Which of the following is a disadvantage of zinc phosphate?

Zinc phosphate is a dental cement commonly used for luting and as a base. One of its notable disadvantages is that it can irritate the dental pulp due to its acidic components when it first sets. The initial acidity of zinc phosphate can lead to pulp irritation, especially if there is not adequate protection of the pulp, such as when it is placed directly over a vital tooth or sensitive pulpal tissue. This is a significant consideration in dental practice, as maintaining pulp vitality and comfort for the patient is a priority.

Understanding the other options helps clarify the issue further. While zinc phosphate does not have sedative properties, its setting time can be relatively fast, which makes it useful in certain situations rather than too slow. Additionally, zinc phosphate is not suitable for all cavity preparations; its use is best indicated in specific cases depending on the cavity's characteristics and the needs of the patient. Therefore, the characteristic of being potentially pulp-irritating is a critical factor that highlights the disadvantages of using zinc phosphate in dental procedures.