Taking Impressions


Taking Impressions

*An accurate impression is critical to ensure good appliance fit and minimal chair-side adjustment.  An appliance that fits the model it was made on but not the patient indicates that distortions may have occurred in the impression-taking or model-pouring procedures.

The durability and quality of an exceptional impression depends on water/powder ratio, spatulation, holding the impression in a stable position for optimum time and the correct position of a tray.

 Size of impression: The trays must extend past the most terminal tooth and clear the anterior teeth.

 Use a measuring guide: Fill bowl with distilled water. Slowly incorporate the powder with the water until all the powder is wet. Spatulate quickly pushing the alginate against the mixing bowl to remove air bubbles and to create a homogenize mixture.

 Place the alginate in the impression tray. Press the loaded spatula against the tray rim and allow the alginate to flow into the tray. Avoid overloading tray as it could cause the patient to gag or displace tissue. Grasp the handle of the tray with the tray facing down. Rotate the tray into the patient's mouth using the opposite hand to retract the opposite corner of the mouth.

 Center over the teeth and instruct the patient to extend their tongue to the palate and then relax on top of the tray. Apply uniformed pressure over pre-molar area with your fingers and use your thumbs to stabilize the mandible, holding under the chin. Hold the tray securely until the alginate has set. Do not allow the patient to bite down on the impression tray.

 Remove the impression tray by holding the tray handle with the thumb and finger, retract the cheek and lip and release the edge of the impression by lifting up on the posterior buccal area, you will hear a suction release. Remove with a snap to prevent distortion.

 Rinse and disinfect the impression and inspect for accuracy. Ensure all teeth are present, there are no voids, distortion of teeth, bubbles on the occlusal surfaces or teeth that have contacted the impression tray.

 Please See YouTube Video for proper impression taking.  Provided by: Dr. Nawy (Braces MD)



http://www.youtube.com/watch?v=6s5IeAnO21A&feature=related

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