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Dental Tribune United Kingdom Edition

July 11-17, 201122 United Kingdom EditionClinical T he most commonly used irrigant in endodontics is sodium hypochlorite. This is a highly alkaline dis- infectant that can dissolve pul- pal tissue and kill most of the bacteria found in infected root canal systems. However it is a highly caustic solution that can cause tissue damage, espe- cially if forced into the periapi- cal tissues, and can also dam- age instruments and clothes. Sodium hypochlorite has many undesirable side effects and an alternative is always be- ing sought. One of the causative agents in failure of root-filled teeth is enterococcus faecalis, which is resistant to the alkaline so- lutions. Consequently, endo- dontists encourage the use of chlorhexidine not only as an endodontic irrigant but also as a final rinse to give long term protection to root canals before obturation. Chlorhexidine itself is a chemical antiseptic that has been used at a low concen- tration of 0.2 per cent as a mouthwash for many years, primarily to reduce plaque and gingivitis. Prolonged use can cause marked tooth discolour- ation as well as altered taste sensation. Higher concentra- tions have been used as a skin wash, although there are case reports of urticaria and contact dermatitis. Chemically chlorhexidine is a cationic bisguanide which is highly lipophyllic and interacts with cell membrane phosphol- ipids and lipopolysaccharides and is consequently bacteri- cidal. It is active against a wide spectrum of bacteria especially gram positives, less so on gram negatives and is also active against fungi. It has proved very effective against E. Fae- calis which has proved resist- ant to sodium hypochlorite and calcium hydroxide and is found in failing root-filled teeth. Much research has been done on the ideal concentra- tion of chlorhexidine for use as an irrigant and the results are often conflicting. A few stud- ies have shown 0.12 per cent Chlorhexidine (ie chlorhexi- dine mouthwash) as effective as 2.5 per cent sodium hy- pochlorite. As an anti-bacterial the majority indicate that the optimal concentration is two per cent. At low concentrations it can take many hours to kill bacteria in a tooth. This can be shortened to minutes at a high- er concentration. Interestingly (for endodon- tists) chlorhexidine has a pro- longed bacteriostatic action. This is an action termed ‘sub- stantivity’. Following irrigation the chlorhexidine binds to sur- rounding tissues and has a slow release affect over an extended period. This can therefore in- Chlorhexidine as an endodontic irrigant Michael Sultan discusses using irrigants in endodontics ‘Chemically chlo- rhexidine is a cationic bisguanide which is highly lipophyllic and interacts with cell membrane phos- pholipids’