Development of a Chlorhexidine-Hexametaphosphate Coating for Titanium to Combat Early Implant Failure

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)


Dental implants are becoming an increasingly popular way to replace missing teeth. Whilst implant survival rates are high, a small number fail soon after placement, with bacterial contamination a principal cause. Bacterial contamination of the implant surface can disrupt osseointegration; the process by which the implant becomes anchored into bone. This work describes the development of a chlorhexidine hexametaphosphate coating for titanium that slowly hydrolyses to release the antiseptic agent chlorhexidine. The aim was to develop a coating that released sufficient chlorhexidine to demonstrate an antimicrobial effect, whilst simultaneously allowing attachment, proliferation and differentiation of human cells involved in osseointegration.
A range of methods were investigated to coat sand blasted and acid etched titanium substrates with chlorhexidine hexametaphosphate. Following initial development, two coatings demonstrated gradual chlorhexidine release over several hours, and were taken forward for antibiofilm efficacy and cytocompatibility testing.
A multispecies biofilm model was developed, characterised, and used to determine the efficacy of the coatings in preventing bacterial biofilm formation on the coated titanium substrates. Cytocompatibility testing was undertaken using human mesenchymal stem cells; the ability of these cells to attach, metabolise, proliferate, and differentiate into bone forming osteoblasts was evaluated.
Results demonstrated that both coatings significantly reduced the biofilm biomass formed up to 72 hours, with a concurrent reduction in metabolic activity in the first 24 – 48 hours. One coating appeared to be cytocompatible, with cells able to perform normal functions and commence osteoblastic differentiation, albeit at a slower rate than those grown on uncoated titanium.
With further refinement, these coatings may have application in the prevention of bacterial contamination of dental implants at surgery. This could contribute to a reduction in rates of early implant failure.
Date of Award24 Mar 2020
Original languageEnglish
Awarding Institution
  • The University of Bristol
SponsorsMedical Research Council
SupervisorMichele E Barbour (Supervisor) & Angela H Nobbs (Supervisor)

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