What is the purpose of an impression tray?

Impression Trays are a very important part of dentistry. These are the trays used in several different specialties to get an impression from the teeth and alveolar processus.

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IMPRESSION TRAYS
FUNCTIONS AND FEATURES OF IMPRESSION TRAYS
TYPES OF IMPRESSION TRAYS
FIGURES 15.1; 15.2
What type of impression tray is used?
What is the purpose of impression material?
What is the purpose of perforations in an impression tray?

Dental impression trays are special devices that dentists use to place the impression material in. They also carry the material inside the mouth with the tray, plus control the whole impression process. These are an essential part of several procedures in dentistry.

Uses:

The most common uses include getting an impression for diagnostic reasons, impression for use in prosthetics for fixed or mobile restorations, impressions in oral surgery, impressions in orthodontics, implantology, maxillofacial surgery and many other disciplines. In other words, an impression is an essential procedure in the field of dental medicine.

Types:

There are several different classifications of dental trays. These days there are many brands on the market that produce their own designs. You will find them in many forms, colors, materials and meant for a number of purposes. Dentists use different ones for different patients. Most of the trays are used many times and sterilized with other instruments of their type.

The first classification depends on the type of material that the tray is made of. Stock trays come in either metal or plastic. Some of the plastic ones are meant for one use only, while others can be used several times. The metal ones are more commonly used. The impression trays that are special can be made of acrylic or shellac. It all depends on the use. In other words, they can be stock trays, that the dentists buy from a supplier, or they can make a tray individually for every patient. Some procedures require an already bought impression tray, while other procedures have to be done with the use of an individual tray. Stock trays are mostly used for primary impressions. They can be full arch, sectional or quadrant. As the name suggests, the full arch gets an impression from the whole arch, the sectional one only from a certain section in the arch, and the quadrant from a single quadrant in the mouth. Individualized special impression trays are used for a secondary impression.

Another classification divides them into trays meant for people with teeth, people without teeth or a combination of the two. Edentulous patients require the use of edentulous trays, which are available for both jaws, upper and lower. These are also done in several sizes since not all patients have the same exact size as the alveolar processus. Dentists have their own technique in choosing the size of the tray. It is done by putting the tray inside the mouth and noticing whether there is enough space for the impression material and whether it covers all the necessary anatomical features needed in the impression. The combined trays have enough space for teeth either in the front or in the back, depending on the individual case. The dentulous ones are deeper compared to the edentulous, and their walls are higher. They have to also fit the teeth in so they require more space. Teeth have to always be centrally located in the tray.

Some impression trays feature perforations, while others don’t. These tiny holes are meant to retain the material and prevent any dimensional change.

SECTION 15 IMPRESSION TRAYS

Impression trays are used in conjunction with various types of materials to take imprints of the patient’s dentition. The type of tray chosen depends on the type of impression needed and the procedure that is indicated.

Figure 15.1

Figure 15.2

Figure 15.3

FUNCTIONS AND FEATURES OF IMPRESSION TRAYS

Used to hold impression material
Can be perforated for better retention
Have a handle for better grasp during placement and removal
Dentate impression trays – for patients with teeth
Edentulous impression trays – for patients with no teeth

TYPES OF IMPRESSION TRAYS

FIGURES 15.1; 15.2

Name

Metal perforated type trays

Features

Autoclavable
Available in different sizes (denoted by nu/>
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What type of impression tray is used?

The most common type of impression tray is the quadrant tray, which covers half of an arch. Other types of impression trays include full and fill trays, which span the entire maxillary or mandibular arch. Once the appropriate type of tray has been selected, it is time to prepare the tray for use.

What is the purpose of impression material?

Purpose of Impression Materials Impression materials are used to make an accurate replica or mold of the hard and soft oral tissues. The area involved may vary from a single tooth to the whole dentition, or an impression may be made of an edentulous mouth.

What is the purpose of perforations in an impression tray?

The perforations allow the impression material to expand through the holes and so be held securely in place. Perforated trays are also suitable for alginate materials but not hydrocolloid which needs to be water cooled.