Long-term Clinical Outcomes of Additively Manufactured Subperiosteal Implants for the Treatment of the Severely Atrophic Maxilla

Jan Łoginoff, Agata Majos, Marcin Elgalal

Full text link: https://pubmed.ncbi.nlm.nih.gov/40399182/ 

Long-term Clinical Outcomes of Additively Manufactured Subperiosteal Implants for the Treatment of the Severely Atrophic Maxilla

1. Scientific Reference

• Study Title: Long-term clinical results of additively manufactured subperiosteal implants for the treatment of the severely atrophic maxilla
• Authors: Jan Łoginoff, Agata Majos, Marcin Elgalal
• Journal: Journal of Cranio-Maxillofacial Surgery
• Year of Publication: 2025
• DOI: 10.1016/j.jcms.2025.04.021

2. Scientific Background

Managing patients with severe maxillary atrophy remains one of the greatest challenges in implant dentistry. When residual bone volume is insufficient to support conventional endosseous implants, treatment often relies on extensive bone augmentation procedures or alternative reconstructive techniques that may increase surgical complexity, treatment duration, and patient morbidity. These limitations are particularly relevant in elderly individuals or medically compromised patients who may not tolerate multiple surgical interventions.

Advances in digital imaging, computer-aided design and manufacturing (CAD/CAM), and metal additive manufacturing have renewed interest in patient-specific subperiosteal implants. Modern fabrication techniques allow titanium frameworks to be individually designed according to each patient’s anatomy, potentially improving implant adaptation while reducing surgical invasiveness. Although encouraging clinical outcomes have been reported, robust long-term evidence remains limited. This study addresses that gap by evaluating the long-term clinical performance of custom-made DMLS subperiosteal implants used for rehabilitation of severely atrophic maxillae.

3. Study Objective

The primary objective of this retrospective investigation was to assess the long-term clinical performance of custom-designed maxillary subperiosteal implants manufactured using direct metal laser sintering (DMLS). Specifically, the authors evaluated implant survival, clinical stability, radiographic findings, and postoperative complications in patients with severe maxillary bone atrophy who were not suitable candidates for conventional implant therapy.

4. Methodology

This study was designed as a retrospective clinical case series involving ten patients presenting with severe maxillary atrophy classified as Cawood and Howell Classes IV to VI. All participants were considered unsuitable for conventional endosseous implant placement because of insufficient bone volume.

Each implant was digitally designed from computed tomography datasets using a CAD/CAM workflow before being manufactured in titanium alloy through direct metal laser sintering. Clinical and radiographic follow-up included assessment of implant adaptation, mechanical stability, implant survival, postoperative complications, and radiological bone changes. The maximum observation period reached ten years for the earliest treated patients.

5. Main Findings

A total of ten custom-made maxillary subperiosteal implants were placed in patients presenting with severe bone atrophy. During the observation period, eight implants remained clinically stable and fully functional, while two required removal because of inadequate adaptation of the implant framework combined with recurrent infections.

Radiographic follow-up of the successfully treated cases demonstrated stable bone conditions with only minimal evidence of bone resorption. Early postoperative complications were generally limited to transient swelling and patient discomfort, both of which resolved without affecting implant function. Late complications were uncommon and were reported in only two patients.

An important long-term observation was that every implant placed in 2015 remained functional after ten years of follow-up. Kaplan–Meier survival analysis estimated a cumulative implant survival probability of 80% at ten years. The authors also describe a surgical protocol using a relatively small number of fixation screws (seven to ten), strategically positioned in areas with sufficient bone volume identified during preoperative CT-based planning. Prosthetic rehabilitation was intentionally delayed for approximately five months to support long-term implant stability under these compromised anatomical conditions.

6. Clinical Analysis

The value of this study lies primarily in its long-term clinical follow-up, an aspect that remains relatively uncommon in the current literature on digitally manufactured subperiosteal implants. Rather than simply reporting implant survival, the investigation provides insight into the durability of a patient-specific treatment strategy for individuals with severe maxillary atrophy who cannot undergo conventional implant rehabilitation.

The findings highlight the potential contribution of a fully digital workflow combining computed tomography, CAD/CAM planning, and DMLS manufacturing. By designing implants that closely match each patient’s anatomy, the surgical protocol aimed to achieve stable fixation while limiting the number of fixation screws and reducing procedural invasiveness. According to the authors, all procedures were performed under local anesthesia in an outpatient setting, illustrating the feasibility of this individualized approach.

The reported failures also provide clinically relevant information. Both implant removals were associated with inadequate implant fit and recurrent infection, suggesting that precise adaptation of the custom framework remains a critical determinant of long-term success. This observation reinforces the importance of meticulous digital planning and manufacturing accuracy throughout the treatment workflow.

Despite these encouraging outcomes, caution is warranted when interpreting the results. The investigation represents a small retrospective case series without a control group, making direct comparisons with bone augmentation procedures, zygomatic implants, or other reconstructive approaches impossible. Consequently, the study should be viewed as evidence supporting the feasibility and long-term potential of customized DMLS subperiosteal implants rather than definitive proof of superiority over established treatment modalities.

7. Clinical Applications

The findings of this study suggest that patient-specific DMLS-manufactured subperiosteal implants may represent a valuable treatment option for patients with severe maxillary atrophy who cannot be rehabilitated using conventional endosseous implants because of insufficient residual bone volume. The investigated population consisted exclusively of patients with Cawood and Howell Class IV to VI maxillary atrophy, highlighting the potential role of this technique in highly complex clinical scenarios.

The proposed treatment protocol integrates a comprehensive digital workflow, including computed tomography imaging, CAD/CAM-based virtual planning, and additive manufacturing of customized titanium frameworks. According to the authors, this individualized design enabled selective fixation in anatomically favorable regions while allowing surgery to be performed under local anesthesia in an outpatient setting. Prosthetic loading was deliberately postponed for approximately five months to optimize long-term implant stability in compromised bone conditions.

Although the reported outcomes are encouraging, the present study does not establish that customized subperiosteal implants should replace conventional bone augmentation procedures or other implant rehabilitation strategies. Instead, the findings support their potential use in carefully selected patients for whom standard treatment options are not feasible.

8. Level of Evidence, Limitations and Transparency

This publication represents a retrospective clinical case series, corresponding to a low-to-moderate level of clinical evidence. While the study provides valuable long-term follow-up data, its design does not permit conclusions regarding comparative effectiveness or causal relationships.

Several methodological limitations should be considered when interpreting the findings. The study included only ten patients, lacked a control group, and investigated a highly selected patient population with severe maxillary atrophy. These characteristics inherently limit the generalizability of the results. Furthermore, the authors acknowledge that larger patient cohorts and longer-term investigations are required to further validate this treatment approach and refine clinical protocols.

No information regarding conflicts of interest, financial support, or affiliations with implant manufacturers is reported in the material provided. Consequently, no conclusions can be drawn regarding potential sources of bias based on the available information.

9. Key Study Points

• Study design: Retrospective clinical case series.
• Level of evidence: Low-to-moderate clinical evidence.
• Study population: 10 patients with severe maxillary atrophy (Cawood and Howell Classes IV–VI).
• Number of implants: 10 custom-made titanium DMLS subperiosteal implants.
• Maximum follow-up: Up to 10 years.
• Primary outcome: Implant survival, clinical stability, radiographic performance, and postoperative complications.
• Main finding: Eight implants remained functional throughout follow-up, whereas two were removed because of poor adaptation and recurrent infection. Kaplan–Meier analysis estimated an 80% implant survival probability at 10 years.
• Additional findings: Radiographic bone stability was maintained in successful cases, and all implants placed in 2015 remained functional after ten years.
• Scientific conclusion: Custom-designed DMLS titanium subperiosteal implants appear to be a promising treatment alternative for selected patients with severe maxillary atrophy who are unsuitable for conventional implant therapy.
• Main limitations: Small sample size, retrospective design, absence of a control group, and the need for larger long-term clinical studies.

10. Scientific Impact

This study adds meaningful long-term clinical evidence to the growing body of literature supporting digitally designed subperiosteal implants for the rehabilitation of severely atrophic maxillae. One of its most valuable contributions is the availability of follow-up data extending to ten years, a duration that remains uncommon in published reports on additively manufactured patient-specific subperiosteal implants.

Beyond reporting implant survival, the investigation illustrates the clinical integration of a fully digital workflow combining computed tomography, CAD/CAM planning, and direct metal laser sintering (DMLS) for the fabrication of individualized titanium frameworks. The study therefore contributes practical evidence regarding the feasibility of personalized implant rehabilitation in patients for whom conventional endosseous implant therapy is not considered possible because of advanced maxillary bone loss.

Although the findings support the long-term potential of this treatment concept, they should be interpreted within the context of the study design. As a retrospective case series involving a limited number of patients, the investigation does not establish comparative clinical superiority over bone augmentation procedures, zygomatic implants, or other reconstructive approaches. Instead, it provides preliminary long-term evidence that may encourage future prospective studies with larger cohorts, standardized treatment protocols, and direct comparative analyses to better define the role of customized subperiosteal implants in contemporary implant dentistry.

11. Editorial Conclusion

This retrospective study provides encouraging long-term clinical observations regarding the use of custom-made DMLS titanium subperiosteal implants for the rehabilitation of patients with severe maxillary atrophy. The reported outcomes suggest that patient-specific implant design, supported by digital planning and additive manufacturing, can achieve durable functional rehabilitation in carefully selected cases where conventional implant placement is not feasible. However, given the limited sample size and retrospective methodology, these findings should be considered exploratory rather than definitive. Larger prospective investigations will be essential to confirm the reproducibility of these results and to clarify the long-term clinical position of customized subperiosteal implants within modern implant rehabilitation strategies.