<bold id="s-d38037e3a46b"> P</bold>
<bold id="s-79cefc099519">roperties of CHX in root canal procedures</bold>
Anti-microbial action of 2% CHX in root canal system- There is a highly significant reduction in the number of microorganisms in the Chlorhexidine-treated specimens after instrumentation and irrigation.
Antibacterial activity against Actinomyces israelii –
Basson & Tait (2001) compared the ex vivo effectiveness of calcium hydroxide, iodine potassium iodide and a CHX solution in disinfecting root canal systems that were infected with Actinomyces israelii. The root canals were exposed to either IKI, calcium hydroxide or 2% CHX for periods of 3, 7 and 60 days. CHX was the only disinfectant that was able to eliminate A. israelii from all samples at all time periods whilst 25% of the specimens treated with IKI and 50% of the specimens treated with Ca(OH)2 still had viable A. israelii after treatment 5.
Antibacterial activity against E. faecalis –
Oncag et al. (2003) evaluated the antibacterial properties of 5.25% sodium hypochlorite, 2% CHX and 0.2% CHX plus 0.2% cetrimide (Cetrexidin) after 5 min and 48 h in extracted human teeth after the canals had been infected by Enterococcus faecalis. The 2% CHX and Cetrexidin were significantly more effective against E. faecalis than the 5.25% NaOCl at both time slots 5.
Antibacterial activity against Staph, Candida & other microbes –
Besides the antibacterial action on E. faecalis & A. israelii, it has been demonstrated that CHX is also antibacterial in action against various bacteria as well as fungi. Two studies (Gomes et al. 2001, Vianna et al. 2004) have investigated the ex vivo antimicrobial activity against endodontic pathogens of three concentrations (0.2%, 1% and 2%) of two forms of CHX (gel and liquid) and compared them with five concentrations of NaOCl (0.5%, 1%, 2.5%, 4% and 5.25%). Both the 2% gel and 2% liquid formulations of CHX eliminated Staphylococcus aureus and Candida albicans within 15 s, whereas the gel formulation killed E. faecalis within 1 min. All of the tested irrigants eliminated Porphyromonas endodontalis, Porphyromonas gingivalis and Prevotella intermedia within 15 secs. The time required for 1.0% and 2.0% CHX liquid to eliminate all microorganisms was the same as the time required for 5.25% NaOCl.
Ercan et al.19 evaluated the antibacterial activity of 2% CHX and 5.25% sodium hypochlorite in infected root canals of incisors and premolars and concluded that both CHX and sodium hypochlorite were significantly effective in reducing the microorganisms in the teeth with necrotic pulps, periapical pathologies, or both, and could be used successfully as an irrigant solution 2.
2. Tissue dissolving action- Although chlorhexidine is a potent antibacterial tissue dissolving capability is very little or nil in comparison to NaOCl. Chlorhexidine is a potent antiseptic, which is widely used for chemical plaque control in the oral cavity. Solutions of 0.1 to 0.2% are normally used for periodontal therapy, while 2% is the concentration of root canal irrigating solutions usually found in the endodontic literature. Chlorhexidine does not have any tissue dissolution properties and therefore cannot be used as a primary irrigant in Endodontics. It is however used as an adjuvant to NaOCL.
NaOCl dissolves the organic tissue effectively & kills microbes and EDTA dissolves the inorganic tissue effectively at the concentration of 17% 6 .
3. Post-op pain- In comparison to sod. Hypochlorite the post-operative pain with chlorohexidine at 6TH hour after irrigation was less with chlorhexidine. There was more post-op pain significantly in teeth irrigated with 5.25% NaOCl in comparison to teeth that were irrigated with 2% CHX 7. But at other time periods like after 24 hours, 4th, 7th day there was no significant difference in the pain level in between two.
4. Substantivity- Chlorhexidine is shown to have the unique ability to bind to the proteins present in human tissues. Protein bound chlorhexidine releases slowly leading to prolonged activity & this phenomenon is known as substantivity that allows for a longer duration of antimicrobial action against a broad spectrum of bacteria and fungi. It is considered that the delivery of an agent to its site of action, in a biologically active form, and in effective doses, increases this agent effects for prolonged periods of time.
Substantivity of chlorhexidine, or its ability to be retained in dentin matrices, could be the reason why chlorhexidine-treated acid-etched dentin may form hybrid layers that are more stable over time. The success of chlorhexidine in increasing the durability of resin-dentin bonds requires that more efforts be made toward understanding the mechanisms responsible for chlorhexidine binding to mineralized and demineralized dentin, in an attempt to optimize how chlorhexidine should be used clinically to maximize its retention and effectiveness 8.
5. Less cytotoxic- The major advantages of chlorhexidine over NaOCl are its lower cytotoxicity and lack of foul smell. Although clinically, 5.25% NaOCl & 17% EDTA has been advocated; but these have serious limitations that include marked reduction in mechanical properties of dentin and erosion of dentinal tubular microstructure. Most complications of the use of NaOCl is its accidental injection beyond the root apex which can cause violent tissue reactions characterized by pain, swelling, hemorrhage, and in some cases, development of secondary infection & paresthesia. In one study, results suggest that chlorhexidine was least cytotoxic followed by IKI and MTAD at any test concentration and NaOCl was most cytotoxic 9.
6. Intracanal medicament- Chlorhexidine is one of the most versatile medicaments in dentistry in both vital as well as non-vital tooth, mainly because of its alkaline pH & also because of its antibacterial action, it can neutralize the remaining tissue debris in root canal. CHX when used as an intracanal medicament is more effective than calcium hydroxide in eliminating E. faecalis from inside dentinal tubules.
7. CHX & Dentin bonding- Coronal leakage involves the recontamination of the tooth's interior. It is a major contributor to endodontic failure. It has been shown that chlorhexidine application prior to acid etching has no adverse effect on immediate composite adhesive bonds in coronal dentine & pulp chamber dentin. Erdemir et. al, reported that endodontic irrigation with chlorhexidine solution significantly increases the bond strength to root dentin. In vitro & in vivo studies, application of 2% chlorhexidine in cavities after acid etch & before hybridization with adhesive monomers prevents the loss of bond strength with time & preserves the integrity of hybrid layer. In radicular dentin, use of chlorhexidine as an endo irrigant may also inhibit the bacteria related activation of metalloproteinases 3.
8. Allergic reactions to CHX- Although sensitivity to chlorhexidine is rare, contact dermatitis is a common adverse reaction. Apart from that, chlorhexidine is liable to a number of rare side effects, such as desquamative gingivitis, discoloration of teeth and tongue or dysgeusia (distorted taste) 2
Interaction of CHX & NaOCl-
The combination of sodium hypochlorite (NaOCl) and chlorhexidine (CHX) forms a precipitate. The presence of the precipitate that is formed due to interaction between NaOCl and CHX has negative effect on the sealing ability of gutta-percha and AH26 sealer 10.