We realize it is not always possible to schedule an additional appointment with the patient to make a new model if there are small blemishes on the cast. If noted on the Rx form, we can make the corresponding adjustments to the model in our laboratory. There are situations, however, where the models are not usable for appliance construction. The following are some examples of such problems resulting from impression taking and/or model pour-up.

The teeth on this model are too thin.

Thin Teeth

The teeth on this model are thin. This is generally due to the alginate pulling away from the tray wall prior to pouring the stone model. Another common reason for thin teeth is the alginate was not allowed to set-up completely while in the patients mouth.

The teeth on this model are too thick.

Thick Teeth

The teeth on this model are thick. This is generally due to the alginate shrinking prior to pouring. Most likely the alginate on this case was allowed to sit out at room temperature for an extended amount of time before the model was poured. Another situation that can cause this type of problem is if the impression tray is moved while the alginate is setting up. This can cause a double impression resulting in excess thickness of the teeth. These models should not be sent to the laboratory for any appliance as multiple areas may be distorted and not noticeable.

Bubbles on Model

This is an example of a model with bubbles.

There are excess bubbles on the surfaces of the teeth and model. This condition generally occurs when the alginate is not properly mixed or handled. Practices using the power spatulating equipment will rarely encounter this type of impression or model. Impressions should also be sprayed with an anti-bubble mist prior to pouring. This will help eliminate excess bubbles in the final cast.