The handle should protrude from the center of the mouth and should be oriented parallel to the sagittal plane. This can be evaluated by looking at the patient's head from above and behind, and by observing the position of the tray handle. Care should be taken to ensure that the tray is properly aligned during the insertion process. This permits the dentist to see the relationship between the labial flange of the tray and the facial surfaces of the teeth or residual ridge. Once the tray is in the mouth, the thumb and forefinger of the left hand should be used to raise the upper lip. Therefore, allowing the patient or the assistant to hold the tray should be avoided. Any movement of the tray during the gelation period will result in an inaccurate impression. The dentist should maintain an even amount of pressure on the tray even if the patient opens or closes the mouth. This can be accomplished most effectively by placing the forefinger of each hand on top of the tray in the premolar area, and by placing the thumbs under the patient's chin. It is essential that the dentist maintain the position of the tray during the entire gelation period. While holding the tray with the left hand, the dentist should use the right hand to remove gauze pads from the patient's mouth. The lips and cheeks should be pulled apically and then outward at a 45-degree angle to properly form the peripheries of the impression. The mandibular impression should be made first because it usually entails less patient discomfort, and patient confidence is increased when an impression has been successfully completed.

Maxillary alginate impression ratio