Cratering around implant: what happened here?

Assuming that there was enough bone bucco-lingually around the implant and the bone was not heated during the osteotomy , there could have been some contamination or pressure applied over the implant during healing. Sometimes you don't get the healing you want. For premolar sites I would have placed diameters in the 3.7 to 4.3 range, and a longer implant, especially in the #5 position to engage the floor of the sinus. I hope everything goes well for your patient.

Also, I assume that at 6 months, it was fully integrated but you do not mention it. If it was not fully integrated, the answer is simple. Remove, graft and replace the implant.

maybe the facial wall cracked or it was too thin around #4 supposedly some people say the larger implant 6.0 has a higher failure rate. Maybe you will have salvaged it ? How many times have people done multiple implants and one fails- that's why for years the big experts put in extra in case one fails. It happens

Probably had some communication with the oral cavity. This is normal with a bone level/2 piece implant. I suspect you will see the same on #4 after healing abutment and or final restoration. I notice on this site a lot of docs are really quick to graft and place membranes with seemingly small defects. Just a different approach I guess.

There are many reasons why you may be experiencing peri-implantitis. First if the patient occluded on this edentulous area and either traumatized the implants or drove food into the area it could lead to bacterial infiltration. It takes up to a year for B-tri-calcium phosphate to turn into bone. You could have had bacterial migration from the lift or from using a 4.6mm implant in a bicuspid area. You have treated the site and you will see if you have rescued it. I would add at least one more implant to redistribute occlusal load over 3 splinted implants in this scenario.

I use ID and have had this happen to me. Sometimes a pinhole communication with the oral cavity is present even when the suture line looks closed . If you think about the blood supply needed to maintain a flap over a larger implant in particular, it is not surprising that some open and result in bone loss. This is particularly true if flap is thin. In thin flaps there is some opinion that maybe the body is trying to re-establish the biological width. I used to be a strict 2-stage practitioner but I now feel placing a healing abutment whenever possible is the better way to go. If I don't, a weekly follow-up after placement to make sure suture line is closed is a good idea. For now, at most, you could place some retrievable temps and follow, though removing is certainly an option. Hope this helps.

A highly tapered implant design will impart high compressive forces to crestal bone. This will result in microfracture and intense early bone remodeling, If the incision site is directly over the implant body, this intense competition for cells will result in fibroblast infiltration. The only way to prevent this is to ether do a remote incision, or change implant systems to decrease your insertion torque. RJM

That is a fascinating and interesting comment. And makes sense. I wonder if there would be a difference if the site was grafted bone or edentulous cortical bone, as the bone density at platform level may be different. Also, Implant Direct has non tapered cortical bone drills 2 or 3 mm long that can be used to expand the osteotomy at platform level to the parallel width of the platform so that there is no stress at platform level. Do you think that makes a difference? The idea of keep the incision away fro the implant site makes perfect sense as well. I have done well over 100 implants using the Implant Direct system and have has this situation less than 5 times. Do you have any further information or literature regarding this issue. Thank you for your response.

I am presuming this was a two stage technique using cover screws not healing abutments and that you used good sterile surgical technique. I also presume that you had a CT scan prior to surgery and that you analysed your implant positioning prior to surgery and that there was plenty of bone surrounding the implants when placed. Of course I would also expect that you did not overheat the bone while drilling. Clearly these are reasonable assumptions but if they did not happen then any of these issues could be a reason for bone loss. If the patient wore her denture post surgery then this could also be a causative factor, especially if stress was placed on the implant. Having said this, it seems to me that you did everything to a high standard. You titled your post “cratering”. Having reviewed many cases of cratering, I would not place your current case in this category. Rather I would categorise it as bone loss. Cratering usually has a pronounced, clearly defined bone loss with peri-implantitis and granulation tissue occupying the defective area. In your case, the #4 implant may develop further bone loss and progressive soft tissue ingression. Only time will tell, and it seems to me from your description that you have done everything possible to reduce that possibility. As with most things in dentistry, it is not likely that you will obtain perfect results every time. There is an accepted failure rate of 5% for implants (although my feeling is that good operators will have a lower rate than this). However it is also generally accepted that a totally acceptable “success” rate is somewhere between 55% to 65%. Therefore there is a “grey” area between absolute failure and acceptable success. It maybe that your #4 will fall into this grey area – not perfect but not a failure. Although dental implants have been used for decades, there are still many aspects about failure we do not understand or why we do not achieve a successful outcome every time. All we can do is eliminate the known causes of failure and practice the best surgical techniques we can. As best I can see, you have done this. If you need to replace this implant then theoretically you should have only a low chance of a second failure. However as a word of caution, I have observed several cases over 25 years where, on replacing a failed implant, the second implant (and in one case a third) also failed. In all these cases, additional implants were placed in other positions in the mouth (under identical conditions) and these additional respective implants were successful. As such, I have concluded that occasionally there are areas of bone which may not be acceptable for implanting. At this stage I have not been able to identify what these reasons may be, but am confident the reasons are biological rather than surgical. With this in mind, you may want to consider placing another implant a little more posteriorly if #4 fails in due course (in seems on the radiograph you showed, there is more vertical bone there anyway).

Yes, CBCT was used and a guide. There's at least 8 mm of B-L bone. Someone suggested that in two stage if there is stress on crestal bone to compression of the platform of a tapered implant, the bone may be compromised and allow for infiltration of fibroblasts and thus granulation tissue. This seems logical. The few cases that I have had this happen there seems to be a small area of non keratinized tissue right above the implant after weeks of healing. I must admit, my incision was right above implant placement which is probably wrong. But that being the case, would is be wise, in 2 stage cases, to place a small membrane over implant before burying it to prevent fibroblast migration? Or does everybody already do that?

There are many excellent suggestions given above to try to come to a conclusion why bone loss is occurring..... truth is we do not really know. What we do know is that bone in the posterior maxilla is not of the best quality for implant stability, especially when the volume of the bone has been drastically reduced...… since a sinus lift was done, longer implants could have been used, and once the graft composed on Beta-TCP was resorbed and turned into vital bone and mineralized, a slight amount of bone loss is to be expected, and the implants could be loaded and would be functional. When reviewing the literature, periimplantitis is a condition that continues to haunt us, and we have not fully learned how to combat or stop this from occurring...but yet we continue to place implants, follow them over the years, and see that even with some bone loss, the implants will continue to serve the patient well...…. we have come a long way in dentistry to give our patients back the teeth they have lost through accident or disease, but we still cannot compete with the Man Upstairs, who gave our patients their original set of teeth...…..

Yes lots of great suggestions , never black and white in this job , but I agree with Dr Ruddick , host factors are a big factors , essentially host response . The question is was there a spontaneous exposure or did a host response to bacterial inflammation lead to an opening . There is a lot we are still learning in this area . As to BTcP all our research and histomorphometry show only 8-12 % ( 3 different studies , UK , Germany and US histologists ) residual material at 10 weeks with all showing over 50% of new host bone . If there is an exposure best to as soon as possible fit a healing cap with Blue M gel or even ledermix . Regards

Wow, what a bunch of excellent comments. Would you please share your follow up after your grafting with all of us. I think in the maxilla micromovement is always a consideration as well. Not sure if there was a partial placed either. I think that tissue opening or more probably never closing (seen more commonly in large diameter implants ) was most likely the cause. I want to add, just for thought, that the implants had different initial stability parameters. The forward implant had nacent bone at the apex where the implant that had what appears to be a nicely done sinus graft, does not benefit in this regard, especially if the graft was same at the same time as the implant placement. We try and find a single cause for these situations but I think often times multiple causes work together to conspire against the implant

This is post 2 month post op. Site appears to have healed nicely.