Infiltrants

Infiltrants are substances or materials designed to penetrate into another solid, filling pores, capillaries, or voids in order to alter, reinforce, or seal the host material. Infiltration can occur by capillary action, diffusion, or under applied pressure, and the infiltrant may polymerize, cure, or remain as a liquid that modifies properties such as permeability, hardness, or moisture resistance. In many disciplines, infiltrants are chosen for low viscosity and compatibility with the substrate.

In dentistry, resin-based infiltrants are low-viscosity polymers used to penetrate early enamel caries lesions that are not yet cavitated. The infiltrant diffuses into porous subsurface enamel, then polymerizes to arrest demineralization and reduce lesion progression, often after etching. The approach aims to preserve tooth structure and avoid drilling, but effectiveness depends on lesion characteristics, technique, and proper clinical selection.

In civil and materials engineering, infiltrants are employed to seal pores, fill microcracks, or consolidate porous solids. Examples include resin or epoxy injections into concrete or stone, or wood impregnations with resins or waxes to improve durability and dimensional stability. In conservation and archaeology, infiltrants may stabilize fragile artifacts by penetrating and reinforcing porous substrates without overly altering appearance.

Limitations and safety considerations vary by material and application. Infiltrants may not fully penetrate large defects, may alter color or mechanical properties, or pose toxicity concerns if misused. Proper substrate preparation, compatibility, and cure control are essential to achieve the intended effects.