It’s been well over 4000 grafts since I last used a collagen membrane. Other dentists are often surprised to hear this – they’ve been using them for so long that they can’t understand how it is possible to graft without them, but the truth is that the latest generation of synthetic materials have rendered them obsolete.
It’s a refreshing change for implant dentistry, where from a grafting & GBR perspective innovative new materials and techniques have seen a disappointing take up throughout the last 20 years. Whilst other technologies have revolutionised the way we work, I speak to implantologists every day who are still using the same xenograft-based materials they’ve been using for their whole career without understanding the biology of host bone regeneration.
Over the years I have found this resistance to change frustrating. I often push back and ask – “do you like using collagen membranes?” I meet very few dentists who do, but they are seen as being a “necessary evil” – a difficult part of the procedure for sure, but a necessary one.
So what does a collagen membrane actually do? According to Melcher & Dreyer (1962), the membrane is used to protect against “invasion by non-osteogenic tissue and prevents distortion of the graft by the pressure of the overlying tissue”. There is no question that these two functions are important:
- you must have a barrier that prevents soft tissue ingress, and
- the graft must be stable, not losing volume and not being disturbed by pressure
So how have I managed to do over 4000 successful grafts without touching a collagen membrane? The answer lies in one of medicine’s oldest materials – Calcium Sulphate. By combining CS with another graft material (my preference is BTCP, but that’s a subject for another day) you get a material that has a built-in hardening function, producing a cell occlusive barrier when the material “sets”. This hardening function also stabilises the graft, securing it in place and preventing pressure from disturbing the material (assuming passive suturing is used in the procedure). Calcium Sulphate is your membrane – it ticks all of the boxes.
Practical Implications
We can take the collagen membrane away, and replace it with Calcium Sulphate, but apart from changing how you carry out the procedure slightly, what other difference does it make to the actual results?
Speed
Modern synthetic materials, like EthOss®, generate bone very quickly. I regularly see 50% new host bone at 12 weeks, with the remaining graft being completely resorbed and replaced by bone within 6-9 months.
Why does it work so quickly? In my opinion, the answer lies in giving the periosteum direct contact with the graft site. As well as being the best source of host blood supply, the periosteum also induces the host stromal cell-derived factors, which elicit the presence of mesenchymal cells essential for osteoblast presence.
A collagen membrane is a barrier between the periosteum and the graft site. By taking it out of the equation we are simply letting the body get on with healing itself much quicker.
Of course, using highly osteo-conductive materials like BTCP also helps!
Reliability
We published a Protocol in 2015, available here (link), discussing our procedure for bone augmentation with simultaneous implant placement. We looked at over 600 grafts and achieved a success rate of 99%. Modern synthetic materials are extremely reliable.
Soft Tissue Healing
This is an area where we need to do more research for sure, as the soft tissue results we see using EthOss® are outstanding. The biocompatible materials appear to give fantastic soft tissue healing and aesthetics, with less pain and less swelling. Patients love it!
This is a great time to be an implant dentist. The results which we are seeing with EthOss are changing the way we can work. As the sector continues to grow in we are being given better tools which can make a real difference to both us as dentists and our patients.
References
Melcher A. H. & Dreyer C. J. (1962). Protection of the Blood Clot in Healing Circumscribed Bone Defects, Journal of Bone & Joint Surgery, 44(B), 424-430.
