At the present time, the majority of dental implants placed each year nationwide, are used to support "fixed" restorations; that is to say, crowns or bridges. Patients are very enthusiastic about these kinds of treatments, and their reliability rivals conventional crowns and bridges. Implant supported crowns and bridges are generally preferred by patients because of their natural feel.
An implant supported crown is composed of three parts, attached together in a stacking system.
The implant is at the bottom of the stack, and it will now act as the mechanical root or footing.
The part that penetrates through the gum tissue and forms a neck, is called an "abutment." The abutment “locks” into place on the top of the implant with a screw. This makes the implant long enough to penetrate through the gum tissue and provides a surface that is ideal for the gum tissue to attach.
The top of the stack is the "crown" and it attaches to the abutment. The crown is the visible portion of a tooth, and the part that you bite on. The crown can be attached to the abutment by either a screw or with dental cement.
A bridge is composed of two or more crowns, connected together and including one or more false teeth. The more "units" that are connected together, the more demanding is the restoration.
You must remember that crowns and bridges replace only the missing teeth. If you are also missing gum tissue and bone, a purely fixed restoration may not give you an acceptable appearance.
In addition, implants that support fixed appliances are asked to bear higher loads and biting forces than implants that support removable appliances. This has an important influence on the number, size and position of the implants selected. This is not a place for cutting costs.