There are two ways to take a dental impression: the old-fashioned way that involves gross fluids sitting in your mouth for a while, and the new way that uses technology to create highly accurate models with a minimum of discomfort.
The Old Way
In traditional dental impressions, the dentist selects a horseshoe tray that approximately fits a patient’s teeth.
The dentist then fills this tray with a thick, rapidly hardening material, like alginate (refined sea algae) or polyvinyl siloxane, a rubber-like silicone product.
Although neither of these products are safe to ingest, they are inert and non-toxic, making them safe for use in the mouth.
The trays remain in the mouth for about five minutes, allowing the fluids to set. These five minutes are crucial: slight movements can cause minor inaccuracies in the final cast. It can be hard to remain still, because neither silicone gel nor refined algae tastes particularly pleasant.
After this time has elapsed, the trays are removed and used as moulds to cast a reasonably accurate statue of your teeth.
We say “reasonably accurate” because the casting process also has potential for slight variations. The several sources of inaccuracies in these casts can sometimes make it hard for dentists to properly fit braces or mouth guards to a patient’s teeth.
The New Way
The new way is better in absolutely every respect. It is easier for the patient, faster, less harmful to the environment, and far more accurate. That’s what you get when you go digital.
Digital dental impressions are created with laser 3D scanners. This technology is similar to that used in military laser guidance systems as well as self-driving cars. The scanner is inserted into the mouth, where it pans over every tooth with a laser.
It measures the time taken for the laser to reflect back to its sensor in order to determine how far away each point of the tooth is.
Then, a computer takes all this data and crunches it into a hyper-accurate 3D model. If the dentist needs a physical model, the computer can use a 3D printer to create one.
The entire scan takes much less of the patient’s time than traditional dental casting. The only time-consuming part of the scan is the computer’s calculation, which does not require your presence in the office. Even better, due to its high accuracy, a 3D scan makes it much easier to properly fit dental appliances.