Chlorhexidine-based antimicrobial coatings for titanium dental implants

• Main Author: Wood, Natalie Jane
• Published: University of Bristol 2015
• Subjects: 617.6
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.683729

Dental implants are a popular solution to missing teeth; they are predominantly formed from titanium due to its biocompatibility, corrosion resistance and high rate of osseointegration. While micro-roughening of the surfaces has been shown to increase osteoblast adhesion and proliferation, it has also been shown to increase the adhesion of bacteria and therefore the likelihood of implant infection and implant failure. Chlorhexidine is a broad spectrum antimicrobial agent used extensively in healthcare, particularly in oral care products such as mouthwash. It has previously been shown to adhere to titanium, forming a saturated surface layer within 60 s; these surfaces exhibited an antimicrobial efficacy against the oral bacterium Streptococcus gordonii. However, this effect was shown to be short-lived as the coated surfaces released their entire chlorhexidine payload within c.a. 2 days' immersion in water. The development of two surface coatings, based on nanoparticle and coacervate technology, is described in this thesis. The aim was to increase the surface retention of chlorhexidine on a titanium surface to provide antimicrobial functionality. An antimicrobial nanoparticle has been developed by combining chlorhexidine with hexametaphosphate. These particles form micron-sized surface aggregates on titanium substrates upon exposure to the nanoparticle suspension. The nanoparticle-coated titanium substrates elute soluble chlorhexidine for 230 days and exhibit an effective antimicrobial action against the oral primary coloniser S. gordonii and oral pathogen Porphyromonas gingivalis. An antimicrobial coacervate has been created through the combination of chlorhexidine and carboxymethyl dextran. When this suspension was drop-cast onto a titanium surface, a confluent film was formed; these film-coated surfaces exhibited an antimicrobial efficacy against S. gordonii. The film was released from the surface after immersion in water for 1 hour. Finally, by applying both coatings, a dual-action antimicrobial surface has been developed