Aesthetic Implant Abutments
Unscrambling The Abutment Puzzle

The use of dental implants is on the rise.  As patients are becoming more educated in dental options, dentists are finding it necessary to offer more choices.  With an increase in proficiency in implant placement via oral surgeons, periodontists, and skilled general dentists, the stigma of implants being too advanced and “experimental” is fading.

Since their introduction, dental implants have been constantly evolving.  From the original Branemark design with its external hex fitting surface, to the introduction of the internal connection, advances in implant designs have been immense. As implant fixtures have changed, so to have the restorative options we have available. Today, we are no longer limited by the proximity of bone to achieve a highly aesthetic result, nor are we forced to accept less than ideal treatment outcomes.  With preplanning and a willingness to explore the possibilities that are available, fixed implant cases can provide you and your patients with natural looking and functioning restorations.

Implant abutments have come a long way over the last twenty years.  The first abutments that were made available by such companies as Nobel Biocare, and Corevent (now Zimmer Dental) were referred to as "stock abutments", and came only in predetermined heights, which provided very few options (Figures 1 & 2). They engaged the external or internal hexes of the implant fixture, which provided all the anti-rotational stability available. They were restricted to a predetermined number of collar heights, usually 1 to 6 millimeters, to allow the margin placement of the final crown to be at the tissue crestal area .The only methods of modification were that of pure subtraction.  The titanium could only be cut and shaped with carbides, diamonds, and stones (Figure 3). It was very difficult, if not impossible to add to them.  In instances where the emergence profiles needed to be expanded, to correct misangled implant fixture placement, or even to increase abutment length to support a cemented crown, clinicians were faced with compromised results.
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Later, angled abutments were provided by implant manufacturers. However, their uses were restricted due to the limited number of predetermined angles that were available, usually 10 to 25 degrees (Figures 4 & 5).  Often, due to implant placement, the hexes, be it internal or external, did not allow for the predetermined core angle to fall into the correct or desired alignment. Their modification once again could only be of a subtractive nature. They were however, a good step forward in the evolution of "stock abutments".


Over the years, many new advances to "stock abutments" have emerged. Recently, the idea of scalloping the collar 360 degrees around the abutment has been introduced (Figure 6).  The abutment collars that are contoured below the margin allow space for soft tissue around the implant, without compromising strength or aesthetics. The concept allows for a ring of soft tissue to form around the abutment and be held in place, thus supporting the tissue and maintaining bone height. With less likelihood of gingival recession, the potential for metal to be exposed in later years is reduced. These abutments are available from Zimmer Dental in a variety of collar heights and angles and are easily shaped and prepared in the laboratory to provide for adequate results in many instances where a stock abutment is warranted (Figures 7, 8, & 9).

Another useful advancement has been the development of the stock Zirconia abutment, such as the Zireal Abutment from 3I (Implant Innovations) (Figure 10).  It provides the benefits of creating a light coloured material at the subgingival margin area, thus preventing the "gray gum syndrome" commonly found with metal abutments. It also provides a more translucent core as a base for future all ceramic restorations (Figures 11 &12).

The latest concept to be introduced to premade "stock abutments" allows for much greater versatility in restorative options (Figure 13). The Ankylos system from Dentsply no longer relies on internal or external hexes for anti-rotational support. The internal fitting connection utilizes a "Morris Taper" or internal cone of less than 6 degrees. By forcing the abutment with it's corresponding positive taper into the implant’s negative taper, a solid seal is created, locking the abutment in place with the strength of a cold weld (Figure 14). Not only is the union strong, but also gap free, protecting against microbial colonization. As there are no hexes to engage, the straight or angled abutment can be placed in any 360-degree rotational position. Angled abutments can now be aligned precisely to their most beneficial position. The design of the implant fixture head, along with that of the abutments also encompasses the concept of maintaining "horizontal biological width" through built in platform switching (Figure 15).

Implant manufacturers have recognized limitations to "stock abutments" and developed the castable abutment. These are commonly referred to as UCLA Abutments, which refers to their place of development. These abutments are comprised of a machined fit gold alloy base which fits to the corresponding implant head combined with a plastic sleeve which can be cut, modified and added to with wax prior to casting (Figure 16). The UCLA Abutment was a giant leap forward in making more aesthetic and more retentive implant restorations.  It allowed the clinician to customize for each implant and situation, the emergence profile, crown margin depth, and abutment angulations.  Off angled implants and those placed in less than ideal positions, now could be restored with more certainty (Figures 17, 18, &19). The fact that the abutment, after being cast, was still all-metal was one of its major aesthetic drawbacks.
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