Which statement about liners is true?

• A. They increase whitening
• B. They provide electrical, thermal, and pulpal protection
• C. They permanently bond to enamel
• D. They dissolve dentin

Answer: (B)

Liners are thin protective layers placed on dentin near the pulp to shield the pulp from irritation during cavity restoration. Their primary role is to provide insulation against temperature changes and electrical stimuli, as well as chemical protection from the restorative materials and acids used in caries removal. This helps maintain pulpal health by reducing sensitivity and inflammation. They’re not whitening agents, they don’t form a permanent bond to enamel, and they don’t dissolve dentin. Some liners can release beneficial ions like calcium or fluoride to support dentin healing, but the essential point is that their purpose is pulpal protection along with thermal and electrical insulation.