A Retrospective Radiological and Clinical Survey of Full-Arch Immediate Fixed Prostheses Supported by Custom-Made Three- Dimensional Printed Subperiosteal Titanium Implants in Patients with Severe Atrophic Jaws: Implant Success Code

Ernesto Vatteroni, Paolo Toti, Ugo Covani, Roberto Crespi, Saverio Cosola, Giovanni-Battista Menchini-Fabris

Full text link: https://pubmed.ncbi.nlm.nih.gov/40080050/ 

A Retrospective Radiologic and Clinical Survey of Full-Arch Immediate Fixed Prostheses Supported by Custom-Made 3D-Printed Subperiosteal Titanium Implants in Patients with Severely Atrophic Jaws: Implant Success Code

1. Scientific Reference

• Study Title: A Retrospective Radiologic and Clinical Survey of Full-Arch Immediate Fixed Prostheses Supported by Custom-Made 3D-Printed Subperiosteal Titanium Implants in Patients with Severely Atrophic Jaws: Implant Success Code
• Authors: Ernesto Vatteroni, Paolo Toti, Ugo Covani, Roberto Crespi, Saverio Cosola, Giovanni-Battista Menchini-Fabris
• Journal: The International Journal of Oral & Maxillofacial Implants
• Year of Publication: 2025
• DOI: 10.11607/jomi.11210

2. Scientific Background

Managing patients with severe maxillary or mandibular atrophy remains one of the most demanding challenges in implant dentistry. Conventional root-form dental implants generally require sufficient bone volume to ensure long-term stability, and advanced bone resorption frequently necessitates extensive augmentation procedures before implant placement.

Recent advances in digital dentistry, including cone beam imaging, CAD/CAM technologies, virtual treatment planning, and additive manufacturing, have renewed interest in subperiosteal implants as a treatment alternative for patients with limited bone availability. Modern patient-specific titanium frameworks can now be designed and manufactured to conform closely to the remaining jaw anatomy, potentially reducing the need for grafting procedures.

Despite this technological progress, the literature lacks standardized criteria for defining success, survival, and failure of subperiosteal implant rehabilitations. As a result, comparisons between studies remain difficult. This investigation addresses that gap by proposing a structured evaluation framework while reporting clinical and radiographic outcomes of digitally designed subperiosteal implants.

3. Study Objective

The primary aim of this retrospective study was to evaluate the clinical and radiographic outcomes of immediately loaded full-arch fixed prostheses supported by custom-made 3D-printed titanium subperiosteal implants in patients with severe jaw atrophy.

A secondary objective was to establish a standardized classification system capable of distinguishing implant success, survival, and failure through the introduction of the Stability–Inflammation–Offset (SIO) criteria.

4. Methodology

This was a retrospective observational study involving patients treated between 2018 and 2021 with patient-specific subperiosteal implants manufactured using a digital CT-based CAD/CAM workflow.

The analysis included 18 patients with a mean follow-up period of approximately 2 years. A total of 26 subperiosteal implants were placed, including 11 maxillary and 15 mandibular implants.

Clinical evaluations focused on implant stability, peri-implant soft tissue conditions, surgical complications, and prosthetic outcomes. Radiographic assessment compared preoperative virtual planning with postoperative implant positioning through three-dimensional analysis of 189 fixation sleeves and osteosynthesis screws.

Implant outcomes were classified according to the newly proposed SIO system, which evaluates:

• Stability (S)
• Peri-implant soft tissue condition or inflammation (I)
• Implant offset between planned and achieved positioning (O)

The final implant classification was determined by the lowest score obtained among these three criteria.

5. Main Results

No implant was lost during the observation period, resulting in a cumulative implant survival rate of 100% at two years.

Regarding implant stability, four mandibular implants exhibited temporary instability. In two cases, fixation screws were replaced with larger-diameter screws, while other cases required modifications of fixation components. These events were classified as survival rather than failure according to the SIO framework.

Soft tissue complications were limited. Two patients developed peri-implant recession or soft tissue dehiscence without persistent inflammation or implant removal. These implants also remained within the survival category.

Radiographic analysis demonstrated a mean overall misalignment of 1.66 ± 0.99 mm between planned and postoperative implant positioning. Horizontal deviations were significantly greater than vertical deviations.

Only one patient exceeded the predefined offset thresholds associated with implant success. Consequently, the overall cumulative success rate according to the SIO classification reached 73.1% after two years.

No prosthetic failures, mechanical complications, or functional complications were reported, resulting in a prosthetic success rate of 100% throughout the follow-up period.

6. Clinical Analysis

One of the most valuable contributions of this study is the distinction it establishes between implant survival and implant success. In implant dentistry, survival alone may not fully reflect the biological, surgical, and prosthetic quality of treatment outcomes. The proposed SIO framework attempts to address this limitation by incorporating parameters that are particularly relevant to subperiosteal implant rehabilitation.

The findings suggest that digitally planned and 3D-printed patient-specific subperiosteal implants can remain functional in severely atrophic jaws over a two-year period while supporting fixed full-arch restorations. Importantly, the study demonstrates that minor biological or mechanical events do not necessarily translate into implant loss.

The radiographic component of the investigation is particularly noteworthy. By quantifying discrepancies between virtual planning and actual implant placement, the authors provide objective data regarding the accuracy of modern digital workflows. Such information may be valuable for surgical planning, especially when operating near critical anatomical structures.

However, these results should not be interpreted as evidence that subperiosteal implants outperform conventional endosseous implants. The study was not designed for comparative evaluation. Instead, it provides observational evidence supporting the feasibility of a digitally driven treatment option for selected patients with severe maxillary or mandibular atrophy.

7. Clinical Applications

The findings may be relevant in several clinical scenarios, including:

• Severe maxillary or mandibular atrophy.
• Full-arch implant rehabilitation in edentulous patients.
• Cases where extensive bone augmentation procedures may be challenging.
• Digital implant workflows involving CT-based planning and CAD/CAM manufacturing.
• Immediate-loading protocols supported by patient-specific titanium frameworks.
• Complex implant rehabilitation requiring individualized anatomical adaptation.

The study specifically supports consideration of digitally manufactured subperiosteal implants as a treatment option for highly resorbed jaws, although further research is required before broader clinical recommendations can be established.

8. Level of Evidence, Limitations, and Transparency

This publication represents a retrospective observational study, which provides a moderate-to-low level of evidence compared with prospective controlled clinical trials.

Several limitations should be considered:

• Small sample size (18 patients).
• Absence of a control group.
• Follow-up limited to approximately two years.
• Potential measurement inaccuracies associated with three-dimensional image superimposition techniques.
• Retrospective study design.

The authors state that the research received no external funding and report no conflicts of interest.

Therefore, while the findings are encouraging, they should be interpreted as preliminary evidence supporting a standardized evaluation framework rather than definitive proof of long-term superiority or predictability.

9. Key Study Points

• Study Type: Retrospective observational study
• Level of Evidence: Retrospective clinical investigation
• Population: Patients with severe maxillary and/or mandibular atrophy
• Number of Patients: 18
• Number of Implants: 26 custom-made subperiosteal implants
• Follow-up Duration: Approximately 2 years
• Primary Evaluation Criteria: Stability–Inflammation–Offset (SIO) classification
• Main Outcome: 100% implant survival at two years
• Success Rate According to SIO Criteria: 73.1%
• Prosthetic Outcome: No prosthetic failures reported
• Scientific Conclusion: The SIO framework provides standardized criteria for defining success, survival, and failure in subperiosteal implant rehabilitation.
• Main Limitations: Small sample size, retrospective design, lack of control group, short-to-medium-term follow-up.

10. Scientific Impact

This study contributes to the growing body of literature investigating digitally manufactured subperiosteal implants as a potential solution for patients with advanced jaw atrophy.

Its most significant contribution is the introduction of a structured classification system designed specifically for subperiosteal implant rehabilitation. By integrating implant stability, peri-implant soft tissue health, and positional accuracy into a single assessment framework, the SIO criteria may facilitate more consistent reporting across future clinical studies.

The research also provides original quantitative data regarding three-dimensional deviations between virtual implant planning and postoperative outcomes, an area that remains relatively underreported in the literature.

Although larger prospective studies are required, this work represents an important step toward establishing standardized outcome measures for digitally designed subperiosteal implant systems and may support future efforts to improve comparability and methodological rigor within this field.

11. Editorial Conclusion

This retrospective investigation highlights the potential role of custom-made 3D-printed titanium subperiosteal implants in the rehabilitation of severely atrophic jaws. While the reported implant survival was excellent over a two-year period, the study’s broader contribution lies in the development of the SIO classification system, which provides a more nuanced approach to evaluating treatment outcomes. Given the limited sample size and retrospective design, the findings should be interpreted cautiously, but they offer valuable groundwork for future clinical research and standardization efforts in advanced implant rehabilitation.