What is a Dental Impression?
A dental impression is a close replica of a patient’s tooth structure and surrounding oral tissue. They are the cornerstone of restorative procedures and appliances.
How Dental Impressions Are Used
Three Main Categories of Dental Impressions
- Preliminary – A preliminary impression replicates a general outline of a patient’s mouth. It is used to diagnose the patient and outline a treatment plan.
- Final – A final dental impression is more detailed. It captures the exact features of a patient’s tooth structures and surrounding tissue. This is what would be used to create casts and dies. Dental lab technicians can also utilize this to reconstruct crowns, bridges, etc.
- Bite Registration – This is an impression of the upper and lower teeth when a patient’s mouth is in the bite position. This type of impression provides an accurate occlusal registration, which is important as it records the normal centric relationship of the maxillary and mandibular arches.
How Dental Impressions Are Created
Traditional
A traditional dental impression uses a combination of trays filled with FDA approved dental putty. Patients bite down onto the tray and putty combination, which leaves an indentation of their mouth structure. As it remains in a patient’s mouth for a few minutes, the impression material hardens thereby creating a mold of their teeth. Traditional impressions are technique sensitive with multiple factors that can affect accuracy. Working closely with your dental laboratory can help you eliminate a lot of common issues that happen with the traditional impression process. You can also increase your chances of getting a great dental impression the first time, by following these proven tips on how to take the perfect impression.
Digital Impressions
A digital impression is a technology that allows dentists to create a virtual, computer-generated replica of the mouth by using an oral scanning device. This technology can capture clear and accurate impression data in just a couple of minutes or less. Once the digital replica is complete, the information is then transferred to a computer and used to create restorations.
Benefits of Digital Impressions
The process of getting a traditional impression taken can be uncomfortable, messy, and unpleasant for both a patient and clinician. Offered as an alternative, digital impressions take the uncomfortable and stressful impression-taking procedure out of the equation. Other benefits of digital impressions include:
- Reduces the incidence of remakes. Digital impressions allow for better-fitting and more anatomically correct restorations. Digital cases with PRO-Craft statistically have a lower remake factor than conventional cases.
- Enables quicker restorations due to excellent margin capture and visibility
- Increases patient satisfaction with faster appointments and less time in the dental chair.
- Reduces patient discomfort and limits gag reflex.
- Decreased overhead costs and inventory. Reduces the need for impression material, shipping, storage, or model sterilization.
- Reduces environmental footprint.
Challenges of Digital Impressions
Even with the cutting-edge technology of a digital impression system, there are still challenges that present themselves. The top challenges of digital impression systems are:
- Significant upfront investment. A digital impression system can range anywhere between $20,000 - $25,000.
- Training courses are required to use a digital impression system.
Digital Impression Systems
Are digital impressions the right direction for your practice? Dentists that have shifted to digital impression systems would never think about changing back. Other dentists still prefer traditional methods or are hesitant with the substantial initial investment of going digital. But as technology continues to offer greater convenience, reduce margin of error, and allow patients to spend less time in the chair, dentists will ultimately see the overall benefits of going digital. Today there are multiple competitors in the world of digital impression systems. Each competitor offers something unique to their brand, and the best fit for your practice will be determined by the needs of your practice.
3Shape TIOS
- Includes an integrated intraoral camera.
- Teeth do not need to be powder-coated prior to scanning
- Scanner has an accuracy of 20 µm
- Produces 3D color impressions
- Can take shades while scanning
- Includes access to 3Dhape Communicate, which is a tool that allows dentists to communicate with their dental laboratory to discuss cases before submitting their scans.
3M True Definition
- Scanner has a reputation for being one of the most accurate on the market and for generating consistent results.
- Has the smallest wand on the market.
- Wand is ergonomically balanced.
- Teeth must be powder-coated prior to scanning.
The Sirona Cerec
- Powder-free scanning.
- Produces precise 3-D impressions in full color. This scanner is accurate to 20 µm
- Wand is designed to feel natural to hold so it’s user-friendly.
- Specifically good for single restorations
iTero
- Compact machine.
- Teeth do not need to be powder-coated prior to scanning
- System offers Invisalign certified connectivity.
Traditional Impressions
By large, traditional impression materials continue to remain unchanged. For example, many dentists continue to use irreversible hydrocolloid (i.e., alignate), which was introduced in the 1940’s. Alignate is economically priced, quick setting, and fairly accurate which makes it a common material used for traditional impressions.
Advancements in dental impression materials occurred with the development of elastomeric impression materials. Polyether (PE) was introduced in the 1960s and Vinyl Polysiloxane (VPS) soon followed in the 1970’s.
- Polyether (PE) - Polyether is a flexible impression material that offers good quality surface detail, creates accurate complete-arch replicas, and is available in various viscosities and set times. Polyether also provides impressive performance in situations where moisture is present (saliva, water, gingival fluids). This feature has certainly set it apart from other impression materials.
- Vinyl Polysiloxane (VPS) or also known as Polyvinyl Siloxane (PVS) - VPS is a hydrophilic impression material that has excellent rigidity and the ability to resist distortion and tearing when being removed from a patient’s mouth. VPS materials are also inherently tasteless and odorless. VPS is available in a range of viscosities from a light body that can be dispensed with a syringe, to a heavy body which can be used for bite impressions. Set times can also differ depending on viscosity and brand name but will often range between 2 to 5 minutes.
Benefits of Traditional Impressions
Even with the technology and benefits of a digital impression system, there are practicing dentists that find advantages in using the conventional method of taking impressions.
- Minimal up-front cost. The standard impression with stock tray averages between $18 to $35.
- No extensive software system needed to integrate with the current platform.
Challenges of Traditional Impressions
- Obtaining correct margin and details
- Acquiring accurate occlusion records
- Maintaining patient comfort
- Increased patient chair-time
- Increased space required for inventory
The Future of Dental Impressions
Will the future of dental impressions be completely digital? As the ever-evolving world of dentistry progresses and digital impression systems continue to improve, what is clear is this technology, like x-rays, is here to stay. Even as other dentists may argue that one method is inherently better than the other, just remember that you can always use a back-to-the basics approach. That is, stay consistent, use the techniques and instruments you feel comfortable with, and don’t take any shortcuts along the way.
