Chlorhexidine Nanoparticles in the Management of Peri-implant Diseases

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The aim of this research is to design and optimise a coating for dental implants that prevents infection.Dental implants can be used to replace a missing tooth or teeth. They are titanium screws which are surgically placed into the jaw, acting as an artificial root to which false teeth can be attached. They allow a patient to eat, speak and socialise more normally than they would without teeth. They are used to treat patients who have lost teeth due to decay, gum disease, major trauma such as road traffic accidents, and head and neck cancers. Approximately 1.5 million people in the UK have dental implants, with numbers increasing every year.After implant placement in the jaw, bone cells (osteoblasts) attach to the surface, laying down new bone and securing the implant in position. This important process is known as 'osseointegration', and takes 6-12 weeks. It permanently anchors the implant in the bone.Osseointegration can, however, be compromised by infection. During or after surgery the implant can be colonised by bacteria. This can lead to inflammation and discomfort (peri-implant mucositis), and, if untreated, can destroy surrounding gum and bone (peri-implantitis). This usually means that the implant is no longer functional, and requires removal. There is often not enough bone left to place a new implant, meaning that either a bone graft or denture is necessary to replace teeth. This can impact on the patient's confidence whilst eating, speaking and socialising. These implant infections can occur in any patient, but particularly affects older or unwell patients, such as those who have had cancer or major trauma.An infection can develop at any point within the lifespan of the implant; immediately after placement in the jaw, or months to years later. Up to 43% of implants develop infection and there is no consensus among clinicians or scientists how to best prevent or treat it. Current methods include professional implant cleaning by a dentist, cleaning with one or more chemicals, and use of antibiotics.Recently, tiny particles ('nanoparticles') have been developed that release an antiseptic agent, chlorhexidine. Chlorhexidine is already used widely in healthcare, including as a pre-operative skin cleanser, in mouthrinse to treat oral infection, in eye drops and in wound dressings. It treats infection by killing the organisms which cause it, including bacteria, fungi and some viruses.Previous research has shown a benefit in using chlorhexidine in the prevention and treatment of dental implant infections, but it has not been investigated in nanoparticle form. During my research project, I will coat titanium with these nanoparticles to determine if they could be used to prevent dental implant infections.I will develop methods to produce an even coating that leaves enough titanium uncovered to allow osseointegration. I will test this coating on bacteria taken from patients with implant infections to find the strength of its antibacterial effect. I will also clarify whether the nanoparticles are harmful to osteoblasts. Based on these combined results, I will optimise the coating for dental implants.If the coating is shown to have a long-term antimicrobial effect, whilst not affecting osseointegration, it could offer a simple and effective prevention for dental implant infections. Information gained from this project could also be useful in other areas of medicine, including joint replacements for hips and knees which are also made from titanium and suffer from similar problems with infection. This means the research could have an impact on infection prevention for many types of implant, not just in dentistry.With a rising number of dental implants in an ageing population, a straightforward method for prevention and treatment of implant infections is a priority for dentists. The global increase in antibiotic resistance means a strategy not reliant on antibiotics is essential.