Influence of sodium hypochlorite on the permeability and structure of cervical human dentine

The effect of 5% sodium hypochlorite and 35% hydrogen peroxide on dentine samples in vitro was investigated. It was demonstrated that both 5% NaOCl and 35% H2O2 depletes the dentine, which can be recorded as weight loss. Sodium hypochlorite removes approximately 14% of dry weight from dentine samples in 24 h; hydrogen peroxide is half as destructive. The hydraulic conductance (Lp) of dentine after treatment with NaOCl is increased over 100%. It is suggested that the use of high concentrations of sodium hypochlorite during root canal treatment may negatively affect the integrity of the root canal wall thereby allowing increased access of caustic bleaching fluids to cervical vital tissues.