Irrigation

In Vitro-the antibacterial effect of CHX

• In vitro, CHX is superior to NaOCl in killing of E. faecalis and Staphylococcus aureus.
• Gomes et al. (2001)
• Oncag et al. (2003)
• Vianna et al. (2004)
• CHX effectively killed C. albicans
• Barkvoll P & Attramadal A (1989)
• Hiom e al. (1992)
• Hamers et al. (1996)
• Waltimo et al. (1999)

In vivo-the antibacterial effect of CHX

• There are no in vivo studies yet available that would confirm the better activity of CHX against E. faecalis in the infected root canal.

MOLECULAR STRUCTURE AND MECHANISM OF ACTION

• Chlorhexidine is a cationic molecule and consists of two symmetric 4-chlorophenly rings, and two bisguanide groups connected by a central hexamethylene chain. Chlorhexidine has a pH of 5.50-7.00 (American Society of Health-System harmacists, 2003). The most common preparation is with the digluconate salt because of its stability and high water solubility
• Being dicationic it electrostatically binds to negatively charged surfaces of bacteria damaging the outer layers of the bacterial cell wall and rendering it permeable. The resulting penetration of chlorhexidine into the cell causes precipitation of the cytoplasm, preventing repair of cell membrane and leading to the destruction of the bacterial cell. At low concentrations, chlorhexidine is only bacteriostatic, causing low molecular weight substances such as potassium and phsphorous to leak out without the cell being irreversibly damaged.
• At higher concentrations it causes irreversible cell damage by precipitation of cytoplasm.
• At neutral pH its action is unimpeded but at acidic pH its action is reduced.