A microbiological assessment of aerosol generated during debond of fixed orthodontic appliances

The aim of this study was to describe the quantity and quality of the bacterial population ejected from the mouth during the process of removing fixed orthodontic appliances. Specifically, the aims were: 1. To estimate the total bacterial load of aerosol clouds generated during adhesive removal at the debond visit. 2. To estimate the numbers of different bacteria within that population and the depth within the human airway to which they may penetrate. 3. To examine and relationship between the patient's standard of oral hygiene and different methods of adhesive removal to the number and diversity of the sampled bacterial population. The study involved the sampling of ambient air adjacent to the patient's mouth, during the process of adhesive removal. Airborne particles were collected by an inertial impactor, which had six different levels simulating different levels in the human airway. Bacteria on the collected particles were cultured for analysis visually and by molecular techniques. The results showed that on average 75% of the bacteria sampled could not be cultured by conventional methods and required molecular analysis to determine their presence. Adhesive removal using a high speed, water-irrigated handpiece resulted in the production of a greater quantity of bacterially contaminated particles, compared the aerosol generated when using a slow speed handpiece. High speed debonding also resulted in those particles being of smaller size and having potential to penetrate deeper into the respiratory system than slow speed aerosol. The concentration or complexity of the bacterial population collected did not appear to be related to a patient's standard of oral hygiene, nor were these factors reduced by the use of a Chlorhexidine or sterile water pre-operative mouth rinse. Regardless of the method of adhesive removal, contaminated particles are generated in a range of sizes, a proportion of which have potential to be inhaled to the deepest level of the lung, i.e. the pulmonary alveoli. It is therefore important that clinical staff take appropriate measures to protect the airway during adhesive removal, e.g. the use of face masks.EThOS - Electronic Theses Online ServiceGBUnited Kingdo