(open tray)

Direct impression

The direct impression technique is more cumbersome but the pay off for the extra work lies in a higher degree of accuracy. As a general rule it is best to always take full arch impressions with a polyvinylsiloxane (AFFINIS®PRECIOUS by coltene®, Aquasil Ultra by Dentsply)  impression material because this will result in the greatest accuracy and ensures the laboratory can develop proper implant protected occlusion and avoid lateral contacts of the implant restoration.

Modify a stock tray by creating a hole cut in to the tray in the area where the impression coping will be located. Use appropriate platform diameter, direct impression coping (also called transfer coping) from the same manufacturer as the implant. Utilizing the correct impression coping will give the technician important information about the manufacturer and platform diameter to avoid any confusion on what parts to use.

Open tray

With the patient in the chair and the transfer coping on hand remove the trans mucosal healing abutment with a hand screw driver. Immediately following the removal of the healing abutment place the impression coping on to the implant, engaging the indexing feature of the implant.

Sometimes the implant will be quite far below the tissue and once the healing abutment is removed the tissue will start to collapse over the implant, making the seating of the transfer difficult. Therefore, working efficiently and expediently is essential.

good seat

Verified seat

Once the impression coping is seated and the retaining screw is hand tightened take an x-ray to verify accurate placement of the transfer on to the implant. The x-ray needs to be taken perpendicular to the long axis of the implant to ensure a clear picture of the mating surface of the implant and impression coping.

Incorrect seat

Try in modified full arch stock tray to ensure the fixation screw of the impression coping extends through the tray. Load full arch impression tray and place over transfer and surrounding teeth. After the impression material has set, unscrew the fixation screw while the tray remains in the patients mouth. Pull out the screw completely to assure the screw is no longer engaged in any way to the implant. Remove the impression from the patient and reattach the screw to the transfer. The transfer coping body should not be removed or separated from the impression material. Place the healing abutment back on to the implant and hand tighten. Impression taking trouble shooting guide.

Full arch impression of the opposing and a bite record also are needed. Send impressions, bite, transfer coping and a copy of the x-ray to the laboratory. Sending a copy of the x-ray to the lab serves as proof the impression coping was seated accurately at the time of impression taking. This might come in handy later on, if there are problems with the restoration supplied by the laboratory and a decision needs to be made where the mistake occurred.