Dental Bases and Liners: Functions, Materials, and Clinical Selection

Bases vs. Liners: Distinct Roles in Restorative Dentistry

Bases (Thicker, Load-Bearing)

Placed in deeper preparations to:

• Protect pulp from thermal, chemical, and galvanic irritation.
• Seal dentin tubules to reduce microleakage.
• Provide mechanical support for the restoration.
• Replace lost tooth structure (bulk).

Liners (Thin, Surface-Coating)

Applied as a thin layer on cavity floor/walls to:

• Seal dentin tubules and reduce postoperative sensitivity.
• Promote adhesion between tooth and restoration.
• Insulate pulp from temperature changes.
• Some provide remineralization (calcium hydroxide) or antibacterial effects.

Common Materials

Material	Typical Use	Key Properties
Glass Ionomer Cement	Base or liner	Fluoride release, chemical adhesion, biocompatible
Zinc Phosphate Cement	Base	High compressive strength, low pH initially
Zinc Oxide Eugenol (ZOE)	Base/liner (sedative)	Soothing to pulp, inhibits polymerization of resins
Calcium Hydroxide	Liner (direct/indirect pulp cap)	High pH, stimulates reparative dentin, antibacterial

Selection depends on cavity depth, remaining dentin thickness, restorative material, and pulp status.