Membrane or Nah?
A little while back one of my friends told me that membranes make no difference for bone grafting. He told me of a prominent oral surgeon who doesn’t use membranes either.
That got me wondering.
Am I wasting my time fidgeting with that little construction-paper-looking POS?
Is it really necessary for me to be spending all of that effort with fancy suturing or tacks (the darn tips keep bending on me) when the membrane might not even matter?
Then one of the doctors taking our online implant course, messaged me. He said that periodontists have told him that they tend to get defects in their graft if they don’t use a membrane. Hmm…
Anecdotally, we’ll find people who swear by them and others who say not to use them.
To the Polls!
Just look at the results from my Instagram poll. Well over 400 people voted — but we didn’t arrive at a decisive answer.
When I asked for references informing the votes, here’s a a few of the answers I got:
“Perio residency, Stability of the graft is key. Whether stabilized by membrane, ti mesh, etc.”
“My boss is crazy and says not to use one. Naturally the opposite must be true.” LOL
“Hom Lay Wang PASS principles”
And my personal favorite: “Yo Momma” (yes, she’s quite authoritative indeed LOL)
Two people referenced the PASS principles article by Hom Lay Wang (He’s from University of Michigan — Go Blue!) So I bought this article. Yes, I actually paid $50 for one journal article…SMH.
But, its an amazing article and it has a great step by step instruction for GBR and it helps answer our membrane question.
In this paper he describes the 4 principles for bone regeneration (PASS):
- Primary wound coverage
- Space creation/maintenance
- Stability of wound & implants.
He lists some benefits of membranes:
- Facilitates early clot formation and wound stabilization
- Assists in cell migration to promote wound closure
- Inhibits epithelial migration into grafted space
The purpose of a membrane in GBR is to protect the space you’re grafting. You’re making a little dome on the bone with a membrane that keeps out the epithelial and connective tissue cells. This allows bone to form underneath the membrane.
Wang mentions a study that compared using a membrane alone to using a membrane + bone graft.
The crazy thing was that when a stiff membrane was used, there was NO DIFFERENCE in the 2 groups.
This suggests that the most important thing in bone grafting is space maintenance and that bone graft material itself may play a minor role. (That blows my mind)
According to Hom Lay Wang,
SPACE MAINTENANCE is they key.
The barrier is the most important thing. Throwing bone inside is nice because it may aid in angiogenesis and also helps keep the membrane propped up.
Granted, he also mentions that there are areas of natural space maintenance — such as sockets, where it may not be necessary to utilize a membrane.
Advice from Switzerland
Next, I turned to one of my heros in bone grafting, Daniel Buser from the University of Bern in Sqitzerland. I bought his book 2 years ago and I found that I always turn back to it for pearls.
He refers to a study on dogs that directly compared the benefits of using a membrane vs not using a membrane. Essentially, if no membrane is used, the new bone formation only occurs at the margins of the bone defect. The formation of new bone is limited to a smaller area.
If a membrane is used, it results in a dramatic change in bone and tissue regulation. The grafted area is protected from infiltration of other cells and the blot clot is allowed to mature undisturbed. When a membrane was used, there were “basically three centers of bone formation, which formed a dome-shaped seal over the openings of the marrow cavity.”
When the membrane was used, there were more areas of bone regeneration.
He recommends that we use a non-cross linked collagen membrane.
Who got it right?
Well, okay, technically you can still try to augment the ridge without a membrane. But according to our friends in Michigan and Switzerland, you’ll be far more successful if you use a membrane.
So, it turns out my friends @k1tpatal and @ryanperiodontics hit the nail on the head. This is what @k1tpatel wrote:
“Wish I could remember but here are my thoughts: You are trying to grow height or width and you’re missing a wall. thus not socket preservation. because of this you need to keep epiithelial cells out which migrate within 3-5 days and not beat the osteocytes which take 6-8 weeks. so need a membrane to keep the epithelium out to let the octeocytes win! “
To help illustrate this answer, I want to show you this awesome diagram from an article by Elgali I, et al 2017. This is a great article btw.
I honestly don’t know all of the little factors and exact mechanisms but this helps remind me of what the goal is–to keep the bone cells protected while they do their thing.
Clinical takeaway: I’ll most definitely use a membrane for my GBR procedures. It is important for keeping my slow moving osteoblasts happy and keeping out the unwanted cells. I wont necessarily use membranes for socket grafts or for immediate placement where there is a small gap in between the implant and the socket walls.
I hope that helps! I know it helped me :)