If there is already an infection that enters or extends to your
sinus, the priority is to clear up the infection and remove the source (the tooth). If the tooth is restorable a
root canal might be another option.
As far as bone grafting, I would generally advise against this if the infection truly does extend to the
sinus. There is the chance that there could be further infection and extension into the
sinus. When the tooth is removed there should be care to attempt to remove as much or all of the infected tissue as possible while hopefully not creating an opening through the
sinus if it doesn't already exist. This may require careful evaluation and meticulous surgery in experienced hands. If there is a perforation, it is important to know how to handle it and hopefully treat it promptly. Assuming all is cleaned out thoroughly and there is no evidence of residual infection, I would then reserve tooth socket bone grafting here where it is not possible to maintain width due to missing or loss of the bony socket wall, especially the outside (buccal). Even with this width reconstruction bone graft, there may still not be enough bone height for an implant due to the level of the
sinus. If this is the case, I would not graft the
sinus area (sinus lift) in the face of infection. This can be done later when all is healthy and sometimes in conjunction with implant placement. It is important to do the right thing based on science and your health and not be overly influenced by
insurance coverage and profit. This goes for the doctor and the patient. I always recommend for the doctor to be a patient advocate, be ethical, educated, and not motivated by greed. My 2 cents!