title: The biofilm-controlling functions of rechargeable antimicrobial N-halamine dental unit waterline tubing.
abstract: OBJECTIVE
  A study was conducted to test the biofilm-controlling functions of N-halamine tubing over an eight-month period.
  
  
  METHODS
  A laboratory system, simulating a teaching dental clinic, was used to test rechargeable N-halamine tubing (T) compared to an untreated control (C) using the unit manufacturer's tubing. For the long-term study, a recharged tubing (RC) treated with bleach was used to compare with the test (T) and the control (C) tubing. Source tap water was cycled through the lines at 1.4 mL/minute, five minutes on and 25 minutes off, eight hours/day, five days/week. Every three weeks, samples of effluent, recovered adherent bacteria from inside tubing surfaces, and SEM images were examined for bacterial and biofilm growth. After sampling, a recharging solution of chlorine bleach (1 : 10 dilution) was run through T and RC lines, left overnight, and rinsed out the next morning. One-way ANOVAs and Spearman correlations were performed to detect significant differences for T, RC, and C, and determine significance with time period and source water, respectively.
  
  
  RESULTS
  Mean log CFU/mL for C effluent > T (p = 0.028), and C tubing > T (p = 0.035). Spearman correlations were significant between effluent and source water level for T (rho = 0.817), and T tubing (0.750); between RC tubing and source water level (rho = 0.836), and time (rho = 0.745); and between C and time (rho = 0.873). SEM imaging confirmed the presence of biofilm inside RC and C, but not inside T.
  
  
  CONCLUSIONS
  N-halamine tubing completely inhibited biofilm formation without negatively affecting the physical properties of the effluent water. Further research on N-halamine tubing using a pure water source is recommended, as T effluent bacterial levels reflected the source tap water quality and proliferation of planktonic bacteria with no biofilm activity.
authors.affiliation: The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA. porteous@uthscsa.edu
authors.forename: Nuala
authors.initials: N
authors.lastname: Porteous
authors.forename: John
authors.initials: J
authors.lastname: Schoolfield
authors.forename: Jie
authors.initials: J
authors.lastname: Luo
authors.forename: Yuyu
authors.initials: Y
authors.lastname: Sun
mesh_terms: D000588:Amines / Q000494:pharmacology*; D000890:Anti-Infective Agents / Q000494:pharmacology*; D001422:Bacterial Adhesion / Q000187:drug effects; D058491:Bacterial Load / Q000187:drug effects; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D002713:Chlorine / Q000737:chemistry; D019551:Dental Disinfectants / Q000494:pharmacology*; D003748:Dental Equipment / Q000382:microbiology*; D004866:Equipment Contamination / Q000517:prevention & control; D004867:Equipment Design; D054879:Halogenation; D006801:Humans; D007440:Intubation / Q000295:instrumentation; D008855:Microscopy, Electron, Scanning; D009584:Nitrogen / Q000737:chemistry; D010865:Pilot Projects; D012825:Silicon; D012973:Sodium Hypochlorite / Q000494:pharmacology; D013499:Surface Properties; D013997:Time Factors; D014871:Water Microbiology; D014881:Water Supply
chemical_list: D000588:Amines; D000890:Anti-Infective Agents; D019551:Dental Disinfectants; D002713:Chlorine; D012973:Sodium Hypochlorite; D009584:Nitrogen; D012825:Silicon