Douglas P Robertson1, William Keys2, Riina Rautemaa-Richardson3, Ronnie Burns4, Andrew J Smith5. 1. Restorative Dentistry, Glasgow Dental School, Glasgow G2 3JZ, UK douglas.robertson.2@glasgow.ac.uk. 2. Dundee Dental School, University of Dundee, UK. 3. Respiratory Research Group, School of Translational Medicine, Education and Research Centre, Wythenshawe Hospital, Manchester, UK. 4. Parkhead Health Centre, Glasgow, UK. 5. Infection and Immunity Section, Glasgow Dental School, Glasgow, UK.