This is one of the 2 mini implants used for retaining a lower complete denture. The broken tip is about 1.5 mm. What could be the reason(s) why it broke? What would you suggest to resolve the issue? Is it acceptable to leave the tip in place, bone graft, and place another one near it? Thanks for your help!
Dr K G comments:
If you want to place a new implant in the same spot, just drill with the pilot drill there and the tip will pop out.Dr AG comments:
Only 2 mini implants was the reason it broke. It looks short also. Looks like you may have bone to place regular implants. Either drill it out with new implant or leave it.Bill McFatter comments:
It looks like there are natural teeth on the upper If this is the case, then, that may be the reason. If the upper arch has a denture then there are several possibilities . While 2 minis are not considered enough , their only function is to aid in retention and 2 can work-but if the 0-ring is not supporting the prosthesis in all axis of movement then the denture can bottom out on the implant ball and the stresses can create this. The O-ring is a cushion against occusal function. Having 5-6 minis gives you more O-ring support hence less breakdown of the O-ring support over time. I suspect your O-rings wore out due to the forces, loss of bone and the change in the way the denture functioned placing greater forces on the implant head and were not evaluated in a timely manner and replaced JMHO BillMatt Helm DDS comments:
While everything you said is true regarding the o-rings in theory, I can tell you based on hundreds of cases that, in practice, the denture bottoming out on the ball head of the implant will not cause it to break. Nor does occlusion have any bearing. Minis are not like regular implants. They rely more on mechanical retention and almost not at all on osteointegration like normal implants do, so they don't get bone loss around the implant unless the bone was greatly overheated during insertion. They also rely on the principle of a v short fulcrum, i.e. a greater ratio of inserted/uninserted implant. Properly inserted there is very little harm that can come to a mini from occlusion, natural dentition, parafunction, or the denture bottoming out on them because the o-ring failed. Remember that the metal housing of the o-ring has plenty of room in it so there is very little force applied on the mini even in the case of o-ring failure. Also, while indeed 4 mandibular minis are ideal, in practice there is often only room for 2 in many cases, and properly inserted they hold up just fine for decades. 5-6 minis is only advised on the maxilla, and you can get away with 4 if you don't have enough space for them. The space for the total number of mini-implants for FUD's is dictated strictly by the total inter-canine distance. You must have a minimum of 5 mm distance between the minis to not risk mandibular fracture in the very resorbed mandibles. Of course fixed bridgework can also be placed on minis, but entirely different guidelines apply in that situation.Bill mcFatter comments:
So why do I see so many broken. Is it the surgical placement? You seem to be saying that it can’t be a functional issue, so it seems it is iatrogenic only or are there other reasons?Matt Helm DDS comments:
To begin with it DIDN'T break because there are only 2, like Dr AG said. Properly done only 2 has no bearing on the success of the case. I have hundreds of cases with only 2, over 10 years old, doing fine. KG is right: just drill with the pilot drill and it should pop out. But you don't really have to. You can leave it there and insert another right next to it. But make it a longer implant, don't overtorque, and insert it completely. Chances are that this broke because of a combination of factors. It looks short and it's in very dense bone, leading to the likelihood that you encountered serious resistance early on and may have overtorqued the implant upon insertion. As a result, it wasn't completely inserted, leaving too much implant above bone, and creating a greater fulcrum force. This was possibly combined also with a defect of that particular implant, because I've seen overtorqued minis before but they never caused a problem. Hint: if you encounter too much resistance too early during insertion, it means that your osteotomy wasn't deep enough or large enough. One solution is to deepen the osteotomy, and possibly go from the 1.1mm drill to the 1.8mm if placing a 2.1mm, with great care though -- minis are much more finicky than regular implants and if you enlarge too much and don't get the minimum 35 nm for primary stability you have to abandon that site. Another solution to encountering resistance too early is to reverse the implant half a turn then continue inserting, repeating as necessary until you insert the mini completely. Of course this also depends on bone density. You'll have an easier time doing this in bone that is less dense than this case. In this particular case you should have had the mini inserted at the very least 2/3 for the reverse technique to work without deepening the osteotomy. Minis are not always as straightforward as regular implants, since they must have that primary stability. If they don't you may as well take it out and place it in another site, because your original site is compromised. Ideally, their tip should engage the caudal mandibular bony plate, but I've found this to not be crucial, if everything else is respected. I don't suggest using the thinner minis with the very tight threads. Much better results are obtained with the 2.1mm minis (or thicker) with the threads more spaced between them.Timothy Carter comments:
You can proceed in any of a number of ways. Regarding the “why” it broke I can’t imagine that being anything that matters because the bottom line is that it broke. I would probably just remove it via a small window in the facial or with a small trephine, depending on how I feel that day. I can’t see any reason to graft the area and if you desire to place another fixture go right ahead. It is interesting to note that this Mini implant that was so popular 15 years ago is basically obsolete now… you can approach this however you want and I think leaving it is acceptable as well.