Ultimate Guide to Dental Impressions: What It Is and How It Works
Ultimate Guide to Dental Impressions: What It Is and How It Works
Blog Article
What is a Dental Impression?
Dental impressions are the process of taking a "negative" image of your teeth, gums, and the surrounding area of your mouth. Just as when you press something into wet clay and it leaves an impression, a dentist uses a special material to make an exact copy of the structure inside your mouth. This copy is called an "impression."
A plaster model of your teeth (also called a "cast" or "study model") is made in a lab using these impressions. This model is a "positive" image of your teeth and gums, which dentists use for various treatments such as:
- Creating crowns and bridges.
- Creating dentures.
- Creating orthodontic appliances (braces to straighten teeth).
- Planning for implants.
- Making protective mouthguards.
- And other restorative tasks.
Simply put, a dental impression is a 3D blueprint of your mouth, based on which precisely fitting appliances are made for your dental treatment.
Techniques for Taking Dental Impressions
There are mainly two types of techniques used to take dental impressions:
1. Conventional Impression Technique
This is the most common and oldest method. It uses an impression tray and impression material.
Impression Tray: This is a U-shaped instrument that is shaped like your dental arch. It is made of plastic or metal and is available in various sizes so that it can fit the patient's mouth exactly.
Impression Material: This material is usually in the form of a paste and is filled into a tray. When it is placed in the mouth and pressed against the teeth, it sets and becomes rubbery in a short time, and takes an accurate impression of your teeth and gums.
Common materials used:
Alginate: This is the most commonly used material because it is cheap, fast, and easy to use. It is made from a mixture of water and powder and sets quickly. However, its accuracy can be less than some other materials, and a plaster model has to be made immediately after it sets.
Polyvinyl Siloxane (PVS): This is a high-precision rubber-based material. It gives very detailed impressions and remains stable even after setting. It is widely used for specific treatments such as crowns, bridges, and implants. It takes a little longer to set in the mouth.
Polyether: Another high-precision material similar to PVS. It also gives very detailed impressions and performs well in humid environments. Its setting time is shorter than PVS, and it is slightly stiffer.
2. Digital Impression Technique
The digital dental impression is a modern and technology-based method that has reduced the need for traditional impressions.
How it works: In this method, a direct 3D digital image of your teeth and gums is taken using a small, handheld scanner (called an intraoral scanner). This scanner is rotated inside the mouth and takes thousands of images that are instantly collected on a computer screen to create an accurate 3D model of your mouth.
Advantages:
More comfortable: The patient does not experience the taste or choking sensation of traditional impression material.
Faster: The scanning process is very fast, and results are seen immediately.
More accurate: Digital scans often provide greater accuracy than traditional impressions, leading to greater precision in treatment.
Environmentally friendly: No material is wasted.
Data storage and sharing: Digital files can be easily stored and shared with labs or other specialists.
Disadvantages:
Expensive: Digital scanners and related software can be costly.
Learning curve: Dentists and staff have to learn to use digital systems.
Procedure for Taking Dental Impressions
Whether the method is traditional or digital, there are some basic steps in the impression-taking process:
Traditional Impression Procedure
Preparation: The dentist will examine your mouth and select an appropriately sized impression tray. Sometimes, an adhesive is applied to the tray to help the material adhere well.
Material Mixing: The impression material (such as alginate or PVS) is mixed with water or other chemicals until it becomes a paste. This must be done very quickly because the material begins to set quickly.
Tray Filling: The mixed material is filled into the impression tray.
Placement: The dentist will carefully place the tray in your mouth and press it against your teeth. During this time, you will feel some pressure.
Allowing to Set: You will need to wait a few minutes (depending on the type of material) to allow the material to set completely. During this time, you should not move your mouth.
Tray Removal: When the material has completely set and hardened, the dentist will carefully remove the tray from your mouth.
Impression Inspection: The dentist will check the quality of the impression taken. If it is not perfect, the procedure may need to be repeated.
Model Making: The impression is sent to a dental lab, or a precise model of the tooth is made in the clinic by filling it with plaster or stone material.
Digital Impression Process
Preparation: The dentist will prepare the teeth in the mouth for scanning, sometimes applying a light coat of powder (if the scanner requires it).
Scanning: The dentist will move a small, handheld intraoral scanner into your mouth. The scanner takes thousands of digital images of the surface of the teeth and gums.
Real-time model: These images are instantly stitched together on a computer screen to create a 3D model of your mouth. You can also see a model of your teeth on the screen.
Verification: The dentist will check the accuracy of the model on the computer and make sure that all the necessary details have been captured correctly. If there are any errors, they can be corrected immediately.
Data transmission: The completed digital model file is sent electronically to the dental lab, where further processes (such as creating a crown via CAD/CAM) begin.
Comprehensive Comparison Between Traditional and Digital Impressions
Both traditional and digital methods of taking dental impressions have their distinct advantages and limitations, which influence clinical choices.
In traditional impressions, dentists take physical impressions of a patient's mouth by filling a tray with a paste-like impression material (such as alginate or PVS). This method has been a mainstay of dental practice for decades because it is relatively inexpensive and can be easily implemented in any clinical setting.
However, patients can often experience discomfort with this method; the strange taste of the material, gag reflex, or pressure from placing the tray in the mouth are common complaints. Additionally, the material takes a certain amount of time to set, and there is a possibility of some physical distortion of the impression during or after this process, which can affect the accuracy of the final restoration. It also takes time to send the physical impression to the lab and create a plaster model of it, and this also includes the cost of couriering.
In contrast, digital impressions use a small, handheld intraoral scanner to capture a 3D image of the tooth directly onto a computer. This process is much more comfortable for patients because there is no material to taste or choke on. The scanning process is extremely fast, and the 3D model of the mouth appears immediately on the computer screen, where its accuracy can be checked and immediately corrected if necessary. This high accuracy, absence of material-related distortions, and instant feedback lead to a more accurate fitting of the dental restoration.
Furthermore, the digital files can be sent to the dental laboratory electronically, saving both time and cost and making the workflow more efficient. However, the initial equipment setup cost, such as a digital scanner and related software, is much higher than the traditional method, which can be a barrier for smaller clinics. Thus, the choice between the two methods is determined by the clinic's budget capacity, priority for patient convenience, and accuracy and efficiency requirements. Report this page