Determination of Minimum Inhibitory Concentration (MIC) of a PolyHexamethylene Biguanide (PHMB) Solution: A Potential Root Canal Irrigant

Background: A polymeric biguanide ‘PolyHexaMethylene Biguanide’ (PHMB) was evaluated for its Minimal Inhibitory Concentration (MIC) against ATCC reference laboratory strain of Enterococcus faecalis (E. faecalis).

Methods: The MIC was determined using criteria’s laid down in DIN 58940-7 and 58940-8 and the corresponding supplementary sheets. Serial dilutions of PHMB were tested against E. faecalis in 96-well microtitre plates and MIC was read as the minimal concentration that allowed no visible growth.

Results: The MIC for PHMB against tested organism was found to be 2 gm/ L (0.2%).

Conclusion: Lower MIC value (2 gm/ L (0.2%)) of PHMB solution against E. faecalis is an indicator of its higher potency against the said microorganism and paves way to further research in its potential use as a root canal irrigant.