Improvement of an additively manufactured subperiosteal implant structure design by finite elements based topological optimization

Improvement of the Design of an Additively Manufactured Subperiosteal Implant Structure Through Finite Element-Based Topology Optimization

1. Scientific Reference

• Study Title: Improvement of the Design of an Additively Manufactured Subperiosteal Implant Structure Through Finite Element-Based Topology Optimization
• Authors: Alberto Carnicero, Andrés Peláez, Andrés Restoy-Lozano, Isaías Jacquott, Ricardo Perera
• Journal: Scientific Reports
• Year of Publication: 2021
• DOI: 10.1038/s41598-021-94980-1

2. Scientific Background

The rehabilitation of patients with severe maxillary atrophy remains one of the most demanding challenges in implant dentistry and oral surgery. Advanced resorption of the maxillary bone often prevents the placement of conventional dental implants, forcing clinicians to consider complex reconstructive procedures such as bone grafting. Although grafting techniques can restore bone volume, they are associated with increased morbidity, extended treatment times, and additional surgical interventions.

Recent advances in digital workflows, computer-aided design, finite element analysis, and metal additive manufacturing have renewed interest in custom-made subperiosteal implants as an alternative treatment strategy. These patient-specific titanium structures are designed to adapt directly to the residual maxillary anatomy and may offer a solution for individuals who are not ideal candidates for extensive bone reconstruction procedures.

Within this evolving field, optimizing implant geometry is essential to improve biomechanical performance, reduce surgical complexity, and enhance the overall efficiency of implant-supported rehabilitation protocols.

3. Study Objective

The purpose of this study was to develop and evaluate an optimized design for a custom-made additively manufactured subperiosteal implant intended for patients affected by severe maxillary atrophy.

The authors aimed to reduce implant volume, decrease manufacturing costs, minimize the number of fixation screws, and simplify surgical placement while maintaining adequate structural strength under simulated masticatory loading conditions.

4. Methodology

This investigation was a preclinical engineering study based on finite element analysis and topology optimization.

The researchers used a previously designed patient-specific subperiosteal implant as the reference model. The geometry was reconstructed from computed tomography data and converted into a three-dimensional digital model for biomechanical analysis.

The implant material was Ti6Al4V titanium alloy, selected for its biocompatibility and widespread use in implantable medical devices. A two-stage topology optimization process was applied using the Solid Isotropic Material with Penalization (SIMP) method.

Five loading scenarios were evaluated. These included standard chewing conditions, critical chewing loads, and several simulated fixation-loss situations designed to represent unfavorable clinical circumstances. Mechanical performance was assessed through Von Mises stress distribution, structural integrity, and fatigue resistance criteria.

The study focused on computational modeling rather than clinical outcomes. The number of patients included was not specified in the available data.

5. Main Results

The initial assessment of the reference implant identified several regions where material could be removed without compromising overall structural stability.

Following the first optimization phase, implant volume was reduced by 18.56% compared with the original design. A second optimization stage achieved an additional 11.21% reduction. Overall, the final optimized model demonstrated a total volume reduction of 27.68%.

The optimization process also eliminated the need for two superior fixation screws that were present in the original configuration. Despite this reduction in material and fixation requirements, the implant maintained acceptable mechanical behavior across all simulated loading conditions.

Under standard chewing loads, the maximum Von Mises stress in the final design reached 199.51 MPa, remaining below the predefined fatigue threshold of 200 MPa. Simulations performed under critical loading and partial fixation-loss conditions did not reveal structural failure that would compromise implant integrity.

The authors concluded that the optimized design achieved a favorable balance between material reduction and mechanical performance.

6. Clinical Analysis

This study highlights how engineering-driven design optimization may contribute to the future development of patient-specific implant solutions for severe maxillary atrophy. Rather than focusing on clinical outcomes, the research addresses a fundamental question in implant design: how to reduce implant complexity without sacrificing biomechanical reliability.

The findings suggest that topology optimization can significantly decrease the amount of titanium required for a custom subperiosteal implant while preserving resistance to simulated functional loads. From a surgical perspective, reducing implant volume and the number of fixation points may potentially simplify placement procedures and decrease the extent of tissue manipulation required during surgery.

However, these observations should be interpreted within the context of a computational study. Mechanical performance predicted by finite element models does not necessarily translate directly into clinical success. Factors such as biological response, implant stability over time, soft-tissue behavior, prosthetic complications, and patient-reported outcomes were not evaluated.

Consequently, the study should be viewed as a design-validation investigation rather than evidence of clinical superiority. Its primary contribution lies in demonstrating the feasibility of combining topology optimization with additive manufacturing technologies to refine the design of customized subperiosteal implants.

7. Clinical Applications

The concepts explored in this study may be relevant in several clinical scenarios:

• Rehabilitation of edentulous patients with severe maxillary atrophy.
• Cases in which extensive bone grafting procedures are undesirable or contraindicated.
• Development of patient-specific subperiosteal implant frameworks.
• Digital implant planning and CAD/CAM-based workflows.
• Additive manufacturing of customized titanium implant structures.
• Complex maxillofacial reconstruction requiring individualized implant design.

Because the study is based on computational simulations, its results should be considered preliminary and require further clinical validation before influencing routine treatment protocols.

8. Level of Evidence, Limitations, and Transparency

This publication represents a preclinical biomechanical and engineering study based on finite element simulations. As such, its clinical level of evidence is limited.

The reported outcomes rely on mathematical modeling and assumptions regarding chewing forces, fixation conditions, and material properties. No prospective clinical trial, patient follow-up, survival analysis, or direct comparison with alternative treatment modalities was performed.

The authors also acknowledge that implant optimization should remain patient-specific and may require additional refinement depending on individual anatomical characteristics.

Regarding transparency, the authors declared that they had no competing interests.

The methodological limitations are primarily related to the absence of clinical validation and the inherent constraints of simulation-based research.

9. Key Study Highlights

• Study Type: Preclinical finite element and topology optimization study.
• Level of Evidence: Low-to-moderate clinical evidence; engineering-based investigation.
• Population or Studies Analyzed: Not specified in the available information.
• Number of Patients or Implants: Based on a patient-specific implant model; exact number not specified.
• Follow-Up Duration: Not specified in the available information.
• Primary Outcome Evaluated: Mechanical performance and fatigue resistance of an optimized subperiosteal implant design.
• Main Result: Total implant volume reduction of 27.68% while maintaining acceptable biomechanical performance.
• Scientific Conclusion: Topology optimization combined with additive manufacturing can improve implant design efficiency while reducing material use and fixation requirements.
• Potential Limitations: Computational nature of the study and lack of direct clinical validation.

10. Scientific Impact

This study contributes to the growing body of research focused on personalized implantology and digitally designed patient-specific solutions for severe bone atrophy. Its significance lies not in demonstrating clinical effectiveness, but in providing a structured methodology for optimizing the geometry of custom-made subperiosteal implants.

The integration of finite element analysis with topology optimization offers a rational framework for improving implant biomechanics while simultaneously addressing practical surgical and manufacturing considerations. By demonstrating substantial reductions in implant volume and fixation requirements, the study supports the feasibility of more efficient implant designs without compromising predicted mechanical behavior.

Although clinical evidence remains necessary, the work represents an important step toward the refinement of digitally manufactured implant systems and may help guide future developments in advanced implant-supported rehabilitation for severely atrophic maxillae.

11. Editorial Conclusion

This study demonstrates the potential value of combining finite element analysis, topology optimization, and additive manufacturing in the design of custom subperiosteal implants for severe maxillary atrophy. The optimized structure achieved a substantial reduction in material volume and fixation requirements while maintaining acceptable biomechanical performance in simulated loading conditions. Although these findings remain preclinical, they provide a promising foundation for future clinical research aimed at improving the treatment of complex edentulous patients requiring advanced implant-supported rehabilitation.