Tuesday, November 12, 2013


There are two types of impressions that we routinely take in this office. The first type is for the fabrication of study models and diagnostic casts. The second is for the construction of laboratory-processed crowns, bridges, and removable partial dentures.

Study Model or Preliminary Impressions
Study model impressions are the most common impressions made in a dental office. A sterilized metal tray or a disposable plastic tray is used for this procedure. The tray is fitted approximately to the dimensions of your upper or lower jaws and will cover your teeth and gum tissue. Once fitted, the tray is partially filled with a soft, viscous impression material. This material has the consistency of thick cookie dough batter. The filled impression tray is placed over your teeth and gently pressed into place. The material will take from 1 to 2 minutes to set.  The impressions are absolutely painless and require no medication or special preparation. The material has a moderately pleasant taste.

From this impression, stone models will be made that are a very close duplicate of your teeth. These models allow us to analyze your teeth and properly design your dental treatment. We investigate the possibilities of orthodontics (braces), custom trays for whitening teeth, and replacement of missing or severely damaged teeth. We make custom trays for final impressions, guides for temporary crowns, mouthguards, splints, etc.

Final Impressions
This type of impression is for fabrication of crowns, bridges, or partial dentures. The impressions are made with a different material, one that is much more accurate in demonstrating the smallest details of the prepared area. Because of the increased need for precision, the impression is different. A custom-fabricated tray is often made from the model made in the preliminary impression. This material will be in place for 3 to 6 minutes. Often, a local anesthetic has been used to prepare the tooth so there should be no discomfort. It is not uncommon that a second or third impression might be taken to ensure the accurate fit of the finished restoration.  If the impression is not right, the final restoration will be compromised.

Occlusal Registration
With both types of impressions, it is standard practice to take an occlusal (bite) registration during the appointment. This gives us the ability to relate the upper and lower jaw models. The impression may be placed on a tray or directly onto the biting surface of your teeth; you will then be instructed to bite down and hold your bite in place until the material sets. The bite registration impression sets very quickly.

If you have any questions about impressions, please feel free to ask us at (512)250-5012. –Omni Dental Group


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