Why do we irrigate?
Successful endodontic treatment, in agreement with what Prof. Schilder, the father of modern endodontics, enunciated, depends on the ability of the operator to mechanically and chemically clean the root canal system and subsequently obturate it three dimensionally.1
The endodontium consists of a space that is easily accessible to rotary and manual instruments (principal canals) and, as has been confirmed by numerous clinical and histological studies, there are spaces that are difficult to access or completely inaccessible (deltas, loops, isthmi, lateral and accessory canals, and dentinal tubules).
In particular lateral and accessory canals are found with significant frequency especially in the apical third of the root and in molar bifurcations.
Canal shaping is unable to reach some areas and they remain untouched by the instruments, no matter what technique is used; thus about half of the endodontium remains untreated.2
The complexity of the endodontium could, however, be one of the determining factors in failure of root canal treatment even in properly treated teeth, due to irregular and sometimes unpredictable spaces that characterize root canals.3-4
In the light of the above one of the most exciting challenges of modern endodontics is represented by the biochemical debridement of the endodontium (accessible and non accessible).
When debridement is performed according to the state of the art (three dimensional) cleaning, the endodontium can then be filled and sealed with cement and gutta-percha at the time of obturation.
Irrigation, therefore, plays a crucial role in determining the outcome of root canal treatment.
What irrigants should be used? A choice based on scientific evidence.
I remember back in my university days, I once took my father to his dentist, a general practitioner, as he had to have root canal treatment. I was particularly struck by the frenetic rinsing with a sodium chloride solution alternated with hydrogen peroxide and asked why this procedure was performed.
He answered that they had been taught to do it this way, without critically motivating his choice.
In every field of medicine, the clinical practitioner must follow logic and must be supported by literature.
Therefore, to rationally choose an irrigant you must first answer the question: “What do we want to remove from the canal?”
The answer is simple; we want to eliminate the organic tissue (pulp), bacteria and toxins, as well as organic and inorganic debris that our rotary and manual instruments inevitably produce.
At this point the choice is easy and natural.
Literature has highlighted sodium hypochlorite in a concentration of 6% as the irrigant of choice inasmuch as it is able to dissolve organic substances and eliminate the bacterial presence and the biofilm from inside the canal.5-10
Complete debridement is achieved by combining a substance capable of eliminating the inorganic component created after the instrumentation. It is
necessary to use a chelating agent namely 17% EDTA or 10% Citric Acid.11-14
A 2% Chlorhexidine aqueous solution has been suggested as an irrigant for the root canal system. This has an antibacterial action but lacks the ability to dissolve the organic and inorganic material.15-16
Furthermore mixing sodium hypochlorite and chlorohexidine generates a toxic and cancerous compound, parachloroanaline and its use as an irrigant is not recommended.17