A range of opportunistic pathogens have been associated with dental unit water systems (DUWS), particularly in the biofilms that can line the tubing. This study therefore aimed to assess the microbiology of DUWS and biofilms in general dental practices across seven European countries, including the United Kingdom (UK), Ireland (IRL), Greece (GR), Spain (ES), Germany (D), Denmark (DK) and the Netherlands (NL). Water supplied by 51% of 237 dental unit water lines exceeded current American Dental Association recommendations of < or = 200 colony-forming units (CFU) ml(-1). Microbiological loading of the source waters was between 0 (Denmark, the Netherlands and Spain) and 4.67 (IRL) log CFU ml(-1); water line samples from the DUWS ranged from 1.52 (ES) to 2.79 (GR) log CFU ml(-1); and biofilm counts ranged from 1.49 (GR) to 3.22 (DK) log CFU.cm(-2). Opportunistic pathogens such as legionellae (DK and ES), including Legionella pneumophila SG1 (DK and GR), and Mycobacterium spp. (DK, NL, GR, D and ES) were recovered occasionally. Presumptive oral streptococci (ES and NL), oral anaerobes (GR), Candida spp. (UK, NL and ES) and blood (GR and IRL) were detected at relatively low frequencies, but their presence indicated a failure of the 3-in-1 antiretraction valve, leading to back siphonage of oral fluids into the water and biofilm phase. These findings confirm that a substantial proportion of DUWS have high levels of microbial contamination, irrespective of country, type of equipment and source water. The study emphasizes the need for effective mechanisms to reduce the microbial burden within DUWS, and highlights the risk of occupational exposure and cross-infection in general dental practice.

Water delivered by dental unit water systems (DUWS) in general dental practices can harbor high numbers of bacteria, including opportunistic pathogens. Biofilms on tubing within DUWS provide a reservoir for microorganisms and should be controlled. This study compared disinfection products for their ability to meet the American Dental Association's guideline of <200 CFU · ml ؊1 for DUWS water. Alpron, BioBlue, Dentosept, Oxygenal, Sanosil, Sterilex Ultra, and Ster4Spray were tested in DUWS (n ‫؍‬ 134) in Denmark, Germany, Greece, Ireland, The Netherlands, Spain, and the United Kingdom. Weekly water samples were tested for total viable counts (TVCs) on yeast extract agar, and, where possible, the effects of products on established biofilm (TVCs) were measured. A 4-to 5-week baseline measurement period was followed by 6 to 8 weeks of disinfection (intermittent or continuous product application). DUWS water TVCs before disinfection ranged from 0 to 5.41 log CFU · ml ؊1 . Disinfectants achieved reductions in the median water TVC ranging from 0.69 (Ster4Spray) to 3.11 (Dentosept) log CFU · ml ؊1 , although occasional high values (up to 4.88 log CFU · ml ؊1 ) occurred with all products. Before treatment, 64% of all baseline samples exceeded American Dental Association guidelines, compared to only 17% following commencement of treatment; where tested, biofilm TVCs were reduced to below detectable levels. The antimicrobial efficacies of products varied (e.g., 91% of water samples from DUWS treated with Dentosept or Oxygenal met American Dental Association guidelines, compared to 60% of those treated with Ster4Spray). Overall, the continuously applied products performed better than those applied intermittently. The most effective products were Dentosept and Oxygenal, although Dentosept gave the most consistent and sustained antimicrobial effect over time.

The purpose of this study was to evaluate dental erosion in 0.1 and 1.0% citric acid in vitro by several different methods and to assess the protective potential of experimentally formed salivary pellicle (24 h in vitro). Bovine enamel slabs were embedded in epoxy resin and polished. Erosion was performed in citric acid for 1, 5 or 10 min and recorded as microhardness loss, as changes of surface roughness (R_a, R_t and R_zDIN) and as calcium release. Additionally, erosive alterations were observed with scanning electron microscopy. Significant microhardness loss on non-pellicle-covered specimens was measured after 1-min exposure to 0.1% citric acid. Microhardness loss was time- and concentration-dependent. Salivary pellicle significantly inhibited both microhardness loss, except after 10-min immersion in 1.0% citric acid, and significantly reduced the increase of surface roughness. There were, however, no significant differences in calcium release between pellicle-covered and non-covered enamel. The results support the general conclusion that salivary pellicle effectively protects enamel surface against short-term erosion in organic acids.

The aim of this clinical-morphological study was to investigate the effects of dental probing on occlusal surfaces by scanning electron microscopy (SEM). Twenty sound occlusal surfaces of third molars and 20 teeth with initial carious lesions of 17- to 26-year-old patients (n = 18) were involved. Ten molars of each group were probed with a sharp dental probe (No. 23) before extraction; the other molars served as negative controls. After extraction of the teeth, the crowns were separated and prepared for the SEM study. Probing-related surface defects, enlargements and break-offs of occlusal pits and fissures were observed on all occlusal surfaces with initial carious lesions and on 2 sound surfaces, respectively. No traumatic defects whatsoever were visible on unprobed occlusal surfaces. This investigation confirms findings of light-microscopic studies that using a sharp dental probe for occlusal caries detection causes enamel defects. Therefore, dental probing should be considered as an inappropriate procedure and should be replaced by a meticulous visual inspection. Critical views of tactile caries detection methods with a sharp dental probe as a diagnostic tool seem to be inevitable in undergraduate and postgraduate dental education programmes.

The aim of this clinical study was to compare the outcome of quantitative laser/light-induced fluorescence (QLF) and visual inspection (VI) for the detection of initial caries lesions on all maxillary and mandibular smooth surfaces in caries-risk adolescents. The subjects were 34 students, mean age 15 yr. A total of 879 buccal and 882 lingual surfaces were air-dried and visually examined at a magnification of x3.5. Fluorescence images of each smooth surface were captured with QLF\clin equipment, and QLF software 2.00 was used to display, store, and analyse the images. Fluorescence loss (deltaF; %) and area of the lesion (A; mm2), and fluorescence loss integrated over the lesion area (deltaQ; deltaF x A; % x mm2), were determined. The presence or absence of initial caries lesions was scored using both VI and QLF. A total of 87.2% of all smooth surfaces were scored as sound or initially carious when assessed by VI + QLF in combination: 4.9% were detected by VI alone and 7.9% by QLF alone. The parameters DeltaF, A, and DeltaQ differed significantly between lesions registered with VI + QLF and QLF alone. It was concluded that (i) QLF seems to be a sensitive method that is suitable for the detection of visually undetected initial caries lesions; and (ii) that the clinical use of QLF is limited by several confounding factors in caries-risk adolescents.