When fitting a custom tray, how far should it be trimmed back from the mucosal reflection?

Trimming the custom tray back appropriately from the mucosal reflection is crucial for achieving an accurate and comfortable impression. The recommended distance is typically 2 mm from the mucosal reflection. This amount of trimming allows the tray to fit snugly without causing discomfort or displacing the oral tissues during the impression process.

The 2 mm distance helps in preventing any potential irritation to the surrounding mucosa and ensures that there is adequate space for the impression material to flow properly into all areas of the arch being recorded. This distance is an established standard in dental practice to enhance accuracy and patient comfort.

Selecting a distance greater than 2 mm, such as 3 mm or 4 mm, may result in missing critical details in the impression due to inadequate coverage, while a distance less than 2 mm, such as 1 mm, could lead to impingement on the soft tissues, causing discomfort or even interfering with the impression result. Thus, a 2 mm trimming from the mucosal reflection strikes an ideal balance between functionality and comfort.