Abutment Definition
In the dental field, an abutment is an element which connects two pieces together. The following are some of the various contexts where an abutment is used:
- A fixed bridge: the abutment teeth are the teeth which aid in supporting the bridge
- Partial removable dentures: the abutment teeth are the teeth which support the partial denture
- Dental implants: the abutment is used to attach a crown, bridge, or removable denture to the dental implant fixture. The implant fixture is a screw-like component which fuses to the bone
Bridge Abutments
A dental bridge abutment is created in a manner that the path for inserting the teeth involved is nearly parallel with one another.
Partial Denture Abutments
A partial denture abutment is unique in the fact that it may incorporate additional elements which can include rest seats, guide planes, and recontouring.
Implant Abutments
This type of abutment is usually called a prosthetic implant abutment. The abutment for a dental implant is responsible for connecting the prosthesis or crown to the actual dental implant. Implant abutments can be created from various materials including titanium, surgical stainless steel, and gold.
Ceramic abutments are able to enhance a ceramic crown as they give it a more natural appearance. However, ceramic abutments require additional care as they are not nearly as strong compared to those made of titanium, gold or other noble metals. Most dentists recommend the use of a metal prosthetic abutment in the posterior molar areas as these areas experience increased masticatory forces.
An abutment will not always be parallel to the long axis of an implant. It is used when the implant is at a different inclination as it relates to the prosthesis the patient is receiving. In most cases, crowns and fixed partial dentures contain a cemented or screw-retained fixation on the abutment, which makes it more secure.
Three Piece Implant
In cases where a three piece implant is used, the abutment is connected to the implant through a screw butt joint. This screw is required to be tightened to a specific torque using a dental torque wrench. This helps to avoid the screw becoming loose while chewing, which often creates a counter-clockwise torque on the implant-abutment interface. Ultimately, this can encourage the abutment screw to become loose. Fortunately, this can largely be prevented with the proper design of the screw and use of the correct abutment torque.
Two Piece Implant
In cases where a two piece implant is used, the abutment is morse tapered or cold welded to the implant. Microbial leakage and colonization between the implant and the abutments can cause inflammatory reactions and even crestal bone loss. Morse taper conical abutments have demonstrated a cumulative implant survival rate of 98.23%, as it relates to the seal performance, microgap formation, torque maintenance, and stability of the abutment.
One Piece Implant
A one piece implant (OPI) works by incorporating the trans-mucosal abutment as an integral part of the actual implant. This type of implant is commonly used with a flapless procedure or in cases of immediate loading. Immediate loading occurs when the crown is placed shortly after the implant is placed.