I am very sorry to hear that the treatment you have undergone seems to have partially failed. From the sounds of things you have had implants placed which was following a bone graft.

Implants like teeth are held in by the bone surrounding them. Failure of an implant to become ingrained in the bone (Osteointegrated) can be due to a number of factors. The few factors are as follows

The quality and amount of the bone in which the implant was placed
The periodontal health surrounding the implant
The time between implant placement and when it was loaded (i.e. when a tooth was placed on it).
The implant system used.
The type of graft used. Either the bone was from another part of your body (autograft), or bone from someone else (allograft).

As you mentioned you had a bone graft. I presume that the bone graft was assessed after its placement and that before the implant was placed the graft was accepted and integrated with your own bone. However a failure for the bone transplant to integrate will obviously affect your implant. If sufficient time was not allowed between the placement of the implant and the acceptance of the bone graft then this could cause the implant to fail.

Like teeth which suffer from periodontal disease and become loose over time, implants also are subject to this and the term “periimplantitis” is sometimes used. Whilst you did not experience any pain, since no nerve is present to cause this, the implant becoming progressively loose is a good indicator of this occurring. The dentist who placed the implants should have made you aware of this, and also gone through measures with you to attempt stop this occurring. Unfortunately as much as we try, you can not always stop this. Once this has begun, like with teeth, antibiotics are not always success or a cure.

Loading of an implant before it is fully osteointegrated can cause the implant to become loose. Some implants are loaded straight away at the time of placement and sometimes the implant is allowed to integrate for approximately 6-9 months before becoming loaded. The best way to think of this is, is placing a stick in thick concrete. If you attempt to move the stick whilst the concrete is setting you will be able to move the stick. Whilst you may not be able to remove the stick, you can essentially dilate the area surrounding the stick. Transferring this analogy to the implant and bone, you dilate the socket in which the implant is placed and create a wider socket for the implant which will effect the stability of the implant. Whilst sometimes you can get away with this, placing an implant like this has about a 50% success rate. Alternatively waiting 6-9 months for it to integrate before loading the implant allows for a much tighter implant socket and a more stable implant.

A lot of research as been done on the type of implant used, and it has been shown that certain dental implants are more successfully integrated then others. Unfortunately this is something which is subject of a great deal of research and controversy and there is not much that you can do about it.

In regards to what can be done?, You can essentially retry the process. Have another graft and attempt another go with having an implant placed. Following some of the measures I mentioned previously will help.

I strongly urge you to contact the dentist taking care of your implants and go through the techniques involved in the care of your implants. Should you have any further questions please feel free to contact me further.

Regards