February 15, 2022
Written by:
Dylan Schubert
An overview of dental impression materials and trays that could benefit dental practices.
There are many different treatments and prosthetics that require a dental impression. One way to create an accurate dental impression is to utilize the correct materials and trays. To help you select the materials and trays best fit for your dental practice, we’ve created this simple overview.
Trays are fabricated with different types of materials, which allows dentists to adapt them to the needs of their patients. Plastic and metal trays are most common with stock trays, while custom trays are typically made from acrylic or shellac. Metal trays are the most accurate option because they are less prone to expansion issues once the impression sets.
When selecting an impression tray, there are typically 2 main types available:
The type of impression tray that best suits your practice will also depend on your specialty.
Tip: After evaluating a patient’s dental arches, first select and try on an impression tray without any material. This allows you to assess any modifications that may be needed, which lower stock trays can often require.
The importance of a good tray system should not be underestimated. A tray that does not support the impression material well will distort and can rebound out of shape when it is removed from the mouth. Just because an impression looks good does not mean it’s accurate. Your laboratory’s work will only be as good as the accuracy of your impression. No matter what impression material you use, investing in a reliable tray system is the foundation of your accuracy. PRO-Craft recommends the Quad Tray system from Clinicians Choice. Many of our clients use it. It is comfortable for the patient and will not rebound.
Countless types of impression materials have become available over the years. Each of these can serve a specific purpose, but the proper impression material should include these qualities:
First impressions are for orthodontic appliances, custom trays for partials or dentures, diagnostic models, opposing models, and temporary coverage for crowns and bridges commonly use alginate. Alginate is typically available in two different settings:
The most common challenges in getting a quality impression are adequate tissue retraction and sufficient moisture control. Dr. Dan Fischer, president and CEO of Ultradent Products, Inc. often says, “There is nothing one can do well, in a quality sense, when it comes to operative dentistry in the presence of bleeding.”
Retraction cord, helps to enhance tissue management techniques by delivering the ferric sulfate solutions sub gingivally for optimum sulcular fluid control. Ideal tissue displacement occurs within one to three minutes after cord placement. Packing cord placement technique also plays an important role in achieving quality, predictable tissue management.
Expasyl from Acteron is an alternative to retraction cord. It is a viscous, rigid paste for gingival retraction that not only opens the sulcus, but also leaves the field dry and ready for impression taking, cementation or digital scanning. It is extruded directly into the sulcus where it holds its rigidity to create space between the tooth and the tissue. It can be used for all procedures requiring gingival retraction including impressions, seating of restorations, fitting rubber dams, restoring class II, III and V cavities.
The laboratories ability to to see the margin as opposed to just trimming to the bottom of the sulcus (not recommended) requires the clinician's impression material to fill the sulcus and go slightly past the margin. The techniques mentioned here will assist in the effort.
Final impressions used for restorations will need to show precise details of the tissue and tooth structure. Materials used for a final impression are typically supplied in three different forms:
When choosing the right impression material, select the one with the qualities that allow you to obtain the most accurate reproduction. Here at Pro-Craft we have monitored our remakes and adjustments for many years. We have found that the materials with the most consistency and lowest remake factor are Aquasil from Dentsply and Impergum from 3M. We believe they have the most consistent quality control.
In the end, the tools you choose to work with should benefit you and provide a successful restoration. Being selective and paying attention to the types of trays, the viscosity of impression material, tissue management along with strict adherence to set times and manufacture instructions will ensure a successful outcome. As always patient satisfaction and the growth of your practice as they share their experience to their friends and families is the ultimate goal.
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