Custom-Made Direct Metal Laser Sintering Titanium Subperiosteal Implants: A Retrospective Clinical Study on 70 Patients

Custom-Made Direct Metal Laser Sintering Titanium Subperiosteal Implants: A Retrospective Clinical Study on 70 Patients

1. Scientific Reference

• Study Title: Custom-Made Direct Metal Laser Sintering Titanium Subperiosteal Implants: A Retrospective Clinical Study on 70 Patients
• Authors: Mauro Cerea, Giorgio Andrea Dolcini
• Scientific Journal: BioMed Research International
• Year of Publication: 2018
• DOI: 10.1155/2018/5420391

2. Scientific Background

The management of patients presenting with severe maxillary and mandibular bone atrophy remains an important challenge in oral implantology. When the residual bone volume becomes insufficient to allow the placement of conventional endosseous implants, therapeutic protocols generally rely on various bone reconstruction techniques or on the use of specific implant concepts.

However, these approaches may result in increased surgical complexity, treatment costs, and overall rehabilitation time. In this context, subperiosteal implants represent a historical alternative that gradually disappeared with the rise of modern osseointegration.

The emergence of the digital workflow in oral surgery, combining CBCT, computer-aided design (CAD/CAM), and metal additive manufacturing, has opened the possibility of revisiting this concept. This study is part of this technological evolution by evaluating custom-made titanium subperiosteal implants manufactured through Direct Metal Laser Sintering (DMLS).

3. Study Objective

The primary objective of the authors was twofold.

Firstly, to present a digital protocol enabling the design and fabrication of custom-made titanium subperiosteal implants through a fully digital workflow.

Secondly, to analyze the clinical outcomes obtained with this therapeutic solution, particularly in terms of implant survival and complications observed after prosthetic loading.

4. Methodology

This was a retrospective clinical study conducted using the medical records of five private dental clinics located in Northern Italy.

The inclusion criteria involved patients over 60 years of age who had received a custom-made DMLS titanium subperiosteal implant between 2014 and 2015, with a fixed restoration and a minimum follow-up period of two years.

Smokers and bruxers were excluded.

A total of 70 patients were included in the analysis after exclusion of five incomplete records or records without available final follow-up.

The primary evaluation criteria were:

• implant survival;
• immediate postoperative complications;
• biological complications;
• prosthetic complications observed during follow-up.

The protocol was based on digital planning integrating CBCT, three-dimensional reconstruction, CAD/CAM design, and DMLS additive manufacturing of grade 5 titanium subperiosteal structures.

5. Main Results

After two years of follow-up, 67 of the 70 implants were still functioning.

Three implants had to be removed because of recurrent infections considered impossible to control, corresponding to an implant survival rate of 95.8%.

Regarding the immediate postoperative period, four patients presented manifestations such as pain, discomfort, edema, or bleeding. These events were resolved through pharmacological treatment without implant loss. The reported incidence was 5.7%.

During follow-up, only one persistent biological complication was observed. This patient required several antibiotic treatments as well as repeated professional hygiene sessions, without implant removal. The incidence of these biological complications was estimated at 1.4%.

Prosthetic complications mainly involved provisional acrylic resin restorations as well as two cases of ceramic chipping on definitive restorations. Their overall incidence was 8.9%.

6. Clinical Analysis

This study provides interesting clinical data on an approach that reintroduces the concept of subperiosteal implants into a modern digital environment.

The originality of the protocol lies less in the principle of the subperiosteal implant itself than in the way it is designed and manufactured. Through three-dimensional planning and additive titanium manufacturing, the authors seek to solve several difficulties historically associated with these devices, particularly imperfect adaptation to the osseous anatomy and manufacturing complexity.

The observed results suggest that a fixed implant-supported rehabilitation can be achieved in patients presenting with advanced bone atrophy without systematically resorting to bone grafting procedures. This perspective is particularly relevant in elderly patients for whom extensive reconstructive procedures may be difficult to accept or perform.

However, caution is required when interpreting these data. The absence of a control group does not allow direct comparison of this strategy with conventional bone regeneration techniques or zygomatic implants. Furthermore, the infectious complications observed demonstrate that the biological management of these devices remains a critical issue.

The results should therefore be considered encouraging preliminary data rather than definitive validation of the technique.

7. Clinical Applications

The data from this study appear particularly relevant in the following situations:

• severe maxillary and mandibular bone atrophy;
• edentulous or severely edentulous patients requiring fixed implant-supported rehabilitation;
• situations in which placement of conventional endosseous implants appears difficult;
• elderly patients refusing or unwilling to undergo complex bone grafting protocols;
• integration of a digital workflow combining CBCT, three-dimensional planning, and CAD/CAM manufacturing.

The authors present this approach as a potential therapeutic option when conventional alternatives are limited or difficult to implement.

8. Level of Evidence, Limitations and Transparency

The level of evidence corresponds to that of a retrospective observational clinical study.

The results are based on the analysis of 70 patients followed for two years, providing useful clinical information but not allowing establishment of superiority over other therapeutic strategies.

The authors themselves identify several limitations:

• retrospective nature of the study;
• relatively limited sample size;
• follow-up duration limited to two years;
• absence of medium- and long-term data;
• absence of direct comparison with other treatments.

Regarding transparency, the authors indicate that the study was self-funded and declare no conflicts of interest related to this work.

9. Key Points of the Study

• Study Type: Retrospective clinical study
• Level of Evidence: Retrospective observational study
• Population Analyzed: Patients over 60 years of age presenting with severe bone atrophy
• Number of Patients: 70
• Number of Implants: 70
• Follow-up Duration: 2 years
• Primary Outcome Evaluated: Implant survival and complications
• Main Result: Implant survival rate of 95.8%
• Biological Complications: 1.4% of surviving implants
• Prosthetic Complications: 8.9% of surviving implants
• Scientific Conclusion: Favorable short-term clinical outcomes for custom-made DMLS titanium subperiosteal implants in patients presenting with severe bone atrophy
• Potential Limitations: Retrospective study, relatively small sample size, follow-up limited to two years, absence of a control group

10. Scientific Impact

This publication contributes to the scientific reassessment of subperiosteal implants in the digital era. While this family of implants had largely disappeared from contemporary clinical practice, the authors demonstrate that customized manufacturing based on three-dimensional reconstruction and DMLS technology makes it possible to envision a new application of this concept.

The interest of the study also lies in the complete integration of the digital workflow, from CBCT acquisition to the customized fabrication of both the implant and the implant-supported prosthesis.

Although the data remain limited to a relatively short follow-up period, this study provides documented clinical results that may serve as a basis for more robust prospective research. It therefore contributes to enriching the literature dedicated to therapeutic solutions for patients suffering from advanced bone atrophy.

11. Editorial Conclusion

This retrospective study highlights the potential of custom-made subperiosteal implants manufactured using DMLS technology in the treatment of elderly patients presenting with severe bone atrophy. The reported results demonstrate a high implant survival rate at two years and a limited number of biological complications. Nevertheless, considering the level of evidence, the absence of a comparative group, and the limited clinical follow-up, these data should be interpreted with caution. Larger prospective studies remain necessary to durably confirm the role of this approach in complex implant rehabilitation.