Dental impressions are an important element of many dental treatment plans, including orthodontics (braces, bridges, crowns, dentures, and veneers) and teeth whitening services. Surgical procedures such as maxillofacial prosthetics and dental implants also routinely require the use of impressions.
Traditional methods of taking impressions rely on the use of trays containing various types of materials to create a mold. These materials have different properties, such as ease of flow, setting time, patient tolerance, rigidity, durability, strength, and the ability to reproduce fine detail accurately. The choice of material can therefore be tailored to the task and to the patient.
Popular traditional impression materials include plaster of Paris, which sets in just minutes, is tolerated well by patients, and will reproduce at a high level of detail. However, it is often used as a casting material, which can add complexity to the process if also used for impressions. Plaster of Paris is also hydrophilic, making it potentially vulnerable to excess salivation or other exposure to water.
Impression compound is an established material that is used less often now that superior products are readily and cheaply available. This material is less brittle than plaster of Paris but tends to be quite thick, has poor flow and is less useful for reproducing fine detail.
Alginate is the most popular impression material and has significant advantages in many dentistry settings. It is inexpensive and achieves a level of surface detail that is appropriate and acceptable for the required procedure in a high proportion of cases. It has short working (1m 45s – 2m 45s) and setting (30s) times, easy flow, and good patient tolerability. However, it is irreversible, and once it is set, it cannot be re-formed. Agar is another hydrocolloid impression material with many of the features of alginate and can also be re-formed, but it is not often used today.
Silicones are commonly used for impressions because they are more elastic and are easy to remove from the mouth after setting. Patients tolerate silicones well, and they have great accuracy and stability. Their disadvantages include cost and sensitivity to other materials, such as latex. Other impression materials that are useful for specific circumstances include polysulfides, and polyether.
The use of digital technology to create dental impressions is increasing, and about half of American dentists now offer a digital scanning service. Digital impressions are taken using an intra-oral scanner, a piece of equipment that will likely become a standard dentistry tool in the next five to 10 years.
Intra-oral scanning allows the dentist to scan the patient’s teeth and gums using a handheld wireless device. The scanner creates a 3D impression that can be viewed and shared by the dentist, patient and dental laboratory. The technology can produce accurate and precise impressions, in addition to being well received by patients. The most obvious advantages of this system are speed and comfort for the patient, along with accuracy and efficiency for the dentist.
Once the scan has been performed, the digital impression is used to manufacture the required prosthesis or appliance using a 3D printer. Digital impressions are most commonly used to produce crowns, implants, inlays, retainers, and aligners. Although there is an initial investment required to use the technology, the ability to produce personalized dental items via 3D printing reduces the overall manufacturing cost. However, it is believed that while digital impressions performed with intra-oral scanners have high levels of precision, they may be less accurate than conventional impressions for large and full arch prostheses.
Another key advantage of intra-oral scanning is its suitability for children, who typically find it more difficult to undergo traditional impression modeling. Children cannot keep their mouths open for as long as adults, and they tend to find the process much more daunting. Other patients who are generally fearful of dentistry, have a strong gag reflex or are otherwise sensitive to impression materials may find digital impressions easier to tolerate.
Other advantages of digital impressions include reduction in waste (molds, material, consumables), a simplified process with fewer steps reducing the risk of errors, and improved opportunities to engage patients in their treatment by presenting easily understood images. The American Dental Association (ADA) conducted a survey in 2021 that showed that 70% of dentists using an intra-oral scanner for digital impressions said that it improved efficiency and 40% saw improved patient outcomes. The most frequent use of scanners was for single tooth-supported crowns, as 90% of dentists used the technology for this treatment.
Making a Lasting Impression
While there are clear advantages to adopting a digital approach to dental impressions, traditional methods are still commonly used. As technology improves and costs drop with increased uptake, digital services are expected to become standard practice during dentist visits.
If you would like to learn more about clear aligners, 3D printing, or more advancements in orthodontic technology, contact the team at OrthoDenco Digital Orthodontic Laboratory today. With over 35 years of experience and 400 active accounts, we have the experience, leading reputation, and innovative 3D printing equipment necessary to meet all of your dental practice’s needs. We are happy to be your trusted go-to orthodontic lab, so you can be there for your patients.