Browsing by Author "Kumar, Dhiraj"

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    An Oxymetazoline-based Nasal Solution Removes Bacteria-Blood Debris on Dental Surfaces and Has Antimicrobial Activity toward Streptococcus mutans Data Sharing Archive
    (2025-01-30) Jones, Robert S; Kumar, Dhiraj; Pride, Morgan; rsjones@umn.edu; Jones, Robert; B-A-M (Biofilm-Apatite-Microbiome) Lab; School of Dentistry
    Data used in the manuscript An Oxymetazoline-based Nasal Solution Removes Bacteria-Blood Debris on Dental Surfaces and Has Antimicrobial Activity toward Streptococcus mutans Background: An over-the-counter vasoconstrictive nasal solution with oxymetazoline (NS-OXY, 0.05%) has potential to be used as a dental pulpal hemostatic medicament. A molecular engineering approach examined NS-OXY and its molecular constituent’s an-timicrobial and blood biomass removal efficacy. Methods: An ex vivo cavity model was developed where standardized prepared teeth were exposed overnight to a model dentinal caries pathogen, S. mutans, and then exposed to Sheep’s blood for 10 minutes, which sim-ulated a pulpal exposure. Cavity preparations were rinsed with OXY (0.05%), ben-zalkonium chloride (BKC-0.025%), NS-OXY (with OXY-0.05% and BKC), ferric sulfate (20%;ViscoStat, FS), and distilled water (DI). For examining the bactericidal effect of NS-OXY, a disc diffusion antimicrobial assay was used where S. mutans was grown (20-hrs) on brain-heart infusion (BHI) w/0.5% glucose agar plates and exposed to the treatment groups. Results: NS-OXY treated samples had a lower residual bacterial or blood biomass than FS (P=.003). The diffusion test showed that NS-OXY, BKC, and FS had zones of inhibition greater than 10 mm, with NS-OXY having higher activity against S. mutans than FS (P=.0002) but lower than BKC (P=0.0082). Conclusions: NS-OXY may con-sidered as a dental hemostatic agent after traumatic and carious pulpal exposure owing to NS-OXY’s antimicrobial and vasoconstrictive properties.
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    Data for Utilizing a degradation prediction pathway system to understand how a novel methacrylate derivative polymer with flipped external ester groups retains physico-mechanical properties following esterase exposure
    (2024-08-22) Kumar, Dhiraj; Ghose, Debarati; Mutreja, Isha; Bolskar, Robert D.; Aparicio, Conrado; Jones, Robert S.; rsjones@umn.edu; Jones, Robert S; B-A-M (Biofilm-Apatite-Microbiome) Lab; School of Dentistry
    The region of failure for current methacrylates (i.e. derivatives of acrylates) are ester bond linkages that hydrolyze in the presence of salivary and bacterial esterases that break the polymer network backbone. This effect decreases the mechanical properties of methacrylate-based materials. The ethylene glycol dimethacrylate (EGDMA) or novel ethylene glycol ethyl methacrylate (EGEMA) discs were prepared using 40μL of the curing mixture containing photo/co-initiators for 40second in a PTFE mold at 1000mW/cm2. The degree of conversion was used as a quality control measure for the prepared disks, followed by physical, mechanical, and chemical characterization of discs properties before and after cholesterol esterase treatment. After 9 weeks of standardized cholesterol esterase (CEase) exposure, EGDMA discs showed exponential loss of material (p=0.0296), strength (p=0.0014) and increased water sorption (p=0.0002) compared to EGEMA discs. We integrated a degradation prediction pathway system to LC/MS and GC/MS analyses to elucidate the degradation by-products of both EGEMA and EGDMA polymers. GC/MS analysis demonstrated that the esterase catalysis was directed to central polymer backbone breakage, producing ethylene glycol, for EGDMA, and to side chain breakage, producing ethanol, for EGEMA. The flipped external ester group linkage design is attributed to EGEMA showing higher resistance to esterase biodegradation and changes in mechanical and physical properties than EGDMA. EGEMA is a potential substitute for common macromer diluents, such as EGDMA, based on its resistance to biodegradation effects. This work inspires the flipped external group design to be applied to analogs of current larger, hydrophobic strength bearing macromers used in future dental material formulations. The data in this record supports the figures in the related manuscript.
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    Fluoride and Gallein Inhibit Polyphosphate Accumulation by Oral Pathogen Rothia dentocariosa - Data Sharing Archive
    (2023-01-25) Kumar, Dhiraj; Mandal, Subhrangshu; Bailey, Jake V.; Flood, Beverly E.; Jones, Robert S.; rsjones@umn.edu; Jones, Robert, S; Earth and Environmental Science; School of Dentistry
    This raw data set supports publication found in Letters in Applied Microbiology: The uptake and storage of extracellular orthophosphate (Pi) by polyphosphate (polyP) accumulating bacteria may contribute to mineral dissolution in the oral cavity. To test the effect of potential inhibitors of polyP kinases on Rothia dentocariosa, gallein (0, 25, 50, 100 µM) and fluoride (0, 50, 100 ppm) were added to R. dentocariosa cultures grown in brain heart infusion broth. At late log growth phase (8h), extracellular Pi was measured using an ascorbic acid assay, and polyP was isolated from bacterial cells treated with RNA/DNAases using a neutral phenol/chloroform extraction. Extracts were hydrolyzed and quantified as above. Gallein and fluoride had minor effects on bacterial growth with NaF having a direct effect on media pH. Gallein (≥25 µM) and fluoride (≥50 ppm) attenuated the bacterial drawdown of extracellular Pi 56.7% (p <0.05) and 37.3% (p <0.01). There was a corresponding polyP synthesis decrease of 73.2% (p<0.0001) from gallein and 83.1% (p<0.0001) from fluoride. Attenuated total reflectance Fourier transform infrared spectroscopy validated the presence of polyP and its reduced concentration in R. dentocariosa bacterial cells following gallein and fluoride treatment. R. dentocariosa can directly change extracellular Pi and accumulate intracellular polyP but the mechanism is attenuated by gallein and NaF.
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    Investigating the Cytocompatibility of a Novel Flipped Ester Group Design Polymer Composites against Oral Keratinocytes
    (2022-05-09) Kumar, Dhiraj; Bolskar, Robert D.; Mutreja, Isha; Jones, Robert S.; rsjones@umn.edu; Jones, Robert S; Minnesota Dental Research Center for Biomaterials and Biomechanics; B-A-M (Biofilm-Apatite-Microbiome) Lab; TDA Research, Inc.
    The methacrylate based polymeric materials have been widely used in dentistry because of the ease in tuning the physico-mechanical properties along with their ability to polymerize at room temperature in a period of seconds without causing deleterious exothermal effects. However, these materials are susceptible to hydrolysis of functional ester groups in the polymer backbone which prompted the development of a novel designer polymer with ester groups present in the side chain instead of the polymer backbone. Previously we have compared the physico-mechanical and stability profile of the new polymer with traditional EGDMA using accelerated aging, esterase, and bacterial incubation models. Another important parameter for polymer design in biological systems, such as use in dentistry, is polymer biocompatibility. The goal of this pilot investigation was to assess the cytocompatibility of novel design polymer EGEMA compared to EGDMA, a diluting agent in dental formulations, and a commercially available formulation Helioseal® (Ivoclar Vivodent). Material discs of the EGEMA, EGDMA, and Helioseal® were test in the presence of oral keratinocytes (TERT-2/OKF-6). After assessing oral keratinocytes cellular metabolic activity and cell morphology, the investigation suggested EGEMA and EGDMA showed comparable cytocompatibility that was statistical more favorable than Helioseal®.
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    A Novel Methacrylate Derivative Polymer That Resists Bacterial Cell-Mediated Biodegradation Data Sharing Archive
    (2021-11-22) Kumar, Dhiraj; Ghose, Debarati; Mutreja, Isha; Bolskar, Robert D.; Jones, Robert S.; rsjones@umn.edu; Jones, Robert S; B-A-M (Biofilm-Apatite-Microbiome) Lab; TDA Research, Inc.; School of Dentistry
    We studied biodegradation resistance of a custom synthesized (by TDA Research Inc) novel ethylene glycol ethyl methacrylate (EGEMA) with ester bond linkages that are external to the central polymer backbone when polymerized. Experiments were designed to compare degradation resistance with Ethylene glycol dimethacrylate (EGDMA) with internal ester bond linkages. The data has been published in an article titled "A Novel Methacrylate Derivative Polymer That Resists Bacterial Cell-Mediated Biodegradation" in the Journal of Biomedical Materials Research: Part B - Applied Biomaterials. The data in this record supports the figures in the published manuscript.
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    The use of Oxymetazoline-based Nasal Solutions to remove Bacteria-Blood Debris and Eradicate Rothia dentocariosa: an ex vivo cavity model study - Data Sharing Archive
    (2025-01-06) Kumar, Dhiraj; Pride, Morgan; Mukherjee, Kaushik; Jain, Gaurav; Mutreja, Isha; Jones, Robert S.; kumard@umn.edu; Kumar, Dhiraj
    Background: This study evaluated the antibacterial properties of a potential pulpal medicament, a nasal solution with oxymetazoline (NS-OXY, 0.05%), against a dentinal caries pathogen. Methods: Using a disc diffusion susceptibility test (n=6), Rothia dentocariosa was grown on brain-heart infusion (BHI) agar plates and exposed to OXY (0.05%), benzalkonium chloride (BKC-0.025%), OXY-NS (with OXY-0.05% and BKC), ferric sulfate (20%; ViscoStat), and distilled water (DI). This was followed by exposure of an ex vivo dental caries model with sheep blood to simulate the clinical pulpotomy procedure. An antibacterial broth inhibition test was conducted by adding the test samples in BHI broth at 37±0.5 °C in an aerobic chamber. Results: In the disc diffusion test, NS-OXY and BKC had the largest zone of inhibition (ZOI) measuring 14.42 mm (±1.62) and 18.92 mm (±4.14) respectively, indicating antibacterial activity. Ferric sulfate demonstrated a smaller ZOI, while OXY alone had no ZOI. The antibacterial broth test showed antibacterial effects with stable OD and pH levels for test samples containing BKC (0.025%) and diluted NS-OXY (0.01%) for up to 20 h. DI- and OXY-treated samples showed an increase in OD, indicating an increase in bacterial count and a concurrent drop in pH. BKC treatment statistically (P<0.05) reduced polyP extracts, which may contribute to blood clot formation. NS-OXY demonstrated antibacterial properties, likely due to the addition of BKC to Rothia dentocariosa. NS-OXY showed concentration dependent biocompatibility with dental pulp stem cells while FS was cytotoxic at the same dilution. Conclusion: These antimicrobial properties, together with OXY’s hemostatic effects, suggest the potential off-label use of NS-OXY during a pulpotomy procedure in primary and permanent teeth. This study provides support for potential future clinical trials of repurposing FDA-approved drugs consisting of oxymetazoline and benzalkonium chloride for dental and other similar applications. Featured Application: An over-the-counter nasal solution containing oxymetazoline has the potential to be used off-label to manage surgical bleeding from dental pulp exposures and provide antimicrobial properties against Rothia dentocariosa, a model gram-positive bacteria associated with deep dentinal caries.