Clinical


cleaning A


Canal


A review of the role of irrigation in contemporary root canal treatment by Adrian JA Stewart BDS, PG Dip Endo (UCL), MSc


pical periodon- titis has been established to be a micro- bial-induced


diseaseı-3. The aim of root


canal treatment is the preven- tion or treatment of apical periodontitis by the elimina- tion of microorganisms from the root canal system and the prevention of subsequent recontamination 4


. To this


end, our primary treatment modality is chemo-mechanical debridement of the root canal 5 Mechanical cleaning of the


.


root canal system with hand or rotary instruments has been shown to engage only a propor- tion of the root canal wall – 35 to 53 per cent of the canal wall surface may remain untouched following preparation6


. Fins,


lateral anatomy and commu- nicating canals render the goal of mechanical removal of all infected tissue impossible; therefore, after gross debride- ment of the vital and non-vital tissue from the canal, the main goal of mechanical preparation is to enable chemical disinfec- tion of the root canal 7


. The functions of endodontic


irrigation include: • Disinfection • Degradation of pulp tissue • Disruption of the biofilm • Removal of the smear layer


30 Ireland’s Dental magazine


Sodium Hypochlorite Sodium Hypochlorite (NaOCl) is recommended as the main endodontic irrigant due its ability to dissolve organic tissue and its broad anti-microbial


• Lubrication of endodontic instruments


• Flushing of debris from the canal In practice, no single


irrigant achieves all of these aims and a combination regime is recommended. Saline and local anaesthetic have each been employed but these provide only a flushing and lubricating function. Irriga- tion with such chemically inert media has been shown to be incapable of adequately reducing the viable microor- ganisms in infected root canal systems 5


.


use can be classified as anti- microbial or decalcifying 4


Irrigants in contemporary .


Mechanical instrumentation


has been shown to result in the burnishing of organic material and dentine debris against the canal wall and into depressions and lateral anatomy 8


. The role of decalcifying


agents such as EDTA incudes chelation of the mineral content of this “smear layer” and the opening of access to the lateral anatomy 9


. Fig 1


Top: A 27G cutaway irrigation needle Bottom: A 30G side-ported needle Middle: A Protaper F2 rotary file for comparison


spectrum 9. Its action on organic


tissue enables it to disrupt and kill biofilms adherent to the root canal walls. Concentrations in use in endodontics range from 0.5 to 5.25 per cent.


Chlorhexidine Chlorhexidine is a bisguanide, generally used in the form of chlorhexidine digluconate. As a root canal irrigant it is gener- ally presented in 2 per cent concentration. While several in vitro studies have shown anti-microbial efficacy to be similar to sodium hypochlo- rite, some in vivo studies have demonstrated chlorhexidine to be inferior with more culture reversals from negative to positive between visits. This is likely to be due to its inability to dissolve pulpal remnants ı0 The major advantages chlo-


.


rhexidine has over sodium hypochlorite are, lower toxicity,


less objectionable smell and taste, and substantivity, meaning it persists on the walls of the canals. Like sodium hypochlorite, chlorhexidine lacks the ability to dissolve the smear layer 4


. Chlorhexidine should not


be used in conjunction with sodium hypochlorite due to the formation of a precipitate or flocculate. This flocculate contains para-chloroaniline (PCA), which is known to be carcinogenic although the level of exposure in such cases is likely to be low. The pres- ence of the flocculate may lead to blockage of narrow anatomy and subsequently hinder adequate penetration of hypochlorite. Alternative concepts for


antimicrobial irrigation include electrochemically-activated water (eg. Sterilox), laser photo activated disinfection


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