Smith, Gordon William Graham
Biofouling of dental handpieces.
PhD thesis, University of Glasgow.
Full text available as:
Dental handpieces (HP’s) are used during semi-critical and critical dental procedures that imply the HP must be sterile at the point of use. The aim of this study was to undertake a quantitative and qualitative analysis of dental HP contamination to inform the development of HP cleaning. Preliminary validation work on protein desorbtion methods and protein detection assays resulted in boiling in 1% sodium dodecylsulphate (SDS) and the o-phthaldialedhyde (OPA) assay (sensitivity 5 μg/ml) selected for further use in this study. A quantitative and qualitative analysis of HP microbial and protein contamination was then undertaken. Before decontamination, bacteria were isolated from high speed HP’s (n=40) (median 200 cfu, range 0-1.9x104 CFU/instrument), low speed HP’s(n-40) (median 400 cfu, range 0-1x104 CFU/instrument) and surgical HP’s (n=20) (median 1x103, range 0-3.7x104 CFU/instrument). A range of oral bacteria were identified in addition to Staphylococcus aureus and Propionibacterium acnes. Protein was detected from high speed HP’s (median 1.3, range 0- 210g), low speed HP’s (median 15.41 μg, range 0 - 448 μg) and surgical HP’s (median 350 μg, range 127.5– 1,936 μg) before decontamination. Serum albumin and salivary mucin were identified on surgical HP’s before decontamination. Calcium based deposits and contaminants trapped in lubricating oil were also detected using scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDX). The efficacy of detergents and a HP cleaning solution at cleaning HP contaminants was assessed in vitro with a standard test soil and disruption of biofilms with a range of cleaning efficacies noted from each cleaning solution tested. Alkaline detergents caused a significant biomass disruption of P. acnes biofilms compared to ROH2O alone. HP cleaning solution resulted in fixation of the biofilm and blood to the surface. The efficacy of novel HP cleaning machines was also assessed using a test soil based on the data generated in this study. Efficacy varied between devices tested with one demonstrating efficient protein removal in all but 1 HP location. The data presented describes a quantitative and qualitative assessment of common contaminants of HP’s, mainly bacteria, salivary mucin and serum albumin. In-vivo biofouling levels of HP’s are several fold lower than standard test soil formulations and consideration should be given to use of HP test soil based on in-vivo data to validate HP cleaning processes. The data generated in this thesis should aid in designing dental HP test soils and cleaning regimens.
Actions (login required)