Survival response of Bacteriovorax in surface biofilm versus suspension when stressed by extremes in environmental conditions.

The Bacteriovorax, previously in the genus Bdellovibrio, are prokaryotes that prey upon many Gram-negative bacteria. They are ubiquitous in salt-water environments and have been reported to have a strong association with biofilms. The purpose of this study was to test the hypothesis that this association affords protection for the Bacteriovorax and enhances their survival in nature when exposed to extreme environmental conditions. Experiments were designed to compare their survival in biofilms versus in suspension when exposed to extremes in salinity and temperature. Natural mixed-population biofilms generated in moderate-salinity (16 per thousand) Patuxent River water and containing Bacteriovorax were exposed to drastic changes in salinity by placing in low-salinity (1 per thousand) river water and salt-free (no measurable salinity) distilled water for up to 14 days. In a separate trial, the biofilm was exposed to extremes in temperature, 5 degrees C and 35 degrees C, for up to 12 weeks in aquarium mesocosms. Simultaneously, suspensions of the Bacteriovorax were exposed to the same extremes in salinity and temperature as biofilms. The results revealed that the Bacteriovorax typically were able to survive for a week or longer while in association with biofilms than when in suspension. These results are consistent with observations from nature and establish that biofilms are important in the survival and ecology of the Bacteriovorax.

Efficacy of Listerine Antiseptic in reducing viral contamination of saliva.

AIM: The anti-viral efficacy of oral antimicrobial rinses has not been adequately studied in terms of potential clinical significance. As a follow-up to an in vitro study on the effect of oral antiseptics on Herpes simplex virus, Type 1, this study was undertaken to evaluate the in vivo effect of an essential oil containing oral antiseptic on the reduction of viral titer in saliva during active viral infection. METHOD: Patients were recruited and evaluated in a single visit protocol at the onset of a perioral outbreak, consistent historically and clinically with recurrent Herpes labialis. Direct immunofluorescence of cytological smears of the lesions/oral fluids was used to confirm Herpes simplex virus types I or II. Patients were randomly assigned to one of two treatment groups: (1) active ingredient and (2) sterile water control. The viral lesion was evaluated as to clinical stage according to standard protocol. Salivary fluid samples were taken: (1) at baseline; (2) immediately following a 30 s rinse; (3) 30 min. after the 30 s rinse; and (4) on the repeat trial, also at 60 min. after the 30 s rinse. All samples were evaluated for viral titer and results compared. RESULTS: In Trial 1, the sample population consisted of 19 males and 21 females with an average age of 29.2 and in Trial 2, 21 males, 19 females with an average age of 28. In both Trials 1 and 2, recoverable infectious virions were reduced to zero after a 30 s experimental rinse; whereas, the control rinse resulted in a non-significant (p>0.05) reduction. The experimental group also demonstrated a continued significant (p<0.05) reduction 30 min. post rinse when compared with baseline while the control group returned to baseline levels. In Trial 2, the 60 min. post rinse follow-up demonstrated a 1-2 log residual reduction from baseline in the experimental group; however, this was not significant. CONCLUSIONS: There is clinical efficacy in utilizing an oral rinse with the antimicrobial agent Listerine Antiseptic in reducing the presence of viral contamination in oral fluids for at least 30 min. after oral rinse. The risk of viral cross contamination generated from these oral fluids in person to person contact or during dental treatment may be reduced.

Efficacy of A-dec's ICX dental unit waterline treatment solution in the prevention and treatment of microbial contamination in dental units.

OBJECTIVE: Even though some chemical agents can disinfect biofilms in dental unit waterlines, there remains concern that all remnants of the biofilm matrix are not eliminated. Even with periodic treatments, the bacterial populations in dental unit waterlines recur rapidly. In addition, with some previously tested products, patient safety, as well as toxic, caustic and corrosive residual chemicals are also a concern. This study evaluated ICX, A-dec's new water treatment solution, in a series of experiments for prevention, microbial spectrum of activity, minimum inhibitory time determination, and treatment of established biofilms. METHODOLOGY: New dental unit waterline tubing was treated continuously during simulated patient care over 28 days with municipal water. It was then treated with ICX. Effluents from lines with established biofilms (averaging > 10(4) CFU/ml at day 0) were treated to assess levels of CFU counts within 21 days of exposure to ICX. RESULTS: Tubing treated with ICX did not develop a detectable biofilm using ruthenium red staining, and microbes in effluents remained undetectable. CONCLUSION: ICX is effective in maintaining the effluent within the American Dental Association's and the Centers for Disease Control's recommendation for < 500 CFU/ml. In addition, considering the preliminary finding that ICX reduces microbial contamination of effluents from established biofilm lines, it may be useful in long-term treatment alone or when coupled with a shock treatment to assist in biofilm destruction.

Effect of a dental unit waterline treatment solution on composite-dentin shear bond strengths.

OBJECTIVE: The control of biofilm and effluent contamination of dental unit water lines (DUWL) includes additions of antimicrobial solutions, as well as automatic dosing units. There are, however, varying reports on the effects of such agents on the bond strength of restorative dental materials and, particularly, between these agents and dental hard tissues. METHODOLOGY: The possible effects of an antimicrobial DUWL treatment solution on the adhesion of composite resin to dentin was evaluated by shear bond strength (SBS) testing. A total of 20 caries-free human molar and premolar teeth were used as the test substrates. The teeth were divided into two sets of 10 teeth which, after appropriate cleaning with water and pumice, were embedded horizontally in dental die stone. The buccal surface of each tooth was ground flat to a 17 microns finish using water-lubricated SiC paper. The teeth were then etched for 15 seconds with 37% H3PO4 and rinsed with either water (control) or a proprietary DUWL treatment (ICX) solution. Thereafter, the teeth were lightly blown dry with clean dry air, and the dentin conditioned with Prime & Bond NT for 20 seconds. The excess solvent was then removed by gentle air drying for 5 seconds, and the conditioner cured with visible light for 10 seconds. A cylinder of composite was placed on the conditioned surface and cured. A second group of 20 caries-free human molar and premolar teeth were used as test substrates to evaluate the effect of the ICX DUWL treatment solution on a different dentin priming system (OptiBond Solo Plus). The teeth in the second group were divided into two sets and after a 15 second etch with 37% H3PO4, were rinsed with water (control) or the proprietary ICX DUWL treatment solution. Thereafter, the teeth were lightly blown dry with clean, dry air and the dentin conditioned with OptiBond Solo for 20 seconds. The excess solvent was then removed by gentle air drying for 5 seconds, and the conditioner cured with visible light for 10 seconds. A cylinder of composite was placed on the conditioned surface and cured. Shear bond strength testing was performed with a universal test machine at the default cross-head speed of 0.1 mm/min. A set of teeth, sectioned, mounted and etched as above but rinsed with a 0.01% mineral oil/water mix prior to conditioning and bonding, was used as the negative control. A separate corrosion testing was performed by immersing brass coupons in water and ICX for 31 days and measuring the weight loss. The brass coupons were bright-dipped, electroless nickel-plated and bright nickel electroplated. RESULTS: The bonding studies indicated that the DUWL treatment solution applied to a cut and etched dentin surface prior to conditioning and bonding with an adhesive system has no effect (p > 0.05) on bond strength for either group of specimens, compared to water. Negative control specimens were found to have minimal bond strengths. The corrosion study indicated no difference in the behavior of the test specimens in ICX compared to those in water, although differences were noted between the different surface finishes applied to the brass substrate. CONCLUSION: The findings of this study demonstrate that exposure of an etched dentin surface to a water-based DUWL treatment mixture has no adverse effects on subsequent adhesion strength. Minimal corrosive attack was noted in the ICX solution and water for brass coupons provided with three different surface finishes.

Effect of a dental unit waterline additive on resin bond strengths.

The literature indicates that the addition of an antimicrobial mouthrinse to self-contained water systems in dental units will control biofilm and effluent contamination; however, reports have varied concerning the possible effects of such agents on adhesive dentistry bond strengths. This study evaluated shear bond strengths and the potential effects of a mouthrinse containing essential oils on cut tooth surfaces by grinding flat the buccal surface of extracted human teeth. Seven groups consisting of five teeth each were etched with 37% H3PO4 solution and rinsed with water or different dilutions of the mouthrinse. Each tooth was blotted dry before a film of adhesive resin was applied to the surface and photocured. A cylinder of composite was placed on the surface and photocured. Shear bond strength testing was performed using a universal test machine. The cut tooth surfaces were ground (using water or the test mouthrinse mixtures as coolant) and evaluated by scanning electron microscopy.