There are some problems that can arise with denture implants. While implant surgery is successful in a high percentage of patients, that leaves a small percentage where implant failure can occur. Implant failure occurs when the implant does not attach to the surrounding bone. When this happens the implant has to be removed, and another attempt can be made at a later time. Some common reasons why dental implants fail to attach to bone include infection around the implant, cigarette smoking, titanium allergies, and lack of healthy bone. As with all types of surgical procedures, there are some risks involved. These include infection, bleeding, and injury to the sinuses, nasal cavity, or nerves near the implant area immediately following surgery. Other complications include bacteria that can lead to periodontal disease and bone loss. Dental implant breakage may also occur, leading to the removal of the broken implant.