An investigation into microbial contamination of orthodontic instruments and materials

• Main Author: Barker, Christopher Stuart
• Published: University of Bristol 2011
• Subjects: 617.64
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.555658

There is little information on the microbial contamination of orthodontic materials received from the manufacturer and if orthodontists pre-sterilise new products prior to use. These items may also become contaminated on the clinic or during laboratory construction. Recent regulations for decontamination in primary dental care (HTM 01- 05) have been introduced requiring a 60 day limit for storage time of sterilised instruments. The aims of this investigation were to determine whether components of fixed and removable orthodontic appliances are free from microbial contamination prior to clinical use; to establish the current practice in orthodontics with regard to pre- sterilisation of new products and to investigate possible re-contamination of sterilised dental instruments. A range of orthodontic materials "as received" from the manufacturer and "bench-top exposed" items were investigated. Bacterial contamination during the construction of removable appliances was evaluated from initial impression, through to delivery of the final appliance. Molecular microbiological techniques were used to obtain bacterial DGGE profiles and facilitate 16S rDNA identification. Questionnaires were distributed to consultant orthodontists to determine their current pre-sterilisation regimes for new orthodontic products. Twenty five dental mirrors were sterilised. These were tested (5 mirrors at each time point) for microbial contamination immediately after autoclaving and then at 31,60,90 and 124 days. Bacteria were isolated from "as received" bands, archwires and impression trays, but the level of contamination was low (0-3.65x102 cfu ml"). This was similar for clinic items. Much higher levels were found on removable appliances (0.97x102-1.52xl03 cfu mll ). There was no cross-contamination from patients to the laboratory; contamination occurred within the laboratory itself. The majority of consultant-led departments do not pre-sterilise materials from the manufacturer (88-97%). There was no bacterial growth from sterilised dental mirrors after 5 days of incubation at 37°C at any time period from 0 to 124 days post sterilisation. In conclusion, materials and appliances are not free from bacterial contamination prior to use in patients; improved cross infection control procedures are needed within the orthodontic laboratory. There is no current evidence for the 60-day storage of sterilised dental instruments as advised by the Department of Health.