Dental implant abutment
Author: George Ghidrai, MD
Implant abutments are artificial devices connected to the dental implants after the healing process. The abutments are used to attach a crown, bridge, or removable denture to the implant fixtures.
There are two classes of abutments: prefabricated and custom-made.
a. Prefabricated abutments
Prefabricated or stock abutments are manufactured in a range of sizes and shapes and are usually delivered by manufacturing companies along with the implants.
Material
Prefabricated abutments can be made from a variety of materials, such as titanium, surgical stainless steel, gold, and, more recently, zirconia.
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Titanium abutments
Titanium abutments are widely used due to the excellent properties of titanium alloys. They have outstanding strength and biocompatibility and can be used for any type of prosthetic restoration.
titanium abutments
Most clinicians feel more comfortable using a metal prosthetic abutment in the posterior molar areas due to the increased masticatory forces.
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Zirconia abutments
Zirconia abutments are more modern abutments and are used better to complement the aesthetics of dental implant restorations.
When all ceramics or zirconia restorations are planned, zirconia implant abutments provide a highly desirable option. When a zirconia abutment is used, the problem of matching the shade of adjacent teeth while hiding the dark color of the metal abutment is avoided.
Moreover, in 2011, a one-piece zirconia implant (fixture and abutment) was introduced into the market.
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Other materials
Besides titanium and zirconia, artificial abutments can be made of gold alloy, stainless steel, or other metal alloys. Although indications are narrower, there are situations in which these may be successfully utilized.
zirconia abutments
gold abutments
How is an implant abutment selected?
When the practitioner selects the abutments, several factors are involved:
The position of the implant: larger artificial abutments are positioned in the back of the mouth due to the increased chewing forces
The type of prosthesis that is executed: crown, fixed bridge, or removable denture; special retainer-type abutments are used to secure implant-supported dentures
How the restoration is attached to the abutments: with dental cement, with lag screws, or with special retainers
Let's examine these factors in more detail:
I. The prosthesis is secured to the abutments with dental cement
In this case, the surface of the artificial abutment is smooth. The restoration is connected to the abutments with dental cement, just like crowns and bridges are fixed on natural teeth.
abutment and implant-supported crown
secured with dental cement
The main advantage is they offer a higher aesthetic performance.
II. The prosthesis is fixed with a lag screw
These restorations require artificial abutments with a threaded hole in the middle.
The restoration is secured with screws that traverse the dental crowns and attach to the threaded holes. After the screws are positioned, the holes that penetrate the crowns are sealed with a composite material.
artificial abutment with a threaded hole
the crown is secured with a lag screw
The advantage is they are easier to maintain and change when the prosthetic fractures.
III. Removable dentures secured with special retainers
Special retainer-type abutments are used to retain dentures using a male-adapter attached to the implant and a female-adapter in the denture.
Compared to conventional dentures, these abutments allow movement of the denture but enough retention to improve the quality of life for denture wearers.
the male-adapters
are attached to the implants
the female-adapters
are housed in the denture
Regardless of the type of adapter, the female portion of the adapter housed in the denture will require periodic replacement.
implant-supported denture
Angulation
An abutment is not necessarily parallel to the long axis of the implant. Angulated abutments are utilized when the implant is at a different inclination in relation to the proposed prosthesis.
In this case, the primary purpose is to make all artificial abutments parallel.
straight abutments
angulated abutments
b. Custom-made abutments
Custom-made abutments are fabricated at the dental laboratory after a dental impression of the top of the implant is made with the adjacent teeth and gingiva. The size, shape, and material depend on the clinical application.
custom-made abutment on a dental cast
What is a Dental Impression?
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A traditional dental impression is an imprint of teeth and soft tissues formed with specific impression materials used in different dentistry areas. The dental impression forms an imprint (i.e., a 'negative' mould) of teeth and soft tissues, which can then be used to create a cast of the dentition.
A digital dental impression is a cutting-edge technology that enables dentists to build a computer-generated, virtual replica of the soft and hard tissues in the mouth. Digital impressions are created with optical scanning devices such as lasers.
Commonly, any abutment can be manufactured at the dental lab: with a smooth surface, threaded holes, and anchoring systems for removable dentures.
Another variation is when the crown and abutment are one piece, and the lag screw traverses both to secure the one-piece structure to the internal thread on the implant.
Regardless of the type of abutment, after the abutment is attached to the implant, an impression is made, and the designed restoration is constructed at the dental laboratory (for more details, see the prosthetic phase).
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structure