Dehiscence of Maxillary Implants for Implant supported Denture: how to proceed?
I installed two implants 3x15mm at #6,11 sites [maxillary right canine, left canine; 13, 23] for an implant retained overdenture. Everything worked out great at that visit. But at the time of uncovery, the patient reported the he had discomfort at #6. I noticed that at least 5-6mm of thread at the apex of the implant are outside the bony housing. The implant has osseointegrated. I can see gray hallow of the implant, I am confident that this was not case when I installed the implant. Maybe the bone was very thin at apex and now I am not sure how how to proceed. Should I explant the implant and reorient its orientation so that it is completely in bone or should I try to regenerate bone around the apex? What do you recommend?
16 Comments on Dehiscence of Maxillary Implants for Implant supported Denture: how to proceed?
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CRS
10/16/2013
It probably happened at surgery you just didn't notice it with such a long implant. If you could post a CT it would be most helpful. Otherwise open a flap and graft it.
Paolo Rossetti - Milano
10/18/2013
If the coronal half of the implant is surrounded by sound bone and the apex is not excessively overhanging, leave it there.
Why grafting around the apex of the implant? What would be the benefit?
In case the apex is protruding a little bit more than acceptable, you may consider to flatten the apex with a high speed bur and a lot of water. In this case a paramarginal flap should be raised, in order to preserve the vascularity around the implant platform.
CRS
10/18/2013
The benefit would be to cover the implant apex since the patient may be brushing up against it or touching it. Let's see 13mm-6mm = 7mm of implant fully in the bone so if you flatten out a 3mm wide implant you have a seven mm implant. With function there will be stress on he implant so grafting will give more bony support since it was placed outside of the alveolar housing. I would recommend fixing it with an onlay graft. It's an overdenture so a standard flap is fine.
Paolo Rossetti
10/18/2013
Crs,
In these kind of dehiscence, the apical half of the implant often perforates the cortical bone in an oblique fashion. This means that the apex may still be in contact with the buccal cortex.
Additionally by perforating the buccal wall you get a bi-cortical Stabilization of the screw, which (in some cases) can make the implant even more stable than a fixture that is correctly positioned.
At last I do not believe that a graft could provide much contribution to the stability of the implant. Grafted bone is often weak. A grafting procedure is also suscettible to a higher rate of complications.
Probably my advice sound unconventional but I think that turning a 15mm implant into a (let's say) 11mm implant with bicortical stabilization, may work.
CRS
10/18/2013
Actually perforating thru the cortical plate is not bicortical stabilization, embedding the implant in the cortex is. An implant outside of the housing doesn't make it more stable but out of alignment with the axial forces of occlusion, it is not a steinmann pin stabilizing a fracture. Don't get why you would not want to correct the dehiscence, it is the correct call since the impant was not placed correctly in the first place.
Gary Omfs
10/22/2013
15mm really? I guess size does matter! as far as I know only the first 8-10mm are active in stress distribution. Anything beyond just ads to complications. I agree with Dr Rosetti that a graft does not add anything to stability, but if the soft tissue layer over the perforating apex is thin, this will probably come to a soft tissue dehiscence and infection too. In that case flattening out and a secondary grafting may be safer than hoping for the best.
Jihad Joseph AKL
10/22/2013
I believe that the thread exposure occurred late after implant insertion i.e. during the remodeling process of the bone.
Sometimes when inserting the fixture, we do feel that the cortical plate has become very thin and may resorb exposing some threads.
So in reality the implant is not outside the bone housing per se, but some of the threads are minimally exposed, and therefore the apex of the implant in its majority is still integrated inside its bed.
I do agree on the fact that a bone grafting will not add any value to the stability in a 15mm implant.
Luckily in some cases, we may even witness periosteal osteoblastic activity diminishing the visibility of the threads. It s part of the continuous remodeling process.
CRS
10/23/2013
. The implant is inert it doesn't move, it was just placed poorly without grafting at surgery in thin bone. I doubt you raised that high of a flap, you would have seen it at placement.There is no blame here just fix it this happens in surgery and learn from it. I get a kick out of all these rationalizations just own it, fix it and move on. You already stated it is of the housing, the grey and be seen and the patient is having symptoms. Gary OMS suggested a nice technique I would have to see a film an photo to advise on the specific grafting tech. Good luck it will be fine
Perioperry
10/23/2013
Blood supply to facial cortex comes largely from overlying periosteum. The buccal cortex is typically very thin in the #6 and #11 areas and would therefore be susceptible to resorption if exposed via a buccal flap. So, access the implant through an incision within the overlying alveolar mucosa, reduce the exposed titanium under copious irrigation, close the incision. Assuming the implant is integrated and stable now, a bone graft would only add complexity and cost with little or no real gain in long term success of the case.
CRS
10/24/2013
I guess needing a minimum of 2mm of bone over an implant is no longer applicable along with placing an implant in the alveolar bone. This is an iatrogenic complication. Grafting here done correctly will work well and I think you will be surprised when the flap is raised and you can see what is really happening. You placed it and need to fix it this comes with the responsibility of being the surgeon. Good luck it sounds like it is fixable
Dr. Nitin Sharma
10/29/2013
CRS
don't mind as a maxillofacial Surgeon how many Bone plates you cover with Bone graft during trauma cases.
Most of them appear to be felt at mucosal areas but still tell me one person who would do a procedure to cover miniplates with Bone graft.
To me if the thread are the reasons for discomfort. Make them flat and do not try any adventure.
CRS
10/31/2013
A bone plate is not a dental implant exposed to the oral flora or occlusal forces. My point is how hard is it to raise a flap and be aware of how much buccal plate is present and where the tip of the implant is., it was just poor technique. I would have put it in correctly at the get go, it didn't migrate after placement. I get a kick out of all the rationalizations to dispute this. And by the way, if a bone plate is an issue after trauma or orthognathic surgery the offending plate is removed since it does not osteointegrate. If something is iatrogenic it needs to be corrected if possible. That's my point, I would just fix it differently in the way I see appropriate. I don't see the relevance of your comment, perhaps the implant will be fine or it will fail, time will tell. Thanks
K. F. Chow BDS., FDSRCS
11/1/2013
Leave it alone if the apex is in no danger of protruding through the mucosa. But if you fear that, then I agree with Perioperry....... open a flap nearby, expose the implant apex and grind it down to bone level and even a little bit below. Then close it. Keep it simple and sweet and avoid unnecessary surgery and keep surgeries minimal whenever possible.
Richard Hughes, DDS, FAAI
11/1/2013
One may smooth down the implant. You should cover the apex with a bone putty and ADM or just ADM. If you do not treat the patient will have constant discomfort. The maxillary cuspid can be tricky.
Paolo Rossetti
11/1/2013
I occasionally see patients having implants with protruding apexes. They are rarely aware of this condition and I have never seen any kind of complication related to it. That's why, as I said before, my thought is to do as little as possible, that is either nothing or trimming the apex.
@Richard H: have you seen many complications related to this condition? Thanks.
Richard Hughes, DDS, FAAI
11/2/2013
I have only seen this a few times. In my cases, I prepare the site prior to implant placement. The maxillary cuspid can be a tough site. You have to consider esthetics, occlusal function, facial plate, size of patient, anatomic variance (trajectory of anterior teeth), Maxillomandibular relationship etc.
I agree with you to keep the treatment to a minimum.
