Which type of cement is known to be most harmful to pulp tissue?

Zinc phosphate cement is known to be the most harmful to pulp tissue due to its acidic pH upon application. When zinc phosphate is mixed, it initially has a lower pH, which can lead to irritation of the pulp tissue, especially if there is not enough protective barrier between the cement and the pulp. This acidity can cause inflammation and necrosis in the pulp tissue if the cement comes into direct contact with it.

In contrast, glass ionomer and resin-modified glass ionomer cements are more biocompatible and have a neutral to slightly acidic pH, which minimizes the risk of pulp damage. Calcium hydroxide, known for its pulp-capping abilities, has a high pH and is often used to promote healing and dentin formation, making it less harmful to pulp tissue. Therefore, zinc phosphate stands out as the cement that poses the highest risk to the dental pulp.