title: Photocatalytic inactivation of biofilms on bioactive dental adhesives.
abstract: Biofilms are the most prevalent mode of microbial life in nature and are 10-1000 times more resistant to antibiotics than planktonic bacteria. Persistent biofilm growth associated at the margin of a dental restoration often leads to secondary caries, which remains a challenge in restorative dentistry. In this work, we present the first in vitro evaluation of on-demand photocatalytic inactivation of biofilm on a novel dental adhesive containing TiO2 nanoparticles. Streptococcus mutans biofilm was cultured on this photocatalytic surface for 16 h before photocatalytic treatment with ultraviolet-A (UV-A) light. UV-A doses ranging from 3 to 43 J/cm(2) were applied to the surface and the resulting viability of biofilms was evaluated with a metabolic activity assay incorporating phenol red that provided a quantitative measure of the reduction in viability due to the photocatalytic treatments. We show that an UV-A irradiation dose of 8.4 J/cm(2) leads to one order of magnitude reduction in the number of biofilm bacteria on the surface of the dental adhesives while as much as 5-6 orders of magnitude reduction in the corresponding number can be achieved with a dose of 43 J/cm(2). This material maintains its functional properties as an adhesive in restorative dentistry while offering the possibility of a novel dental procedure in the treatment or prevention of bacterial infections via on-demand UV-A irradiation. Similar materials could be developed for the treatment of additional indications such as peri-implantits.
authors.affiliation: Nanotechnology and Functional Materials, The Ångström Laboratory, Uppsala University, Uppsala, Sweden.
authors.forename: Yanling
authors.initials: Y
authors.lastname: Cai
authors.forename: Maria
authors.initials: M
authors.lastname: Strømme
authors.forename: Asa
authors.initials: A
authors.lastname: Melhus
authors.forename: Håkan
authors.initials: H
authors.lastname: Engqvist
authors.forename: Ken
authors.initials: K
authors.lastname: Welch
mesh_terms: D018441:Biofilms / Q000254:growth & development / Q000528:radiation effects*; D003731:Dental Caries / Q000517:prevention & control; D003738:Dental Cements / Q000009:adverse effects*; D003773:Dental Plaque / Q000382:microbiology / Q000532:radiotherapy; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000648:ultrastructure; D050296:Microbial Viability / Q000528:radiation effects; D008855:Microscopy, Electron, Scanning; D013295:Streptococcus mutans / Q000502:physiology / Q000528:radiation effects / Q000648:ultrastructure; D014025:Titanium; D014467:Ultraviolet Therapy
chemical_list: D003738:Dental Cements; C009495:titanium dioxide; D014025:Titanium
keywords: Streptococcus mutans; biofilm inactivation; metabolic activity assay; photocatalysis; titanium dioxide