Preclinics of Conservative Dental Medicine · MU Sofia
23. Third principle of caries treatment – liners and insulation bases: requirements, types of materials, configurations and placement.
Covers the intermediate layers placed between deep dentin and the filling: varnishes, liners and bases, with their thicknesses and the biological, thermal, electrical and strength requirements they must meet. It then lists the main materials with their uses and cautions, and a table of approximate layering by remaining dentin thickness. Placement steps, the closed and open sandwich techniques, and common mistakes close the note.
Topic 23 of 53 in the MU Sofia syllabus for Preclinics of Conservative Dental Medicine (Dental Medicine, Year 3). The free AceMed note covers it in 7 sections, about 808 words (7 min of reading), with 17 flashcards.
In this note
Introduction
Definitions and thicknesses
Requirements
Materials
Configuration and placement
Main mistakes
Key points
Introduction
Before a cavity is filled (obturatio cavi dentis, the third principle of caries treatment), deep dentin needs an intermediate layer between the restoration and the pulp. Liners and insulating bases protect the pulp from chemical, thermal and electrical injury and support the filling; placed wrongly or too thick, they weaken the restoration and cause leakage.
Definitions and thicknesses
Cavity varnish / sealer: a film only micrometres thick (copal varnish about 2–5 µm) that seals the dentinal tubules and reduces early leakage under amalgam. No insulation, no strength; today an adhesive or a desensitiser usually replaces it.
Liner: a thin layer, usually up to 0.5 mm, on the dentin nearest the pulp. It is a chemical barrier and, when it contains calcium hydroxide or calcium silicate, a therapeutic (medicated) liner: antibacterial and stimulating tertiary (reparative) dentin.
Base (insulating base, dentin substitute): a thicker layer, usually 1–2 mm, that replaces lost dentin, insulates the pulp, supports the restoration and gives a flat floor.
Liners protect the pulp biologically; bases insulate and carry load. Both cover only dentin, never the enamel margins.
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