IADR Abstract Archives
Bubble Formations by Sodium-Hypochlorite Limit its Penetration but not for Chlorine-Dioxide During Endodontic Irrigation
Objectives: Success of endodontic treatment depends on the microbial eradication efficiency from the complex root canal system. Irrigants used for chemical disinfection should be able to penetrate into all hidden pulpal parts. However, during irrigation gas bubbles are formed and stay trapped locking tubules or canals, therefore the irrigants are not able to pass mechanically through. Our aim of was to investigate whether irrigants are able to penetrate (evaporate into and redissolve distally) through the obstructive gas bubbles.
Methods: 1) One uL of Enterococcus feacalis suspension (ATCC29212, 9x107CFU/ml) was placed on inoculation loops above 37C° 10 mL of 2.5% sodium-hypochlorite (NaOCl) or 0.12% hyperpure chlorine-dioxide (ClO2) or distilled water (dH2O) in airtight bottles. One and 10 minutes later the surviving bacteria were plated and two days later the growing colonies were counted. 2) Durham tubes filled up with bacterial suspension were placed in closed Eppendorfs in which the level of irrigants was lower than the orifice of Durham. After 10 minutes in 37C° thermostat, surviving bacteria were measured by the above method. 3) The penetration depths of irrigants were determined by bleaching of stains centrifuged into dentinal tubules by microscopy.
Results: 1) Gas phase of ClO2 killed all bacteria already in one minute. NaOCl decreased initial bacterial count only with one order of magnitude, while dH2O did not alter the bacteria amount. 2) Redissolved ClO2 eradicated totally the bacteria, while NaOCl and dH2O were inefficient. 3) Gas bubbles were formed during NaOCl infiltration and the reaction-diffusion front was limited around 300 µm.
Conclusions: Gas bubbles produced by NaOCl reactions stop its own penetration, therefore unviolated bacteria can remain after its application. ClO2 is volatile and have powerful antibacterial effects in both gas and redissolved phases. Therefore, we suggest to apply ClO2 as a final irrigant for more efficient disinfection. Supported by Hungarian NKFIH_OTKA_K112364 and KFI_16-1-2017-0409.
Methods: 1) One uL of Enterococcus feacalis suspension (ATCC29212, 9x107CFU/ml) was placed on inoculation loops above 37C° 10 mL of 2.5% sodium-hypochlorite (NaOCl) or 0.12% hyperpure chlorine-dioxide (ClO2) or distilled water (dH2O) in airtight bottles. One and 10 minutes later the surviving bacteria were plated and two days later the growing colonies were counted. 2) Durham tubes filled up with bacterial suspension were placed in closed Eppendorfs in which the level of irrigants was lower than the orifice of Durham. After 10 minutes in 37C° thermostat, surviving bacteria were measured by the above method. 3) The penetration depths of irrigants were determined by bleaching of stains centrifuged into dentinal tubules by microscopy.
Results: 1) Gas phase of ClO2 killed all bacteria already in one minute. NaOCl decreased initial bacterial count only with one order of magnitude, while dH2O did not alter the bacteria amount. 2) Redissolved ClO2 eradicated totally the bacteria, while NaOCl and dH2O were inefficient. 3) Gas bubbles were formed during NaOCl infiltration and the reaction-diffusion front was limited around 300 µm.
Conclusions: Gas bubbles produced by NaOCl reactions stop its own penetration, therefore unviolated bacteria can remain after its application. ClO2 is volatile and have powerful antibacterial effects in both gas and redissolved phases. Therefore, we suggest to apply ClO2 as a final irrigant for more efficient disinfection. Supported by Hungarian NKFIH_OTKA_K112364 and KFI_16-1-2017-0409.