Weinvestigatedtheeffectofphotodynamictherapy(PDT)withhematoporphyrinmonomethylether(HMME)ontheviabilityofStreptococcusmutans(S.mutans)cellsonbiofilmsinvitro.Streptococcusmutansistheprimaryetiologicalagentofhumandentalcaries.Sincedentalcariesarelocalizedinfections,suchplaque-relateddiseaseswouldbewellsuitedtoPDT.Thediodelaserusedinthisstudyhadthewavelengthof635nm,whoseoutputpowerwas10mWandtheenergydensitywas12.74J/cm~2.HMMEwasusedasphotosensitizer.Sampleswerepreparedandpidedintofivegroups:(1)HMME;(2)Laser;(3)HMME+Laser;(4)Controlgroup(+)withchlorhexidine;and(5)Controlgroup(-)withsterilephysiologicalsaline.InoculumofS.mutansincubatedwithHMMEalsoexaminedwithfluorescencemicroscopy.PDTexhibitedasignificantly(P<0.05)increasedantimicrobialpotentialcomparedwith20μm/mLHMMEonly,laseronly,0.05%chlorhexidine,and0.9%sterilephysiologicalsaline,whichreducedtheS.mutansofthebiofilmmosteffectively.Laserand0.05%chlorhexidinewerecausedreductionintheviablecountsofS.mutanssignificantlydifferent(P<0.05)also,butthesetwotesttreatmentsdidnotstatisticallydifferfromeachother.HMMEgroupdidnotstatisticallydifferwithnegativecontrolgroup.FluorescencemicroscopyindicatedthatHMMElocalizedprimarilyintheS.mutansofthebiofilm.ItwasdemonstratedthatHMME-mediatedPDTwasefficientatkillingS.mutansofbiofilmsandausefulapproachinthetreatmentofdentalplaque-relateddiseases.
