Browsing by Author "Heersink, Joanna"

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Development of a laboratory model to assess the removal of biofilm from interproximal spaces by powered tooth brushing
(2002-11) Adams, Heather; Winston, Matthew T.; Heersink, Joanna; Buckingham-Meyer, Kelli; Costerton, J. William; Stoodley, Paul
Purpose: To develop an interproximal laboratory model to compare the potential effectiveness of powered brushing to remove biofilm plaque from interproximal spaces beyond the reach of bristles. Materials and Methods: Streptococcus mutans biofilms were first grown onglass microscope slides in a drip-flow reactor. The slides were removed and positioned in the interproximal model. Each slide was exposed to 15 seconds powered brushing with either the Sonicare® Elite or the Braun Oral-B 3D Excel. The thickness of the biofilm was measured with confocal microscopy at various distances from the bristle tips. Results: The Sonicare® Elite reduced the thickness of biofilm by 57% at a distance of 0-5 mm from the bristle tips, 46% at 5-10 mm and 43% at 10-15 mm, relative to biofilm in areas unexposed to brushing. All reductions in thickness were statistically significant (P< 0.01). The Braun Oral-B 3D reduced the biofilm thickness by 16%, 13%, and 19% at the same distances respectively, but the thickness reductions were not statistically significant from those in the unexposed areas (P> 0.1).
How to optimize the drop plate method for enumerating bacteria
(2001-03) Herigstad, Becky; Hamilton, Martin A.; Heersink, Joanna
The drop plate (DP) method can be used to determine the number of viable suspended bacteria in a known beaker volume. The drop plate method has some advantages over the spread plate (SP) method. Less time and effort are required to dispense the drops onto an agar plate than to spread an equivalent total sample volume into the agar. By distributing the sample in drops, colony counting can be done faster and perhaps more accurately. Even though it has been present in the laboratory for many years, the drop plate method has not been standardized. Some technicians use 10-fold dilutions, others use twofold. Some technicians plate a total volume of 0.1 ml, others plate 0.2 ml. The optimal combination of such factors would be useful to know when performing the drop plate method. This investigation was conducted to determine (i) the standard deviation of the bacterial density estimate, (ii) the cost of performing the drop plate procedure, (iii) the optimal drop plate design, and (iv) the advantages of the drop plate method in comparison to the standard spread plate method. The optimal design is the combination of factor settings that achieves the smallest standard deviation for a fixed cost. Computer simulation techniques and regression analysis were used to express the standard deviation as a function of the beaker volume, dilution factor, and volume plated. The standard deviation expression is also applicable to the spread plate method.
Influence of the sonicare toothbrush on the structure and thickness of laboratory grown Streptococcus mutans biofilms assessed by digital time-lapse and confocal microscopy
(2003) Heersink, Joanna; Costerton, J. William; Stoodley, Paul
Purpose: To evaluate the effect of powered brushing with the Sonicare electronic toothbrush on the structure and thickness reduction of S. mutans biofilms using digital time-lapse microscopy (DTLM) and confocal microscopy (CM) techniques. Materials and Methods: S. mutans biofilms grown on glass microscope slides on BHI and 2% sucrose were exposed to Sonicare for 15 seconds with the bristle tips just contacting the slide, and at distances of 0.5, 1.0, and 1.5 mm above the slide. Results: With direct bristle contact, the reduction in biofilm thickness was greater than 99%. DTLM showed the break up and detachment of biofilm caused by the shear forces generated by the rapid bristle motion in real time. The Sonicare was shown to significantly reduce biofilm thickness even when the bristles were 1 mm above the biofilm. The percent biofilm thickness reduction was inversely proportional to the bristle distance. This study demonstrates the Sonicare toothbrush effectively removed biofilm from hard flat surfaces both by direct bristle contact and by fluid dynamic shear forces alone. Clinical significance: The effectiveness of the Sonicare to remove biofilm, even when the bristles were not in direct contact, suggests that the generated shear forces may help remove dental plaque in hard-to-reach areas such as interproximal spaces and periodontal pockets.
Measuring antimicrobial effects on biofilm bacteria: From laboratory to field
(1999) Zelver, Nick; Hamilton, Martin A.; Pitts, Betsey; Goeres, Darla M.; Walker, Diane K.; Sturman, Paul J.; Heersink, Joanna