What is the role of a liner in deep amalgam preparations?

• A. To protect the pulp when depth approaches the pulp and to promote dentin formation
• B. To seal margins
• C. To bond to enamel
• D. To provide a decorative layer

Answer: (A)

When the preparation nears the pulp, a liner serves to shield the pulp from irritation and to encourage the dentin-pulp complex to form reparative dentin. It creates a thin, biologically active barrier—calcium hydroxide liners are classic choices because their high pH and bioactivity stimulate dentin formation beneath the restoration. This protective effect is the primary reason for placing a liner in deep amalgam cases. It is not intended to seal margins like varnish or bonding agents, nor to bond to enamel, and it isn’t a decorative layer. After the liner, a base may be used for insulation before placing the amalgam.