I am sorry to hear about the problems you have experienced with your dental treatment.

Implant failure whilst uncommon does occur in some situations. Your chronic sinus infection should not have caused the loss of your implant since an anterior implant is away from the maxillary sinus.

I personally, inform all my patient of the risk of implant failure, but there are reasons why the implant treatment might not work, and many of these are often identifiable prior to the commencement of treatment. For example, prior to treatment you can assess the amount of bone that is present. Whilst there is a risk of infection, you have to look at the reason for the infection. i.e was the infection due to bacteria from the previous tooth? Did the infection arise post surgery? How good was the periodontal hygiene following implant healing?

Another factor for implant success is if the implant had a crown placed on it straight away or time was allowed for the implant to heal, and then the crown was placed.

Following on from that, you have mentioned that your dentist is now recommending bone grafting. The price of bone grafting varies according to the amount of bone required, and the type of bone to be used. You have the option of having bone taken from your own body, either another part of the mouth or the hip, or having it from a donor.

Bone from a donor can be from another human or animal. The cost of the grafting is then dependent on the answers to this.

Bone grafting does increase the price of the implant and you will be on average looking to pay at least about £1900 for bone grafting in the maxilla.

I hope i have helped

Regards