This is a question I get asked frequently and it’s not a simple one to answer. My experiences of mixing EthOss with other graft materials are fairly limited – it is something that I have done but only rarely – and we don’t have any published evidence in this area so please proceed with caution if you decide to look at this yourself.
Bearing this in mind, let’s take a look at the different materials which you could mix with EthOss:
The most common mixture I look at personally is with synthetic hydroxyapatite (HA).
HA is a different class of material to B-TCP and Calcium Sulphate (the two components of EthOss) due to its long-term resorption profile. My personal experience is that HA usually does not fully resorb, the particles stay in the body indefinitely. This changes the nature of the graft procedure – it is no longer a true “regenerative” procedure if we have remnant graft long-term.
As long as the HA is synthetic I am prepared to accept this, but I don’t believe it is the optimal outcome.
The key reason for mixing HA with EthOss is stability.
Occasionally I will see patients with defects where stability of the graft site gives me cause for concern. This could be due to either the size of the defect or the location (the posterior mandible can suffer from higher soft tissue pressure which can impact stability). It can also be a consideration in sinus lifts – the constant movement of the sinus membrane can impact graft stability. This is particularly an issue in larger sinus lifts, or a sinus lift where for some reason the implant is not being simultaneously placed to give a slight “tenting” effect on the sinus membrane.
In these cases adding some HA can give extra stability to the graft, reducing the risk of loss of volume in a challenging setting. You do not need a large amount of HA – I would usually add around 20% compared to the volume of EthOss.
See the case below where I was restoring the Pontic site for aesthetic reasons.
The other main material people often want to mix with EthOss is PRF. I don’t have any experience doing this personally so it is hard to comment, but I’ve always been put off this idea by the effect that the proteins in blood can have on the setting of Calcium Sulphate (it is well documented that proteins can impact the setting reaction of the material).
However, I do know there are a group of clinicians who regularly mix EthOss with PRF and you can see some of their cases on the EthOss Case Studies group on Facebook. It would be very interesting to see some research in this area, particularly to see if there is a significant impact on soft tissue response.
I haven’t mixed my grafts with autogenous for years – I just don’t see the need when I’m completely happy with the results I get with EthOss. I know many people consider autogenous to be the “gold standard” so I can understand it, but I just don’t see the benefits.
I have no experience at all of mixing EthOss with xenografts and I wouldn’t recommend this – the materials often suffer from the same extremely slow resorption profile of synthetic HA’s, but with the drawback that more and more patients are objecting to the animal content on ethical or religious grounds. You might also need to consider using a collagen membrane to guard against soft tissue ingress as a result of giant cell reaction to the foreign xenograft material which could hinder the blood supply access to the site and have a negative overall impact.
There hasn’t been any research done on mixing EthOss with the above materials so this is quite speculative and I would repeat that this should always be done with extreme caution and only by experienced EthOss users. It is interesting to see the results people are getting though and I would urge you to share your experience on the EthOss Case Studies group online so we can learn and develop these techniques as a community.
When we look at stability another tool in our arsenal is using titanium mesh cages. Whilst they do come with the drawback of needing a second surgery for removal, I am seeing some amazing cases with other clinicians using cages – particularly the more modern cage designs with larger holes that allow for more intimate contact between the periosteum and the graft. I’m very interested in exploring these options myself and will be writing about this in the future.