October 1, 2001
by Vincent J. Morgan, DDS
The stealth shouldered abutments are designed for any type of cement-retained restoration as well as an integrated abutment crown restoration with “Diamond Crown” by DRM Laboratories. Stealth abutments in conjunction with Bicon’s new aluminum oxide sleeves provide enhanced aesthetics with all-ceramic crowns. The stealth shouldered abutments are available in diameters of 3.5 mm, 4.0 mm, and 5.0 mm. Determining the appropriate diameter abutment is dependent upon the amount of space available for a proper emergence profile. A congenitally missing maxillary lateral incisor with less than 5.0mm of edentulous space can be aesthetically restored in a predictable manner with the use of the 3.5mm stealth shouldered abutment and an aluminum oxide sleeve (Fig. 1).
The sizes and shapes of the stealth shouldered abutments virtually eliminate the need for modified or angled abutments; since angulation adjustments can be made in the prosthesis. The prosthetic shoulder and coronal portion of each diameter of stealth shouldered abutment are identical. The difference among the abutments of a given diameter is the relative distance of the abutment’s hemispherical base from the end of its shaft, and the height of its hemispherical base.
Bicon’s non-shouldered cement retained abutments may still be the abutments of choice for many clinical situations particularly when using gold margins in non-aesthetic areas or for telescopic restorations.
A very efficient way to adjust the size and shape of the aluminum oxide sleeve is to place it onto an actual stealth abutment in an abutment prep holder and to hold it against the rotating 10″ diamond wheel of a model trimmer (Fig. 12).
The clear acrylic sleeve for the 5.0 mm abutment can be used with any of its four diameters of stealth emergence cuffs. The acrylic sleeve can serve as: a temporary crown (Fig. 8), an impression transfer (Fig. 7), an occlusal registration (Fig. 9), an adjustment coping, or as a waxing sleeve for the technician. In addition to the two-piece sleeve for the 5.0 mm diameter abutments, there are one-piece acrylic sleeves for each diameter of shouldered abutments.
Aluminum oxide sleeves are available for each diameter of shouldered abutments (Fig. 10). The aluminum oxide sleeve can act as an impression transfer (Fig. 11) as well as the core for an affordable all-ceramic crown (Fig. 14).
The system also includes a polycarbonate analog or transfer die (Fig. 13).
Following are step-by-step instructions for the chairside selection, temporization, and impression of a stealth shouldered abutment for a cement-retained restoration.
1. After removal of the temporary abutment and selection of the appropriate abutment diameter (Fig. 2 and Fig. 3), the abutment height is chosen with the aid of a shoulder depth gauge.
2. The gauge is placed into the well of the implant to record the appropriate subgingival shoulder height (Fig. 4).
3. Place and tap the appropriate abutment into the well of the implant (Fig. 5).
4. Select and modify, if necessary, the appropriate emergence cuff and sleeve or a one-piece sleeve depending upon the desired emergence profile. Only the 5.0mm wide stealth abutment has the option of using a two-piece sleeve.
5. Snap the emergence cuff and sleeve onto the stealth shouldered abutment.
Note: The stealth emergence cuff may be used alone or in conjunction with the stealth acrylic sleeve (Fig. 6).
6. The emergence cuff and sleeve is then incorporated into the temporary prosthesis (Fig. 8).
7. Another set of emergence cuffs and sleeves are used for recording the occlusal registration (Fig. 9).
8. A transfer impression of the abutment is taken with either an acrylic sleeve or an aluminum oxide sleeve (Fig. 11).
9. After pouring a soft tissue model a crown is fabricated by adding an all-ceramic porcelain e.g. AllCeram by DegussaNey or Celabien by Noritake to the sintered aluminum oxide sleeves.
10. After final contouring and glazing, the all-ceramic crown is delivered to the patient for final cement bonding to the Bicon shouldered abutment with “Diamond Link” by DRM Laboratories. (Fig. 14).
Dr. Morgan maintains a private practice at the Implant Dentistry Centre in Boston, MA.
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