Triple-tray impressions have grown to be one of the most popular techniques for taking single-unit impressions. Who wouldn’t want to save time and material costs getting the prep, the opposing and the bite all in one process? But triple-tray impressions are also one of the hardest impression techniques to get right.
At California Dental Arts, over 50% of the impressions we receive are triple-tray impressions, and we see a higher remake percentage across the board due to a number of factors. And a seemingly small number of remakes per month can have a tremendous negative financial impact on your practice. Taking an accurate impression is the first and most important step for setting up your dental lab for success. Here are a few tips for taking a great first impression.
Use a supportive tray.
To help ensure you always take an accurate impression, first look to your tray.
Flexure from pressure points can be a common problem with many plastic triple trays. A rigid tray with sidewalls provides maximum support for impression materials, which prevents distortions when the lab pours the die stone.
Create proper adhesion.
When your impression goes to the lab, it takes a lot of abuse, enduring multiple pours to create working and solid models. Chemical and mechanical adhesion will help the impression material adhere to the tray to prevent separation when we remove the first pour—and create a durable impression for creating a solid model and possible die plug.
Capture better margins.
Displacing tissue with packing cord helps move the gums away from teeth to capture clear margins. Some impression materials displace tissue without it. However, in our experience, doctors who pack cord have a lower remake percentage. Having clearly defined margins eliminates guesswork when the lab trims the margins under 10x magnification. It also reduces the chance that we will need to return the case and have the dentist trim the die.
Use sufficient material.
An insufficient amount of high-quality impression material can cause poor model quality that may be unusable in the lab. Die stone will engage undercuts in an exposed tray and, when the model and die department removes the die stone, the impression material tends to come out of the tray, eliminating the lab’s ability to pour a solid model. After you take an impression, look it over before sending it to the lab to make sure the tray isn’t showing through the impression material.
Capture enough teeth.
Without enough teeth captured in the impression, the lab tech can’t articulate a model with confidence. Capture at least two to three adjacent teeth, focusing on molars, to give the lab enough information to set the correct bite. When you’re done, take a separate bite to help the lab verify the tray impression.
Perfect your seating technique.
Proper tray placement posterior to the last tooth allows an impression to be taken with the teeth in a closed position. If the patient cannot close fully, you won’t be able to capture the last molar. Alternately, patients may bite through material on the prep. Make sure your patients can close properly, avoiding the posterior crossbar on the tray, to record an accurate bite registration.
Paying attention to small details can yield large returns when it comes to reducing your remake percentage. When in doubt, take an extra impression and we’ll pour both to determine the best one—at no extra charge.