smeerlaag

Smeerlaag, in dental terminology often translated as smear layer, is a thin, irregular layer that forms on dentin surfaces and root canal walls during instrumentation with dental burs, ultrasonic tips, or other cutting tools. It is a composite of organic and inorganic debris, including dentin particles, remnants of pulp tissue, microorganisms and their by-products, salivary proteins, and other contaminants from the procedural environment.

The layer can obscure or partially occlude dentinal tubules and may influence the behavior of subsequent treatments. Depending on the context, the smear layer can hinder the penetration of disinfectants, irrigants, and bonding agents, potentially affecting the sealing of restorations or root canal fillings. Some view it as a protective barrier that limits tubule irritation, but contemporary practice generally aims to remove or modify it to improve disinfection and bonding.

Removal and management of the smear layer typically involve irrigation protocols that combine organic and inorganic removal. Sodium hypochlorite is used to dissolve organic material, while chelating agents such as EDTA or citric acid target inorganic components. These agents are often used with sonic or ultrasonic activation to enhance efficacy. Alternative approaches include specialized irrigants like MTAD or chlorhexidine-based protocols, and in some cases laser or photodynamic methods.

Clinical implications vary by discipline. In endodontics, smear layer removal is commonly favored to enhance disinfectant penetration and sealant bonding. In restorative dentistry, removal often improves bonding to dentin, though care is taken to minimize unnecessary dentin removal and sensitivity. The decision to remove or preserve the smear layer depends on material choice, technique, and clinical goals.