Innovative Landing Zones for One-Piece, Rigidly Fixated Patient-Specific Subperiosteal Implants in Dental Rehabilitation of Severe Maxillary and Midfacial Defects

Nils-Claudius Gellrich, Philippe Korn, Philipp Jehn, Fritjof Lentge, Michael-Tobias Neuhaus, Björn Rahlf.

Full text link: https://pubmed.ncbi.nlm.nih.gov/41413547/

Innovative Landing Zones for One-Piece, Rigidly Fixated Patient-Specific Subperiosteal Implants in Dental Rehabilitation of Severe Maxillary and Midfacial Defects

1. Scientific Reference

• Study Title: Innovative Landing Zones for One-Piece, Rigidly Fixated Patient-Specific Subperiosteal Implants in Dental Rehabilitation of Severe Maxillary and Midfacial Defects.
• Authors: Nils-Claudius Gellrich, Philippe Korn, Philipp Jehn, Fritjof Lentge, Michael-Tobias Neuhaus, Björn Rahlf.
• Journal: Head & Face Medicine.
• Publication Year: 2025 
• DOI: 10.1186/s13005-025-00549-y.

2. Scientific Background

Restoring oral function after extensive maxillary or midfacial resection remains one of the greatest challenges in contemporary implant dentistry and maxillofacial surgery. Conventional rehabilitation generally relies on vascularized or non-vascularized bone reconstruction before implant placement, an approach that depends heavily on successful bone healing and adequate soft tissue conditions. These prerequisites are frequently compromised in patients who have undergone oncologic resection, radiotherapy, severe facial trauma, or multiple reconstructive procedures.

Patient-specific subperiosteal implants have recently re-emerged as an alternative for selected complex cases, benefiting from advances in digital planning, CAD/CAM technology, and additive manufacturing. The present study explores an extension of this concept by introducing novel fixation sites located at the lateral skull base and the pterygoid processes. Rather than depending exclusively on conventional maxillary buttresses, this strategy seeks mechanically reliable anchorage in preserved craniofacial structures, potentially expanding treatment options for patients with extensive bone loss.

3. Study Objective

The purpose of this case series was to investigate the feasibility of newly designed patient-specific IPS Implants® Preprosthetic incorporating extensions toward the lateral skull base and/or the pterygoid processes. The authors aimed to determine whether these additional fixation areas could provide sufficient mechanical stability to support prosthetic rehabilitation in patients presenting with severe maxillary and midfacial defects that could not be managed using conventional implant anchorage alone.

4. Methodology

This publication is a single-center observational case series evaluating an advanced design concept for patient-specific IPS Implants® Preprosthetic. Patients treated between 2020 and 2024 at the Department of Oral and Maxillofacial Surgery, Hannover Medical School, were screened for inclusion. The study was conducted in accordance with the Declaration of Helsinki and received approval from the institutional ethics committee (No. 8552_BO_K_2019).

Among 100 patients rehabilitated with IPS Implants® Preprosthetic over a nine-year period, 13 patients required implant design modifications following finite element method (FEM) analysis. These modifications were indicated when standard maxillary buttress fixation was considered biomechanically insufficient. Depending on the individual anatomy, additional extensions toward the lateral skull base, the pterygoid process, or both were incorporated into the implant design.

Preoperative planning combined cone beam computed tomography (CBCT), prosthetically driven backward planning, CAD/CAM digital workflow, and selective laser melting for implant manufacturing. Clinical evaluation focused on primary implant stability, prosthetic rehabilitation, perioperative and postoperative complications, soft tissue management, infection, implant fracture, and masticatory function. Patients were followed for 9 to 52 months, with a median follow-up of 37.5 months.

5. Main Findings

The thirteen patients represented highly challenging clinical scenarios involving extensive maxillary and midfacial defects. Most cases resulted from ablative tumor surgery, while others included severe facial trauma, complex maxillary atrophy, ectodermal dysplasia, and previous failures of conventional implant rehabilitation. In every patient, FEM analysis demonstrated that traditional maxillary fixation sites would not provide sufficient biomechanical stability, leading to individualized modifications of the implant framework.

The additional fixation strategy varied according to the anatomical defect. Eight patients received unilateral extensions toward the lateral skull base, one traumatic case required bilateral skull base extensions, and several patients also received unilateral or bilateral extensions to the pterygoid processes to improve stress distribution across the implant framework.

Throughout the observation period, no mechanical implant failures were reported. Functional stability was achieved immediately after insertion, and prosthetic rehabilitation was successfully completed in all included patients. The authors did not observe secondary loss of implant stability or peri-implantitis. Mild mucositis around posterior posts occurred in some cases, and one prosthetic bar required trimming because of soft tissue remodeling without affecting implant performance. One implant was eventually removed because of chronic pain associated with infection. Two patients died during follow-up; however, these deaths were not described as being related to the implant treatment.

6. Clinical Analysis

The principal contribution of this study lies in its biomechanical rather than material innovation. Instead of introducing a new implant system, the authors propose expanding the available fixation zones for patient-specific subperiosteal implants by utilizing preserved craniofacial structures located beyond the traditional maxillary buttresses. In patients with extensive maxillary destruction following oncologic resection, radiation therapy, or severe trauma, these conventional support areas may no longer provide sufficient stability for immediate prosthetic rehabilitation. By extending fixation toward the lateral skull base and the pterygoid processes, the proposed design seeks to overcome these anatomical limitations.

An important aspect of this approach is that functional rehabilitation is achieved through individualized implant engineering rather than through reconstruction of missing bone volume. The customized framework is designed to compensate for anatomical deficiencies by adapting pillar position, implant geometry, and load distribution according to each patient’s prosthetic requirements. This represents a different treatment philosophy from conventional bone graft-based reconstruction, where implant placement depends on the successful regeneration of adequate bone.

The study also highlights the growing importance of a comprehensive digital workflow in complex implant rehabilitation. Cone beam CT imaging, prosthetically driven backward planning, CAD/CAM design, finite element analysis (FEM), and—in selected cases—intraoperative navigation were integrated into the treatment process to optimize implant positioning and biomechanical performance. According to the authors, these technologies contribute to accurate planning and may improve the predictability of highly individualized reconstructions.

Nevertheless, these findings should be interpreted within the appropriate clinical context. This investigation demonstrates technical feasibility in a carefully selected group of patients rather than establishing superiority over established reconstructive protocols. The reported outcomes suggest that this design concept may provide an additional therapeutic option for highly complex maxillary defects, but they should not be considered sufficient evidence to replace conventional reconstructive approaches.

7. Clinical Applications

The findings of this case series are primarily applicable to highly complex implant rehabilitation where conventional fixation strategies are no longer feasible because of extensive anatomical destruction.

Potential clinical indications described by the authors include:

• extensive maxillary defects following ablative tumor surgery;
• combined maxillary and midfacial defects with or without previous radiotherapy;
• severe maxillary atrophy in which conventional buttress fixation is biomechanically insufficient;
• complex post-traumatic craniofacial defects;
• patients with previous failures of bone reconstruction or conventional implant rehabilitation;
• digitally planned CAD/CAM workflows requiring individualized implant design and biomechanical optimization.

Rather than proposing a replacement for established reconstructive techniques, the study suggests that patient-specific subperiosteal implants incorporating lateral skull base and pterygoid extensions may represent a valuable alternative in carefully selected patients with severe maxillary and midfacial bone loss. Their use should remain limited to individualized treatment planning supported by detailed three-dimensional imaging, biomechanical analysis, and multidisciplinary surgical expertise.

8. Level of Evidence, Limitations and Transparency

This publication is a single-center case series, providing an early level of clinical evidence focused primarily on the technical feasibility of an innovative implant design. As an observational study without randomization, a control group, or direct comparison with conventional reconstructive techniques, its findings should be interpreted as preliminary rather than definitive. Although the reported median follow-up of 37.5 months offers valuable medium-term clinical information, the study was not designed to establish comparative effectiveness or long-term superiority.

Several methodological limitations are acknowledged by the authors. The most important is the small sample size, with only 13 patients included despite a larger institutional experience of 100 IPS Implants® Preprosthetic cases. Furthermore, each reconstruction was individually designed according to highly variable anatomical conditions, including oncologic defects, traumatic injuries, severe maxillary atrophy, and ectodermal dysplasia. This substantial heterogeneity limits the generalizability of the reported outcomes and prevents meaningful statistical comparisons.

Regarding transparency, the study evaluates IPS Implants® Preprosthetic, a patient-specific implant system manufactured by KLS Martin®, which is also referenced throughout the digital planning workflow. Within the material provided, no explicit declaration of conflicts of interest or industry funding is reported. Therefore, no conclusions regarding potential financial relationships can be drawn from the available information alone.

9. Key Study Highlights

• Study design: Single-center observational case series.
• Level of evidence: Low to moderate (case series).
• Study population: 13 patients selected from an institutional cohort of 100 patients treated with IPS Implants® Preprosthetic.
• Number of patients: 13.
• Number of implants: 13 customized patient-specific subperiosteal implants incorporating modified fixation designs.
• Follow-up: 9–52 months (median follow-up: 37.5 months).
• Primary outcome: Clinical feasibility of additional fixation extending toward the lateral skull base and/or pterygoid processes.
• Digital workflow: CBCT-based prosthetically driven planning, CAD/CAM design, finite element method (FEM) analysis, selective laser melting manufacturing, and intraoperative navigation in selected cases.
• Main finding: Immediate functional stability and successful prosthetic rehabilitation were achieved in all included patients, with no reported mechanical implant failures during follow-up.
• Reported complications: Occasional localized mucositis, one prosthetic bar adjustment due to soft tissue remodeling, and one implant removal because of chronic pain associated with infection.
• Scientific conclusion: Patient-specific subperiosteal implants incorporating novel cranial fixation sites appear to be a technically feasible solution for selected patients with severe maxillary and midfacial defects when conventional anchorage is insufficient.
• Main limitations: Small sample size, absence of a control group, heterogeneous patient population, and lack of comparative clinical evaluation.

10. Scientific Impact

This study contributes to the growing body of evidence supporting the use of patient-specific subperiosteal implants for the rehabilitation of complex maxillary defects by introducing an innovative biomechanical concept rather than a new implant material. Its primary scientific contribution is the description of alternative fixation zones located at the lateral skull base and the pterygoid processes, expanding the range of anatomical support available when conventional maxillary buttresses have been compromised by extensive disease or previous treatment.

The proposed design builds upon the authors’ previous work with IPS Implants® Preprosthetic while extending its application to patients presenting with particularly severe anatomical deficiencies. By integrating finite element analysis (FEM) into the digital planning process, the study illustrates how biomechanical simulation can guide individualized implant design and optimize load distribution before surgery. This represents an important step toward increasingly personalized implant rehabilitation based on patient-specific anatomy rather than standardized implant positioning.

Beyond the implant itself, the study also highlights the expanding role of digital implant workflows, combining CBCT imaging, prosthetically driven planning, CAD/CAM design, additive manufacturing, and intraoperative navigation. These technologies collectively support a highly customized treatment approach for patients who may not be suitable candidates for conventional bone reconstruction.

Because this investigation is based on a limited case series, its findings should be regarded as proof of feasibility rather than definitive clinical validation. Larger prospective studies, multicenter investigations, and comparative clinical trials will be necessary to determine the long-term reliability, reproducibility, and potential advantages of this concept relative to established reconstructive protocols.

11. Editorial Conclusion

This case series presents an innovative extension of patient-specific subperiosteal implant design for the rehabilitation of severe maxillary and midfacial defects. By introducing additional fixation at the lateral skull base and the pterygoid processes, the authors demonstrate that rigid implant stabilization can be achieved in carefully selected patients with highly compromised anatomy. The integration of advanced digital planning, biomechanical analysis, and CAD/CAM manufacturing illustrates the potential of personalized implantology in complex reconstructive surgery. Although the reported clinical outcomes are encouraging, the evidence remains limited by the observational design and small sample size. Consequently, these findings should be viewed as an important technical advancement that warrants confirmation through larger, comparative clinical studies before broader clinical adoption can be recommended.