Two-Piece Versus Single-Piece Patient-Specific Titanium Subperiosteal Implants in Atrophied Edentulous Mandibles: A Finite Element Analysis

Mariam Ahmed Roshdy, Maha Wagdy El Kerdawy, Adel Hamdy Abo El Fetouh, Mahmoud Mokhtar El Far

Full text link: https://pubmed.ncbi.nlm.nih.gov/40779986/

Two-Piece Versus Single-Piece Patient-Specific Titanium Subperiosteal Implants in Atrophied Edentulous Mandibles: A Finite Element Analysis

1. Scientific Reference

• Study Title: Two-piece versus single-piece patient-specific titanium subperiosteal implants in atrophied edentulous mandibles: A finite element analysis
• Authors: Mariam Ahmed Roshdy, Maha Wagdy El Kerdawy, Adel Hamdy Abo El Fetouh, Mahmoud Mokhtar El Far
• Journal: Computers in Biology and Medicine
• Year of Publication: 2025
• DOI: 10.1016/j.compbiomed.2025.110897
• PMID: 40779986

2. Scientific Background

Managing severely atrophied edentulous mandibles remains one of the most demanding situations in implant dentistry. While bone augmentation procedures and advanced reconstructive techniques can expand treatment possibilities, they are not suitable for every patient due to anatomical limitations, systemic conditions, or the invasiveness of the procedures. In these circumstances, patient-specific titanium subperiosteal implants have re-emerged as an alternative solution, benefiting from modern digital workflows, three-dimensional imaging, and CAD/CAM manufacturing technologies.

Traditionally, customized subperiosteal implants have been manufactured as a single-piece framework. More recently, two-piece designs have been introduced to facilitate surgical placement and adaptation. However, evidence comparing the mechanical performance of these two designs has been lacking. This study addresses that gap by evaluating their biomechanical behavior through three-dimensional finite element analysis, providing insights into how implant design may influence stress distribution in complex mandibular rehabilitations.

3. Study Objective

The purpose of this investigation was to compare the biomechanical performance of two patient-specific titanium subperiosteal implant designs—a conventional single-piece framework and a recently introduced two-piece framework. Using three-dimensional finite element analysis, the authors sought to determine whether differences existed in stress distribution within the peri-implant bone, implant framework, fixation screws, and prosthetic restoration under simulated functional loading.

4. Methodology

This was a preclinical three-dimensional finite element analysis (3D FEA).

The digital model was generated from a multislice computed tomography scan of an edentulous mandible. Two customized subperiosteal implant frameworks were simulated: a single-piece titanium framework on one side of the mandible and a two-piece titanium framework on the contralateral side. Both frameworks supported a cement-retained prosthesis with a shortened dental arch resting on four abutments and opposed a maxillary tissue-supported complete removable denture.

Two loading simulations were performed using a unilateral oblique force of 50 N applied at an angle of 30° to the mandibular second premolar region. The primary outcomes included peri-implant bone stress, von Mises stress within the implant framework, fixation screws and prosthesis, as well as total deformation of the fixation screws.

5. Main Findings

The numerical simulations demonstrated that peri-implant bone stress values were generally comparable between the single-piece and two-piece implant configurations. Likewise, fixation screw stresses and overall screw deformation showed only minimal differences between the two designs, suggesting similar mechanical behavior for these components under the simulated loading conditions.

A clear distinction emerged, however, in the implant framework itself. The two-piece design exhibited substantially higher von Mises stress than the single-piece framework. Under equivalent loading conditions, the recorded stress reached 150.09 MPa for the two-piece framework compared with 60.74 MPa for the single-piece design, representing more than a twofold increase.

Within the scope of this computational model, the framework represented the only component demonstrating a marked biomechanical difference between the two implant concepts.

6. Clinical Analysis

This study contributes valuable biomechanical evidence regarding the structural behavior of customized titanium subperiosteal implants designed for the rehabilitation of severely resorbed edentulous mandibles. The findings indicate that dividing the framework into two components does not substantially alter stress transmission to the surrounding bone or fixation screws, suggesting that both designs may provide comparable load distribution to these structures.

The most notable observation concerns the implant framework itself. Higher internal stresses within the two-piece design may indicate a less favorable mechanical response under the simulated conditions. Although increased framework stress does not automatically translate into clinical failure, it may represent an important consideration during implant design and engineering.

These findings should be interpreted cautiously. Finite element analysis is a computational modeling technique that estimates biomechanical behavior under standardized assumptions rather than reproducing the complexity of biological tissues or long-term clinical function. Consequently, this investigation cannot establish differences in implant survival, biological complications, prosthetic success, or patient outcomes. Instead, it provides a theoretical foundation that may guide future experimental and clinical research aimed at optimizing patient-specific subperiosteal implant designs.

7. Clinical Applications

The results may be relevant for clinicians involved in the rehabilitation of patients presenting with severe mandibular atrophy when extensive bone grafting or other highly invasive reconstructive procedures are not indicated.

The study also provides useful information for professionals involved in digital implant planning, CAD/CAM manufacturing, and the development of customized subperiosteal implant frameworks. Nevertheless, because the evidence is based exclusively on computational simulation, these findings should not be interpreted as definitive clinical recommendations without validation through prospective clinical studies.

8. Level of Evidence, Limitations and Transparency

This publication represents a preclinical computational study based on three-dimensional finite element analysis, which corresponds to a relatively low level of clinical evidence compared with prospective clinical trials or systematic reviews.

The methodology allows standardized evaluation of biomechanical performance but does not assess biological healing, implant survival, prosthetic complications, or long-term clinical outcomes. Consequently, the conclusions are limited to the simulated mechanical environment.

The methodological limitations primarily relate to the inherent assumptions of finite element modeling and the absence of clinical validation.

The information provided does not report any conflicts of interest, funding disclosures, or author affiliations with implant manufacturers.

9. Key Study Highlights

• Study type: Preclinical three-dimensional finite element analysis (3D FEA)
• Level of evidence: Preclinical computational study
• Population or studies analyzed: Digital model generated from one edentulous mandibular CT scan
• Number of patients or implants: Not specified in the available data
• Follow-up duration: Not applicable
• Primary outcome: Biomechanical comparison between single-piece and two-piece patient-specific titanium subperiosteal implant frameworks
• Main finding: Peri-implant bone and fixation screw stresses were similar, whereas the two-piece framework exhibited substantially higher von Mises stress (150.09 MPa versus 60.74 MPa)
• Scientific conclusion: The single-piece framework demonstrated more favorable biomechanical performance at the framework level, while the remaining evaluated parameters were largely comparable.
• Limitations: Computational simulation without clinical validation or long-term patient outcomes.

10. Scientific Impact

This study provides original biomechanical evidence on an implant design question that has received little attention in the current dental literature. According to the authors, this is the first investigation directly comparing single-piece and two-piece patient-specific titanium subperiosteal implant frameworks using finite element analysis.

Rather than proposing new clinical protocols, the research improves understanding of how framework configuration influences mechanical stress distribution. The findings suggest that although both designs behave similarly in terms of peri-implant bone and fixation screw loading, the single-piece framework demonstrates a mechanical advantage within the implant structure itself. These observations may inform future optimization of customized implant designs while highlighting the need for prospective clinical investigations to determine whether the observed biomechanical differences translate into meaningful clinical outcomes.

11. Editorial Conclusion

This finite element study indicates that both single-piece and two-piece patient-specific titanium subperiosteal implants exhibit comparable biomechanical behavior for peri-implant bone and fixation screws under the simulated conditions. The principal distinction lies in the implant framework, where the single-piece design demonstrated lower internal stress. Although these findings contribute valuable information for the engineering of customized subperiosteal implants, their clinical significance should be confirmed through well-designed clinical studies before influencing therapeutic decision-making.