What are common reasons for rejecting an alginate master impression?

The rejection of an alginate master impression is often due to issues that significantly compromise the quality and accuracy of the impression. In this case, the presence of voids and underextensions can lead to a failure in capturing the essential morphological features of the oral cavity, which are critical for creating an accurate and comfortable removable partial denture. Voids can create areas where detail is lost, while underextensions can result in insufficient coverage and retention in the final prosthetic design. An impression with these issues cannot be used reliably, since it will not allow for proper fitting or occlusion of the final restoration.

Good detail and stability would typically indicate that the impression is of high quality, while moisture on the surface generally suggests contamination but may not necessarily lead to outright rejection if corrected. Excess material may not impact the overall impression quality if the essential contours are captured, but it can complicate the handling and evaluation process. Thus, while all the factors are relevant, voids and underextensions critically undermine the impression's utility, justifying rejection.