absence of clinical validation and reliance on computational simulations.

10. Scientific Impact

This study contributes to the growing body of research investigating personalized implant rehabilitation through advanced manufacturing technologies. While patient-specific titanium subperiosteal implants have already been explored in the literature, the application of yttria-stabilized zirconia to this indication remains relatively under-investigated.

The research introduces a structured workflow that combines digital imaging, finite element analysis, topology optimization, and ceramic additive manufacturing into a unified development strategy. By demonstrating the feasibility of reducing material volume while substantially increasing surface area, the study expands current knowledge regarding the design possibilities of ceramic implant systems.

Another important contribution is the exploration of lattice-based architectures as a means of tailoring implant geometry according to biomechanical requirements. This concept may inspire future investigations aimed at optimizing the balance between structural strength and biological integration.

Ultimately, the work serves as a foundation for future experimental and clinical studies evaluating the long-term mechanical behavior and biological performance of topology-optimized ceramic subperiosteal implants.

11. Editorial Conclusion

This study presents an innovative approach to the design of patient-specific subperiosteal implants for severely atrophic maxillae by combining digital planning, topology optimization, finite element analysis, and ceramic 3D printing. The computational results suggest that a lattice-enhanced zirconia design can maintain mechanical stability while substantially increasing implant surface area. Although the findings remain preclinical and require validation through physical testing and clinical investigations, the study provides a valuable contribution to the development of next-generation customized implant solutions for complex oral rehabilitation.