Impression options and procedures, esthetic zone

The first choice the restorative dentist must make is whether the impression will be performed at the abutment or fixture level. This is dependent upon a number factors, including: position of the implant relative to adjacent structures (teeth or implants), depth of soft tissue, morphology of the soft tissue, restorative space, posterior inter-occlusal space and dentist preference.

As space is not normally a limiting factor in the anterior zone an open or closed tray technique are both options. Material choice is again dependent upon the preferences of the restorative dentist. The material should be one that would be utilized in conventional fixed dental prosthesis construction (polyethers, polyvinylsiloxanes, putty – wash combinations, etc).  The literature is also conclusive on this subject,  impression materials of those  previously mentioned categories are all suitable with no one product demonstrable better.

Since space is less an issue in the anterior zone, intra-oral scanners are more readily used. With the increasing use of the digital realm it is possible through the use of scan bodies or specific healing abutments to capture the location and orientation of the implant architecture without the use of impression material. This approach is becoming increasingly more popular and potentially will reduce costs and reduce treatment times.

The critical part of the  impression is the capturing of the internal geometry of the implant (i.e.: NobelReplace Select tri-lobe, external hex or the Conical Connection internal hex design)  insuring the final restoration is oriented correctly. 

Of note: the accuracy of the final impression is dependent on the complete seating any of impression components. Verification of proper component seating via radiograph is recommended. The literature is conclusive that all procedures have some form inaccuracy that must be expected.

Abutment Level Impression

If the impression is to be at the abutment level this can be a custom, multi-unit or stock abutment (can be either cement or screw retained).  In the screw retained option the utilization of a custom or stock angulated abutment (allows for a screw from the lingual surface) or the angulated screw channel approach (ASC). 

Of equal importance in the impressioning of the implant is the capturing of the soft tissue. It is critical that the soft tissue architecture has been developed with the provisional restoration and has matured to the point that minimal change will occur. It is advisable that the abutment of choice be placed and removed a minimum number of times or if possible, not at all. This will assure the stability of the soft tissue and deliver the desired result as it relates to the inter-proximal contact point, papilla and overall gingival health. 

Implant Level Impression

If the impression is to be at the implant level the choices of open / closed tray are available. In both instances it is essential that radiographic verification is made to insure the seating of the impression coping. With implant placement being further subgingival  or subcrestal one needs to be sure that either soft or hard tissue is not impeding the complete seating of the impression coping. With the advent of platform switching  the new conical connection for NobelReplace, the conical connection for NobelActive, this is less of a problem since the impression copings are narrower than the implant platform. Still careful examination and visualization of the seating of all components are critical. If a provisional restoration is already in place the soft tissue form should be fully developed and matured. The final restoration would mirror the emergence profile and tissue support developed previously. 

To minimize potential for soft tissue prolapse when the provisional restoration or healing cap is removed, consider making a custom impression coping.  (See Digital Textbook, Chapter 17, Recording Emergence Profile in Impressions)