Preclinics of Conservative Dental Medicine · MU Sofia
44. Irrigation of the root canal system – ideal irrigant, solutions, mode of action, armamentarium, technique, activation.
Covers root canal irrigation as the chemical half of chemomechanical preparation, setting out its five aims and the properties of an ideal irrigant. A table compares sodium hypochlorite, EDTA, chlorhexidine, citric acid and saline by concentration, action and limits. It then explains hypochlorite's mode of action, the sequence of irrigants, the syringe and needle setup with a step-by-step technique, and four activation methods, ending with key points.
Topic 44 of 53 in the MU Sofia syllabus for Preclinics of Conservative Dental Medicine (Dental Medicine, Year 3). The free AceMed note covers it in 6 sections, about 866 words (7 min of reading), with 17 flashcards.
In this note
Introduction
Aims and the ideal irrigant
Solutions and mode of action
Armamentarium and technique
Activation
Key points
Introduction
Irrigation is the chemical half of chemomechanical preparation. Files shape the canal but leave a large part of its wall untouched – fins, isthmuses, oval extensions, lateral canals – and only a liquid reaches these areas. Accidents during irrigation belong to topic 45.
Aims and the ideal irrigant
Irrigation has five aims:
flushing – washes out dentin chips and debris, so they are not packed apically and do not block the canal;
tissue dissolution – dissolves vital and necrotic pulp remnants where files do not reach;
antimicrobial action – kills microorganisms and disrupts biofilm;
smear layer removal – the 1–2 µm layer of organic and inorganic debris that instruments smear over the wall and into the tubules;
lubrication of instruments, which lowers friction and the risk of file fracture.
The ideal irrigant is broadly antimicrobial (also against biofilm), dissolves organic tissue, removes the smear layer, inactivates endotoxin, is non-toxic to periapical tissues, has low surface tension (wets and penetrates), acts for a long time (substantivity), does not weaken dentin or stain the tooth, and is cheap, stable and easy to use. No single solution has all these properties, so irrigants are used in sequence: sodium hypochlorite for the organic part, a chelator (EDTA) for the inorganic part.
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