Inhibitory effect of PVDF tubes on biofilm formation in dental unit waterlines.
OBJECTIVE
It has been reported that dental unit waterlines (DUWLs) are contaminated with bacterial biofilm, and that water discharged from a DUWL contains bacteria that might be opportunistic pathogens. This study aimed to investigate the ability of polyvinylidene fluoride (PVDF) tubing to inhibit bacterial contamination in DUWLs.


METHODS
Newly installed dental units were equipped with either a conventional polyurethane tube (unit A) or a PVDF tube (unit B), and the numbers of bacteria discharged from high- and low-speed handpiece lines were counted using R2A agar plates. Bacterial attachment on surfaces was observed with a scanning electron microscope (SEM) up to 185 days. Bacterial outflow during 1-day clinical service from a DUWL after 1-year usage was also examined. The surface free energy of each tube was determined based on the measurement of contact angles.


RESULTS
The number of bacteria discharged from unit B was lower than from unit A at 80 days and thereafter. SEM examination demonstrated that the unit A tube was covered by biofilm constituting rods and filaments after 94 days, while no biofilm was observed in the unit B tube even after 185 days. After 1-year of usage, the unit B released significantly less bacteria than the unit A at every sampling period of 1-day clinic work. Surface free energies, calculated from contact angles measured, of PVDF and polyurethane tubes were 37.7 and 77.8, respectively.


CONCLUSIONS
The present results indicate that PVDF tubes, which have lower surface free energy than the conventional tubes, were effective in inhibiting biofilm formation and reducing bacterial outflow from DUWLs.
Yabune
Toshiaki
T
Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka 565-0871, Japan.
Imazato
Satoshi
S
Ebisu
Shigeyuki
S
D001422:Bacterial Adhesion; D018441:Biofilms; D015169:Colony Count, Microbial; D003748:Dental Equipment / Q000382:microbiology*; D004203:Disinfection / Q000379:methods*; D004866:Equipment Contamination / Q000517:prevention & control*; D004867:Equipment Design; D006801:Humans; D008855:Microscopy, Electron, Scanning; D011140:Polyurethanes / Q000737:chemistry; D011145:Polyvinyls / Q000737:chemistry*; D013499:Surface Properties; D013997:Time Factors; D014871:Water Microbiology; D005465:Fluorocarbon Polymers
D011140:Polyurethanes; D011145:Polyvinyls; C024865:polyvinylidene fluoride; D005465:Fluorocarbon Polymers