Which factor can lead to insufficient material bulk in amalgam restorations?

Insufficient depth of isthmus is a critical factor that can lead to inadequate bulk in amalgam restorations. The isthmus is the narrow connection area between two cavities in a tooth preparation. When the depth of the isthmus is insufficient, there isn't enough space to accommodate the amalgam material adequately. This can result in a restoration that lacks the necessary bulk to provide proper support and minimize the risk of fracture or dislodgement over time.

The design of the cavity preparation, including the width and depth, is essential for ensuring that the restorative material can be placed adequately. An insufficiently deep isthmus may compromise the integrity and longevity of the restoration, leading to potential failure. Therefore, it is crucial to follow guidelines for cavity preparation to achieve the appropriate dimensions that will support a successful amalgam restoration.

Other factors could contribute to issues with amalgam restorations but do not directly relate to the bulk of the material itself. Proper dental hygiene and effective curing time, while important in different contexts, do not specifically affect the bulk of the material once placed. Improper mixing technique is also important, as it can influence the quality of the amalgam but not the actual bulk in terms of cavity preparation design.