the invention relates to a method for reducing the viability of detrimental oral microorganisms in an individual , said method comprising subjecting the individual &# 39 ; s oral cavity to a bioactive glass , the average particle size of which is less than 100 μm . furthermore , this invention concerns a method for the prevention of dental caries and / or gingivitis in an individual , said caries being caused by a cariogenic bacteria ; or for prevention or treatment of periapical infections . further the invention relates to a method for the whitening and / or mechanical cleaning of an individual &# 39 ; teeth .