ABUTMENT LEVEL IMPESSION SET UP

Distortion

Abutment level impressions fall in to two categories. One subdivision is just an impression over the already installed abutment in the patients mouth, without any hardware. Work up model work in a traditional fashion. This type of impression consistently produces the poorest results in regards to distortion and unreadable margins.

Impression coping

To ease the tooling and handling requirements for the restoring dentist, Straumann® pioneered the solid abutment system where the surgeon often installs the final abutment already and the dentist has to use a plastic coping that snaps over the abutment for impression purposes. Many manufacturers (Nobel easy™ abutment and snappy™, Astra direct abutment, Biomet 3i™ Provide™, BioHorizons® simple solution) have followed in pursuit due to the popularity of this system.

Impression

Record on an inventory list implant brand, platform diameter and abutment height. What parts (e.g. transfers, analogs, burn out copings) and how many of each the dentist sent with the case. Verify impression copings match information provided on the hopefully included surgical report. In case there is a mismatch of the impression coping diameter or color coding and the information from the surgical report (some transfers are cross compatible with other implant brands), call the Dr. to verify implant brand, diameter and abutment height.

Analog

Order appropriate analog (clone parts) and burnout coping if the Dr. has not already included all necessary parts as a set. Snap analog in to the embedded impression coping, lining up the indexing-antirotational feature of the analog with the plastic transfer. Avoid rotating the analog when pressing the analog in to the coping.

Reduction coping

Pitfalls of the solid abutment system stem from the use of plastic impression copings and inadequate positioning features on the abutments and transfers. It is not uncommon for the dentist to press the plastic coping 180 degrees reverse on to the abutment due to the inherent plasticity of the impression coping. This is rarely detectable by the technician and results in a costly remake of the restoration.

Another issue arises if the abutment needs reduction in height or to correct angulation problems. In case the abutment does need reduction the dentist should take the impression first and then reduce only what is absolutely necessary. The laboratory technician can reduce the analog on the finished model to desired specs and provide the dentist with a reduction coping.