August 19, 2017
Below is a recent post on Facebook by an esteemed colleague who encountered some complications with Zygoma implants. Complications that were also common in my own practice, and which led to our development and implementation of Zygoma-Plus.
Below is my response,
Thanks for sharing these cases, one of the most common complications reported with Zygoma implants. Management is certainly difficult in the presence of the implant bodies.
The problem with the classic approach ed modem Branemark and variations of thereof is that often there is very little bone at the crestal floor of the sinus, which will undergo resorption and remodelling following the surgical trauma and the accomodation of an implant body.
The other problem when aiming for bicortical stabilisation, is that the crestal bone at the floor of the sinus gets in the way of the implant mount, and it is not possible to drive the implant in further. This leads to a palatal emergence of the head of the implant, inadequate restorative space among other restorative issues, and poor hygiene leading to exaggerated bone loss around the implant and potential oro-antral communication and often also sinusitis. On the other hand when forcing the implant deeper to attain a better position, the wider implant mount destroys the very bone that would be relied upon for a secondary point of stabilisation.
The presence of the implant within the sinus, either in space or without separation from the sinus mucosa, can also cause breakdown of the mucosa over the implant surface, and a foreign body effect within the sinus leading to sinusitis.
Both the surgical and restorative issues above have lead to evolution of many techniques including extra-maxillary placement. However, like any other kind of fixture placed within soft tissue alone, extra maxillary implants are susceptible to breakdown of the overlying soft tissue and buccal dehiscences leading to various other problems, including the potential breakdown of the thin wall on the lateral aspect of the sinus and thereby affecting the sinus nonetheless.
From personal experience, I had poor results with extramaxillary implants due to dehiscences and numerous issues associated with a lack of restorative space. However in the right situation (based on anatomy and when positioned deep enough) these can work well.
My technique today by default involved sinus elevation and grafting, which we call “Zygoma-Plus”. I have placed well over 500 using this technique in various combinations (unilat, bilat, and quad) and the results so far are encouraging.
More than a third of the cases in the Zygoma-Plus group also involve a sinus impaction graft (aka “Sinus Crush”) and in the absence of bicortical fixation.