Pressure Necrosis DOESN'T EXIST
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- Опубліковано 3 лис 2022
- Oh, Pressure Necrosis. The bane of implantologists everywhere. The ominous phantom that fatally dooms our implants and cackles at our helpless frustration. The nemesis of good torque. The catch-all scapegoat for our failed implants. There's only one problem: Pressure Necrosis isn't real. Yep, I said it. Pressure Necrosis ISN'T REAL!
How can this be?? So many lectures and anecdotes identifying this mysterious phenomenon as the source of our implant woes. Surely all these highly-educated people can't be wrong, right? Well, it sure looks that way-and it's not really their fault. It's very difficult to identify why implants fail because there are so many factors that go into making them work. Pressure Necrosis is our way of explaining the incomprehensible.
However, when we stop to consider the science behind Pressure Necrosis, things start to unravel. First of all, what is Pressure Necrosis? Like, mechanically, what causes the bone to die? And what happens when bone DOES die? Probably not what you'd expect...
Check out the video to see more about Pressure Necrosis!
Check out the full Stanley Institute Continuum at stanleyinstitute.com.
On the one hand they say - dont overtorque the implant so you dont put too much pressure on the bone. Then densah burs come in and do exactly that - put quite bit of pressure on the bone.
You are exactly right. It can’t work just sometimes and make sense.
Double standard for sure.
With Densah, it is grinding up loose bone that it is tightened into, it's not High pressure to a solid cortical plate, 2 very different things
Wolff's Law rules!
There are studies showing implants with 150 N-cm of insertion torque do just fine. One that comes to mind is this: Pressure Necrosis and Osseointegration
Alan Meltzer, DMD, MScD;† Harold Baumgarten, DMD;* Tiziano Testori, MD, DDS;¶ Paolo Trisi, DDS, PhD‡
Of course, with extremely high insertion torque on narrow implants, fracture of implant head is a concern.
Great paper that was way ahead of it’s time. I think your point about insertion torque and implant driver stripping is where the confusion really came from. Our orthopedic colleges don’t measure torque during insertion of their fixation screws. They also only use grade 23 titanium alloy which is nearly 40% stronger than grade 4 which is used in a lot of dental implants. Using a weaker implant would thus create a concern for torque but not because of pressure on the bone but rather plastic deformation of the implant. Over time one can see how this could easily become a source of confusion.
just re-read that paper again. Classic!
Insufficient Blood Supply? Why then does a fractured mandible heal only in 4 weeks?
I think you’re spot on. If you think about under what conditions create high insertion torques they typically involve engaging compact bone. Compact bone has poor internal circulation. Most of its blood supply comes from endosteum, periosteum, or the peridontal ligaments. Stated in a simple way high insertion torque equates to crappy bone! So my theory is that pressure necrosis is not the cause of perceived higher failure rates and the real cause is poor bone quality.
Viewpoint of a engineer, at the absolute end of the video you hit the nail on the head; Osseointegration is what permanently connects an implant to the bone. On soft bone, it just means that the implant takes a long time to become as secure as the bone.
In hard bone, the implant may not osseointegrate as well as soft bone. The implant is relying on mechanical forces only on the threads to resist biting forces. Even hard bone will experience some creep, from radial forces from the implant insertion and from chewing forces. This creep results in less ultimate strength in the socket holding the insert. If radial forces are too high in non vascular hard bone, bone tissue can mechanically fail and cannot heal like vascular bone?
Are you using the bone tap on a hand piece or doing by hand with wrench? Also do you ever use the implant itself as the tap where you back out the implant a few turns and then insert it back in?
I use the implant as the tap when necessary. I will use the hand piece until I start to hit its limit (usually 70Ncm) then I use the hand wrench to finalize the placement with a two forward and one reverse motion.
Will very high insertion torque cause implant fracture?
Yes they can! But, I have never seen a medical grade 23 titanium fail! Implants made with weaker titanium like grades 3 & 4 can be easily identified with a simple google image search for “broken dental implant”. That is why I say “implant design MATTERS!”
Why not just oversize the osteotomy instead of backing out?
The last drill is designed to the pitch diameter of the implant. There is no way to oversized the osteotomy without using non OEM drills which presents additional risk factors. It is pretty easy to put the implant in reverse and accomplish the goal of creating space.