As a key instrument for taking dental impressions, dental impression trays are essential for getting an accurate negative imprint of the teeth. The tray holds the impression filling used to set the mold, allowing the operator to place the impression material properly within the patient’s mouth.
However, not all dental impression trays are created equal. It takes the right dental impression tray to capture every part of the oral cavity, from the teeth to the gums and surrounding tissues. Once an accurate impression is achieved, the imprint can be used to create a precise three-dimensional model of the patient’s mouth.
The models made with dental impressions can be used for different dental specialties and treatments, such as orthodontics, prosthodontics, mouth guards, whitening trays, and dental crowns and bridges. The permanent dental record is also helpful to have as documentation of the before-and-after phases.
This article explores the different types of dental impression trays, how to choose the right impression tray, as well as some common errors while taking dental impressions and how to avoid them. Keep reading to find out the secrets behind selecting dental impression trays and using them effectively.
Types of Dental Impression Trays
There are three key factors to consider when selecting impression trays: size, shape and material. Learn more about those characteristics to know how to choose the right type of tray for a dental impression procedure.
Naturally, every patient will have a different sized mouth. Because of this, dental impression tray sizes can range from XX-Small to XX-Large. Small to medium dental impression trays are perfect for children and female patients, while large dental impression trays are better suited for adult males.
To make sure a dental impression tray is the right size for a patient, look at whether it covers all of the dental pieces when testing the tray. Pay extra close attention to whether the most posterior teeth get included. In addition, make sure the dental impression tray is slightly loose so there is enough space between the tray and the teeth for the impression material to fill up.
Just like size, the shape of a dental impression tray can vary, too. Depending on the type of procedure the impression is intended for, an impression may need to be taken of the whole mouth or just one part of it. To make choosing the right tool easier, dental impression trays come in different shapes for the lower teeth, upper teeth and quadrants of the mouth.
Dental impression trays come in many different materials, which means they are easily adapted to the specific needs of a procedure. Different dental impression tray materials may have different distinguishing features, making some types better for accomplishing certain tasks. For example, perforated trays tend to have better retention of the impression material.
Below are three common dental impression tray materials:
- Plastic: Plastic dental trays are popular because dental professionals can make cuts to adjust the tray to the exact shape of a patient’s mouth. While plastic trays are often single-use, some plastic varieties may be sterilized and reused.
- Stainless steel: As opposed to disposable dental impression trays, stainless steel trays are a sustainable option. Along with protecting the environment, purchasing stainless steel trays pays off in the long run because they do not have to be replaced as frequently.
- Metal: Like stainless steel, metal impression trays may be reused, making them common for taking prostheses impressions, but they do not have quite as long of a lifespan as stainless steel impression trays.
How to Choose Dental Impression Trays
The right dental impression trays depend on the purpose of the trays and each patient’s individual fit. Using the right impression tray is essential because using the wrong one can lead to defects in the impression.
In general, a good dental impression tray will have these five qualities:
- Stability: An impression tray should be rigid in use.
- Extension: The tray needs to extend enough to support an impression of all the structures needed.
- Retention: Along with features that aid retention of the impression, the tray should include occlusal stops.
- Robust handle: An integral handle is typically best for an impression tray.
- Reusability: If the tray is not designed for single-use, it must be able to withstand autoclave sterilization.
In addition to these features, there are more patient-specific variables to consider. Of course, tray size will vary with the size of the patient’s mouth. For pediatric dental procedures, it is important to be aware that a small dental impression tray for adults is not equivalent to a size small tray for children.
The shape of the dental impression tray will be chosen according to which part of the patient’s anatomy is being captured. Whether the impression needs to be of a quadrant, full arch or opposing dentition will decide which tray shape will be the best fit. Upper and lower jaw trays are typically sold separately, so it is important to determine which is needed before buying.
Finally, the specialty of the trays should be taken into account. For example, dental impression trays used for implantology should be adaptable for patients who have dental implants that are very close together. On the other hand, because dental impression trays for orthodontics typically depend more on the orthodontist’s preference, it might make the most sense to invest in reusable trays.
Disposable Dental Impression Trays vs. Stainless Steel Impression Trays
Understanding what material dental impression trays are made of is an important consideration when purchasing.
One major draw of plastic dental trays is their low price compared with other types of impression trays. Although plastic trays may be lower in price, they usually are not intended for multiple uses, which means more plastic trays must be purchased to have enough impression trays on hand. Because they must continually be replaced, disposable dental impression trays create a false economy and cost more than reusable trays over time.
On the other hand, multi-use dental impression trays like stainless steel trays are a smart investment for dental practices that frequently use impression trays. Because stainless steel trays can be sterilized and reused, they allow offices to save both money and the environment. Stainless steel trays cut down on waste, so they are an eco-friendly choice for any office. Some stainless steel impression trays are even made from a combination of new and recycled materials.
Plastic dental impression trays are also most often chosen for their flexibility. However, many disposable plastic trays are too flexible to ensure an accurate impression. In contrast, stainless steel impression trays are rigid and sturdy, allowing for a more precise impression.
A flexible disposable tray also makes dimensional distortion more likely, especially when excessive pressure gets applied during the impression making process. Due to the amount of space between the teeth and the tray’s side walls, more impression material is needed to fill the gap, which often results in dimensional shrinkage. However, stainless steel trays provide a more fixed fit to produce a more accurate impression.
Dental Impression Errors
Getting a good dental impression is critical because a bad impression can be bad for business. Poor dental impressions can lead to any of the following:
- Remake bills from the laboratory
- Wasting costly materials
- Repeat visits for the patient
- Additional chair-side time
- Undue distress and expenses for the patient
Fortunately, correcting poor dental impression practices can prevent bad impressions from ever happening. When taking a dental impression, watch out for these seven common mistakes:
1. Improper Tray Selection
Using the wrong tray for a dental impression can result in an inaccurate final product. For example, using a disposable plastic tray with putty silicone and a light-bodied material can cause excess stress on the putty. If the tray is made from flexible plastic, this added stress can deform the tray.
Additionally, it is critical to use the proper impression tray to get the right dental impression size. The wrong tray will not be able to capture the entirety of older patients’ oral cavities.
2. Air Voids
When there is saliva on the teeth, tiny bubbles can form within the impression. To avoid these air voids, teeth should be thoroughly rinsed and air-dried before applying the light-bodied material. And remember, blood can also cause internal bubbles, so make sure to rinse and dry thoroughly.
3. Marginal Tears
Sometimes, a thin portion of the impression margin can tear during removal. Using a more durable impression material, such as polyether, can decrease the chances of a marginal tear. Keeping the impression tray in the mouth long enough for the materials to set is key to allowing the impression material to develop its strength.
4. Poor Margin Detail
Along with tears, margins can suffer from poor detail. Although it can be easy to focus solely on capturing the prepared tooth, there must be adequate data in the rest of the impression for the laboratory to mount the case accurately and create a usable design. Often, the cause of poor margin detail is using the wrong-sized tray or not filling the impression tray enough to record a sufficient number of teeth.
5. Selecting the Wrong Impression Material
In addition to underfilling the impression tray, using the wrong impression material with too much viscosity can cause an insufficient flow of the impression material into tighter areas. Other issues may arise if the impression material does not mix properly. Always use the right-sized mixing tip to ensure a workable impression material.
6. Rushing the Impression
If the impression taking process is rushed, the impression material will not have enough time to set, resulting in an inaccurate impression. Additionally, rushing through the preparation process can have negative effects. Taking the time to make sure the area is entirely clean and clear of residue before taking the impression will increase the chances of a precise impression.
7. Failure to Keep the Patient Still
If a patient cannot sit still, there may be pulls and drags during the impression taking process, which will show up as elongated distortions. Any movement or adjusting of the impression material before the set is complete will result in an unclear impression. Communicate to the patient that the impression material must be kept stable the entire time it is within their mouth.
How to Take Accurate Dental Impressions
To avoid making the mistakes above, here are five tips for taking an accurate dental impression:
1. Choose the Right Tray Size
Because using the correctly sized tray is so crucial, take time to test the tray inside the patient’s mouth without any impression material. Check that the tray fits over the bite registration to ensure it is the right size before filling it with the impression material. Doing a quick trial run will also show the patient what to expect when the actual impression is taken.
When the patient practices biting down on the empty tray, take a look at the opposite side of the arch to get a better idea of what the teeth coming together should look like. Doing so will also allow the patient to feel how they need to bite down correctly during the impression.
2. Keep the Margins Clear
To get an accurate impression, the margins must be kept visible, dry and free of both saliva and blood. To make sure the margins are visible, syringe around the prepared tooth once with the material and lightly blow air around it before continuing to syringe the remaining material. Using a gingival cord packer to pack gingival retraction cord to further isolate the tooth is another way to help keep the margins clear.
3. Get the Timing Down
Before pouring the impression material, make sure to read the material instructions to ensure the impression gets enough time to set. Because some materials may respond differently to various temperatures, it is important to consult the manufacturer’s directions on what the perfect timing is. Using a timer to keep track of mixing time and set time will result in more accurate impressions.
4. Get the Entire Arch
When in doubt, take a full-arch impression. A full-arch impression will give the lab more information and ensure there is sufficient data within the impression. Additionally, a full-arch impression allows the opposite side of the arch to stabilize the contact between teeth, providing more accurate jaw movements and lessening the chance of interference with tooth contact.
5. Watch Out for Gagging
Keeping a patient still while taking an impression is important because too much movement can distort the impression. However, even when a patient tries to remain as still as possible, there is always the chance that they gag unexpectedly. For patients who are more susceptible to gagging, it is best to use the least amount of impression material possible because excess heavy body material is typically what triggers the gag reflex.
In addition, having the patient sit up straight with their legs on the floor may reduce the likelihood of gagging by allowing them to lean forward and lessen the feeling of the material running down their throat. For more severe cases, instruct the patient to focus on breathing through their nose and have an assistant start a conversation to distract them. Diversion tactics are also a good way to ensure a patient doesn’t move accidentally.
Order Stainless Steel Dental Impression Trays From ProDentUSA
As the foundation of an accurate dental impression, the tray is the secret to ensuring a good end result. Although using the wrong tray will be like trying to take an accurate measurement with a shifting tape measurer, the correct dental impression tray will fit just right and deliver a precise outcome. In addition, the right type of dental impression tray will be sustainable and cost-effective.
For an accurate, durable and reusable tray you can depend on, use a stainless steel dental impression tray from ProDentUSA. All of the impression trays from ProDentUSA are made from reliable, long-lasting stainless steel. Our products are also made with renewable resources by using recycled stainless steel, meaning they are an eco-friendly and socially responsible choice.
All of our instruments are backed by the ProDent Promise, which means they are designed to last and guaranteed to satisfy. Because we manufacture all our own products, we can offer lower prices than the competition and provide you with a high-quality, affordable impression tray option. At ProDentUSA, we pride ourselves on spreading smiles, one instrument at a time.