I keep getting sinus infections after maxillary surgery, why?

It depends: It really depends on what kind of maxillary surgery you had. If the drainage opening from your sinus to your nose is blocked it can contribute to chronic infections. You may need to have your sinus irrigated to clear this but really need to see your surgeon to make a diagnosis as to why you are having problems. I would also advise that you stop smoking as this will aggravate your sinus