Biomechanical Evaluation of Conventional, Zygomatic, Zygomatic Bone-Anchored Subperiosteal and Maxilla-Anchored Subperiosteal Implants for the Rehabilitation of the Completely Edentulous Maxilla: A Finite Element Stress Analysis

Berivan Deniz, Mehmet Emre Yurttutan.

Full text link: https://pubmed.ncbi.nlm.nih.gov/40604849/

Biomechanical Evaluation of Conventional, Zygomatic, Zygomatic Bone-Anchored Subperiosteal and Maxilla-Anchored Subperiosteal Implants for the Rehabilitation of the Completely Edentulous Maxilla: A Finite Element Stress Analysis

1. Scientific Reference

• Study title: Biomechanical Evaluation of Conventional, Zygomatic, Zygomatic Bone-Anchored Subperiosteal and Maxilla-Anchored Subperiosteal Implants for the Rehabilitation of the Completely Edentulous Maxilla: A Finite Element Stress Analysis.
• Authors: Berivan Deniz, Mehmet Emre Yurttutan.
• Journal: BMC Oral Health.
• Publication year: 2025.
• DOI: 10.1186/s12903-025-06387-3.

2. Scientific Background

Managing severe maxillary atrophy remains one of the greatest challenges in implant dentistry. Progressive bone resorption, combined with maxillary sinus pneumatization and poor bone quality, often limits the placement of conventional dental implants without prior bone augmentation procedures. Although techniques such as sinus floor elevation, onlay grafting and Le Fort I osteotomy have expanded treatment possibilities, these procedures are associated with additional surgical complexity, longer rehabilitation times and increased patient morbidity.

Alternative anchorage concepts have therefore gained considerable attention. Zygomatic implants provide posterior skeletal support by engaging the zygomatic bone, while custom-made subperiosteal implants have recently re-emerged thanks to advances in digital imaging, CAD design and additive manufacturing. These patient-specific devices are intended to maximize available anatomical support without relying on extensive grafting procedures. Understanding how these different implant concepts distribute functional loads is essential for optimizing implant design and improving biomechanical performance before clinical application. This study addresses this question through finite element analysis comparing three distinct rehabilitation strategies for the severely atrophic edentulous maxilla.

3. Study Objective

The purpose of this investigation was to compare the biomechanical behavior of three implant rehabilitation concepts for the severely atrophic edentulous maxilla using three-dimensional finite element analysis. Specifically, the authors evaluated how vertical and oblique occlusal forces were transmitted through cortical bone, trabecular bone, implants, abutments, prosthetic frameworks and fixation screws when using conventional implants combined with zygomatic implants, maxilla-anchored subperiosteal implants and zygomatic bone-anchored subperiosteal implants. The primary objective was to identify which implant design provided the most favorable stress distribution under simulated functional loading.

4. Methodology

This investigation is a preclinical computational study based on three-dimensional finite element analysis (FEA). Rather than evaluating clinical outcomes in patients, the researchers developed a digital biomechanical model of a completely edentulous atrophic maxilla reconstructed from computed tomography (CT) data. The model was generated using dedicated segmentation, computer-aided design (CAD) and finite element simulation software to reproduce the anatomical structures involved in implant-supported rehabilitation.

Three implant configurations were created and analyzed:

• Model 1: two conventional implants combined with four zygomatic implants.
• Model 2: bilateral custom-made subperiosteal implants extending toward the zygomaticomaxillary buttress without covering the zygomatic bone.
• Model 3: bilateral custom-made subperiosteal implants designed to extend over the zygomatic buttress, providing additional skeletal anchorage.

Each model was subjected to two simulated loading conditions intended to reproduce functional mastication:

• Vertical loading: 150 N applied per tooth.
• Oblique loading: 100 N applied per tooth at a 30° angle from the buccal toward the palatal direction.

The analysis evaluated maximum tensile stress (Pmax), maximum compressive stress (Pmin), and von Mises stress within cortical bone, trabecular bone, implants, abutments, prosthetic metal frameworks and, where applicable, the fixation screws of the subperiosteal implants. The authors assumed all materials to be homogeneous, isotropic and linearly elastic for computational purposes, while acknowledging that these assumptions represent an inherent limitation because living bone exhibits anisotropic and heterogeneous mechanical behavior.

5. Main Results

The finite element simulations demonstrated clear biomechanical differences among the three rehabilitation concepts. Overall, Model 1, combining conventional and zygomatic implants, generated the highest stress concentrations within cortical bone under both vertical and oblique loading conditions. In contrast, Model 3, incorporating a zygomatic bone-anchored custom-made subperiosteal implant, consistently produced the lowest cortical bone stress values, indicating a more favorable distribution of occlusal loads across the supporting skeletal structures.

A similar trend was observed in trabecular bone for tensile stresses (Pmax), with the conventional/zygomatic implant configuration producing greater stress accumulation than either subperiosteal design. However, compressive stresses (Pmin) within trabecular bone were highest in Model 2, suggesting that different anchorage strategies influence the internal load transfer patterns in distinct ways.

The mechanical behavior of the implant components differed from that of the surrounding bone. Von Mises stresses within the implants themselves were greatest in Model 3, whereas Model 1 exhibited the lowest implant stress values. Conversely, stresses within the prosthetic metal framework were highest in Model 1 and lowest in Model 3, reflecting different mechanical load-sharing mechanisms between the implants and the prosthetic superstructure. The fixation screws used in the subperiosteal implant designs also experienced higher von Mises stresses in Model 3 than in Model 2, particularly around the piriform aperture.

Taken together, these findings indicate that implant geometry and anchorage location substantially influence stress distribution throughout the implant-supported restoration. Within the limitations of this computational model, the zygomatic bone-anchored subperiosteal implant demonstrated the most favorable biomechanical behavior for reducing stress transmission to the supporting bone, although this benefit was accompanied by increased stresses within certain implant components.

6. Clinical Analysis

This study provides valuable biomechanical insight into the rehabilitation of the severely atrophic edentulous maxilla by comparing three implant concepts that rely on fundamentally different anchorage strategies. Rather than focusing on implant survival or clinical success, the investigation examines how implant design influences the transmission of functional loads through the bone–implant–prosthesis complex. This distinction is important because stress distribution plays a key role in the long-term mechanical performance of implant-supported rehabilitations.

One of the principal observations is that the custom-made subperiosteal implant anchored to the zygomatic buttress produced the lowest stress concentrations within both cortical and trabecular bone. From a biomechanical standpoint, this suggests that expanding skeletal support beyond the residual alveolar ridge may improve load dissipation in patients with advanced maxillary resorption. Such findings are particularly relevant for cases in which conventional implant placement is compromised by insufficient bone volume and where extensive grafting procedures would otherwise be required.

The study also illustrates that reducing stress within the supporting bone does not necessarily reduce stress throughout the entire implant system. While Model 3 protected the surrounding bone more effectively, it simultaneously generated higher von Mises stresses within the implants and fixation screws. This shift indicates that part of the functional load is transferred from the biological tissues to the metallic components. The study therefore highlights the need to evaluate implant systems as integrated biomechanical assemblies rather than considering bone response alone. Whether these increased stresses could influence mechanical fatigue or long-term component durability cannot be determined from this computational model.

Another clinically relevant aspect is the importance of implant design customization. The findings suggest that the selection of anchorage zones—particularly the piriform aperture and the zygomatic buttress—has a substantial influence on stress distribution. This observation supports the growing role of digital planning, patient-specific implant design and CAD/CAM technologies in managing complex maxillary atrophy. By tailoring implant geometry to individual anatomy, clinicians may improve biomechanical load transfer while minimizing stress concentration within the remaining bone.

Nevertheless, these findings should be interpreted cautiously. Finite element analysis provides a highly controlled numerical simulation and cannot replicate the biological processes that influence long-term implant performance, including bone remodeling, osseointegration dynamics, healing capacity and patient-specific variability. Consequently, the results should not be interpreted as evidence of clinical superiority for one treatment approach over another. Instead, they offer biomechanical evidence that may guide implant design and inform future prospective clinical investigations evaluating survival rates, biological complications, prosthetic outcomes and long-term clinical performance.

7. Clinical Applications

The findings of this study are primarily relevant to the biomechanical planning of implant rehabilitation in patients presenting with a severely atrophic completely edentulous maxilla. Within the limitations of this finite element model, custom-made subperiosteal implants—particularly those incorporating zygomatic buttress anchorage—demonstrated a more favorable distribution of functional loads within the supporting bone than the conventional implant configuration evaluated.

These results may assist clinicians and researchers when considering treatment strategies for patients in whom conventional implant placement is limited by insufficient bone volume. The study suggests that optimizing implant geometry and selecting appropriate skeletal anchorage sites can significantly influence biomechanical behavior. As a result, patient-specific subperiosteal implants designed using digital planning workflows and CAD/CAM technologies may represent an alternative design approach for complex maxillary rehabilitation where extensive bone augmentation is undesirable or technically challenging.

However, these applications should be interpreted strictly within the context of a computational analysis. The study does not evaluate implant survival, biological complications, prosthetic success or patient-reported outcomes. Consequently, the biomechanical advantages observed in the simulations should not be considered sufficient evidence to recommend one implant system over another in clinical practice. Further prospective clinical studies are required to determine whether the numerical findings translate into improved long-term treatment outcomes.

8. Level of Evidence, Limitations and Transparency

This publication is a preclinical finite element analysis (FEA) and therefore represents preclinical biomechanical evidence rather than clinical evidence. While finite element modeling is a well-established method for investigating stress distribution in implant dentistry, it cannot directly predict clinical success or long-term biological performance.

The authors acknowledge several methodological limitations. All materials were modeled as homogeneous, isotropic and linearly elastic, whereas living bone is inherently heterogeneous and anisotropic. Consequently, the simulations cannot fully reproduce the biological complexity of the implant–bone interface, including bone remodeling, healing processes, patient-specific variations in bone quality and functional adaptation over time.

In addition, the investigation was entirely computational and did not include clinical follow-up, survival analysis or validation against patient outcomes. Therefore, the observed stress distributions should be interpreted as biomechanical predictions rather than clinical performance indicators.

Based on the information available in the published article, no conflicts of interest, commercial affiliations with implant manufacturers or industry-related funding relevant to the interpretation of the results are reported in the provided material.

9. Key Study Highlights

• Study type: Preclinical three-dimensional finite element analysis (FEA).
• Level of evidence: Preclinical biomechanical investigation.
• Study model: A three-dimensional digital reconstruction of a severely atrophic completely edentulous maxilla generated from computed tomography (CT) data.
• Sample size: One anatomical digital model incorporating three different implant rehabilitation designs. No clinical patient cohort was included.
• Follow-up period: Not applicable. No clinical follow-up was performed.
• Primary outcome: Evaluation of maximum tensile stress (Pmax), compressive stress (Pmin) and von Mises stress within cortical bone, trabecular bone, implants, abutments, prosthetic framework and fixation screws under simulated vertical and oblique loading conditions.
• Main finding: Among the three rehabilitation concepts, the zygomatic bone-anchored custom-made subperiosteal implant (Model 3) produced the lowest stress concentrations within the supporting bone, whereas the combined conventional and zygomatic implant configuration (Model 1) generated the highest bone stresses. Conversely, implant components experienced greater mechanical stresses in Model 3.
• Scientific conclusion: Implant geometry and skeletal anchorage location substantially influence biomechanical stress distribution. Within this computational model, the zygomatic bone-anchored subperiosteal implant demonstrated the most favorable bone stress distribution, although clinical validation remains necessary.
• Main limitations: Computational simulation, simplified material assumptions (homogeneous, isotropic and linearly elastic materials), absence of biological variables and lack of clinical outcome assessment.

10. Scientific Impact

This study contributes meaningful biomechanical evidence to the growing body of research on implant rehabilitation for the severely atrophic maxilla. Its originality lies in the direct comparison of three distinct rehabilitation concepts—including two custom-made subperiosteal implant designs—within a single finite element model. According to the authors, comparable biomechanical analyses evaluating these specific implant configurations had not previously been reported.

Rather than simply comparing implant systems, the investigation highlights how implant design and skeletal anchorage strategy influence the overall distribution of functional loads throughout the implant–prosthesis complex. The findings demonstrate that reducing stress within the supporting bone may increase stress within the metallic implant components, emphasizing the importance of evaluating the biomechanical behavior of the entire restorative system rather than focusing exclusively on bone response.

The study also reinforces the growing role of digital implantology. As patient-specific subperiosteal implants become increasingly feasible through CAD/CAM design and advanced manufacturing technologies, biomechanical analyses such as this may support future implant development and optimization. Nevertheless, because the investigation remains entirely computational, its conclusions should be regarded as a foundation for future clinical research rather than evidence supporting immediate changes in clinical protocols. Prospective studies evaluating implant survival, prosthetic performance and biological complications will be essential to determine whether these biomechanical advantages translate into improved patient outcomes.

11. Editorial Conclusion

This finite element investigation demonstrates that implant design has a substantial influence on biomechanical stress distribution during the rehabilitation of the severely atrophic edentulous maxilla. Among the configurations evaluated, the custom-made subperiosteal implant anchored to the zygomatic buttress achieved the most favorable reduction in bone stress while redistributing mechanical loads toward the implant components. Although these findings provide valuable guidance for implant design and digital treatment planning, they remain based on computational modeling and should not be interpreted as clinical proof of superiority. Future well-designed clinical studies are required to determine whether these biomechanical observations translate into improved long-term outcomes for patients undergoing complex maxillary implant rehabilitation.