Research Interests:
Research Interests:
Here we report the synthesis, materials characterization, antimicrobial capacity, and cytocompatibility of novel antibiotic-containing scaffolds. Metronidazole (MET) or Ciprofloxacin/(CIP) was mixed with a polydioxanone (PDS)polymer... more
Here we report the synthesis, materials characterization, antimicrobial capacity, and cytocompatibility of novel antibiotic-containing scaffolds. Metronidazole (MET) or Ciprofloxacin/(CIP) was mixed with a polydioxanone (PDS)polymer solution at 5 and 25 wt% and processed into fibers. PDS fibers served as a control. Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), tensile testing, and high-performance liquid chromatography (HPLC) were used to assess fiber morphology, chemical structure, mechanical properties, and drug release, respectively. Antimicrobial properties were evaluated against those of Porphyromonas gingivalis/Pg and Enterococcus faecalis/Ef. Cytotoxicity was assessed in human dental pulp stem cells (hDPSCs). Statistics were performed, and significance was set at the 5% level. SEM imaging revealed a submicron fiber diameter. FTIR confirmed antibiotic incorporation. The tensile values of hydrated 25 wt% CIP scaffold were significantly lowe...
Research Interests:
Materials Science, Chemistry, Dentistry, Biofilms, Nanofibers, and 15 moreElectrospinning, Medicine, Humans, Diffusion, Dental, Antimicrobial, Disinfection, Guided Tissue Regeneration, Enterococcus faecalis, Elastic Modulus, Ciprofloxacin, Materials Testing, Biocompatible Materials, Metronidazole, and Dental Pulp
Fulvic acid, a major organic compound extract of Shilajit has been the focus of dental research for the past few years. Shilajit, a sticky tar-like substance of dark brownish color, was used during the ancient times, thousands of years... more
Fulvic acid, a major organic compound extract of Shilajit has been the focus of dental research for the past few years. Shilajit, a sticky tar-like substance of dark brownish color, was used during the ancient times, thousands of years ago and continues to be the traditional method today in India to aid with curing bone/cartilage diseases. Shilajit has also been proven to have anti-inflammatory and pain suppressing effects. This experiment determined the minimum inhibitory concentration (MIC), which is the lowest concentration of fulvic acid, an active component of shilajit that inhibits the visible growth of S. mutans. This experiment also determined the minimum bactericidal concentration (MBC) which is the lowest concentration of fulvic acid that kills S. mutans. A 3-day procedure to determine the growth vs inhibition of the S. mutans was conducted and bacterial readings were recorded using a spectrophotometer after treating S. mutans with 10% formaldehyde, crystal violet stain, a...
Research Interests:
Research Interests:
Research Interests:
Objective: This study investigated the effects of human breast milk and its components on the nutritional aspect of the caries process due to Streptococcus mutans UA159 biofilm formation. Study design: Human breast milk was collected from... more
Objective: This study investigated the effects of human breast milk and its components on the nutritional aspect of the caries process due to Streptococcus mutans UA159 biofilm formation. Study design: Human breast milk was collected from 11 mothers during 3-9 months postpartum. To test for the effect on biofilm formation, a 16-hour culture of S. mutans was treated with dilutions of human breast milk and several major components of human breast milk, lactose, lactoferrin, IgA, and bovine casein in sterile 96-well flat bottom microtiter plates for 24 hours. The biofilms were fixed, washed, stained with crystal violet, and extracted. Absorbance was measured to evaluate biofilm growth mass. Results: Dilutions 1:10-1:2,560 of the human breast milk samples increased biofilm formation by 1.5-3.8 fold compared to the control. Lactoferrin decreased biofilm formation significantly in all dilutions (average milk concentration of 3 mg/ml). Lactose had no effect at average breast milk concentrations (60 mg/ml) except at its lowest concentration (15 mg/ml) where it was increased. IgA significantly decreased biofilm formation at its highest concentration of 2,400 μg/ml (average milk concentration 600 μg/ml). Casein caused significantly increased biofilm formation at all concentrations tested above the average milk content (2.3 mg/ml). Conclusions: The results of this study demonstrate an increase in S. mutans biofilm formation by human breast milk 3-9 months post partum. Among its major components, only casein significantly increased biofilm formation among the concentrations analyzed. Lactose had no effect except at 15 mg/ml. Lactoferrin and IgA significantly decreased S. mutans biofilm formation at their highest concentrations. This information expands the current knowledge regarding the nutritional influence of breastfeeding and validates the necessity to begin an oral hygiene regimen once the first tooth erupts.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Background. Peri-implant diseases are emerging issues in contemporary implant dentistry. As biofilms play a critical role in peri-implant diseases, the characteristic of resisting bacterial adhesion would be ideal for dental implants. The... more
Background. Peri-implant diseases are emerging issues in contemporary implant dentistry. As biofilms play a critical role in peri-implant diseases, the characteristic of resisting bacterial adhesion would be ideal for dental implants. The aims of the study were to compare titanium (Ti) and zirconia (Zr) implants regarding the amount of biofilm formation at different time frames and assess the distribution of biofilm on different aspects of dental implants. Methods. Biofilm was developed on Ti and Zr dental implants with a peri-implant-related multispecies model with Streptococcus oralis, Actinomyces naeslundii, Veillonella dispar, and Porphyromonas gingivalis, for 3 and 14 days. Quantitative assessment was performed with the measurement of total bacterial viability (colony forming units, CFU/mg). Scanning electron microscopy (SEM) was used to evaluate biofilm formation on different aspects of the implants. Results. Three-day-old biofilm on Ti implants was significantly higher than t...
Research Interests:
Research Interests:
Background Streptococcus pyogenes is an important global human pathogen that causes pharyngitis, and antibacterial therapy has become an important part of the overall therapy for pharyngitis. As natural derivatives, honey and green tea... more
Background Streptococcus pyogenes is an important global human pathogen that causes pharyngitis, and antibacterial therapy has become an important part of the overall therapy for pharyngitis. As natural derivatives, honey and green tea are often recommended for patients with pharyngitis in traditional Chinese medicine without experimental theoretical basis on wether the combined effect of honey and green tea on pharyngitis is better than they alone. The aims of this study were to explore the effects of artificial honey (AH) and epigallocatechin-3-gallate (EGCG) on S. pyogenes and elucidate the possible mechanisms, which were investigated using MIC (the minimum inhibitory concentration), FIC (fractional inhibitory concentration) index, growth pattern, biofilm formation and RT-qPCR. Results The MIC of AH on S. pyogenes was 12.5% (v/v) and the MIC of EGCG was 1250 μg/ml. The FIC index of AH and EGCG was 0.5. The planktonic cell growth, growth pattern and biofilm formation assays showed...
Research Interests:
Research Interests:
Previous studies have suggested that sera from animals immunized with whole Streptococcus mutans cells may cross-react with human and monkey heart sarcolemmal tissues. In the present study, sera and saliva from rats and rabbits immunized... more
Previous studies have suggested that sera from animals immunized with whole Streptococcus mutans cells may cross-react with human and monkey heart sarcolemmal tissues. In the present study, sera and saliva from rats and rabbits immunized peripherally with ribosomal preparations from S. mutans 6715 (serotype g) or GS-5 (serotype c) were examined for their ability to react with normal human heart sarcolemmal and kidney glomerular tissues by using enzyme-linked immunosorbent and immunofluorescence assays. The results showed that antibodies to serotype g and c ribosomal preparations do not react with either the human heart or renal antigens. Sera from mice immunized with human heart tissue and from a patient with a high anti-streptolysin O titer reacted strongly with human heart sarcolemmal and kidney glomerular tissues. These data indicated that ribosomal preparations from S. mutans lack the putative human heart cross-reactive determinant and suggest that the use of an S. mutans riboso...
Research Interests:
Research Interests:
Atherosclerosis is a specific form of arteriosclerosis where the walls of arteries began to thicken as a result of bacterial invasion and accumulation of inflammatory white blood cells. There could be a direct correlation of... more
Atherosclerosis is a specific form of arteriosclerosis where the walls of arteries began to thicken as a result of bacterial invasion and accumulation of inflammatory white blood cells. There could be a direct correlation of atherosclerosis and the intake of nicotine. Nicotine has been reported to increase the amount of the cariogenic oral bacteria known as Streptococcus mutans; thus possibly leading to an increase of dental caries. Serotype K S. mutans has been associated strongly with atherosclerosis. Objective: This study focused on the biofilm formation of S. mutans serotype K when incubated in various dilutions of nicotine. Methods: S. mutans UA159 (stereotype C), and stereotype K strains 89, 52, and 51 were cultured in tryptic soy broth (TSB) overnight and then added to dilutions of TSB with 1% sucrose (TSBS) containing concentrations of nicotine between 0 and 32 mg/ml. Each dilution was added to 96-well microtiter plates, inoculated with bacteria and incubated for 24 hours ae...
Research Interests:
Streptococcus mutans is gram-positive cocci, facultative anaerobic bacterium commonly found in the human oral cavity, and significantly contributes to caries. The quorum sensing system plays an important role in microbial cellcell... more
Streptococcus mutans is gram-positive cocci, facultative anaerobic bacterium commonly found in the human oral cavity, and significantly contributes to caries. The quorum sensing system plays an important role in microbial cellcell interactions that leads to development of dental plaque. S. mutans produces glucosyltransferases together with the glucan binding proteins in order to facilitate the adherence of glucans to the tooth surface, thereby forming biofilms. Moreover, previous studies indicate that in the presence or absence of sucrose, a cell surface protein called antigen I/II plays an important role in the adherence process of S. mutans. There is a relationship between smoking and dental caries, in which the smoking population has a higher incidence of dental caries than a non-smoking population. Nicotine is one of the most important components in tobacco. In this study we investigated the effects of nicotine on quorum sensing in S. mutans. An S. mutans wild type UA159 and its...
Research Interests:
Caries-free subjects or individuals with low caries susceptibility exhibited significantly higher (P less than 0.001) levels of naturally occurring salivary immunoglobulin A (IgA) and serum IgG, IgA, and IgM antibodies to a Streptococcus... more
Caries-free subjects or individuals with low caries susceptibility exhibited significantly higher (P less than 0.001) levels of naturally occurring salivary immunoglobulin A (IgA) and serum IgG, IgA, and IgM antibodies to a Streptococcus mutans ribosomal preparation than subjects with high caries susceptibility. Absorption of saliva and serum samples with S. mutans ribosomal preparations, but not with other S. mutans antigens or with Escherichia coli and Neisseria gonorrhoeae ribosomal preparations, removed the antibody activity. Absorption with Streptococcus sanguis ribosomes and NH4Cl-washed S. mutans ribosomes partially removed the anti-S. mutans ribosome antibody activity. These results provide evidence that naturally occurring salivary and serum antibodies to the S. mutans ribosomal preparation correlate with susceptibility to dental caries.
Research Interests:
Ingestion of a vaccine containing killed Streptococcus mutans, originally isolated from each volunteer, daily for 10 consecutive days induced increased levels of specific secretory immunoglobulin A (sIgA) antibodies to S. mutans cells and... more
Ingestion of a vaccine containing killed Streptococcus mutans, originally isolated from each volunteer, daily for 10 consecutive days induced increased levels of specific secretory immunoglobulin A (sIgA) antibodies to S. mutans cells and two cell surface proteins, glucosyltransferase and surface antigen I/II, in parotid saliva and tears of four healthy males and in parotid saliva, tears, colostrum, and milk of a pregnant woman. In addition, these antibodies inhibited glucosyltransferase activity. Both IgA1 and IgA2 antibodies were induced. The levels of IgA antibodies in all secretions remained significantly above preimmunization levels for more than 50 days after oral administration of antigen. A second series of immunizations for 7 consecutive days resulted in even higher levels of sIgA antibodies, which peaked earlier and persisted longer than those observed after the primary immunizations. No increase in levels of antibodies in serum were detected in any subject. Antibodies rea...
Research Interests:
Chronic periodontitis is a common inflammatory disease initiated by a complex microbial biofilm and mediated by the host response causing destruction of the supporting tissues of the teeth. Host recognition of pathogens is mediated by... more
Chronic periodontitis is a common inflammatory disease initiated by a complex microbial biofilm and mediated by the host response causing destruction of the supporting tissues of the teeth. Host recognition of pathogens is mediated by toll-like receptors (TLRs) that bind conserved molecular patterns shared by groups of microorganisms. The oral epithelial cells respond to most periodontopathic bacteria via TLR-2 and TLR-4. Many studies have previously reported the presence of elevated numbers of viable exfoliated epithelial cells (SEC) in the saliva of patients with chronic periodontitis. In addition to the membrane-associated receptors, soluble forms of TLR-2 (sTLR-2) and TLR-4 (sTLR-4) have been identified and are thought to play a regulatory role by binding microbial ligands. sTLR-2 has been shown to arise from ectodomain shedding of the extracellular domain of the membrane receptor and sTLR-4 is thought to be an alternate spliced form. The objective of this study was to investiga...
Research Interests:
We investigated the direct and indirect (residual) antibacterial effects of various concentrations of triple antibiotic paste (TAP) loaded into a methylcellulose system. Enterococcus faecalis (E. faecalis) was grown on sterilized dentin... more
We investigated the direct and indirect (residual) antibacterial effects of various concentrations of triple antibiotic paste (TAP) loaded into a methylcellulose system. Enterococcus faecalis (E. faecalis) was grown on sterilized dentin blocks (n = 60) and treated with clinically used TAP (1,000 mg/mL), low concentrations of methylcellulose-based TAP (100, 10, and 1 mg/mL), placebo paste, or 1.5% NaOCl (n = 10). The pastes were then removed, and biofilm disruption assays were performed. Additional dentin blocks (n = 120) were pretreated with the same experimental groups (n = 20). The pastes were rinsed off, and the samples were immersed independently in phosphate-buffered saline for 2 and 4 weeks (n = 10). E.faecalis was then grown on the dentin blocks, and biofilm disruption assays were performed. Fisher's Exact and Wilcoxon rank sum tests were used for statistical analyses. With regard to direct antibacterial effects, all treatment groups demonstrated complete eradication of b...
Research Interests:
This article presents details of fabrication, biological activity (i.e., anti-matrix metalloproteinase [anti-MMP] inhibition), cytocompatibility, and bonding characteristics to dentin of a unique doxycycline (DOX)-encapsulated halloysite... more
This article presents details of fabrication, biological activity (i.e., anti-matrix metalloproteinase [anti-MMP] inhibition), cytocompatibility, and bonding characteristics to dentin of a unique doxycycline (DOX)-encapsulated halloysite nanotube (HNT)-modified adhesive. We tested the hypothesis that the release of DOX from the DOX-encapsulated nanotube-modified adhesive can effectively inhibit MMP activity. We incorporated nanotubes, encapsulated or not with DOX, into the adhesive resin of a commercially available bonding system (Scotchbond Multi-Purpose [SBMP]). The following groups were tested: unmodified SBMP (control), SBMP with nanotubes (HNT), and DOX-encapsulated nanotube-modified adhesive (HNT+DOX). Changes in degree of conversion (DC) and microtensile bond strength were evaluated. Cytotoxicity was examined on human dental pulp stem cells (hDPSCs). To prove the successful encapsulation of DOX within the adhesives-but, more important, to support the hypothesis that the HNT+D...
Research Interests:
Chemistry, Dentistry, Medicine, Polymerization, Adhesive, and 15 moreHumans, Nanotubes, Dental, Mechanical Stress, Dental Pulp Stem Cells, Doxycycline, Dentin, Dental Bonding, Materials Testing, Resin Cements, Matrix Metalloproteinase, Dental Pulp, Dentin bonding agents, Matrix metalloproteinase inhibitors, and Cell culture techniques
Research Interests:
To present a case of endodontic failure obturated with a methacrylate-based root filling material, Resilon/RealSeal (RS). To determine if RS is susceptible to biodegradation by endodontically relevant microbes by a method known to show RS... more
To present a case of endodontic failure obturated with a methacrylate-based root filling material, Resilon/RealSeal (RS). To determine if RS is susceptible to biodegradation by endodontically relevant microbes by a method known to show RS degradation. Emulsions of RS were dispersed in agar with minimal bacterial nutrients in culture plates. Lipase PS served as a positive control. Pseudomonas aeruginosa, Fusobacterium nucleatum, Prevotella intermedia, Porphyromonas gingivalis, Porphyromonas asaccharolytica, Enterococcus faecalis, Streptococcus sanguis, Streptococcus mutans, Staphylococcus aureus, and Staphylococcus epidermidis were tested for their ability to biodegrade RS. The bacteria were inoculated in the plates and examined daily for RS degradation for 7 days. Degradation of the emulsified RS manifested in the formation of clear zones around P aeruginosa, P intermedia, P asaccharolytica, S aureus, and S epidermidis. No degradation was seen with the other tested bacteria or in pl...
Research Interests:
Microbiology, Chemistry, Dentistry, Medicine, Humans, and 12 moreBacteria, Degradation, Quintessence, Staphylococcus epidermidis, Root Canal, Root Canal Filling Materials, Enterococcus faecalis, Dental Pulp Cavity, PORPHYROMONAS GINGIVALIS, Prevotella intermedia, Fusobacterium nucleatum, and Methacrylates
ABSTRACT Objectives: The objective of this study was to develop an antibacterial cement and evaluate its mechanical strength and antibacterial activity. Methods: The newly synthesized quaternary ammonium bromide (QAB)-containing... more
ABSTRACT Objectives: The objective of this study was to develop an antibacterial cement and evaluate its mechanical strength and antibacterial activity. Methods: The newly synthesized quaternary ammonium bromide (QAB)-containing antibacterial polymers were initially evaluated using a MIC/MBC test and then incorporated into Fuji II LC cement. Compressive strength (CS) and viabilities of oral cavity-producing bacteria S. mutans and lactobacillus were used to evaluate the mechanical strength and antibacterial activity of the cement, respectively. Flexural (FS) and diametral tensile strengths (DTS) were tested as well. The specimens were conditioned in distilled water at 37 oC for 24 h prior to testing. Results: The cement showed a significant antibacterial activity to both oral bacteria, accompanying with an initial CS reduction. The effects of chain length and loading of the QAB were significant. Conclusions: It was found that the antibacterial effect of the substitute chain lengths from free QAB seem more significant in water than those from their polymers after integrating to the cement. It was also found that the antibacterial activity against lactobacillus was higher than that against S. mutans. This work was sponsored by NIH challenge grant (RC1) DE020614.
Research Interests:
Research Interests:
Pharmacology, Microbiology, Dentistry, Biofilms, Nanofibers, and 15 moreMedicine, Humans, Biofilm, PMC, Drug Delivery Systems, High Pressure Liquid Chromatography, Lactobacillus Casei, Streptococcus, Periodontitis, Drug Therapy, Ciprofloxacin, Metronidazole, Aggregatibacter actinomycetemcomitans, Polydioxanone, and In Vitro Techniques
Carious lesions fluoresce under blue light. The primary cariogenic bacterium Streptococcus mutans has been shown previously to fluoresce within blue light wavelengths. In this study we wanted to determine the role of hemin and various... more
Carious lesions fluoresce under blue light. The primary cariogenic bacterium Streptococcus mutans has been shown previously to fluoresce within blue light wavelengths. In this study we wanted to determine the role of hemin and various growth media on the fluorescing properties of S. mutans under planktonic (total biomass) and biofilm (biofilm mass) growth conditions. UA159 was grown for 24 h at 37oC in Tryptic Soy Broth (TSB), Brain Heart Infusion (BHI) and Todd Hewitt broth (THB) with and without hemin in 5% CO2. Biofilm was grown for 24 h in a 96 well sterile microplate in the above described media with and without hemin. A stock solution of Protoporphyrin –IX was prepared and diluted to concentrations ranging from 1.6-3.1×10-4 g/ml. A SpectraMax (M3) was used to determine the fluorescence from UA159. RFU of total biomass and biofilm mass was assessed by exciting at fixed wavelengths of 385 and 405 nm at a spectral band width of 10 nm. Emission spectra at 770 nm were observed with...
Research Interests:
Aims The purpose of this study was to compare the effect of hop extracts with diverse β-acid concentrations on Streptococcus mutans biofilm formation. Methods and Results Ten different hop extracts, with α-acid concentrations similar to... more
Aims The purpose of this study was to compare the effect of hop extracts with diverse β-acid concentrations on Streptococcus mutans biofilm formation. Methods and Results Ten different hop extracts, with α-acid concentrations similar to those found in commercial beer products and β-acid concentrations ranging from 2.6 to 8.1%, were added to distilled water to make standardized concentrations. S. mutans isolates were treated with hop extract dilutions varying from 1:2 to 1:256. The minimum inhibitory, minimum bactericidal and minimum biofilm inhibitory concentrations were determined and the optical density was evaluated. Live/dead staining confirmed the bactericidal effects. Biofilm formation of several strains of S. mutans was significantly inhibited by hop extract dilutions of 1:2, 1:4, 1:8, 1:16 and 1:32. Strong negative correlations were observed between α- and β-acid concentrations of the hop extracts and S. mutans total growth and biofilm formation. Conclusions The use of hop e...
Research Interests:
caries-active subjects. immunoglobulin A antibodies in caries-free and Streptococcus mutans fimbriae: salivary Characterization of preparations enriched for
Research Interests:
Identification of inexpensive and technically simple immunological tests useful in predicting the progression to AIDS in human immunodeficiency virus (HIV)-infected patients would be especially welcome in developing countries, in which... more
Identification of inexpensive and technically simple immunological tests useful in predicting the progression to AIDS in human immunodeficiency virus (HIV)-infected patients would be especially welcome in developing countries, in which 80% of HIV-infected patients reside and health budgets are low. In the current study, we evaluated CD4+ and total lymphocyte counts and the concentrations in serum of beta 2-microglobulin, p24 antigen, and immunoglobulin A (IgA) as predictors of disease progression in 74 Panamanian HIV-positive patients and 50 HIV-negative healthy individuals. Total lymphocyte and CD4(+)-cell counts for AIDS patients (1,451 +/- 811 cells/microliters, P < 0.001, and 238 +/- 392 cells/microliters, P < 0.0001, respectively and asymptomatic patients (2,393 +/- 664 cells/microliters, P > 0.05, and 784 +/- 475 cells/microliters, P < 0.001, respectively) were lower than those observed for healthy subjects (2,596 +/- 631 cells/microliters and 1,120 +/- 296 cells/m...
Research Interests:
This study investigated the effect that infant formula had on biofilm growth of Streptococcus mutans. Specifically, it compared biofilm growth in media containing lactose-based and sucrose-based formulas. It also analyzed biofilm... more
This study investigated the effect that infant formula had on biofilm growth of Streptococcus mutans. Specifically, it compared biofilm growth in media containing lactose-based and sucrose-based formulas. It also analyzed biofilm formation with formulas of varying iron content. Biofilm growth was tested with the specific infant formula components sucrose, lactose, and ferric chloride. The study was designed to determine if these types of infant formulas and components affected S. mutans biofilm formation differently. A 24-hour culture of S. mutans was treated with various concentrations of infant formula diluted in bacteriological media. To test for biofilm formation, S. mutans was cultured with and without the infant formula and formula components. The biofilms were washed, fixed, and stained with crystal violet. The absorbance was measured to evaluate biofilm growth and total absorbance. Sucrose-based formulas provided significant increases in biofilm growth when compared to lacto...
Research Interests:
This study evaluated selected properties of a prototype root repair cement containing surface pre-reacted glass ionomer fillers (S-PRG) in comparison to mineral trioxide aggregate (MTA) and intermediate restorative material (IRM). The... more
This study evaluated selected properties of a prototype root repair cement containing surface pre-reacted glass ionomer fillers (S-PRG) in comparison to mineral trioxide aggregate (MTA) and intermediate restorative material (IRM). The antibacterial effect of S-PRG, MTA, and IRM cements was tested against Porphyromonas gingivalis and Enterococcus faecalis after 1 and 3 days of aging of the cements. The set cements were immersed in distilled water for 4 h to 28 days, and ion-releasing ability was evaluated. Initial and final setting times of all cements were evaluated using Gilmore needles. The push-out bond strength between radicular dentin and all cements was tested at different levels of the roots. S-PRG and IRM cements, but not MTA cement, demonstrated significant antibacterial effect against P. gingivalis. All types of cements exhibited significant antibacterial effect against E. faecalis without being able to eliminate the bacterium. S-PRG cement provided continuous release of f...
Research Interests:
Materials Science, Dentistry, Author, Composite Material, IRM, and 15 moreMta, Surface Properties, Root Canal Filling Materials, Enterococcus faecalis, Oxides, Materials Testing, Calcium Compounds, Semiconducting Aluminum Compounds, Silicates, Ions, PORPHYROMONAS GINGIVALIS, Glass Ionomer Cement, Dental Cements, Ion Release, and Drug combinations
Objective: To examine the effects of cola-flavored beverages and caffeine on growth and metabolism of Streptococcus mutans biofilm. This study was designed to determine if carbonated beverages or caffeine can increase S. mutans growth and... more
Objective: To examine the effects of cola-flavored beverages and caffeine on growth and metabolism of Streptococcus mutans biofilm. This study was designed to determine if carbonated beverages or caffeine can increase S. mutans growth and biofilm formation and metabolic activity in vitro, potentially leading to increased S. mutans-associated cariogenicity in children that consume them. Study Design: Six different cola-flavored products, plus pure caffeine, and pure high fructose corn syrup (HFCS), at different concentrations similar to those in the beverages were tested. A 16-hour culture of S. mutans was treated with different dilutions in bacteriological media. To test for the effect on biofilm formation, the biofilm was stained with crystal violet. The absorbance was determined to evaluate biofilm growth. Biofilm metabolic activity was measured based on biofilm having the ability to reduce XTT to a water-soluble orange compound. Results: The inclusion of HFCS in the beverages, as...
Research Interests:
This study investigated the antimicrobial and osteogenic properties of titanium (Ti) disks superficially modified with tetracycline (TCH)-incorporated polymer nanofibers. The experiments were carried out in two phases. The first phase... more
This study investigated the antimicrobial and osteogenic properties of titanium (Ti) disks superficially modified with tetracycline (TCH)-incorporated polymer nanofibers. The experiments were carried out in two phases. The first phase dealt with the synthesis and characterization (i.e., morphology, mechanical strength, drug release, antimicrobial activity, and cytocompatibility) of TCH-incorporated fibers. The second phase was dedicated to evaluating both the antimicrobial and murine-derived osteoprecursor cell (MC3T3-E1) response of Ti-modified with TCH-incorporated fibers. TCH was successfully incorporated into the submicron-sized and cytocompatible fibers. All TCH-incorporated mats presented significant antimicrobial activity against periodontal pathogens. The antimicrobial potential of the TCH-incorporated fibers-modified Ti was influenced by both the TCH concentration and bacteria tested. At days 5 and 7, a significant increase in MC3T3-E1 cell number was observed for TCH-incor...
Research Interests:
This study aims to synthesize and characterize biodegradable polymer-based matrices loaded with CaO nanoparticles for osteomyelitis treatment and bone tissue engineering. Poly(ε-caprolactone) (PCL) and PCL/gelatin (1:1, w/w) solutions... more
This study aims to synthesize and characterize biodegradable polymer-based matrices loaded with CaO nanoparticles for osteomyelitis treatment and bone tissue engineering. Poly(ε-caprolactone) (PCL) and PCL/gelatin (1:1, w/w) solutions containing CaO nanoparticles were electrospun into fibrous matrices. Scanning (SEM) and transmission (TEM) electron microscopy, Fourier transformed infrared (FTIR), energy dispersive X-ray spectroscopy (EDS), contact angle (CA), tensile testing, and antibacterial activity (agar diffusion assay) against Staphylococcus aureus were performed. Osteoprecursor cell (MC3T3-E1) response (i.e., viability and alkaline phosphatase expression/ALP) and infiltration into the matrices were evaluated. CaO nanoparticles were successfully incorporated into the fibers, with the median fiber diameter decreasing after CaO incorporation. The CA decreased with the addition of CaO, and the presence of gelatin made the matrix very hydrophilic (CA = 0°). Increasing CaO concentr...
Research Interests:
Materials Science, Dentistry, Electron Microscopy, Nanofibers, Electrospinning, and 15 moreNanoparticles, Medicine, PMC, Bacteria, Gelatin, Alkaline phosphatase, Osteomyelitis, Fourier transform infrared spectroscopy, Oxides, Materials Testing, Calcium Compounds, CaO, Biocompatible Materials, Cell Survival, and Bone and Bones
Fusobacterium nucleatum is one of the most numerically prevalent bacteria associated with gingivitis and is associated with bacteremia of oral origin. The interaction between oral bacteria and host defense is a central mechanism linking... more
Fusobacterium nucleatum is one of the most numerically prevalent bacteria associated with gingivitis and is associated with bacteremia of oral origin. The interaction between oral bacteria and host defense is a central mechanism linking oral and systemic diseases. We hypothesized that the metabolic oxidative activity of peripheral blood neutrophils is stimulated by exposure to F. nucleatum. Objective: To evaluate the oxidative response of human peripheral blood neutrophils, in terms of priming and activation, to F. nucleatum. Materials & Methods: The oxidative activity of peripheral blood neutrophils was evaluated by lumiol-enhanced chemiluminescence. Assays were conducted using F. nucleatum ATCC 10953. In addition, Staphylococcus aureus ATCC 9144 and Aggregatibacter actinomycetemcomitans ATCC 33384 were used as bacterial controls. All bacteria were killed by exposure to UV light prior to use in the assays. Comparisons among the groups were performed using ANOVA. Results: Activation...
Objective: The purpose of this study was to compare the effects of different levels of nicotine and tobacco extract exposure on Streptococcus mutans biofilm formation and the inhibitory effect of the polyphenol epigallocatechin-3 gallate... more
Objective: The purpose of this study was to compare the effects of different levels of nicotine and tobacco extract exposure on Streptococcus mutans biofilm formation and the inhibitory effect of the polyphenol epigallocatechin-3 gallate (EGCG) found in green tea. This study addressed the results of biofilm assays with EGCG and varying relative concentrations of nicotine and tobacco extract consistent with primary, secondary and tertiary levels of smoking exposure. Primary smoking exposure to nicotine has been demonstrated to significantly increase biofilm formation, while EGCG has been demonstrated to reduce S. mutans biofilm formation.Methods:S. mutans was treated with varying levels of nicotine or cigarette smoke condensate (CSC) concentrations (0–32 mg/ml and 0–2 mg/ml, respectively) in Tryptic Soy broth supplemented with 1% sucrose for different lengths of time simulating primary, secondary and tertiary smoking exposure with and without 0.25 mg/ml EGCG. The amount of total grow...
Research Interests:
Streptococcus mutans serotype k strains comprise <3% of oral isolates of S. mutans but are prominent in diseased cardiovascular (CV) tissue. Collagen binding protein (CBP) genes, cbm and cnm, are prevalent in serotype k strains and are... more
Streptococcus mutans serotype k strains comprise <3% of oral isolates of S. mutans but are prominent in diseased cardiovascular (CV) tissue. Collagen binding protein (CBP) genes, cbm and cnm, are prevalent in serotype k strains and are associated with endothelial cell invasion. Nicotine increases biofilm formation by serotype c strains of S. mutans, but its effects on serotype k strains and strains with CBP are unknown. Saliva contains arginine which alters certain properties of the extracellular polysaccharides (EPS) in S. mutans biofilm. We examined whether nicotine and arginine affect sucrose-induced biofilm of S. mutans serotypes k (n = 23) and c (n = 10) strains with and without CBP genes. Biofilm mass, metabolism, bacterial proliferation, and EPS production were assessed. Nicotine increased biomass and metabolic activity (p < 0.0001); arginine alone had no effect. The presence of a CBP gene (either cbm or cnm) had a significant effect on biofilm production, but serotype ...
Research Interests:
The adhesion of pathogenic bacteria to the host surface is an essential step in the development of numerous infections, including dental caries. Attachment of Streptococcus mutans, the main etiological agent of human dental caries, to the... more
The adhesion of pathogenic bacteria to the host surface is an essential step in the development of numerous infections, including dental caries. Attachment of Streptococcus mutans, the main etiological agent of human dental caries, to the tooth surface may be mediated by glucan synthesized by glucosyltransferase (GTF) and by cell surface proteins, such as P1, which bind to salivary receptors. Fimbriae on the surfaces of many microorganisms are known to function in bacterial adhesion. Previous studies in this laboratory have initially characterized the fibrillar surface of S. mutans. The purpose of this investigation was the comparison of the antigenic properties of fimbria preparations of S. mutans isolates from five caries-resistant (CR) and six caries-susceptible (CS) subjects. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of S. mutans fimbrial preparations revealed five major protein bands at 200, 175, 157, 86, and 66 kDa in preparations from CR and CS subjec...
Research Interests:
Immunology, Biology, Adolescent, Medicine, Virulence, and 15 moreHumans, Child, Female, Dental Caries, Male, Middle Aged, Adult, Streptococcus mutans, Polyacrylamide Gel Electrophoresis, Cell Surface Markers, Bacterial Adhesion, Enzyme Linked Immunosorbent Assay, Pathogenic Bacteria, Child preschool, and Sodium Dodecyl Sulfate
Streptococcus mutans has been identified as the major etiological agent of human dental caries. The first step in the initiation of infection by this pathogenic bacterium is its attachment (i.e., through bacterial surface proteins such as... more
Streptococcus mutans has been identified as the major etiological agent of human dental caries. The first step in the initiation of infection by this pathogenic bacterium is its attachment (i.e., through bacterial surface proteins such as glucosyltransferases, P1, glucan-binding proteins, and fimbriae) to a suitable receptor. It is hypothesized that a mucosal vaccine against a combination ofS. mutans surface proteins would protect against dental caries by inducing specific salivary immunoglobulin A (IgA) antibodies which may reduce bacterial pathogenesis and adhesion to the tooth surface by affecting several adhesins simultaneously. Conventional Sprague-Dawley rats, infected withS. mutans at 18 to 20 days of age, were intranasally immunized with a mixture of S. mutans surface proteins, enriched for fimbriae and conjugated with cholera toxin B subunit (CTB) plus free cholera toxin (CT) at 13, 15, 22, 29, and 36 days of age (group A). Control rats were either not immunized (group B) o...
Research Interests:
PurposeRecent findings on the effects of smoking and nicotine on oral microorganisms and on microbial interactions with human cells were reviewed. A PubMed search identified recent publications in English that addressed the effects of... more
PurposeRecent findings on the effects of smoking and nicotine on oral microorganisms and on microbial interactions with human cells were reviewed. A PubMed search identified recent publications in English that addressed the effects of smoking and nicotine on oral microorganisms: growth, biofilm formation, plaque composition, enzyme regulation, and cross-species interactions. Interactions of tobacco-exposed microbes with human tissues are also discussed.Recent FindingsSmoking alters the oral microbiome. Nicotine increases the pathogenicity of oral microorganisms, either by increasing expression of virulence factors or by increasing the amount of biofilm formed. Nicotine affects human cells via nicotine acetylcholine receptors (nAChRs), and the prokaryote homolog may explain how nicotine affects microbial cells. Interactions of nicotine exposed microbial and human tissues likely contribute to cardiovascular disease.SummaryThe evidence supports the destructive oral and systemic effects of smoking and nicotine exposure, leading to development or exacerbation of dental caries, periodontitis, stomatitis, and heart diseases.
We investigated the direct and residual antibacterial effects of intracanal antimicrobials against bacterial biofilms obtained from infected mature and immature teeth with necrotic pulps. Sterile dentin slabs (n = 100) were inoculated... more
We investigated the direct and residual antibacterial effects of intracanal antimicrobials against bacterial biofilms obtained from infected mature and immature teeth with necrotic pulps. Sterile dentin slabs (n = 100) were inoculated with bacterial biofilms obtained from root canals of an immature or a mature tooth with pulpal necrosis and incubated anaerobically for 3 weeks (n = 50 per biofilm). Dentin infected with each type of biofilm received 1 week of treatment with 1 or 5 mg/mL double antibiotic paste (DAP) in methylcellulose hydrogels, calcium hydroxide, or placebo paste or received no treatment (n = 10). The pastes were removed, and biofilm disruption assays were performed. Additional dentin slabs (n = 100) were pretreated with the same treatments (n = 20). The pastes were rinsed off, and the samples were immersed in phosphate-buffered saline for 1 week. Thereafter, samples from the treatment groups were infected with bacterial biofilm from both clinical sources mentioned e...
Research Interests:
We evaluated the effect of various antimicrobials used in endodontic regeneration on a 3-week-old Enterococcus faecalis biofilm. E. faecalis biofilm was grown on standardized dentin samples for 3 weeks. Infected dentin samples were... more
We evaluated the effect of various antimicrobials used in endodontic regeneration on a 3-week-old Enterococcus faecalis biofilm. E. faecalis biofilm was grown on standardized dentin samples for 3 weeks. Infected dentin samples were randomized into 8 experimental groups (n = 8) and treated with calcium hydroxide (Ca[OH]2), 500 mg/mL of double antibiotic paste (DAP, equal portions of metronidazole and ciprofloxacin), low dilutions of DAP (1 or 0.1 mg/mL loaded into a methylcellulose vehicle system), sterile saline, or placebo paste (only methylcellulose) for 7 days. The other experimental groups were treated with 1.5% sodium hypochlorite (NaOCl) or 2% chlorhexidine gluconate (CHX) solutions for 5 minutes. After the assigned treatments, the bacterial biofilms were detached from dentin, spiral plated, and quantified using an automated counting machine. Permutation tests followed by Sidak post hoc multiple comparisons were used for statistical analyses (α = 0.05). The infected dentin treated with 1.5% NaOCl or 500 mg/mL of DAP provided complete eradication of bacterial biofilm. Furthermore, the infected dentin treated with 2% CHX, Ca(OH)2, or 1 mg/mL of DAP had a comparable antibiofilm effect, but they were not able to completely eradicate bacterial biofilm. No significant difference in the antibiofilm effect was observed between 500 mg/mL of DAP, Ca(OH)2, 1.5% NaOCl, and 2% CHX. At least 1 mg/mL of DAP in a methylcellulose vehicle system is required to eliminate a substantial amount of E. faecalis biofilm. Furthermore, the antibiofilm effects of 1.5% NaOCl and 2% CHX irrigation solutions were comparable with that of 500 mg/mL of DAP and Ca(OH)2.
Research Interests:
The aim of this study was to investigate the residual antibacterial effect of human radicular dentin treated with various concentrations of triple antibiotic paste and double antibiotic paste (DAP). Sterilized dentin specimens were... more
The aim of this study was to investigate the residual antibacterial effect of human radicular dentin treated with various concentrations of triple antibiotic paste and double antibiotic paste (DAP). Sterilized dentin specimens were randomly assigned to 6 treatment groups and a no-treatment control group (n = 45 per group). For treatment groups, specimens were treated with either TAP or DAP at various concentrations (1000, 1, or 0.5 mg/mL) for 2 weeks. Then, each specimen was irrigated with 5 mL saline and incubated in phosphate-buffered solutions for 3, 7, 14, or 30 days. After that, Enterococcus faecalis was cultured on the specimens for 3 days. Each specimen was then transferred to a tube containing 200 μL saline, sonicated, and vortexed to detach the bacterial biofilm. The detached biofilm was spiral plated, and the number of colony-forming units was determined using an automated counting machine. Dentin specimens treated with 1000 mg/mL TAP or DAP had a significant residual anti...
Research Interests:
Research Interests:
Dentistry, Biofilms, Humans, Spectrophotometry, Root Canal Irrigants, and 11 moreAnti-Bacterial Agents, Endodontics, Calcium Hydroxide, Bacterial Load, Enterococcus faecalis, Microbial Sensitivity Tests, Ciprofloxacin, Minocycline, Nephelometry and Turbidimetry, Metronidazole, and PORPHYROMONAS GINGIVALIS
Streptococcus mutans has been implicated as the major causative agent of dental caries. Although restorative treatment for caries is thought to temporarily eliminate the carious challenge, there are few reports of alterations in salivary... more
Streptococcus mutans has been implicated as the major causative agent of dental caries. Although restorative treatment for caries is thought to temporarily eliminate the carious challenge, there are few reports of alterations in salivary mutans streptococci (MS) numbers and no reports of changes in salivary IgA antibody to S. mutans following restorative treatment. This study investigated the effects of treatment in 12 caries-active children. Numbers of MS decreased slightly from pre- to postrestoration levels in six subjects and increased in five subjects. However, there were no significant differences in pre-to postrestoration numbers of total oral streptococci, MS, the percentage of MS/total oral streptococci, salivary IgA antibody levels to S. mutans, or correlations between bacterial counts and IgA antibody levels. These results indicate that successful restorative treatment does not alter mutans streptococcal numbers and suggest the need for more effective methods for reducing...