A subperiosteal dental implant is a type of implant that is meant to be inserted between the bare surface of a tooth-bearing bone and the membrane that covers (and is attached to) that bone. Before the subperiosteal implant can be inserted between this mucoperiosteal membrane and the bone directly underneath it, the mucoperiosteal membrane first has to be surgically detached from the underlying bone.
A subperiosteal dental implant is indicated for clients who have, at the site of the implant, a higher proportion of the less-dense cancellous or spongy bone and for whom a bone graft is not possible. Also, subperiosteal implants are only allowable for patients who have lost most of the thickened (alveolar) bone that underlies the tooth sockets. Once a tooth is lost, the alveolar bone is gradually reabsorbed by the body. A subperiosteal implant should not be fitted over this alveolar bone as the close fit between the bone and the implant will be gradually lost as the alveolar bone disappeared. Also, the renowned dental surgeon, Dr. Leonard I. Linkow advises that a subperiosteal implant would best be attached to dense cortical bone, which is usually more extensive on the lower jaw than on the upper jaw.
The procedure for a subperiosteal implantation, though not complex, is a fairly involved process that would likely require more planning, time, and work than the equivalent procedures for endosseous (or “in-bone”) implants. Dr. Linkow prescribes at least two separate surgeries for this type of implant to ensure that the implant would closely correspond to the ridges, depressions, and contours of the bone. The first surgery primarily involves making a very precise impression of the site of implantation. The second surgery, which takes place about four weeks later, is the time when the prepared implant is actually inserted between the bone and the mucoperiosteal membrane. The close fit between the bone and the implant is the key to the subperiosteal implants success rate.
The subperiosteal dental implant typically has four exposed posts to which are attached a corresponding superstructure which, in turn, is enclosed within the base of the actual denture.
A properly attached subperiosteal implant is held in place by the healed mucoperiosteal membrane and by the underlying bone to which the implant has been specifically shaped and fitted. All subperiosteal dental implants are personalised implants; no implant can be suitable for more than one patient.