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Positively Charged Polyvinylidene Fluoride Membrane: A Potential Alternative for Absorbent Paper Points in
Wing-Yee Yeung1, Patricia A Tordik1, Frederico C Martinho1
1Division of Endodontics, Department of Advanced Oral Sciences and Therapeutics, University of Maryland, Baltimore, Maryland.
Introduction:
This study compared the absorbency capacity of paper points (PPs) with positively charged and noncharged polyvinylidene fluoride membranes (PVDFMs) and investigated the ability of PPs and PVDFMs to bind and remove endotoxin.
Methods:
Three commercially available PPs were compared with PVDFM (Millipore Sigma, Burlington, MA) prototype points. We recorded the initial dry weight for each PP and PVDFM using a digital balance to ±0.0001 precision for absorbency. PPs and PVDFMs were then immersed in deionized water and weighed to obtain the wet weight. The absorbency was calculated with the following formula: percent increase = ([wet weight - dry weight]/dry weight) × 100. For endotoxin removal, we first quantified endotoxin remaining in wells after immersing PPs and PVDFMs in a 24-well plate containing 10 endotoxin units/mL Escherichia coli O55:B5 (Lonza, Walkersville, MD). We then extracted and quantified endotoxin from PPs and PVDFMs. Endotoxin was quantified using the Kinetic-QCL test (Lonza).
Results:
The absorbencies for the positively charged and noncharged PVDFMs were higher than the PPs (P < .05), with no difference between them (P > .05). The positively charged PVDFMs removed more endotoxin than the noncharged PVDFMs and the PPs (P < .05). Moreover, the noncharged PVDFMs bound and removed more endotoxin than any PPs (P < .05).
Conclusions:
PVDFM prototype points are more absorbent than PPs. Moreover, the positively charged PVDFM points are more effective in binding and removing endotoxin than noncharged PVDFMs and PPs. This study suggests that positively charged PVDFMs with a 0.22-μm pore size could potentially replace PPs used in endodontics.
