Types of Impression Trays
Types of Impression Trays
Dental impression trays are needed for taking imprints of the soft tissues or teeth for making dentures or maxillofacial prosthetics. It comprises of
a tray that fits autoclave sterilizer comfortably to the upper or lower gums or teeth. The tray contains a viscous material that covers the dental arch. The
material sets to form an elastic mass, which is used for developing the dental cast.
The impression material containing the impression of the dentition is then transferred to a dental laboratory where it is processed. Apart from making
dentures, the dental casts are needed for manufacturing crowns, veneers, bridges, mouth guards and abutments for dental implants.
Importance of Impression Trays
Without creating an accurate impression of the dentition, you intraoral camera cannot develop dentures that closely resemble the real teeth and fit comfortably in the gum. Hence, using an appropriate
impression tray for taking the imprint of the teeth and soft tissues is a prerequisite for a satisfactory restoration work.
Types of Impression Trays
Stock Trays
Stock trays are widely used for taking the primary impression of the teeth and gum. They are made of plastic or metal. Polystyrene and nylon are
usually used for constructing the disposable plastic trays. The reusable metal stock trays, although expensive than the disposable impression trays,
produce the better dentition impressions. The rigidity of the root canal endodontic metal trays helps to hold the impression material firmly in place, thereby enabling production of a more accurate
impression. To take an accurate impression with a stock tray, the teeth should be fitted properly in the middle of the trough of the tray. These trays
come in different sizes. Depending upon the size of the dental arch, you can select a large, medium or small impression tray. Impression materials
commonly added to the impression trays include silicones, sodium alginate and polyether.
Custom Trays
Custom trays are ideal for complicated denture works. Acrylic and shellac are used for constructing these special trays. Compared with stock trays, it
takes a shorter time to capture an impression with a custom tray. They are rigid and adjustable. They can be customized to fit comfortably to the
dental arch of the patient. Custom trays can be designed in the dental laboratory or they can be easily manufactured at the chair side.
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