What is a common reason for the failure of alginate impressions?

A common reason for the failure of alginate impressions can indeed be attributed to multiple factors, and all of the listed choices contribute to the overall quality and accuracy of the impression.

Using too much powder can lead to a thicker mix, which might not adequately capture fine details of the oral anatomy, resulting in an impression that does not fit well or lacks precision. An incorrect water-to-powder ratio is crucial, as an improper mixture can alter the setting time and consistency of the alginate, further impacting the detail that can be captured. Additionally, working with expired alginate materials can compromise the physical and chemical properties of the impression material, leading to poor performance. As these materials are time-sensitive, their use past the expiration date often results in reduced setting and failure to take accurate impressions.

All these factors work together, highlighting the importance of proper technique and material management to ensure high-quality dental impressions.