Abutments Coming Loose on Splinted Implants: Reasons?

Hi Dr. R, External hex implants tend to have screws loosen. If there is any play between the restorative platform and the abutments, the screws become a large source of abutment retention and they distort and then loosen. These look like Nobel Biocare Branemark MKII, 3.75 or maybe 4.0. It will be tough to redo the bridge and guarantee the same thing won't happen. You may just have to schedule 6 month appointments to change the screws. Good Luck

I suspect those are either multiunit or estheticone abutments by nobelbiocare. The abutment screws are torqued to 20 Ncm but the retaining screws that attach the crowns to the abutments are torqued to 10Ncm. The splinted units shouldn't loosen so check the occlusion especially in lateral excursions. These don't need antirotational features since they're splinted, but the weak retaining screws are easily loosened if put under too much lateral force. If the occlusal load is off axis from the long axis of the implants, this could contribute to the loosening as well.

I had that happen repeatedly with a patient, lower posterior three implants splinted together screw retained...I took one screw out, the middle one and they haven't loosened up since...been 8 plus years

I don't have the privelidge of knowing what you started with, but why are you splinting these? If it's because of severe atrophy or a bony defect, then why wouldn't you place a mini- hybrid denture. I know respondents are growing tired of this opinion, but aren't we placing implants to avoid these oh nightmares. From a nonrestorative view point , it seems probable that something must be moving, to allow fixtures to loosen. Bv

There may be hyper occlusion and or parafunction. The casting may have a poor fit to the implant abutments and or platforms. The prosthesis is not restored with an implant protected occlusal concept! For BV the concept of splinting the implants is a classic concept and it can be found in Mischief, Cranin et al.

That should be Mischief.

This I pad is killing me. It should read Misch.

Didn't learn from misch. Wish I could regurgitate some of his stuff, but you will never convince me that splinted implants that are being levered everytime one of these parts gets loose is better than free standing implants. The structure is only as strong as it's weakest link. I'll take my chances with individual implants, when it's feasable. In a splinted case , when one fails the otherone fails most of the time. Fixed hybrids do better with less implants; ie. Less variables. Just one opinion. Bv

Richard , my i-pad just died as well. Will not hold a charge. Bv

Can't Id implants/fixtures as well as others but if the bone loss pattern under the splinted implants is compared to the lack of bone loss around the single , I can show you why I don't like splinting. Bv

unfortunately, in your x-ray showing above, I, couldn't recognize the height of abutments under crowns. and you did not say anything about your patient's occlusion and para-functions and dental system (absence or existence of teeth on other side ) .

Agree with Dr. Hughs, could be parafuntional forces. I had a Nobel Active screw loosen (tooth #3) that was tightened to 35 ncm. It was a custom abutment not a Nobel part (I know...). This patient with no periodontal problems was clenching and grinding her way to type II/III mobility on #4 and #5, as well as a screw loose. I tightened her screw and made an bruxism appliance and all is well. Mobility is gone and her screw isn't loose. (Pun intended). Love seeing all the posts.

The x-ray appears that the casting does not line up with the implants in a perfect way. The three abutments look like they were cast as one unit. If the casting is not perfect screws will always come loose. This can not be fixed leaving the existing restoration. BUT This is easy to fix, if I am corect about the cast to abutments. Place individual abutments and a cemented 3 unit splint over the separated abutments. You will still be splinted ( if you wish this ) but the abutment fit to the implants will be perfect and the screws will be much less likely to loosen.

BV, according to Misch and others it is best to splint (implant protected occlusion). I do splint in some cases and others I do not! A lot of when to splint and when not depends upon where in the mouth your treating, available bone, C/I ratio, size of patient, bone density and the list goes on! One has to consider the patient's ability to maintain hygiene, occlusal parafunction, diet, social habits etc. I perform the surgery and prosthodontics. The prosthetic side is far more challenging. Not a sermon, just a thought!

Dr Hughes, there is no doubt that the restorative portion is more difficult. In my short term , I have found that if you splint or place hybrids, you are better off with fewer implants, at least in gross defects, s/p tumor ablation etc.. As you say, you have to consider everthing ! You may all be seated!! Bv

One cannot compare hybrids to 2-4 splinted. They are different animals. However, hybrids, in my opinion are a disservice to the patient. They would be best served by a removable prosthesis.

So dr. Hughes , the hybrid is a disservice to the 19 yo female who i Just Tx planned after a nerve sparring en bloc resection of an ameloblastoma or the 45 yo rim resection of giant cell granuloma. A panel of high level acedemics and practicing surgeons agreed that it is the only method for these two scenarios. If these patients were your daughters, would you place partial dentures or single implants, that have platforms 5-7 mm below the most adjacent natural tooth. Wow, after tumor ablation and reconstruction I think I'll call them both and tell them we are just placing valplast remavables. Just kidding. Think I will stick to my plan. It has worked too many times before. Yes they get them cleaned about e every 3-5 months. Bv Ic

Sorry , lost my train of thought after reading the above entry. If we can see an area where you have a metal to metal discrepancy even on my I-phone. Not sure why you would even pose the question, without correcting this first . Is this a "forest for the trees" scenario? Bv

Those splinted implants are probably branemark external hex implants. Get new screws if you don't know the history and replace them with new ones. Check off axis load potential and possibly make the patient a night guard.

BV, Why not a bar supported over denture? You see the problem with academics is just that. They are academics! Sometimes commoc sense has to rule.

We need academics, but some academics are too rigid in thought and have a limited experience. On one my prior post, when I stated that hybrids (fixed detachable) was a disservice, and removable pros was better, I ment to say that a bar retained removable prosthesis was better!

These acedemics , place a lot of implants,and have probably forgotten more than I know. I have no problem with a bar over denture ,when indicated. The two scenarios I presented,not so much. These patients have perfect oh, ortho appliances,missing the same number of teeth as the presented case. They will get mini-hybrid dentures. Bv

The issue in the case in the photo looks like laboratory issue (die stone water to powder ratio, water/powder ratio with investment, metal expansion etc). These issues usually occur with screw retained cases.

Dr. Hughes , so are going to tell m. Block , Ed Ellis , Bruce Epker , Doug sinn , Larry wolford and gill Triplett , that they are lacking common sense. never seen you operate, but have operated with these" academics " and they can operate circles around most surgeons. It is almost sacrolidge to not mention R.V. Walker, but he didn't place a lot of dental implants,however he and bill bell had/have a pretty good grasp on bone biology and have placed a preverbial pile of bony implants. Some academics choose to be teachers for the passion of teaching , and thank God for them. I do my best to avoid making the broad sweeping generalization . Current b/p 120 / 48, hr 52, o2 sat. At room air 99%. Bv

No, I said some. Block et al., are excellent.

The screws do not seem to engage much of the available thread within the implant. Are these the correct length screws? What is the bare minimum number of threads a screw requires to maintain proper torque?

These appear to be Brane clones with an external hex and should be able to use any fixation screw for a branemark implant to replace. I would agree check occlusion. At this stage I would recommend replacing all three screws to ensure that you have no issues with worn threads on the screws. Also check with magnification to make sure the screw seat in each has no blebs preventing the screws from seating fully.

I, too, think the screws are not the right ones or posibly too short. Look at the individual non-splinted implant screw. It's 3/4 of the way down the implant length. Make sure you are getting the proper screws and not a lab processing screw. Just my 2 cents.

These screws cannot possibly be the right ones ! .....they are way too short. Change that... and problem is most likely solved...hopefully threads are not damaged in implant??