In-vitro Investigation of Nitrogen-doped Titanium Dioxide as an Antimicrobial Filler in Polymeric Bonding Agents

  • N. A. Ahmad Fauzi

Student thesis: Doctoral ThesisDoctor of Dental Surgery (DDS)


Aim: To develop a novel aesthetic resin composite using a nitrogen-doped
titanium dioxide (N-TiO2) filler that possesses photocatalytic antimicrobial
properties against cariogenic bacteria.
Setting: Biomaterials and oral microbiology laboratories, Bristol Dental School.
Design: In-vitro study to produce an aesthetic composite resin, with long-term
antimicrobial properties under visible light. This was done by incorporating a
N-TiO2 filler within the resin.
Methods: N-TiO2 powder was manufactured by heating commercial TiO2
with urea. Free radical release from the N-TiO2 powder under visible light
irradiation was analysed using spectrophotometry. The N-TiO2 powder was incorporated into dental resin and the photocatalytic activity assessed using a dye under both visible light and dark conditions. Using XTT assay to measure the cellular metabolic activity, the antibacterial properties of the N-TiO2 within the resin discs were tested against cariogenic bacteria.
Results: Doping nitrogen into TiO2 resulted in a band gap shift towards the visible light spectrum, which enabled the compound to release reactive oxygen species when exposed to visible light. When incorporated into dental resin, the N-TiO2 still demonstrated sustained release of reactive oxygen species, maintaining its photocatalytic activity and showing an antibacterial effect towards Streptococcus mutans under visible light conditions.
Conclusions: N-TiO2 filled resin showed great promise as a potential aesthetic resin-based adhesive for orthodontic bonding.
Date of Award26 Nov 2020
Original languageEnglish
Awarding Institution
  • The University of Bristol
SupervisorAnthony J Ireland (Supervisor), Bo Su (Supervisor) & H M H N Bandara (Supervisor)


  • Titanium dioxide
  • orthodontics
  • Bonding agents
  • White spot lesion

Cite this