Dental implants are a solution for replacing missing teeth, offering a stable and long-lasting foundation for prosthetic restorations. An implant replaces the root of a natural tooth, providing the anchor to support a crown, bridge, or denture. Made from biocompatible materials like titanium, these devices integrate directly with the bone structure, a process known as osseointegration. This fusion allows the replacement tooth to function with the strength and stability of a natural tooth, preserving jawbone health and facial structure. The selection of an implant type is guided by the patient’s anatomy and the extent of bone available for placement.
Endosteal Implants
Endosteal implants, meaning “in the bone,” are the most widely used type of dental implant. These implants are shaped like small screws or tapered posts and are surgically inserted directly into the jawbone’s interior. Titanium is the preferred material due to its high strength and ability to fuse with human bone tissue.
The procedure often follows a two-stage protocol. It begins with the surgical placement of the titanium post into the jawbone under the gum line. A period of healing, known as osseointegration, is required for the bone to bond with the implant surface, which typically takes several months. Once the implant is stable, a second minor procedure attaches the abutment, the connector piece that extends above the gum line.
Finally, the prosthetic tooth, such as a custom-made crown, is affixed to the abutment, completing the restoration. Endosteal implants are the standard treatment when a patient possesses sufficient width and height of healthy jawbone to support the implant fixture. Their high success rate and ability to function like natural tooth roots make them the preferred choice for single-tooth replacement or supporting multi-unit bridges.
Subperiosteal Implants
Subperiosteal implants, which translates to “on the bone,” are a historical alternative to the endosteal design. Instead of being placed within the jawbone, this type consists of a custom-fabricated metal framework that sits directly on the surface of the jawbone, beneath the gum tissue. The framework has posts that protrude through the gums to serve as attachment points for a denture or bridge.
This method was developed and used in the 1940s and 1950s for patients who had experienced significant bone loss and lacked the volume necessary for implants to be anchored inside the jaw. The framework rested on the broader, denser cortical bone structure rather than integrating with the interior bone.
However, the use of subperiosteal implants has largely been discontinued in favor of modern endosteal techniques, often combined with bone grafting. Historically, this design suffered from a lack of long-term stability, leading to hardware exposure, chronic infections, and eventual bone resorption. While largely obsolete, they remain a distinct category based on their unique placement outside the bone.
Zygomatic Implants
Zygomatic implants are the most specialized and complex of the three types, reserved for individuals with severe atrophy or bone loss in the upper jaw (maxilla). Unlike other implants that rely on the alveolar bone, these devices anchor into the dense zygomatic bone, commonly known as the cheekbone. This placement bypasses the severely resorbed maxillary bone, which is inadequate to support standard endosteal fixtures.
Due to the distance between the mouth and the cheekbone, zygomatic implants are notably longer than conventional implants, often measuring between 30 and 52.5 millimeters. The procedure is more intricate, requiring advanced surgical skill to place the implant at an angle into the zygoma. This method is employed to avoid the lengthy healing time associated with extensive bone grafting or sinus lift procedures.
The benefit of using the dense zygomatic bone is that a prosthetic bridge can frequently be attached immediately after surgery, allowing for immediate function. Zygomatic implants provide a viable, graft-free solution for patients who are not candidates for traditional implants due to extreme bone deficiency in the posterior upper jaw.
Factors Influencing Implant Selection
Selecting the appropriate dental implant type is primarily driven by the quantity and quality of the patient’s jawbone. The determining factor is bone density and volume, assessed through advanced imaging like cone-beam computed tomography (CBCT) scans. If the patient has adequate bone height and width, the endosteal implant is the default and most reliable choice due to its long-term success through osseointegration.
When bone loss is moderate, the dental professional may still choose the endosteal route but preface the implant placement with a bone augmentation procedure, such as grafting, to build up the necessary structure. If bone loss in the upper jaw is profound, the specialized zygomatic implant becomes the preferred option. This choice avoids the need for grafting, reducing overall treatment time and surgical complexity compared to extensive bone augmentation surgeries.
Overall patient health plays a role, as conditions like uncontrolled diabetes or heavy smoking can compromise the healing process and the success of osseointegration. The location of the missing teeth influences the decision, especially when considering the proximity of the maxillary sinuses, which often necessitates grafting or the use of zygomatic implants. Ultimately, the decision balances the patient’s anatomical limitations, overall health, surgical complexity, and the desire for a fixed, long-lasting prosthetic solution.