The concept of the All-on-4 was based on a graft-less procedure where no bone grafting is to be incorporated. Although I use bone grafting as necessary, especially in areas where teeth are extracted, the basis of the angling techniques of the implants is intentionally done in order to avoid the sinus and the necessary grafting in otherwise conventional techniques.
Hi and thank you for your question.One of the reasons for doing an All on Four is to avoid doing surgery in the sinuses, but in some situations there is so much bone loss that to be able to do an All on Four you need to do sinus lifts. Get evaluated by an office that has 3D imaging (CBCT) , I suggest an Oral & Maxillofacial Surgeon's office. I have done many of those cases and although they take a bit longer, to the patients is is well worth it. Good luck to you, I hope you get your Dream Smile!Dr. Juan C. ArroyoOral & Maxillofacial Surgeon