A crown impression or scan is only as good as the margin you can see. The cord packer tucks retraction cord into the sulcus to open it and control fluid — get this step right and the lab gets a clean, readable margin.
Before a fixed-prosthesis impression or digital scan, the gingival margin has to be exposed and dry. Gingival retraction cord placed in the sulcus does this — and the instrument that places it is the cord packer. This guide covers tip choice and technique.
What a cord packer does
A cord packer has a thin, blunt, often serrated circular tip that tucks retraction cord gently into the gingival sulcus without cutting the tissue or bouncing the cord back out. The cord displaces the gingiva laterally and vertically and absorbs sulcular fluid, exposing the prepared margin for an accurate impression or scan.
Tip sizes and patterns
- 2.0 mm tip — the everyday size for most anterior and premolar sulci.
- 2.6 mm tip — for wider sulci and thicker cords.
- UP-1 / angled patterns — angulations that reach the distal of posterior teeth where a straight tip can't sit.
- ErgoLite version — a light resin handle for comfort during longer prosthodontic appointments.
A lightly serrated edge grips the cord so it stays put as you pack; a smooth edge slides more but can let the cord lift.
Packing technique
- Cut a length of cord and loop it around the prep.
- Start packing at the interproximal, tucking the cord apically into the sulcus with the packer angled slightly toward the root.
- Work around the tooth; the previously packed cord holds the rest in place.
- Leave a tag to find the cord for removal before impression/scan.