Clinical performance of additively manufactured subperiosteal implants: a systematic review

Clinical Performance of Additively Manufactured Subperiosteal Implants: A Systematic Review

1. Scientific Reference

• Study Title: Clinical Performance of Additively Manufactured Subperiosteal Implants: A Systematic Review
• Authors: Eduardo Anitua, Asier Eguia, Christoph Staudigl, Mohammad Hamdan Alkhraisat
• Journal: International Journal of Implant Dentistry
• Year of Publication: 2024
• DOI: 10.1186/s40729-024-00521-6

2. Scientific Background

The rehabilitation of patients with severe maxillary or mandibular bone atrophy remains one of the most challenging situations in implant dentistry. In cases where residual bone volume is insufficient for conventional endosseous implants, clinicians often need to consider advanced treatment approaches, including bone augmentation procedures, zygomatic implants, or patient-specific reconstructive solutions.

Subperiosteal implants were introduced decades before the widespread adoption of osseointegrated root-form implants. However, limitations related to manufacturing methods, surgical protocols, and long-term biological complications contributed to their decline in clinical use. Recent advances in digital workflows, computer-aided design and manufacturing (CAD/CAM), additive manufacturing technologies, and modern titanium alloys have renewed interest in this treatment modality.

As customized subperiosteal implants become increasingly available through digital planning and 3D manufacturing processes, understanding their clinical performance is essential. This systematic review was conducted to evaluate the available evidence regarding implant survival and complication rates associated with these contemporary implant designs.

3. Study Objective

The primary objective of this systematic review was to assess the survival and complication rates of modern subperiosteal implants designed using digital CAD workflows and manufactured through additive manufacturing technologies.

The authors aimed to determine whether these contemporary patient-specific implants provide satisfactory clinical outcomes in patients with severe bone atrophy and to evaluate the currently available evidence supporting their use in oral rehabilitation.

4. Methodology

The review was conducted according to PRISMA guidelines and was prospectively registered in the PROSPERO database (CRD42023424211). Literature searches were performed in Medline/PubMed, Scopus, and the Cochrane Library, with additional searches including reference screening, manual searches, grey literature, and internet-based sources.

Thirteen studies met the eligibility criteria and were included in the qualitative synthesis. These consisted of five cohort studies and eight case series. Collectively, the studies reported outcomes from 227 patients treated with 227 additively manufactured subperiosteal implants.

The primary outcomes assessed were implant survival and the occurrence of biological or technical complications. Due to substantial heterogeneity among the included studies in terms of design, methodology, implant characteristics, and outcome reporting, a quantitative meta-analysis was not feasible.

5. Main Results

The review analyzed data from 227 patients with a weighted mean age of 62.4 years. The weighted mean follow-up period across the included studies was 21.4 months.

At the end of the reported follow-up periods, 97.8% of implants remained functional, with only five implant failures documented. These findings indicate a high short-term implant survival rate.

Soft-tissue-related complications represented the most frequently reported adverse events. Partial implant exposure occurred in 58 implants, corresponding to 25.6% of the evaluated cases. Persistent soft-tissue infections or infections requiring clinical management were reported in 12 patients (5.3%).

Among the patients who received provisional prostheses, fractures of interim restorations were reported in 8 out of 155 cases (5.2%). Additional postoperative complications such as pain, discomfort, swelling, or bleeding were also documented in several studies included in the review.

6. Clinical Analysis

This systematic review provides an important overview of the current evidence regarding digitally designed and additively manufactured subperiosteal implants. The available data suggest that these patient-specific devices may offer a viable treatment option for individuals presenting with advanced alveolar bone atrophy or complex maxillofacial defects.

One of the most relevant observations is the high short-term implant survival reported across the included studies. These outcomes indicate that modern manufacturing technologies may have addressed some of the limitations historically associated with traditional subperiosteal implant systems. Improved anatomical adaptation, digital planning, and fixation with osteosynthesis screws may contribute to greater mechanical stability and clinical predictability.

However, the review also highlights a significant prevalence of soft-tissue complications. The frequency of partial framework exposure suggests that long-term peri-implant soft tissue management remains a critical consideration when using these devices.

Importantly, the findings should not be interpreted as definitive evidence of superiority over alternative treatment modalities. The available literature is based exclusively on observational studies, and follow-up durations remain relatively limited. Consequently, while the results are encouraging, they should be considered preliminary until confirmed by more robust prospective investigations.

7. Clinical Applications

Based on the available evidence, additively manufactured subperiosteal implants may be relevant in several clinical scenarios, including:

• Severe maxillary or mandibular bone atrophy.
• Complex implant-supported rehabilitation cases.
• Patients requiring full-arch oral rehabilitation.
• Maxillofacial reconstruction following oncologic resection procedures.
• Cases where extensive bone grafting procedures may not be feasible or desirable.
• Digital implant workflows incorporating CAD/CAM technologies and patient-specific treatment planning.

These applications should be considered within the limitations of the currently available evidence and individual patient characteristics.

8. Level of Evidence, Limitations, and Transparency

Although this publication is a systematic review, the included evidence was derived exclusively from observational cohort studies and case series. No randomized controlled trials were identified during the literature search.

Using the GRADE framework, the authors ultimately classified the overall strength of evidence as very low. Several factors contributed to this assessment, including methodological heterogeneity, variability in implant designs and treatment protocols, limited sample sizes, and the absence of long-term comparative data.

The authors also reported that the heterogeneity of the included studies prevented a formal meta-analysis. As a result, the conclusions rely primarily on qualitative synthesis rather than pooled statistical estimates.

No conflicts of interest are mentioned in the excerpts provided. Therefore, this information cannot be confirmed from the available material.

9. Key Study Highlights

• Study Type: Systematic review
• Level of Evidence: Very low (GRADE assessment)
• Number of Studies Included: 13
• Number of Patients/Implants: 227 patients, 227 implants
• Mean Follow-Up: 21.4 months (weighted mean)
• Primary Outcome: Implant survival and complication rates
• Main Finding: 97.8% of implants remained functional during follow-up
• Most Frequent Complication: Partial framework exposure (25.6%)
• Scientific Conclusion: Favorable short-term survival with a notable incidence of soft-tissue complications
• Key Limitations: Heterogeneous study designs, observational evidence only, lack of long-term data

10. Scientific Impact

This review contributes to the growing body of literature evaluating the clinical role of patient-specific subperiosteal implants in contemporary implant dentistry. By consolidating evidence from multiple observational studies, it provides one of the most comprehensive assessments currently available on the performance of additively manufactured subperiosteal implant systems.

The findings support the growing interest in digital implant rehabilitation workflows and suggest that modern manufacturing technologies may have improved the clinical viability of a treatment concept that was historically associated with significant limitations.

At the same time, the review underscores the need for caution. The available evidence remains limited in quality, and many unanswered questions persist regarding medium- and long-term outcomes, biological stability, and comparative effectiveness against alternative treatment strategies.

As such, this study serves both as a summary of current clinical experience and as a call for higher-quality research capable of establishing the long-term role of customized subperiosteal implants within advanced implant rehabilitation protocols.

11. Editorial Conclusion

This systematic review indicates that additively manufactured subperiosteal implants can achieve high short-term survival rates in patients with severe bone deficiencies and complex reconstructive needs. Nevertheless, soft-tissue complications remain relatively common, and the overall level of scientific evidence is currently limited.

For clinicians involved in advanced implant rehabilitation, these findings suggest that customized subperiosteal implants may represent a promising treatment option in carefully selected cases. However, longer follow-up studies and stronger clinical evidence are still required before definitive conclusions can be drawn regarding their long-term predictability and clinical superiority.