In teeth sealed to eliminate microleakage, which material is used?

• A. Zinc phosphate cement
• B. Resin cement
• C. Glass ionomer
• D. Polycarboxylate cement

Answer: (A)

Minimizing microleakage depends on creating a tight, durable bond between the tooth and the restorative material so fluids cannot travel at the margin. The material that best supplies this seal is capable of chemically bonding to dentin or enamel, remains stable in the moist oral environment, and resists dissolution after setting.

Zinc phosphate cement relies mainly on a mechanical, film-thickness seal and does not form a chemical bond to tooth tissue. Its acidic setting reaction can irritate the pulp, and it has relatively higher solubility in the mouth, all of which make it less than ideal for preventing microleakage over time.

Glass ionomer cements, on the other hand, form a chemical bond with dentin and enamel through ionic exchange, have good resistance to dissolution after setting, and often release fluoride that can help thwart secondary caries. These properties give a more reliable marginal seal and better control of microleakage, which is why glass ionomer is commonly used in situations where minimizing leakage is a priority.

Resin cements can also provide excellent, highly durable seals when proper bonding protocols are followed, but they are technique-sensitive. Polycarboxylate cements offer some bonding but generally do not seal as effectively as glass ionomer or modern resin systems.

So the key concept is that a material offering chemical bonding to tooth structure, low solubility, and stable marginal sealing is preferred to eliminate microleakage, with glass ionomer cement being a prime example.