Abutment

In engineering, abutment refers to the substructure at the ends of a bridge span or dam whereon the structure's superstructure rests or contacts. Single-span bridges have abutments at each end which provide vertical and lateral support for the bridge, as well as acting as retaining walls to resist lateral movement of the earthen fill of the bridge approach. Multi-span bridges require piers to support ends of spans unsupported by abutments. Dam abutments are generally either side of a valley or gorge but may be artificial in order to support arch dams such as Kurobe Dam in Japan.

The term may also refer to the structure supporting one side of an arch, or masonry used to resist the lateral forces of a vault. The word derives from the verb "abut", meaning to "touch by means of a mutual border".

Use of abutments in engineering

An abutment may be used for the following:

Abutment (dentistry)

In dentistry, an abutment is a connecting element. This is used in the context of a fixed bridge (the "abutment teeth" referring to the teeth supporting the bridge), partial removable dentures (the "abutment teeth" referring to the teeth supporting the partial) and in implants (used to attach a crown, bridge, or removable denture to the dental implant fixture). The implant fixture is the screw-like component that is osseointegrated.

Bridge abutments

Dental bridge abutments are made such that the path of insertion of the teeth involved is nearly parallel with each other.

Partial denture abutments

Partial denture abutments are unique in that they may incorporate elements such as rest seats, guide planes, and recontouring.

Implant abutments

These are usually called prosthetic implant abutments. These abutments can be made from a variety of materials, such as titanium, surgical stainless steel and gold. More modern abutments are now also made from zirconia, which is a white ceramic, to better complement the aesthetics of a dental implant restoration. The two images to the right show a ceramic abutment and the ceramic crown bonded to it. The images to the right show how a ceramic abutment can enhance a ceramic crown by giving it a more lifelike appearance. Ceramic abutments have to be used with care, however, since their compressive strength is nowhere near that of titanium, gold or other noble metals. Most clinicians feel more comfortable using a metal prosthetic abutment in the posterior molar areas, due to the increased masticatory forces present in these areas.