An accurate and precise impression is essential for a successful treatment outcome. If the patient’s impression has errors, the dental lab cannot fabricate a quality product and your patient will be unhappy with their restoration. Plus, you’ll spend more time chairside as you adjust the restoration, meaning less time with other patients. In a perfect world, you would identify impression errors before sending them to the lab. Today on the blog, we share tips on avoiding the most common impression errors.
Using the incorrect tray size
Selecting the right tray size is critical when taking impressions. Ensure the tray is large enough to cover the patient’s teeth that you need to impress, but not so big that the tray touches the gums. The tray should not show through the impression material once complete. When using full-mouth trays, try placing it in the patient’s mouth and ask them to bite down gently. This gauges the size of the tray and ensures it is wide enough to capture the entire dental arch, but not too large.
Mixing the impression material incorrectly
Properly mixed impression material should not have any streaks. If it does, keep mixing until it is uniform in color. Work quickly so that the material does not begin setting before you use it. If you’re using a cartridge to fill the tray, bleed the material slightly before attaching the automix tip, which helps the catalyst and base flow equally.
Ensure that the area inside the patient’s mouth is clean. Various aspects can interfere with the integrity of the impression: excess core build-up, adhesives that leave a greasy coating, retraction cord or gauze, just to name a few. Therefore, before taking the impression, be sure to rinse the area with water and thoroughly dry the area to remove any contaminants. Using a clean utensil, mix the impression material in a clean bowl and be sure to wear a new pair of gloves.
If your margins aren’t good, then your impression won’t be either, and you’ll end up with a poorly made restoration. If you encounter any voids around the margin, it’s likely because the tissue wasn’t retracted or fluids accumulated around the prep area, preventing the impression material from flowing adequately around the margins. Solve this problem by retracting gum tissue or using a retraction paste around the gingival sulcus after you prep the tooth. We prefer to use a diode laser to help make the sulcus area wider and improve the visualization of the tooth’s margin.
Bubbles in the impressions
If blood, saliva, or other fluids get trapped in the impression material, it’ll result in a bubble or void in the impression. This could result in a thinner product, which is not ideal when dealing with all-ceramic restorations, which already aim for minimal thickness. To avoid this problem, thoroughly dry the impression area, then stop any soft tissue bleeding by using a hemostatic agent.
Marginal tears are common if you remove the impression tray before the material thoroughly sets. It can also occur by using a low-quality impression material or one with a low viscosity. Choosing a more viscous material can help avoid this problem. If you need to retake the impression, be sure to remove any impression material remnants before taking it again.
Getting in a hurry when making the impression
You must take your time to ensure the retraction cord is in place and that the material is mixed properly. However, don’t take too long to get the impression. If you try to take the impression after the material begins to set, it’s too late and you will get an impression that is unusable.
Allowing the patient to move
We get it: having an impression taken isn’t going to be your patient’s idea of a good time. But nonetheless, the patient must sit still. Let your patient know what to expect while getting their impression. Advise them to lean back against the headrest, breathe through their nose and try to relax. Also, gently remind the patient that if you aren’t able to get a good impression the first time, you’ll have to repeat the process again. Nobody wants to have to redo an impression!
Premier Dental Arts is a full-service dental lab located in Kingsport, Tennessee. We offer the industry’s highest quality products and look forward to partnering with you. To learn more or set up a consultation, please call (888) 732-5221.