title: Can protein contamination be removed from hand endodontic instruments?
abstract: OBJECTIVE
  The aim of this study was to quantify total protein adhering to hand endodontic files and to measure and compare the efficacy of ultrasonic cleaning and washer-disinfectors, with and without presoaking, in protein removal from clinically contaminated endodontic files.
  
  
  METHODS
  Total protein contamination of the endodontic files was quantified using an assay reagent colorimetric method. Twelve general dental practitioners were recruited to collect clinically contaminated files. One hundred and fifty clinically contaminated files were allowed to air-dry in sterile plastic containers and a further 60 files were immersed, working end down, in enzymatic detergent immediately following clinical use. Thirty clinically contaminated files were tested for total protein contamination as a positive control. Sixty files were subjected to ultrasonic cleaning and 30 to processing in each of the washer-disinfectors. The presoaked files were divided into two groups of 30 for processing in the washer-disinfectors. A further group of brand-new, unused files were tested for protein contamination as a negative control.
  
  
  RESULTS
  Protein was present on 29 of the 30 new files tested. The median total mass of protein recovered from clinically contaminated hand endodontic instruments was 2.046 microg. The most effective method of presterilisation cleaning tested was a presoak in Alkazyme followed by processing in the Miele G7881 washer-disinfector.
  
  
  CONCLUSIONS
  The most effective method of presterilisation cleaning for hand endodontic files is a presoak in Alkazyme, an alkaline enzymatic detergent, followed by processing in a Miele G7881 washer-disinfector. This study provides up-to-date evidence that newer methods of presterilisation cleaning may fail to remove protein from endodontic hand instruments totally. This may have implications for all reusable dental instruments.
authors.affiliation: Clinical Dental Sciences, University of Liverpool, UK. cwblackadder@btinternet.com
authors.forename: Christine L
authors.initials: CL
authors.lastname: Whitworth
authors.forename: Karen
authors.initials: K
authors.lastname: Davies
authors.forename: Nikolaus O A
authors.initials: NO
authors.lastname: Palmer
mesh_terms: D000468:Alkalies / Q000627:therapeutic use; D003124:Colorimetry; D003666:Decontamination / Q000379:methods*; D019551:Dental Disinfectants / Q000627:therapeutic use; D003902:Detergents / Q000627:therapeutic use; D004203:Disinfection / Q000295:instrumentation; D004866:Equipment Contamination / Q000517:prevention & control*; D006801:Humans; D007101:Immersion; D010447:Peptide Hydrolases / Q000627:therapeutic use; D011506:Proteins / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000627:therapeutic use; D018915:Root Canal Preparation / Q000295:instrumentation*; D012967:Sodium Dodecyl Sulfate / Q000627:therapeutic use; D013501:Surface-Active Agents / Q000627:therapeutic use; D014465:Ultrasonics
chemical_list: D000468:Alkalies; D019551:Dental Disinfectants; D003902:Detergents; D011506:Proteins; D000644:Quaternary Ammonium Compounds; D013501:Surface-Active Agents; D012967:Sodium Dodecyl Sulfate; D010447:Peptide Hydrolases