Which of the following would not be acceptable on an alginate impression?

A void of frena and tuberosities would not be acceptable on an alginate impression because these anatomical landmarks are crucial for accurately capturing the anatomy of the patient’s mouth. An impression serves to create a reliable model for further dental procedures, and omitting important structures like frena (the bands of tissue connecting lips or cheeks to the gums) and tuberosities (the rounded bony prominences at the back of the jaw) can lead to misfitting dentures or appliances.

In contrast, a clear recording of all anatomical landmarks is essential to ensure the impression is comprehensive and usable. The shape being consistent with the dental arch indicates that the impression accurately reflects the curvature and contours necessary for proper dental work. Additionally, the absence of bubbles is critical as any bubbles can create inaccuracies in the model, potentially leading to complications in fitting or function. Consequently, maintaining the integrity of the impression by capturing all relevant landmarks, including the frena and tuberosities, is vital for successful dental treatment outcomes.