| Today, most dental implants are made of titanium, a metal that has special qualities that make it useful for this purpose. Titanium develops a thin film on its surface that protects it from corrosion. It is resistant to acids, salt solutions and oxygen, among other things. Titanium also is almost completely nonmagnetic and is extremely strong for its weight. Perhaps most important, the body does not reject titanium implants as foreign objects. When implants are placed in bone, the bone grows around the implant in a process called osseointegration. Titanium implants come with many types of surfaces, including acid etched, plasma sprayed, acid etched and grit blasted, and hydroxyapatite coated. Hydroxyapatite is a part of what bone is made from. It bonds with bone in a process called biointegration. There are several types of implants. Root-Form Implant
These are the most popular type of implant. Root-form implants are called endosseous or endosteal implants, meaning they are placed in the bone. They look like screws, thick nails or cones, and come in various widths and lengths. For root-form implants to be successful, the bone needs to be deep enough and wide enough to provide a secure foundation. Your dentist decides which type of implant to use based on the quality of the bone in your jaw and the type of crown, bridge or denture that will be placed on the implant. Root-form implants can be inserted in a two-stage process — the traditional way of placing them — or in a single-stage procedure. In the two-stage procedure, the implant is "buried" under the gum tissue for three to four months and then exposed during a second surgical procedure. In a single-stage procedure, the implant is placed in the bone and remains exposed in the mouth. Ramus-Frame Implant
This type of implant can be used if the lower jawbone is too thin for a root-form or subperiosteal implant. A Ramus-frame implant is embedded in the jawbone in the back corners of the mouth (near the wisdom teeth) and near the chin. Once it is inserted and the tissue heals, a thin metal bar is visible around the top of the gum. Dentures are made that can fit onto this bar. Ramus-frame implants also can stabilize weak jaws and help to prevent them from fracturing. Transosseous Implant
Transosseous implants originally were designed to be used in people who had very little bone in their lower jaws and who had no bottom teeth. However, they are rarely used today because placing them requires extensive surgery, general anesthesia and hospitalization. Also, their use is limited to the lower jaw. Placing transosseous implants involves inserting two metal rods from below the chin, through the chin bone, until they are exposed inside the mouth. The rods that can be seen inside the mouth are used to attach a denture. Most clinicians today prefer to use bone grafts and one of the other endosseous implant methods described earlier instead of the transosseous method because they are equally effective and do not require the level of surgery needed when placing transosseous implants. Blade-Form Implant
This type of implant also is known as a plate-form implant. It is a type of endosseous implant (placed in the bone), but it is used less frequently than a root-form implant. Blade-form implants are flat rectangles of metal with one or two metal prongs on one long side. A blade implant is placed in the jaw so that the prong(s) stick out into the mouth where they will support crowns or bridges. ©2002-2005 Aetna, Inc. All rights reserved. Reviewed by the faculty of Columbia University College of Dental Medicine | 
