Abstract from Håkon Valens lecture at symposium PDT-4. Human antimicrobial PDT. ESP-IUPB World Congress, Light & Life, Barcelona, Spain. August 25-30. 2019. Bacteria in the oral cavity lives primarily in polymicrobial biofilms. Oral mature biofilms may contain several hundred different bacterial species, and over 600 different species have been shown to colonize the oral cavity. […]