Microbial contamination in dental unit waterlines

Abstract

The quality of water in a dental unit is of considerable importance because patients and dental staff are regularly exposed to water and aerosol generated from the dental unit. The aim of this study was to evaluate the occurrence of microbial contamination in dental unit waterlines. Water samples were collected aseptically from the waterlines (reservoir, triple-syringe, high-speed) of 15 dental units. After serial dilution to 1:10(6) in APHA, the samples were seeded by the pour-plate technique and cultured in plate count agar (Difco) for 48 h at 32 degrees C. Analysis was based on the number of colony forming units (CFU). The Wilcoxon non-parametric test indicated that the levels of water contamination were highest in the triple-syringe (13 of 15) and in the high-speed (11 of 15); both levels were higher than those of the water reservoir. There was no significant statistical difference between the level of contamination in the triple-syringe and the high-speed as determined by the Mann-Whitney test [p(H0) = 40.98%; Z = - 0.2281]. Because biofilm forms on solid surfaces constantly bathed by liquid where microorganisms are present, these results indicate that the water in the dental unit may be contaminated by biofilm that forms in these tubules.

Isolation of Pseudomonas aeruginosa strains from dental office environments and units in Barretos, state of São Paulo, Brazil, and analysis of their susceptibility to antimicrobial drugs

“…These figures agree with those reported by Walker et al (30), showing that water supplies of 51% of the dental units in seven European Union countries exceeded the current ADA-recommendations for permissible levels of bacterial contamination. Table 1 also demonstrates that, from forty dental clinics of the city of Barretos, São Paulo, Brazil, in agreement with results reported by Souza-Gugelmin et al (29) the number of P. aeruginosa cells in the water coming from dental equipment was lower than that coming from the water syringe and high-speed drill.…”

“…Costerton et al (10) reported that biofilm fragments dispersed by the municipal water system. Nevertheless, the high percentage of cells counted in handpieces, also reported by Souza-Gugelmin et al (29), should be a convincing indication of the large colonization of the DUWL units by opportunistic pathogens.…”

Comparison of the microbial load of incoming and distal outlet waters from dental unit water systems in Istanbul

“…As classic culture methods for measuring CFUs are only capable of detecting around 5% of the actual total microbial load, the level of contamination in DUWS is considerably worse than the reported figures (Barer and Harwood 1999). On other hand, as Souza-Gugelmin et al (2003) concluded, the use of water with an initial low contamination level did not prevent its increase within DUs. So, high microbiological quality inlet water doesn't warrant a clean DUWS.…”

Effectiveness of a pre-procedural mouthwash in reducing bacteria in dental aerosols: randomized clinical trial

“…32,33 One limitation of the present study is that it presents results for a single dental procedure, prophylaxis with an ultrasonic scaler that has been shown to have a great potential for aerosol generation in the dental office. 1,2,3,4,5,39 However, other dental procedures can also generate a large amount of aerosol with infectious components launched into the dental environment, such as the air turbine handpiece, 6,7 air-water from a three-way syringe 8 and sodium bicarbonate jet. 39 Therefore, one could assume that rinsing with CPC would yield similar benefits if used before the majority of dental procedures.…”

“…The use of certain equipment such as ultrasonic devices, 1,2,3,4,5 highspeed dental handpieces 6,7 or three-way syringes 8 may spread aerosols and splatters containing microorganisms in the environment. These microorganisms may cause cross-infections in the dental office, jeopardizing the health of patients and dental professionals.…”