Which type of cement is considered the worst for a deep restoration due to the potential for pulpal irritation?

• A. Glass ionomer
• B. zinc phosphate
• C. composite resin
• D. RMGI

Answer: (B)

Zinc phosphate cement is often considered the least favorable choice for deep restorations primarily due to its potential for pulpal irritation. This is largely attributed to its acidic nature, which can produce an immediate low pH environment during the initial setting phase. When applied in deep cavities, this acidity can lead to chemical irritation of the dental pulp, especially if the dentin is already compromised or if the restoration is placed without adequate protective measures.

In contrast, glass ionomer and resin-modified glass ionomer (RMGI) cements have a neutral to slightly acidic pH, which is generally less irritating compared to zinc phosphate. Additionally, glass ionomer materials possess the added benefit of fluoride release, which can aid in the remineralization process of the affected tooth structure. Composite resins, while also suitable for deep restorations, do not pose the same immediate inflammatory risk as zinc phosphate due to their composition and polymerization process.

Overall, the choice of cement material in deep restorations is crucial for minimizing the risk of pulpitis, and zinc phosphate cement is recognized for its potential to cause pulpal discomfort, thus making it a less desirable option.