subperiosteal implants
Osseointegration of subperiosteal implants using bovine bone substitute and various membranes
Full text link : https://pubmed.ncbi.nlm.nih.gov/11168194/
Osseointegration of Subperiosteal Implants Using Bovine Bone Substitute and Various Membranes
1. Scientific Reference
- Study Title: Osseointegration of Subperiosteal Implants Using Bovine Bone Substitute and Various Membranes
- Authors: Merete Aaboe, Søren Schou, Erik Hjørting-Hansen, Mogens Helbo, Daniel Vikjær
- Journal: Clinical Oral Implants Research
- Year of Publication: 2000
- DOI: 10.1034/j.1600-0501.2000.011001051.x
2. Scientific Background
Managing patients with severe jawbone atrophy remains one of the most demanding challenges in implant dentistry. Successful placement of endosseous dental implants depends on adequate bone volume and quality, making bone augmentation procedures a common prerequisite in advanced cases. However, grafting techniques increase surgical complexity and may be associated with additional morbidity.
Subperiosteal implants were originally developed as an alternative for patients with extensive bone deficiency but gradually fell out of favor due to inconsistent biological outcomes. Earlier experimental work by the same research group demonstrated incomplete osseointegration when these implants were used beneath barrier membranes alone. This prompted the investigation of whether combining guided bone regeneration with an osteoconductive bovine bone substitute could enhance bone formation around custom-made subperiosteal implants. The study therefore explores a biologically driven strategy aimed at improving implant integration in situations where conventional implant placement may be difficult.
3. Study Objective
The primary objective of this experimental investigation was to determine whether complete osseointegration of individually fabricated titanium subperiosteal implants could be achieved by combining a bovine-derived bone substitute (Bio-Oss®) with different barrier membranes. The authors also sought to assess whether this approach could reduce the extensive marrow spaces previously observed around similar implants in an earlier experimental study.
4. Methodology
This was a preclinical animal study conducted using nine adult Copenhagen White rabbits.
Each rabbit received one custom-manufactured commercially pure titanium subperiosteal implant on each tibia, resulting in 18 implants. The space beneath the implant framework was densely packed with Bio-Oss® particles soaked in blood. The grafted area was then randomly covered with one of three membrane types:
- Non-resorbable expanded polytetrafluoroethylene (ePTFE)
- Resorbable Polyglactin 910 mesh
- Resorbable bilayer collagen membrane
Cortical perforations were created beneath each implant to facilitate migration of osteogenic cells into the regenerative space. After 12 weeks, undecalcified histological sections were prepared for microscopic evaluation of implant integration and newly formed bone. Based on previous experimental findings, no control group without Bio-Oss® was included.
5. Main Findings
Histological analysis demonstrated complete osseointegration of all 18 subperiosteal implants, regardless of the membrane used.
Most Bio-Oss® particles became incorporated within newly formed woven bone, while remaining particles were surrounded by osteoid tissue and active osteoblasts, indicating ongoing bone remodeling. Compared with the authors’ previous investigation, marrow spaces surrounding the implants appeared substantially reduced.
The ePTFE membranes maintained their structural integrity throughout the observation period without evidence of collapse or inflammatory cell infiltration. In contrast, both resorbable membranes exhibited minor collapse. Areas immediately beneath these degradable membranes showed superficial signs of bone resorption, although the underlying mechanism could not be established. Importantly, no inflammatory reaction or resorption of the Bio-Oss® particles themselves was identified during the study period.
6. Clinical Analysis
This study provides valuable biological evidence supporting the concept that guided bone regeneration combined with an osteoconductive grafting material may substantially improve the osseointegration of subperiosteal implants under experimental conditions.
Rather than acting solely as a space filler, the bovine bone substitute appears to serve multiple biological functions by supporting membrane stability, providing an osteoconductive scaffold for new bone deposition, and promoting a more homogeneous bone architecture around the implant. The reduction in marrow spaces compared with previous experiments suggests improved maturation of the regenerated tissue.
The comparison between membrane types also highlights the importance of mechanical stability during bone regeneration. Non-resorbable ePTFE membranes preserved the regenerative space more effectively, whereas the degradable membranes experienced limited collapse and were associated with superficial remodeling of the adjacent newly formed bone. The authors appropriately refrain from attributing causality, as the mechanism responsible for this observation remains uncertain.
Despite these encouraging findings, caution is required when translating the results into clinical practice. The investigation was performed in rabbit tibiae rather than severely resorbed human jaws, and implant performance under functional loading was not evaluated. Consequently, while the biological principles demonstrated are promising, they cannot be considered direct evidence for clinical efficacy in human implant rehabilitation.
7. Clinical Applications
The findings may be relevant for researchers and clinicians investigating treatment options for severe alveolar ridge atrophy and complex implant rehabilitation.
From a biological perspective, the study supports further investigation of combining osteoconductive xenografts with guided bone regeneration techniques to enhance bone formation around custom subperiosteal implants. These observations may contribute to the development of future reconstructive protocols for patients with extensive bone loss.
However, because this research is limited to an experimental animal model, the results should not be interpreted as direct clinical recommendations for implant therapy in humans without further clinical validation.
8. Level of Evidence, Limitations and Transparency
This publication represents a preclinical animal experiment, corresponding to a relatively low level of clinical evidence.
Several methodological limitations should be considered:
- Animal model rather than human clinical investigation.
- Descriptive histological evaluation without statistical analysis.
- No functional loading of the implants.
- Observation period limited to 12 weeks.
- Absence of a control group without Bio-Oss®, although this decision was justified by the authors based on previous experimental findings.
Regarding transparency, the investigators acknowledge receiving financial support from research foundations as well as material support from several manufacturers, including Geistlich Pharma, Johnson & Johnson Dental, and Martin Medizin-Technik. No explicit author conflict of interest is reported beyond these disclosures.
9. Key Study Highlights
- Study design: Preclinical animal study
- Level of evidence: Low (experimental animal model)
- Study population: Nine Copenhagen White rabbits
- Number of implants: 18 custom-made titanium subperiosteal implants
- Follow-up period: 12 weeks
- Primary outcome: Histological osseointegration of subperiosteal implants
- Main finding: Complete osseointegration was achieved in all implants irrespective of membrane type.
- Scientific conclusion: Combining Bio-Oss® with guided bone regeneration membranes promoted complete implant integration and reduced marrow space formation compared with previous experimental observations.
- Main limitations: Animal model, descriptive design, lack of statistical analysis, absence of functional loading, and short observation period.
10. Scientific Impact
This investigation represents an important contribution to the experimental development of modern subperiosteal implant concepts. Rather than simply demonstrating bone formation, it provides histological evidence that combining an osteoconductive bovine xenograft with barrier membranes may enhance the biological environment surrounding custom-made subperiosteal implants.
The study also offers valuable comparative information regarding the biological behavior of different membrane materials during guided bone regeneration. Although membrane stability differed between the tested materials, complete osseointegration was consistently achieved, suggesting that the addition of Bio-Oss® played an important supportive role in maintaining regenerative potential.
Equally important, the authors acknowledge that the long-term behavior of newly formed bone under functional loading remains unknown. Their work therefore establishes a foundation for future biomechanical and clinical investigations rather than providing definitive evidence for clinical implementation.
11. Editorial Conclusion
This preclinical study demonstrates that combining a bovine bone substitute with guided bone regeneration membranes can achieve complete histological osseointegration of custom-made subperiosteal implants in a rabbit model. The findings strengthen the biological rationale for integrating osteoconductive graft materials into regenerative protocols designed for complex implant reconstruction. Nevertheless, because the evidence is derived from an animal experiment without functional loading or long-term clinical evaluation, further human studies remain essential before these results can be translated into routine clinical practice.
