Which portion of the maxillary impression tray should be seated in the mouth first?

When taking a maxillary impression, it is important to understand the anatomical considerations and the design of the impression tray. The posterior portion of the maxillary impression tray should be seated in the mouth first due to the natural contour of the maxilla and how the tray fits around the palate and the posterior teeth. By starting with the posterior part, the tray can be more effectively positioned against the hard palate, allowing for a more stable and accurate impression.

Seating the posterior first helps ensure that the tray is adequately placed and minimizes the risk of discomfort for the patient. This technique also allows the clinician to manage the seating process effectively without dislodging the anterior portion of the tray, which is crucial for obtaining a comprehensive impression that captures the full arch details.

In contrast, starting with the anterior portion could lead to misalignment or the tray being improperly seated, resulting in inaccurate impressions. Thus, the step of seating the posterior portion first is vital for achieving the desired outcome in maxillary impressions.