As tissue management is crucial to achieving an acceptable impression, proper clinical technique goes a long way in determining the overall quality of procedural outcome. For conventional impression-making, in order to allow enough material into the sulcus to create an undistorted impression and then to ensure complete material removal, clinicians must create at least a 0.2mm space between tooth and gingiva. This allows the impression material to adequately flow into the space while minimizing the possibility of tearing, which can ruin the impression and cause gingival irritation and inflammation. For digital scanning, the minimal space requirement is less strict, however, gingival tissue must still be displaced and hemostasis maintained to achieve a desirable outcome.
Most commonly, mechanical gingival displacement is done with either a single or double retraction cord. Gingival retraction cords are either pre-impregnated with an astringent, hemostatic agent or soaked in one prior to performing the procedure. In the latter case, it is recommended that the cord is soaked for approximately 20 minutes before use for thorough saturation. Upon evaluating the health of the gingiva and depth of the sulcus, the clinician can then determine whether to use a single- or double-cord approach. For optimal retraction and impressions involving subgingival margins, a double-cord technique is generally preferable, but when there is minimal sulcular depth, you may be limited to placing only a single cord.
In the case of double-cord retraction, first, a thin-diameter cord is placed at the base of the gingival sulcus where it should be cut and made flush to prevent bleeding during tooth preparation. As this technique can cause tissue damage, maintaining a gentle, delicate approach and using a quality, minimal thickness cord packer is key to mitigating trauma. After the placement of the thin-diameter cord and completion of the tooth preparation, a second wider cord is then placed on top of the first to displace the gingival margin. Prior to the wider cord being removed and making the impression, it should be wet so that it does not tear gingival tissue and cause bleeding. Once the wider cord is removed, the final impression should be made immediately. The gingiva should be displaced for up to 30 seconds and allow you to capture a clear impression.
Traxodent®, a clay-based gingival retraction paste by Premier Dental®, provides an easy, atraumatic alternative to the retraction cord technique. Using the paste requires little instruction—simply dispense it into the area around the prepared tooth and have the patient bite down on a cotton retraction cap (also available from Premier). After two minutes, the paste is removed by rinsing the area with water. For additional hemostasis and gingival displacement, an armamentarium of both Traxodent and/or a retraction cap can be used in conjunction with retraction cord. Aside from a slight increase in chairside time and material costs, there is little downside to using all of these tools in tandem if the situation warrants it—it’s a small price to pay for achieving the best possible impression.
To learn more and purchase Traxodent, retraction caps and other tissue management products, please visit Premier’s website.