title: Dental adhesives with bioactive and on-demand bactericidal properties.
abstract: OBJECTIVE
  The aim of the present work was to perform the first in vitro evaluation of a new interfacial bond-promoting material-and-method concept for on-demand long term bacteria inhibition in dental restoration procedures.
  
  
  METHODS
  The bioactivity, mechanical bonding strength and photocatalytic bactericidal properties, induced by low dose ultraviolet-A (UV-A) irradiation of dental adhesives containing crystalline titania nanoparticles (NPs), were analyzed.
  
  
  RESULTS
  Dental adhesives with a NP content of 20wt% were shown to be bioactive in terms of spontaneous hydroxylapatite formation upon storage in simulated body fluid and the bioactivity was found to be promoted by chemical etching of the adhesives. The mechanical bonding strength between the adhesives and a HA tooth model was shown to be unaffected by the NPs up to a NP content of 30wt%. Elimination of Staphylococcus epidermidis in contact with the adhesives was found to depend both on UV photocatalytic irradiation intensity and time. Efficient elimination of the bacteria could be achieved using a UV-A dose of 4.5J/cm(2) which is about 6 times below the safe maximum UV dose according to industry guidelines, and 20 times below the average UV-A dose received during an ordinary sun bed session.
  
  
  CONCLUSIONS
  The combined features of bioactivity and on-demand bactericidal effect should open up the potential to create dental adhesives that reduce the incidence of secondary caries and promote closure of gaps forming at the interface towards the tooth via remineralization of adjacent tooth substance, as well as prevention of bacterial infections via on-demand UV-A irradiation.
authors.affiliation: Uppsala University, Sweden. ken.welch@angstrom.uu.se
authors.forename: Ken
authors.initials: K
authors.lastname: Welch
authors.forename: Yanling
authors.initials: Y
authors.lastname: Cai
authors.forename: Håkan
authors.initials: H
authors.lastname: Engqvist
authors.forename: Maria
authors.initials: M
authors.lastname: Strømme
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D001840:Dental Bonding; D003799:Dental Stress Analysis; D017886:Durapatite; D008422:Materials Testing; D008826:Microbial Sensitivity Tests; D053758:Nanoparticles; D055668:Photochemical Processes; D019279:Resin Cements / Q000737:chemistry* / Q000494:pharmacology / Q000528:radiation effects*; D013212:Staphylococcus epidermidis / Q000187:drug effects*; D013718:Tensile Strength; D014025:Titanium; D014466:Ultraviolet Rays
chemical_list: D000900:Anti-Bacterial Agents; D019279:Resin Cements; C009495:titanium dioxide; D017886:Durapatite; D014025:Titanium