There are several different types of implants. The type that is best for a particular patient can be determined by an oral surgeon, periodontist or dentist. The type chosen will also depend on the type of tooth replacement that the implant will support (e.g., crown, denture, bridge). The most commonly used types of implants are endosseous (also called endosteal), which means they are placed inside the bone. The main types of endosseous implants include:

• Root form. This is the most common form of dental implant. A root form implant is placed into the jaw like the root of a tooth. Some are cylindrical in shape, with threads like a screw, while others are smooth. Some are straight walled while others are tapered. Each type of implant may have specific advantages depending on the nature of the bone into which it will be placed. It can support a crown, denture or bridge, but requires bone that is wide and deep enough to anchor the implant.
  
  
• Blade form. Instead of a cylindrical artificial root, a flat, rectangular metal structure with posts rising from one side is inserted into the jawbone. It may have one or multiple posts, which serve as abutments to support a crown, denture or bridge. It is not as popular as the root form implants.
  
  
• Ramus-frame. These implants are inserted in the bone of the back corners of the mouth and at the front, above the chin. A thin metal bar connects them, following the arch of the jaw. This bar is used to support a denture. Ramus-frame implants can be used with thin jawbones that will not support other types of implants. They also help to prevent the fracturing of a weak jaw.

While these types of implants are the most common, they are not the only types that may be used. Two other types of implants may also be used in limited circumstances:

• Subperiosteal. This type of implant is placed over the bone (on top of it) instead of inside it. The soft tissues grow over it and stabilize it. It can be used to support a crown, denture or bridge, but is no longer commonly used since the root form implants were developed. This was a popular implant system before the advent of root form implants.
  
  
• Transosseous. Also called transmandibular. This form of implants is inserted from the underside of the chin and through the jawbone using extensive surgery that typically requires general anesthesia and hospitalization. The posts of the implants rise through the jawbone into the mouth, where they are used to support a denture. It can only be used on the lower jawbone. Transosseous implants can be used when there has been serious loss of bone. However, bone grafting followed by root-form implants are the preferred method.