If you don't have enough amount of bone to support the implant then your doctor may need to perform a sinus lift or bone graft before placing your artificial teeth. Usually, a sinus lift is advised when the tooth has been extracted a long time ago and the bone in the upper jaw has deteriorated to such an extent that the sinus has expanded into the space. Bone grafts may be required when you have untreated periodontal disease or if your bone mass has deteriorated, for example