38 results on '"Khajotia SS"'
Search Results
2. P2 - Development of in-office bleaching gels containing co-doped titanium dioxide nanoparticles
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Kury, M, Khajotia, SS, Florez, FLE, and Cavalli, V
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- 2023
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3. Optimization of an ultra-bright real-time high-throughput renilla luciferase assay for antibacterial assessment of Streptococcus mutans biofilms.
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Hiers RD, Khajotia SS, Merritt J, and Esteban Florez FL
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- Titanium chemistry, Luciferases, Nanoparticles, Microbial Sensitivity Tests, Streptococcus mutans drug effects, Biofilms drug effects, Luminescent Measurements, Anti-Bacterial Agents pharmacology, High-Throughput Screening Assays methods
- Abstract
Objective: The present work demonstrates the optimization of a renilla-based real-time, ultra-bright, non-disruptive, high-throughput bioluminescence assay (HTS) to assess the metabolism of intact Streptococcus mutans biofilms and its utility in screening the antibacterial efficacy of experimental nanofilled dental adhesive resins containing varying concentrations of nitrogen-doped titanium dioxide nanoparticles (N_TiO
2 )., Methods: Optimization of the assay was achieved by screening real-time bioluminescence changes in intact Streptococcus mutans biofilms imposed by the various experimental biofilm growth parameters investigated (bacterial strain, growth media, sucrose concentration, dilution factor, and inoculum volume). The optimized assay was then used to characterize the antibacterial efficacy of experimental nanofilled dental adhesive resins. The assay's ability to discriminate between bacteriostatic and bactericidal approaches was also investigated., Results: Relative Light Units (RLU) values from the HTS optimization were analyzed by multivariate ANOVA (α = 0.05) and coefficients of variation. An optimized HTS bioluminescence assay was developed displaying RLUs values (brightness) that are much more intense when comparing to other previously reported bioluminescence assays, thereby decreasing the error associated with bioluminescence assays and displaying better utility while investigating the functionalities of antimicrobial nanofilled experimental dental adhesive resins with proven long-term properties., Significance: The present study is anticipated to positively impact subsequent research on dental materials and oral microbiology because it serves as a valuable screening tool in metabolic-based assays with increased sensitivity and robustness. The assay reported is anticipated to be further optimized to be used as a co-reporter for other Luc based assays., (Copyright © 2024 Elsevier Inc. All rights reserved.)- Published
- 2024
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4. Characterization of Experimental Nanoparticulated Dental Adhesive Resins with Long-Term Antibacterial Properties.
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Hiers RD, Huebner P, Khajotia SS, and Florez FLE
- Abstract
Experimental adhesives with functional nitrogen-doped titanium dioxide nanoparticles (N_TiO
2 ) have been shown to display improved properties. However, these materials have not been characterized regarding their degree of conversion (DC), biaxial flexure strength (BFS), surface roughness (SR), elastic modulus (EM), and long-term antibacterial functionalities. Experimental adhesives were synthesized by dispersing N_TiO2 (10%, 20%, or 30%, v / v %) into OptiBond Solo Plus (OPTB, Kerr Corp., USA). Unpolymerized adhesives (volume = 50 μL/drop, n = 3/group) were individually placed onto a heated (37 °C) attenuated total reflectance (ATR) monolithic diamond crystal (Golden Gate, Specac). The spectra of composites were obtained with a Fourier-transform infrared (FTIR) spectrometer (Nicolet IS50; 500-4500 cm-1 ; resolution = 4 cm-1 , 10 internal scans/spectrum) before and after polymerization. Disk-shaped specimens (diameter = 6.0 mm, thickness = 0.5 mm) for BFS ( n = 12/group), SR and EM ( n = 3/group), and for antibacterial testing ( n = 18/group/time-point) were fabricated and photopolymerized (1 min each; 385-515 nm, 1000 mW/cm2 ; VALO). DC values (%) were calculated from pre- and post-polymerization spectra using the two-frequency method and tangent-baseline technique. BFS was assessed using a universal testing machine (Instron 68TM-5, crosshead speed = 1.27 mm/min, 25 °C). SR and EM were investigated using an atomic force microscope (Multimode 8) with aluminum-coated silicon probes (8 nm pyramidal tip, spring constant 40 N/m, Bruker). Antibacterial testing was performed by growing Streptococcus mutans biofilms (UA159- ldh , 37 °C, microaerophilic) on the surfaces of specimens for 24 h and then measuring the relative luminescence units (RLU) with a Biotek Synergy HT multi-well plate reader. Results demonstrate that experimental materials containing 10%, 20%, and 30% of N_TiO2 displayed higher levels of DC, had better mechanical properties, and were able to exert strong and durable antibacterial properties without visible light irradiation and after extended periods of simulated shelf-life and aging in PBS. The reported experimental materials are expected to increase the service lives of polymer-based bonded restorations by decreasing the incidence of secondary caries., Competing Interests: The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.- Published
- 2022
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5. Novel Experimental In-Office Bleaching Gels Containing Co-Doped Titanium Dioxide Nanoparticles.
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Kury M, Hiers RD, Zhao YD, Picolo MZD, Hsieh J, Khajotia SS, Esteban Florez FL, and Cavalli V
- Abstract
The present study reports on the development and testing of novel bleaching agents containing co-doped metaloxide nanoparticles (NP; 0%, 5%, 10% v/w) and hydrogen peroxide (HP, 0%, 6%, 15%, and 35%). Bovine blocks (n = 200, A = 36 mm2) were obtained and randomly distributed into experimental groups (n = 10/group). NPs were incorporated into gels before bleaching (3 sessions, 7 days apart, 30 min/session, irradiated with violet light-LT). Color changes (ΔE00, ΔWID), mineral content (CO32−, PO43−), and topography were assessed (spectrophotometer, ATR-FTIR, and AFM) before and after bleaching procedures (14 days). Metabolic status and three-dimensional components of non-disrupted Streptococcus mutans biofilms were investigated using a multimode reader and confocal microscopy. The results indicate that ΔE00 and ΔWID significantly increased with NPs’ concentrations and LT. The enamel’s mineral ratio was adversely impacted by HP, but alterations were less pronounced when using NP-containing gels. The enamel’s topography was not damaged by the bleaching protocols tested. The bioluminescence results show that bleaching protocols do not render latent antibacterial properties to enamel, and the confocal microscopy results demonstrate that the 3-dimensional distribution of the components was affected by the protocols. The proposed nanotechnology improved the bleaching efficacy of experimental materials independent of hydrogen peroxide or irradiation and did not adversely impact the enamel’s surface properties or its chemical content.
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- 2022
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6. Predictive alternative methods for assessing biocompatibility of dental materials: A NIST-NIDCR workshop report.
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Petersen EJ, Elliott JT, Bancos S, Caldwell B, Khajotia SS, Kleinstreuer NC, Margerrison E, and Pfeifer C
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- National Institute of Dental and Craniofacial Research (U.S.), United States, Biocompatible Materials toxicity
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- 2022
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7. Antibacterial efficacy of non-thermal atmospheric plasma against Streptococcus mutans biofilm grown on the surfaces of restorative resin composites.
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Nima G, Harth-Chu E, Hiers RD, Pecorari VGA, Dyer DW, Khajotia SS, Giannini M, and Florez FLE
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- Luminescent Measurements methods, Microbial Sensitivity Tests, Microbial Viability drug effects, Streptococcus mutans ultrastructure, Surface Properties, Time Factors, Anti-Bacterial Agents pharmacology, Biofilms drug effects, Composite Resins, Plasma Gases pharmacology, Streptococcus mutans drug effects
- Abstract
The aim of this study was to evaluate the antimicrobial efficacy of non-thermal atmospheric plasma (NTAP) against Streptococcus mutans biofilms. Resin discs were fabricated, wet-polished, UV sterilized, and immersed in water for monomer extraction (37 °C, 24 h). Biofilms of bioluminescent S. mutans strain JM10 was grown on resin discs in anaerobic conditions for (37 °C, 24 h). Discs were divided into seven groups: control (CON), 2% chlorhexidine (CHX), only argon gas 150 s (ARG) and four NTAP treatments (30 s, 90 s, 120 s, 150 s). NTAP was applied using a plasma jet device. After treatment, biofilms were analyzed through the counting of viable colonies (CFU), bioluminescence assay (BL), scanning electron microscopy (SEM), and polymerase chain reaction (PCR). All NTAP-treated biofilm yielded a significant CFU reduction when compared to ARG and CON. BL values showed that NTAP treatment for 90 s, 120 s or 150 s resulted in statistically significantly lower metabolic activity when compared to the other groups. CHX displayed the lowest means of CFU and BL. SEM showed significant morphological changes in NTAP-treated biofilm. PCR indicated damage to the DNA structure after NTAP treatment. NTAP treatment was effective in lowering the viability and metabolism of S. mutans in a time-dependent manner, suggesting its use as an intraoral surface-decontamination strategy., (© 2021. The Author(s).)
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- 2021
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8. Size-resolved spatial distribution analysis of aerosols with or without the utilization of a novel aerosol containment device in dental settings.
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Esteban Florez FL, Thibodeau T, Oni T, Floyd E, Khajotia SS, and Cai C
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The coronavirus disease 2019 pandemic has imposed unprecedented occupational challenges for healthcare professionals. In dentistry, handheld instruments such as air and electric handpieces, ultrasonic scalers, and air/water syringes are capable of generating aerosols, droplets, and splatter, thereby exposing dental professionals to airborne contaminants such as viruses, bacteria, and fungi. The objective of the present study was to determine the spatial distribution of aerosols by size (0.30 to 20.00 μ m) and the efficacy of a novel aerosol containment device (ACD) in a large operatory room with 12 dental chairs. Real-time portable laser aerosol spectrometers were used to measure the size-resolved number concentration of aerosols generated by a collision nebulizer. Results reported demonstrate that aerosol number concentrations significantly decreased as a function of distance with or without the utilization of the ACD. The ACD was able to efficiently decrease (up to 8.56-fold) the number and size distribution of particles in a large dental clinic. The novel device demonstrated higher efficiency for particles shown to contain the highest levels of severe acute respiratory syndrome coronavirus 2 in Chinese hospitals, thereby showing great promise to potentially decrease the spreading of nosocomial pathogens in dental settings., (© 2021 Author(s).)
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- 2021
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9. Assessment of Streptococcus mutans biofilms on orthodontic adhesives over 7 days.
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Schneider BJ, Hiers RD, Currier GF, Kadioglu O, Johnston SE, Zhao YD, Esteban Florez FL, and Khajotia SS
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- Biofilms, Humans, Dental Cements, Streptococcus mutans
- Abstract
Introduction: The purpose of this study was to compare the metabolism of Streptococcus mutans biofilms after 1-7 days of growth on different orthodontic adhesives., Methods: Specimens of 6 commercial orthodontic adhesives were fabricated in custom-made molds and polymerized using a light-emitting diode light-curing unit. Bioluminescent S mutans (UA159:JM10) biofilms were grown on ultraviolet-sterilized specimens for 1, 3, 5, and 7 days (n = 18 biofilms/d/product) in anaerobic conditions at 37°C. The metabolism of biofilms (relative luminescence unit [RLU]) was measured 0, 2, 4, and 6 minutes after exposure to D-luciferin solution using a microplate reader. A linear mixed-effects model was used to analyze the logarithm of RLU (log RLU). The model included fixed effects of products, days, and minutes. Tukey-Kramer post-hoc tests were then performed on the significant predictors of log RLU (α = 0.05)., Results: Days (P <0.0001) and minutes (P <0.0001) were independent predictors of log RLU, but the products were not (P = 0.5869). After adjusting for minutes, the log RLU was analyzed with a post-hoc test, and all differences between days were significant with the exceptions of day 3 from day 5 (P = 0.0731) and day 5 from day 7 (P = 0.8802). After adjusting for day, log RLU was analyzed with a post-hoc test and all differences in minutes were significant., Conclusions: No significant differences in the metabolism of S mutans biofilms were observed among the 6 orthodontic adhesives. Biofilms that were grown for 3 days demonstrated the highest levels of biofilm metabolism as evidenced by higher mean log RLU values relative to 1, 5, and 7-day growth durations., (Copyright © 2021 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.)
- Published
- 2021
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10. Growth hormone effects on healing efficacy, bone resorption and renal morphology of rats: histological and histometric study in rat calvaria.
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Chaves LH, Giovanini AF, Zielak JC, Scariot R, Gonzaga CC, Storrer CLM, Khajotia SS, Esteban Florez FL, and Deliberador TM
- Abstract
Previous reports demonstrated the utility of systemic application of growth hormone (GH) in the treatment of bone defects. Very few studies correlated bone repair efficacy with hepatic and renal side effects promoted by locally-delivered GH. The objectives of this study were to assess the bone repair properties along with hepatic and renal adverse effects promoted by local application of GH in a rat model. Thirty-two rats were randomly divided (4 groups; n = 8/group), as follows: (i) AB (autogenous bone + local application of saline solution [SS]), (ii) AB+ (autogenous bone + SS local application + SS irrigation), (iii) AB/GH+ (autogenous bone + SS local application + GH irrigation) and (iv) AB/GHL+ (autogenous bone + GH local application + GH irrigation). Critical-sized defects (diameter = 5.0 mm) were surgically created by a single operator in the calvaria of rats. Defects were filled with ground autogenous bone. Defects pertaining to AB+ and AB/GH+ received a mixture of autogenous bone and a SS-saturated (0.02 mL) collagen sponge covered with bovine cortical membrane. Defects in group AB/GHL+, were filled with the same biomaterials saturated with GH (0.02 mL). SS (0.1 mL) or GH (0.1 mL, equivalent to 0.4 IU) were applied locally on alternate days (8 weeks) in animals in groups AB, AB+ and AB/GH+ or AB/GHL+, respectively. Bone repair properties was determined in hematoxylin/eosin-stained slices using traditional histologic and histomorphometric techniques along with optical microscopy and digital image analysis. Statistical differences among groups was determined using Kruskal-Wallis and Tukey post hoc tests (α = 0.05). Histology results indicated that AB and AB+ displayed greater presence of autogenous bone as compared to AB/GH+ and AB/GHL+. Histomorphometric results indicated significantly higher osteoid matrix formation in AB and AB+ when compared to AB/GHL+ ( p = 0.009). Kidneys and livers were found to have their glomeruli preserved in AB and AB+. Strong glomeruli necrosis and large areas of protein deposition were found in AB/GH+. Abnormal small-sized glomeruli were found in AB/GHL+. The utilization of autogenous bone graft associated with local application and irrigation with GH was shown to not improve the bone repair in calvarial critical-sized defects in a rat model., (© 2020 The Authors.)
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- 2020
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11. Sorption, solubility and cytotoxicity of novel antibacterial nanofilled dental adhesive resins.
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Esteban Florez FL, Kraemer H, Hiers RD, Sacramento CM, Rondinone AJ, Silvério KG, and Khajotia SS
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- Adhesiveness, Cell Survival drug effects, Dental Pulp cytology, Humans, Solubility, Water chemistry, Anti-Bacterial Agents chemistry, Anti-Bacterial Agents toxicity, Nanostructures chemistry, Resins, Synthetic chemistry, Resins, Synthetic toxicity
- Abstract
Dental adhesives hydrolyze in the mouth. This study investigated the water sorption (SOR), solubility (SOL) and cytotoxicity (CYTO) of experimental adhesives containing nitrogen-doped titanium dioxide nanoparticles (N_TiO
2 ). Specimens (n = 15/group [SOR, SOL]; n = 10/group [CYTO]) of unaltered Clearfil SE Protect (CSP), OptiBond Solo Plus (OSP), Adper Scotchbond (ASB) and experimental adhesives (OSP + 25% or 30% of N_TiO2 ) were fabricated, desiccated (37 °C) and tested for SOR and SOL according to ISO Specification 4049 (2009). CYTO specimens were UV-sterilized (8 J/cm2 ) and monomer extracted in growth medium (1, 3 or 7 days). Human pulp cells were isolated and seeded (0.5 × 104 ) for MTT assay. SOR and SOL data was analyzed using GLM and SNK (α = 0.05) and CYTO data was analyzed with Kruskal-Wallis and SNK tests (α = 0.05). SOR and SOL values ranged from 25.80 μg/mm3 (30% N_TiO2 ) to 28.01 μg/mm3 (OSP) and 23.88 μg/mm3 (30% N_TiO2 ) to 25.39 μg/mm3 (25% N_TiO2 ). CYTO results indicated that pulp cells exposed to experimental materials displayed comparable viabilities (p > 0.05) to those of OSP. Experimental materials displayed comparable SOR, SOL and CYTO values (p > 0.05) when compared to unaltered materials. N_TiO2 incorporation have not adversely impacted SOR, SOL and CYTO properties of unaltered adhesives.- Published
- 2020
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12. Advanced characterization of surface-modified nanoparticles and nanofilled antibacterial dental adhesive resins.
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Esteban Florez FL, Trofimov AA, Ievlev A, Qian S, Rondinone AJ, and Khajotia SS
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Nanotechnology can improve the performance of dental polymers. The objective of this study was to modify the surfaces of nanoparticles with silanes and proteins, characterize nanoparticles' agglomeration levels and interfaces between nanoparticles and the polymeric matrix. Undoped (n-TiO
2 ), nitrogen-doped (N_TiO2 ) and nitrogen-fluorine co-doped titanium dioxide nanoparticles (NF_TiO2 ) were synthesized and subjected to surface modification procedures in preparation for Small-Angle X-Ray Scattering (SAXS) and Small-Angle Neutron Scattering (SANS) characterizations. Experimental adhesives were manually synthesized by incorporating 20% (v/v) of n-TiO2 , N_TiO2 or NF_TiO2 (as-synthesized or surface-modified) into OptiBond Solo Plus (OPTB). Specimens (n = 15/group; d = 6.0 mm, t = 0.5 mm) of OPTB and experimental adhesives were characterized using Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS), 2-D ToF-SIMS chemical imaging and SANS. SAXS results indicated that surface-modified nanoparticles displayed higher scattering intensities in a particle-size dependent manner. ToF-SIMS results demonstrated that nanoparticles' incorporation did not adversely impact the parental polymer. 2-D ToF-SIMS chemical imaging demonstrated the distribution of Ti+ and confirmed nitrogen-doping levels. SANS results confirmed nanoparticles' functionalization and revealed the interfaces between nanoparticles and the polymer matrix. Metaloxide nanoparticles were successfully fabricated, incorporated and covalently functionalized in a commercial dental adhesive resin, thereby supporting the utilization of nanotechnology in dentistry.- Published
- 2020
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13. The Applicability of a Drop Penetration Method to Measure Contact Angles on TiO 2 and ZnO Nanoparticles.
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Garner SM, O'Rear EA, Khajotia SS, and Florez FLE
- Abstract
In this study, six solvents (water, diiodomethane, bromonaphthalene, formamide, ethanol and ethylene glycol) were examined for three nanoparticle substrates, zinc oxide and titanium dioxide (21 nm and 100 nm), with the goal of assessing the suitability of a modified drop penetration method (DPM) for orders of magnitude smaller particles. Nanoparticles were compressed into flat discs and the solvent dropped on the surface while the image with time was recorded. Contact angles were in reasonable agreement with literature over the range of 20-80°, but failed to provide acceptable results for surface energy components. It was necessary to eliminate certain solvents and substrates not meeting the selection criteria.
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- 2020
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14. Pairing orthodontic adhesive resins and light-curing units for optimal degree of conversion.
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Soyland R, Currier GF, Kadioglu O, Li J, Esteban Florez FL, Rueggeberg FA, and Khajotia SS
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- Humans, Orthodontic Brackets, Polymerization, Spectroscopy, Fourier Transform Infrared, Composite Resins chemistry, Curing Lights, Dental, Light-Curing of Dental Adhesives, Materials Testing, Orthodontics instrumentation
- Abstract
Objectives: The purpose of this study was to identify the combination of orthodontic adhesive resins and light-emitting diode (LED) light-curing units (LCUs) that result in the highest degree of resin conversion (DC). The hypothesis tested was that pairing orthodontic resins with LCUs from the same manufacturer produces higher DC versus unpaired resins and LCUs., Methods: Pre-polymerization spectra of adhesive resins (Transbond XT [3M Unitek], BracePaste [American Orthodontics] or Opal Bond MV [Opal by Ultradent]) were obtained at oral temperature (37°C) using an attenuated total reflectance (ATR) diamond crystal (Golden Gate, Specac) in a Fourier-transform infrared (FTIR) spectrometer (Nicolet IS50). Resin specimens were polymerized using various LCUs (Ortholux Luminous [3M Unitek], Blue Ray 3 [American Orthodontics], or VALO Ortho Cordless [Ultradent Products, Inc.]) before obtaining post-polymerization infrared (IR); spectra. Twelve LCU-resin combinations were tested (n = 20/combination), half with a bracket present (Mini Diamond Twin, Ormco) and half without. DC values (%) were calculated using the two-frequency method and tangent-baseline technique. Data for each resin were statistically analyzed using General Linear Models and Student-Newman-Keuls post hoc tests (α = 0.05)., Results: Statistically significant differences were found within each resin for the groups without brackets present (P < 0.0001), the groups with brackets present (P < 0.0001), and the groups with brackets when compared with the manufacturer-paired group without a bracket (P < 0.0001)., Conclusions: Adhesive resins and LCUs from the same manufacturer did not consistently result in statistically higher mean DC values than unpaired combinations. Metal brackets do not uniformly reduce the degree of conversion of adhesive resins when assessed using IR spectrometry., (Copyright © 2020 World Federation of Orthodontists. Published by Elsevier Inc. All rights reserved.)
- Published
- 2020
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15. Optimization of a real-time high-throughput assay for assessment of Streptococcus mutans metabolism and screening of antibacterial dental adhesives.
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Esteban Florez FL, Hiers RD, Zhao Y, Merritt J, Rondinone AJ, and Khajotia SS
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- Anti-Bacterial Agents, Biofilms, Extracellular Polymeric Substance Matrix, Humans, Reproducibility of Results, Dental Cements, Streptococcus mutans
- Abstract
Objective: The present work shows the optimization of a high-throughput bioluminescence assay to assess the metabolism of intact Streptococcus mutans biofilms and its utility as a screening method for nanofilled antibacterial dental materials., Methods: The assay was optimized by monitoring changes in bioluminescence mediated by variation of the experimental parameters investigated (growth media and sucrose concentration, inoculum:D-Luciferin ratio, dilution factor, inoculum volume, luminescence wavelength, replicate and luciferase metabolic activity). Confocal microscopy was then used to demonstrate the impact of biofilm growth conditions on the 3-D distribution of extracellular polymeric substance (EPS) within Streptococcus mutans biofilms and its implications as confounding factors in high-throughput studies (HTS)., Results: Relative Luminescence Unit (RLU) values from the HTS optimization were analyzed by multivariate ANOVA (α = 0.05) and coefficients of variation, whereas data from 3-D structural parameters and RLU values of biofilms grown on experimental antibacterial dental adhesive resins were analyzed using General Linear Models and Student-Newman-Keuls post hoc tests (α = 0.05). Confocal microscopy demonstrated that biofilm growth conditions significantly influenced the quantity and distribution of EPS within the 3-D structures of the biofilms. An optimized HTS bioluminescence assay was developed and its applicability as a screening method in dentistry was demonstrated using nanofilled experimental antibacterial dental adhesive resins., Significance: The present study is anticipated to positively impact the direction of future biofilm research in dentistry, because it offers fundamental information for the design of metabolic-based assays, increases the current levels of standardization and reproducibility while offering a tool to decrease intra-study variability., (Copyright © 2019 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)
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- 2020
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16. The Role of Marine Organic Extract in Bone Regeneration: A Pilot Study.
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Zielak JC, Vendramini I, Corso PFCL, Muller LL, Crivellaro VR, Khajotia SS, Esteban Florez FL, Scariot R, Elsalanty M, Deliberador TM, and Storrer CLM
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- Animals, Ceramics chemistry, Female, Hydroxyapatites chemistry, Osteoblasts drug effects, Osteoclasts drug effects, Pilot Projects, Sheep, Biocompatible Materials chemistry, Biocompatible Materials pharmacology, Bone Regeneration drug effects, Nacre chemistry, Nacre pharmacology
- Abstract
Novel biomaterials capable of accelerating the healing process of skeletal tissues are urgently needed in dentistry. The present in vivo study assessed the osteoconductive and osteoinductive properties of experimental biphasic bioceramics (HA-TCP) modified or not by a nacre extract (marine organic extract, MOE) in a sheep model. Fabrication of MOE involved mixing ground nacre (0.05 g, particle sizes < 0.1 mm) with glacial ethanoic acid (5 mL, pH 7) for 72 hours using external magnetic stirring (25°C). Nonreactive carriers (sterile polythene tubes; 3/animal, radius: 2.5 mm, length: 10.0 mm) pertaining to the control (empty) or experimental groups (HA-TCP or MOE-modified HA-TCP) were implanted intramuscularly into the abdominal segment of the torso in sheep ( n = 8, age: 2 years, weight: 45 kg). Euthanization of animals was performed at 3 and 6 months after surgery. Tissues harvested were subjected to macroscopic and radiographic assessments. Specimens were then stained for histological analysis. Both control and experimental animals were capable of inducing the neoformation of fibrous connective tissue at both time points where superior amounts of tissue formation and mineralization were detected for experimental groups (unaltered (at 3 and 6 mos) and MOE-modified HA-TCP (at 3 mos)). Histological results, however, revealed that mature bone formation was only observed for specimens fabricated with MOE-modified HA-TCP in a time-dependent manner. The present study has successfully demonstrated the in vivo utility of experimental biphasic bioceramics modified by MOE in an ectopic grafting sheep model. Promising osteoconductive and osteoinductive properties must be further developed and confirmed by subsequent research., Competing Interests: The authors of the present work declare that no financial or nonfinancial conflicts of interest are associated with this publication., (Copyright © 2020 João César Zielak et al.)
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- 2020
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17. Physicochemical, Mechanical, and Antimicrobial Properties of Novel Dental Polymers Containing Quaternary Ammonium and Trimethoxysilyl Functionalities.
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Bienek DR, Giuseppetti AA, Frukhtbeyn SA, Hiers RD, Esteban Florez FL, Khajotia SS, and Skrtic D
- Abstract
The aims of this study were to evaluate the physicochemical and mechanical properties, antimicrobial (AM) functionality, and cytotoxic potential of novel dental polymers containing quaternary ammonium and trimethoxysilyl functionalities (e.g., N-(2-(methacryloyloxy)ethyl)-N,N-dimethyl-3-(trimethoxysilyl)propan-1-aminium iodide (AM
sil1 ) and N-(2-(methacryloyloxy)ethyl)-N,N-dimethyl-11-(trimethoxysilyl)undecan-1-aminium bromide (AMsil2 )). AMsil1 or AMsil2 were incorporated into light-cured (camphorquinone + ethyl-4-N,N-dimethylamino benzoate) urethane dimethacrylate (UDMA)/polyethylene glycol-extended UDMA/ethyl 2-(hydroxymethyl)acrylate (EHMA) resins (hereafter, UPE resin) at 10 or 20 mass %. Cytotoxic potential was assessed by measuring viability and metabolic activity of immortalized mouse connective tissue and human gingival fibroblasts in direct contact with monomers. AMsil -UPE resins were evaluated for wettability by contact angle measurements and degree of vinyl conversion (DVC) by near infra-red spectroscopy analyses. Mechanical property evaluations entailed flexural strength (FS) and elastic modulus (E) testing of copolymer specimens. The AM properties were assessed using Streptococcus mutans (planktonic and biofilm forms) and Porphyromonas gingivalis biofilm. Neither AMsil exhibited significant toxicity in direct contact with cells at biologically relevant concentrations. Addition of AMsil s made the UPE resin more hydrophilic. DVC values for the AMsil -UPE copolymers were 2%-31% lower than that attained in the UPE resin control. The mechanical properties (FS and E) of AMsil -UPE specimens were reduced (11%-57%) compared to the control. Compared to UPE resin, AMsil1 -UPE and AMsil2 -UPE (10% mass) copolymers reduced S. mutans biofilm 4.7- and 1.7-fold, respectively (p ≤ 0.005). Although not statistically different, P. gingivalis biofilm biomass on AMsil1 -UPE and AM AMsil2 -UPE copolymer disks were lower (71% and 85%, respectively) than that observed with a commercial AM dental material. In conclusion, the AM function of new monomers is not inundated by their toxicity towards cells. Despite the reduction in mechanical properties of the AMsil -UPE copolymers, AMsil2 is a good candidate for incorporation into multifunctional composites due to the favorable overall hydrophilicity of the resins and the satisfactory DVC values attained upon light polymerization of AMsil -containing UDMA/PEG-U/EHMA copolymers., Competing Interests: D.R.B., A.A.G., S.A.F., and D.S. are employees of the non-profit ADA Foundation, which has applied for a patent describing synthesis and uses of polymerizable multifunctional antimicrobial quaternary ammonium monomers.- Published
- 2019
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18. Does the implant-abutment interface interfere on marginal bone loss? A systematic review and meta-analysis.
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Rosa EC, Deliberador TM, Nascimento TCLD, Kintopp CCA, Orsi JSR, Wambier LM, Khajotia SS, Esteban Florez FL, and Storrer CLM
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- Humans, Reference Values, Risk Assessment, Risk Factors, Time Factors, Alveolar Bone Loss etiology, Dental Abutments adverse effects, Dental Implant-Abutment Design adverse effects, Dental Implants adverse effects
- Abstract
The objective of this systematic review was to compare the conical internal connection (IC) with the external hexagonal connection (EH) on the occurrence of marginal bone loss (ΔMBL). Different databases were used to carry out the selection of the elected studies. The studies were judged according to the risk of bias as "high", "low" and "unclear" risk. For the meta-analysis we included only studies that could extract the data of ΔMBL, survival rate (SR) and probing depth (PD). No statistically significant differences were found for ΔMBL data at one, three- and five-year survival rates between implant connections (p <0.05), however statistically significant differences were found for PD between EH and IC implants (1-year follow-up) -0.53 [95%CI -0.82 to -0.24, p = 0.0004]. This present systematic review demonstrated that there are no significant differences between IC and EH implants for both ΔMBL and SR at 1, 3 e 5 years after functional loading, although better PD values were observed for implants pertaining to the IC connections. Considering the high heterogeneity, more well-delineated, randomized clinical trials should be conducted.
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- 2019
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19. Flexural properties of rectangular nickel-titanium orthodontic wires when used as ribbon archwires.
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Lin L, Currier GF, Kadioglu O, Florez FLE, Thompson DM, and Khajotia SS
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- Dental Alloys, Dental Stress Analysis, Elasticity, Flexural Strength, Humans, Materials Testing, Nickel, Orthodontic Wires, Titanium
- Abstract
Objective: To compare the flexural properties of rectangular nickel-titanium (Ni-Ti) orthodontic wires in occlusoapical and faciolingual orientations using a standardized test method., Materials and Methods: Twenty-two rectangular Ni-Ti wire groups were tested in occlusoapical (ribbon) orientation: eight conventional Ni-Ti products, five superelastic Ni-Ti products, and nine thermal Ni-Ti products (n = 10 per group). Six products of thermal Ni-Ti wire were tested in faciolingual (edgewise) orientation. A three-point bending test was performed to measure deactivation force at 3.0-, 2.0-, 1.0-, and 0.5-mm deflections of each rectangular wire at 37.0 ± 0.5°C. Analysis of variance and post hoc Student-Newman-Keuls tests were used to compare the mean values of the different groups (α = .05)., Results: The ranges of deactivation forces varied greatly with different kinds, sizes, products, and deflections of Ni-Ti wires. One product of conventional and superelastic Ni-Ti wires had steeper force-deflection curves. Four products had similarly shaped flat force-deflection curves, whereas the sixth product had a moderately steep force-deflection curve. Thermal Ni-Ti wires had smaller deactivation forces ranging from 0.773 N (78.8 g) to 2.475 N (252.4 g) between deflections of 1.0 and 0.5 mm, whereas wider ranges of force from 3.371 N (343.7 g) to 9.343 N (952.7 g) were predominantly found among conventional Ni-Ti wires between deflections of 3.0 and 2.0 mm., Conclusions: Clinicians should critically select archwires for use in the occlusoapical orientation not only based on Ni-Ti wire type, size (0.022 × 0.016-in or 0.025 × 0.017-in), and product but also with deactivation deflections from 0.5 and 1.0 mm to obtain light forces in the occlusoapical orientation.
- Published
- 2019
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20. Antibacterial dental adhesive resins containing nitrogen-doped titanium dioxide nanoparticles.
- Author
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Esteban Florez FL, Hiers RD, Larson P, Johnson M, O'Rear E, Rondinone AJ, and Khajotia SS
- Subjects
- Biofilms growth & development, Anti-Bacterial Agents chemistry, Anti-Bacterial Agents pharmacology, Biofilms drug effects, Dental Cements chemistry, Dental Cements pharmacology, Nanoparticles chemistry, Nitrogen chemistry, Nitrogen pharmacology, Streptococcus mutans physiology, Titanium chemistry, Titanium pharmacology
- Abstract
The development of dental adhesive resins with long-lasting antibacterial properties is a possible solution to overcome the problem of secondary caries in modern adhesive dentistry., Objectives: (i) Synthesis and characterization of nitrogen-doped titanium dioxide nanoparticles (N_TiO
2 ), (ii) topographical, compositional and wettability characterization of thin-films (unaltered and experimental) and, (iii) antibacterial efficacy of N_TiO2 -containing dental adhesives against Streptococcus mutans biofilms., Materials and Methods: Nanoparticles were synthesized and characterized using different techniques. Specimens (diameter = 12 mm, thickness ≅ 15 μm) of OptiBond Solo Plus (Kerr Corp., USA) and experimental adhesives [50, 67 and 80% (v/v)] were fabricated, photopolymerized (1000 mW/cm2 , 1 min) and UV-sterilized (254 nm, 800,000 μJ/cm2 ) for microscopy, spectroscopy, wettability and antibacterial testing. Wettability was assessed with a contact angle goniometer by dispensing water droplets (2 μL) onto four random locations of each specimen (16 drops/group). Drop profiles were recorded (1 min, 25 frames/s, 37 °C) and contact angles were calculated at time = 0 s (θINITIAL ) and time = 59 s (θFINAL ). Antibacterial testing was performed by growing S. mutans (UA159-ldh, JM10) biofilms for either 3 or 24 h (anaerobic conditions, 37 °C) with or without continuous light irradiation (410 ± 10 nm, 3 h = 38.75 J/cm2 , 24 h = 310.07 J/cm2 ) against the surfaces of sterile specimens., Results: N_TiO2 was successfully prepared using solvothermal methods. Doped-nanoparticles displayed higher light absorption levels when compared to undoped titania. Experimental adhesives demonstrated superior antibacterial efficacy in dark conditions., Conclusions: The findings presented herein suggest that N_TiO2 is a feasible antibacterial agent against cariogenic biofilms., (Copyright © 2018 Elsevier B.V. All rights reserved.)- Published
- 2018
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21. Bioluminescence Analysis of Antibacterial Photodynamic Therapy Using Methylene Blue Mediated by Low-Intensity Level Laser Against Cariogenic Biofilms.
- Author
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Esteban Florez FL, Mendonça de Oliveira MR, de Oliveira Júnior OB, Hiers RD, Khajotia SS, and Pretel H
- Subjects
- Colony Count, Microbial, Dental Caries drug therapy, Humans, Low-Level Light Therapy methods, Luminescent Measurements methods, Methylene Blue pharmacology, Anti-Infective Agents pharmacology, Biofilms drug effects, Photochemotherapy methods, Streptococcus mutans drug effects
- Abstract
Objective: A non-destructive and real-time bioluminescence (BL) assay was used to determine the utility of antimicrobial photodynamic therapy (aPDT) treatments mediated by methylene blue (MB) and laser irradiation (LI) against intact biofilms that are capable of producing caries (cariogenic). The efficacy of antibacterial photodynamic treatments has been currently determined by using either viable colony counts (VCC) or metabolic assays (Alamar Blue) that were demonstrated to have critical limitations when used on microcolony-forming bacteria such as Streptococcus mutans., Materials and Methods: Resin composite specimens were fabricated, wet-polished, ultraviolet-sterilized, and stored in water (72 h). S. mutans (strain JM10) biofilms were grown [24 h; 0.65 × THY with 0.1% (w/v) sucrose] on the surfaces of sterile specimens. Antibacterial treatments were performed by using MB (0.0005% and 0.001%) with or without LI (660 ± 10 nm, 6 J/cm
2 ). Specimens treated with chlorhexidine gluconate served as the negative control group. The efficacy of aPDT treatments was determined in terms of BL for intact biofilms and VCC for sonicated bacteria., Results: BL results were corrected by using the Greenhouse-Geisser method and were analyzed with repeated-measures analysis of variance and post hoc Bonferroni test (α = 0.05). VCC results were analyzed by using Kruskal-Wallis and Dunn's multiple-comparisons post hoc tests (α = 0.05). Our findings demonstrated that experimental treatments significantly decreased the viability of S. mutans biofilms (p < 0.05). Moderate reductions in cellular viability were observed on biofilms subjected to aPDT treatments., Conclusions: This study demonstrated that aPDT has promising potential to be used as an additional method to control oral cariogenic biofilms.- Published
- 2018
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22. Real-time assessment of Streptococcus mutans biofilm metabolism on resin composite.
- Author
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Esteban Florez FL, Hiers RD, Smart K, Kreth J, Qi F, Merritt J, and Khajotia SS
- Subjects
- Anti-Bacterial Agents, Biological Assay, Luminescent Measurements, Biofilms, Composite Resins, Dental Materials, Streptococcus mutans
- Abstract
Objective: The release of unpolymerized monomers and by-products of resin composites influences biofilm growth and confounds the measurement of metabolic activity. Current assays to measure biofilm viability have critical limitations and are typically not performed on relevant substrates. The objective of the present study was to determine the utility of firefly luciferase assay for quantification of the viability of intact biofilms on a resin composite substrate, and correlate the results with a standard method (viable colony counts)., Methods: Disk-shaped specimens of a dental resin composite were fabricated, wet-polished, UV-sterilized, and stored in water. Biofilms of Streptococcus mutans (strain UA159 modified by insertion of constitutively expressed firefly luc gene) were grown (1:500 dilution; anaerobic conditions, 24h, 37°C) in two media concentrations (0.35x and 0.65x THY medium supplemented with 0.1% sucrose; n=15/group). An additional group of specimens with biofilms grown in 0.65x+sucrose media was treated with chlorhexidine gluconate solution to serve as the control group. Bioluminescence measurements of non-disrupted biofilms were obtained after addition of d-Luciferin substrate. The adherent biofilms were removed by sonication, and bioluminescence of sonicated bacteria was then measured. Viable colony counts were performed after plating sonicated bacteria on THY agar plates supplemented with spectinomycin. Bioluminescence values and cell counts were correlated using Spearman correlation tests (α=0.05)., Results: Strong positive correlations between viable colony counts and bioluminescence values, both before- and after-sonication, validated the utility of this assay., Significance: A novel non-disruptive, real-time bioluminescence assay is presented for quantification of intact S. mutans biofilms grown on a resin composite, and potentially on antibacterial materials and other types of dental biomaterials., (Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.)
- Published
- 2016
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23. Concurrent quantification of cellular and extracellular components of biofilms.
- Author
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Khajotia SS, Smart KH, Pilula M, and Thompson DM
- Subjects
- Culture Media, Imaging, Three-Dimensional methods, Software, Streptococcus mutans physiology, Bacteriological Techniques methods, Biofilms, Microscopy, Confocal methods
- Abstract
Unlabelled: Confocal laser scanning microscopy (CLSM) is a powerful tool for investigation of biofilms. Very few investigations have successfully quantified concurrent distribution of more than two components within biofilms because: 1) selection of fluorescent dyes having minimal spectral overlap is complicated, and 2) quantification of multiple fluorochromes poses a multifactorial problem., Objectives: Report a methodology to quantify and compare concurrent 3-dimensional distributions of three cellular/extracellular components of biofilms grown on relevant substrates., Methods: The method consists of distinct, interconnected steps involving biofilm growth, staining, CLSM imaging, biofilm structural analysis and visualization, and statistical analysis of structural parameters. Biofilms of Streptococcus mutans (strain UA159) were grown for 48 hr on sterile specimens of Point 4 and TPH(3) resin composites. Specimens were subsequently immersed for 60 sec in either Biotène PBF (BIO) or Listerine Total Care (LTO) mouthwashes, or water (control group; n=5/group). Biofilms were stained with fluorochromes for extracellular polymeric substances, proteins and nucleic acids before imaging with CLSM. Biofilm structural parameters calculated using ISA3D image analysis software were biovolume and mean biofilm thickness. Mixed models statistical analyses compared structural parameters between mouthwash and control groups (SAS software; α=0.05). Volocity software permitted visualization of 3D distributions of overlaid biofilm components (fluorochromes)., Results: Mouthwash BIO produced biofilm structures that differed significantly from the control (p<0.05) on both resin composites, whereas LTO did not produce differences (p>0.05) on either product., Conclusions: This methodology efficiently and successfully quantified and compared concurrent 3D distributions of three major components within S. mutans biofilms on relevant substrates, thus overcoming two challenges to simultaneous assessment of biofilm components. This method can also be used to determine the efficacy of antibacterial/antifouling agents against multiple biofilm components, as shown using mouthwashes. Furthermore, this method has broad application because it facilitates comparison of 3D structures/architecture of biofilms in a variety of disciplines.
- Published
- 2013
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24. Commentary. Early hardness of self-adhesive resin cements cured under indirect resin composite restorations.
- Author
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Khajotia SS
- Subjects
- Hardness, Humans, Materials Testing, Polymerization, Surface Properties, Composite Resins chemistry, Dental Materials chemistry, Dental Restoration, Permanent, Resin Cements chemistry, Self-Curing of Dental Resins methods
- Published
- 2011
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25. Dental education in a flat world: advocating for increased global collaboration and standardization.
- Author
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Donaldson ME, Gadbury-Amyot CC, Khajotia SS, Nattestad A, Norton NS, Zubiaurre LA, and Turner SP
- Subjects
- Accreditation trends, Clinical Competence standards, Consensus, Education, Dental trends, European Union, Forecasting, Global Health, Humans, Licensure, Dental trends, Models, Educational, Societies trends, United States, Accreditation standards, Education, Dental standards, International Cooperation, Licensure, Dental standards, Societies standards
- Abstract
Globalization is a broad term referring to the increasing connectivity, integration, and interdependence of economies, societies, technologies, cultures, and political and ecological spheres across the world. This position paper was developed by a working group of the 2007 American Dental Education Association (ADEA) Leadership Institute. The authors explore the effect that globalization has had on dentistry and dental education to date and hypothesize what dental education could look like in the years ahead. While the paper is written from a North American perspective, some of the authors bring international expertise and experience to the topic of global dental education in a flat world. Specific issues and barriers addressed in this position paper include variations in accreditation and licensure requirements in dental education throughout the world; the historical development of dental education models (odontology and stomatology) and the need for congruency of these models in the global environment; the competency-based model of education and its relevance to development and implementation of global dental competencies; and the slow adoption of technological advances in dental education for promoting collaborations and encouraging resource sharing among countries. These challenges are discussed as they affect the implementation of a standardized global dental education that can lead to improved access to oral health care services and better oral and overall health for the citizens of the world.
- Published
- 2008
26. Antibacterial activity of chitosan-based matrices on oral pathogens.
- Author
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Sarasam AR, Brown P, Khajotia SS, Dmytryk JJ, and Madihally SV
- Subjects
- Absorbable Implants microbiology, Aggregatibacter actinomycetemcomitans drug effects, Ethanol pharmacology, Membranes, Artificial, Microbial Viability drug effects, Muramidase pharmacology, Porosity, Sodium Hydroxide pharmacology, Solutions pharmacology, Streptococcus mutans drug effects, Surface Properties, Tissue Scaffolds chemistry, Tissue Scaffolds microbiology, Anti-Bacterial Agents pharmacology, Chitosan chemistry, Chitosan pharmacology, Mouth microbiology
- Abstract
Chitosan is a well sought-after polysaccharide in biomedical applications due to its biocompatibility, biodegradability to non-toxic substances, and ease of fabrication into various configurations. However, alterations in the anti-bacterial properties of chitosan in various forms is not completely understood. The objective of this study was to evaluate the anti-bacterial properties of chitosan matrices in different configurations against two pathogens-Gram-positive Streptococcus mutans and Gram-negative Actinobacillus actinomycetemcomitans. Two-dimensional (2-D) membranes and three-dimensional (3-D) porous scaffolds were synthesized by air drying and controlled-rate freeze drying. Matrices were suspended in bacterial broths with or without lysozyme (enzyme that degrades chitosan). Influences of pore size, blending with Polycaprolactone (PCL, a synthetic polymer), and neutralization process on bacterial proliferation were studied. Transient changes in optical density of the broth, adhesion characteristics, viability, and contact-dependent bacterial activity were assessed. 3-D porous scaffolds were more effective in reducing the proliferation of S. mutans in suspension than 2-D membranes. However, no significant differences were observed on the proliferation of A. actinomycetemcomitans. Presence of lysozyme significantly increased the antibacterial activity of chitosan against A. actinomycetemcomitans. Pore size did not affect the proliferation kinetics of either species, with or without lysozyme. NaOH neutralization of chitosan increased bacterial adhesion whereas ethanol neutralization inhibited adhesion without lowering proliferation. Mat culture tests indicated that chitosan does not allow proliferation on its surface and it loses antibacterial activity upon blending with PCL. Results suggest that the chemical and structural characteristics of chitosan-based matrices can be manipulated to influence the interaction of different bacterial species.
- Published
- 2008
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27. Microleakage in the proximal walls of direct and indirect posterior resin slot restorations.
- Author
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Fruits TJ, Knapp JA, and Khajotia SS
- Subjects
- Acid Etching, Dental methods, Dental Cavity Preparation, Dental Marginal Adaptation, Gingiva, Humans, Inlays, Molar, Nanocomposites, Tooth Cervix, Composite Resins, Dental Leakage prevention & control, Dental Restoration, Permanent methods, Dentin-Bonding Agents
- Abstract
This study compared the degree of microleakage in the proximal walls of direct and indirect resin slot restorations in relation to the types of dentin bonding systems and the location of gingival margins. Two Class II slot preparations were prepared and restored in each of 60 extracted human molars using direct (Filtek Supreme) and indirect (Tescera ATL) restorative resin materials. Various types of dentin bonding systems, including self-etching (OneStep Plus/Tyrian SPE, iBond, Xeno III) and etch and rinse systems (All-Bond 2, Prime & Bond NT) were used to restore the prepared teeth. The gingival proximal wall was placed apical to the cementoenamel junction (CEJ) in 1 proximal box and coronal to the CEJ in the other. The specimens were stained and evaluated for microleakage using a digital imaging and analysis system. Significant differences were found in the degree of microleakage observed in the various restorative groups. In general, the group restored with indirect resin had less microleakage than the direct resin groups. Factors, such as type of dentin bonding system and location of gingival margins, exert a substantial influence on the degree of microleakage that occurred along the walls of proximal resin restorations.
- Published
- 2006
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28. Deactivation force-deflection behavior of multistranded stainless steel wires.
- Author
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Taneja P, Duncanson MG Jr, Khajotia SS, and Nanda RS
- Subjects
- Dental Stress Analysis, Elasticity, Humans, Materials Testing, Orthodontic Appliance Design, Pliability, Stress, Mechanical, Surface Properties, Dental Alloys chemistry, Orthodontic Wires, Stainless Steel chemistry
- Abstract
This investigation measured the deactivation (unloading) force-deflection behavior of selected multistranded stainless steel orthodontic wires. The guidelines from the revised American National Standards Institute/American Dental Association Specification No. 32 for orthodontic wires (type 2, nonlinear elasticity) were used to perform a 3-point bending test to obtain data for the deactivation force levels at 3, 2, 1, and 0.5 mm, and permanent deformation values. The study tested 20 wire designs: triple-stranded twisted wires, 5- and 6-stranded coaxial wires, and 8- and 9-stranded braided rectangular wires of selected cross-sections. Twenty specimens were tested for each wire design. The specification guidelines for testing provided a means for obtaining comparative unloading force delivery data for the deflections tested. Multistranded wires of significantly different cross-section, weave, and strand number fell within relatively narrow ranges of force delivery at the 0.5-mm (1.7-42.7 grams-force [gmf]) and 1-mm (31.1-134.2 gmf) deflections and wider ranges of force levels at the 2-mm (57.0-320.5 gmf) and 3-mm (72.5-451.8 gmf) deflections. All wires exhibited some permanent deformation, but none averaged greater than 0.66 mm. The testing also showed that multistranded wires of significantly different design exhibit similar force levels. The guidelines of the revised Specification No. 32 yielded deactivation data with regard to force delivery and provided comparisons of the wire designs tested.
- Published
- 2003
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29. A radiographic recall evaluation of 894 endodontic cases treated in a dental school setting.
- Author
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Benenati FW and Khajotia SS
- Subjects
- Adolescent, Adult, Aged, Aged, 80 and over, Chi-Square Distribution, Child, Dental Pulp Cavity diagnostic imaging, Dental Restoration Failure, Female, Follow-Up Studies, Humans, Male, Middle Aged, Oklahoma, Outcome Assessment, Health Care methods, Radiography, Time Factors, Endodontics education, Root Canal Obturation standards, Schools, Dental
- Abstract
A radiographic recall evaluation of 894 endodontic cases treated by dental students at the University of Oklahoma College of Dentistry was conducted by faculty. The purpose of this study was to determine the success of standardized nonsurgical endodontic treatments by using radiographic techniques of determination and to compare the results to similar studies at other dental schools. Cases were labeled as successful, acceptable, questionable, and failing. Observations included time since treatment, age, gender, and tooth type. The combined percentage of successful and acceptable cases was 91.05%. Differences in percentage of success among recall time intervals were statistically significant (p < 0.01), as were the percentages of success between tooth types treated (p < 0.05). Success rate was not affected by age or gender (p > 0.05). The overall rate of successful and acceptable cases in this study was found to compare favorably with those from recall studies conducted at other dental schools.
- Published
- 2002
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30. Effect of cyclical lateral forces on microleakage in cervical resin composite restorations.
- Author
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Fruits TJ, VanBrunt CL, Khajotia SS, and Duncanson MG Jr
- Subjects
- Barium Compounds, Bicuspid, Bisphenol A-Glycidyl Methacrylate, Dental Marginal Adaptation, Dental Stress Analysis, Elasticity, Humans, Materials Testing, Silicon Dioxide, Statistics, Nonparametric, Bite Force, Composite Resins, Dental Leakage etiology, Dental Restoration, Permanent adverse effects, Dental Restoration, Permanent methods, Tooth Cervix
- Abstract
Objective: The aim of this study was to assess the effect on microleakage of cyclic lateral fatigue forces in different types of cervical resin composite restorations., Method and Materials: V-notch cavities were prepared at the cementoenamel junction in 60 extracted human premolars and restored with a bonding system along with one of the following resin composites: hybrid resin composite, microfilled resin composite, and flowable resin composite (20 each). Ten specimens from each group of 20 were subjected to 8,400 cycles of lateral fatigue forces (44 N) at the occlusal half of the clinical crown in a machine specifically developed for this purpose. The other 10 specimens of each group served as controls, representing the microleakage that occurred without lateral fatigue forces. All specimens were stained with a 50% silver nitrate solution and sectioned sagittally. A scoring system of 0 to 6 was used to record the amount of die penetration along the restoration-tooth interface., Results: There was leakage in both the fatigued specimens and the nonfatigued control specimens. There were significant differences in the mean values of microleakage for the restorative materials studied. In the nonfatigued groups, hybrid resin specimens exhibited significantly more microleakage at the dentin-resin interface than did microfilled or flowable resin specimens. In the fatigued groups, hybrid resin specimens exhibited significantly more leakage at the dentin-resin interface than did microfilled resin specimens., Conclusion: The least elastic resin composite tested, the hybrid material, generally showed the most leakage. This suggests that the elasticity of these resin composite restorative materials may be a factor in the amount of microleakage in cervical restorations.
- Published
- 2002
31. The effect of saliva on shear bond strengths of hydrophilic bonding systems.
- Author
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Webster MJ, Nanda RS, Duncanson MG Jr, Khajotia SS, and Sinha PK
- Subjects
- Acid Etching, Dental, Acrylic Resins chemistry, Analysis of Variance, Animals, Bisphenol A-Glycidyl Methacrylate chemistry, Cattle, Compomers chemistry, Dental Enamel ultrastructure, Dental Stress Analysis instrumentation, Equipment Failure, Orthodontic Appliance Design, Random Allocation, Stainless Steel chemistry, Statistics as Topic, Stress, Mechanical, Surface Properties, Time Factors, Adhesives chemistry, Dental Bonding, Dental Cements chemistry, Orthodontic Brackets, Resin Cements chemistry, Saliva, Artificial chemistry
- Abstract
Failure of orthodontic bonded attachments and brackets is mostly attributed to contamination of the enamel surface. To overcome this problem, materials have been developed that purportedly overcome the moisture and contaminants present in the oral environment. This study compared the shear bond strengths of 2 lightcured hydrophilic bonding systems, Transbond XT with MIP (3M/Unitek, Monrovia, Calif) and Assure (Reliance Orthodontics, Itasca, Ill) with a hydrophobic bonding system, Transbond XT with XT primer (3M/Unitek). Comparison tests were conducted under 4 enamel surface conditions: (1) etched and dried; (2) etched and moistened with artificial saliva; (3) etched, primed, and moistened with artificial saliva; and (4) etched, primed, moistened with artificial saliva, and reprimed. In addition, an adhesive remnant index score was used to determine the amount of adhesive remaining on the tooth. Stainless steel brackets with mesh-backed pads (n = 144) were bonded to bovine teeth. Bond strength was then tested in shear using an Instron mechanical testing instrument. There were significant differences in the bond strengths among the products (P <.05), within surface treatments (P <.05), and among the different bonding materials in combination with various surface treatments (P <.05). Treatments 1 and 4 showed the highest mean bond strengths adhesive remnant index scores, whereas treatments 2 and 3 showed the lowest mean bond strengths and scores.
- Published
- 2001
- Full Text
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32. Fluoride concentrations in bottled water.
- Author
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Bartels D, Haney K, and Khajotia SS
- Subjects
- Analysis of Variance, Colorimetry instrumentation, Coloring Agents, Fluoridation standards, Food Labeling, Food Packaging, Humans, Statistics as Topic, Zirconium, Cariostatic Agents analysis, Fluorides analysis, Water analysis
- Abstract
Bottled water use and lack of adequate labeling have given rise to questions regarding fluoride intake. This study examined fluoride concentration of commercially available bottled water products, determined if significant differences existed among the products, and explored packaging date as a variable on the concentration of fluoride. The values were compared to the ADA guideline for optimally fluoridated water and the American Academy of Pediatric Dentistry recommended schedule for fluoride supplementation. Five commercial brands were chosen for the study. Three bottles of each brand, each with different batch dates, were purchased. Following calibration, six tests were conducted on each bottle using the Hach DR-100 Colorimeter System for fluoride analysis and the values were recorded. Data were analyzed using a two-tailed ANOVA and Tukey's HSD Test (p = 0.05). The results showed that significant differences in fluoride concentrations existed among the five brands. For three brands, significant differences existed between the batches. All products had fluoride concentrations that fell below the ADA accepted standards for optimally fluoridated water. Due to the significant variability in fluoride concentration between products and batches, dental providers should advise their patients that bottled water might not contain optimal levels of fluoride.
- Published
- 2000
33. Effect of toothbrushing on elemental release from dental casting alloys.
- Author
-
Wataha JC, Lockwood PE, Frazier KB, and Khajotia SS
- Subjects
- Analysis of Variance, Dental Casting Technique, Elements, Hydrogen-Ion Concentration, Materials Testing, Metals analysis, Nickel analysis, Spectrophotometry, Atomic, Statistics, Nonparametric, Toothpastes, Biocompatible Materials chemistry, Dental Alloys chemistry, Toothbrushing
- Abstract
Purpose: This study assessed the effect of toothbrushing on the elemental release from common dental casting alloys., Materials and Methods: A Au-Pt high-noble alloy, a Au-Pd high-noble alloy, a Pd-Cu-Ga noble alloy, and a Ni-Cr base-metal alloy were placed into a biological medium for 1 week to allow equilibration of elemental release, then brushed for 30 minutes at 90 strokes/min under 200 g of force with a soft toothbrush. The brushing was performed in neutral saline or lactic acid at pH 4 with or without toothpaste. The alloys were then transferred back into a biological medium for 1 week. Atomic absorption spectroscopy was used to measure the mass lost from each alloy during and in the week after brushing. Mass loss was expressed as micrograms per square centimeter of alloy surface, and the various brushing conditions were compared by analysis of variance and Tukey multiple comparison intervals (alpha = 0.05)., Results: During brushing, element release increased significantly over nonbrushed controls for all alloys except the Ni-Cr. Toothpastes, acidic solutions, or combinations of these conditions with toothbrushing further enhanced elemental release, but Ni release from the Ni-Cr alloy increased the most (30-fold). In the week after brushing, brushing alone increased elemental release only from the Ni-Cr alloy. However, toothpastes and acidic solutions increased elemental release for all alloys significantly, except for the Au-Pd alloy. In general, elemental release during brushing was far greater than in the week after brushing., Conclusions: Under the conditions of this study, toothbrushing increased the elemental release from dental casting alloys.
- Published
- 1999
- Full Text
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34. Elimination, via high-rate laser dilatometry, of structural relaxation during thermal expansion measurement of dental porcelains.
- Author
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Khajotia SS, Mackert JR Jr, Twiggs SW, Russell CM, and Williams AL
- Subjects
- Analysis of Variance, Dental Equipment, Differential Thermal Analysis methods, Hot Temperature, Stress, Mechanical, Thermodynamics, Dental Porcelain chemistry, Lasers
- Abstract
Objectives: Thermal expansion measurement of glassy materials is complicated by thermal history effects. Excess volume--trapped in quenched dental porcelains after firing--collapses via structural relaxation on first slow heating during conventional dilatometry, making the thermal expansion coefficient (alpha) obtained on first heating unreliable. The purpose of this study was to determine whether porcelain thermal expansion measurement at high thermal rates could minimize the influence of thermal history., Methods: Eight thermal expansion specimens each of six body porcelains and the Component No. 1 (leucite-containing) frit prepared according to the patent by Weinstein et al. (US Patent No. 3,052,982) were subjected to three heat-cool conventional dilatometry runs at 3 degrees C/min, while eight thermal expansion specimens of each porcelain were reserved as untreated controls. Eight hollow, cylindrical specimens of the same brands were subjected to three heat-cool laser dilatometer thermal expansion runs at 600 degrees C/min, while eight cylindrical specimens of each porcelain were reserved as untreated controls. Thermal expansion data (25-500 degrees C) of all specimens were subjected to repeated measures analysis of variance., Results: The alpha obtained on first slow heating was significantly lower than values for succeeding slow heat and cool runs in all porcelains (P < 0.001). High-rate alpha obtained on first heating was not significantly different from values of succeeding heat and cool runs in all porcelains (P > 0.05)., Significance: Conventional dilatometer measurements demonstrated occurrence of structural relaxation, as evidenced by the significant difference in the first heating and subsequent runs. High-rate laser dilatometry eliminated structural relaxation, thereby providing a thermal expansion measurement that is free of interference from thermal history effects.
- Published
- 1999
- Full Text
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35. Options for posterior ceramic restorations.
- Author
-
Khajotia SS and Shillingburg HT Jr
- Subjects
- Aluminum Oxide, Aluminum Silicates, Bicuspid, Ceramics, Humans, Magnesium Oxide, Molar, Dental Porcelain, Dental Restoration, Permanent methods, Metal Ceramic Alloys
- Published
- 1999
36. Effect of pH on element release from dental casting alloys.
- Author
-
Wataha JC, Lockwood PE, Khajotia SS, and Turner R
- Subjects
- Analysis of Variance, Dental Alloys analysis, Hydrogen-Ion Concentration, Mass Spectrometry, Materials Testing methods, Materials Testing statistics & numerical data, Spectrophotometry, Atomic, Time Factors, Dental Alloys chemistry
- Abstract
Statement of Problem: Dental casting alloys are subjected to transient acidity in the oral environment, yet most studies have not investigated the effects of these transient environments on elemental release from alloys. Elemental release is important because it plays a significant role in alloy biocompatibility., Purpose: It was hypothesized that acidic environments would increase elemental release from dental alloys during exposure and after the acidic environment was removed. This hypothesis was based on the known increase in release of nickel from nickel-based alloys in an acidic environment., Material and Methods: High-noble, noble, and base metal casting alloys were exposed for 30 minutes to solutions with pH ranging from 1 to 7. Elemental release of representative elements was measured by means of atomic absorption spectrometry during the exposure and in the week after the exposure. This release was compared with elemental release in the week before the exposure., Results: High-noble and noble alloys were resistant to acidic environments. A pH of 4 did not increase elemental release during or after exposure. A pH 1 environment slightly elevated release of Ag, Cu, and Pd in some alloys. However, a Ni-based alloy released large amounts of Ni during the acidic exposure of pH 1 or 4, and more importantly, in the week after the exposure as well. Increased time of exposure to acid did not alter elemental release from noble or high-noble alloys, but markedly increased release from the Ni-based alloy., Conclusions: Transient exposure of casting alloys to an acidic oral environment is likely to significantly increase elemental release from Ni-based alloys, but not from high-noble or noble alloys.
- Published
- 1998
- Full Text
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37. Fracture toughness and load relaxation of dentin bonding resin systems.
- Author
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Khajotia SS, Dhuru VB, Fournelle RA, and McKinney MA
- Subjects
- Acrylates chemistry, Analysis of Variance, Materials Testing, Methacrylates chemistry, Polyurethanes chemistry, Stress, Mechanical, Composite Resins chemistry, Dentin-Bonding Agents chemistry, Resin Cements chemistry
- Abstract
Objectives: The fracture toughness (KIC) and load relaxation of four dentin bonding resins were determined to characterize some of the mechanical properties of these materials after polymerization., Methods: A total of 40 single-edge notch bar specimens were fabricated, 10 each of four commercially available brands, and subjected to three-point bending until fracture, as described in ASTM Standard E399-83 (1991a). The critical stress intensification factor, KIC, was derived for each specimen and compared by analysis of variance and Scheffé's multiple comparisons test (p < 0.01). To study the load relaxation characteristics, five rectangular specimens (without notches) of each brand were subjected to three-point loading until a predetermined limiting load value was reached. The test load was allowed to relax for 4 min, after which the specimen was unloaded to the zero load condition, and the load was allowed to build up on its own accord for 3 min. Load relaxation values were measured from the chart, and the mean percent load drop was calculated. The load relaxation data were compared using analysis of variance and Scheffé's multiple comparisons test (p < 0.05)., Results: The fracture toughness (KIC) values of the four adhesive resins studied in this investigation ranged from 0.37-0.94 MPa.m0.5 and were statistically different from each other (p < 0.001). The load relaxation values were found to be greatest within the first 0.5 min, with the total load relaxation of the four bonding agents ranging from 16%-30%. Two of the materials studied showed significantly different short-term load relaxation behavior than the other two resins (p < 0.05)., Significance: Bonding agents can be implicated as one of the factors that weaken the interface between the dentin and the composite restorative material. These materials are capable of a rapid short-term response, demonstrating significant load relaxation in the first 0.5 min after loading.
- Published
- 1997
- Full Text
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38. Potential interference of leucite crystallization during porcelain thermal expansion measurement.
- Author
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Mackert JR Jr, Khajotia SS, Russell CM, and Williams AL
- Subjects
- Aluminum Silicates analysis, Analysis of Variance, Crystallization, Hot Temperature, Metal Ceramic Alloys chemistry, Regression Analysis, Thermodynamics, X-Ray Diffraction, Aluminum Silicates chemistry, Dental Porcelain chemistry
- Abstract
Objectives: The elevated temperatures and slow heating and cooling rates associated with a thermal expansion run provide a thermal treatment comparable to those previously shown to produce leucite crystallization in dental PFM porcelains. The purpose of this study was to determine whether the exposure of dental porcelains to the time-temperature profile of a thermal expansion run could result in leucite crystallization, a potential interference with the accurate determination of the thermal expansion coefficient., Methods: A total of 112 thermal expansion specimens were prepared, 16 each of six commercially available body porcelains, as well as the "Component No. 1" (leucite-containing) frit of the Weinstein et al. (1962) patent. In a randomized design, the leucite contents of specimens subjected to a 3 degrees C/min thermal expansion run were compared to those of untreated controls. The leucite content of each specimen was determined via quantitative X-ray powder diffraction using an Al2O3 internal standard. One-tailed t-tests were applied to determine whether the dilatometer thermal treatment produced a statistically significant increase in leucite content., Results: The heat treatment afforded by a 3 degrees C/min dilatometer run was not sufficient to induce measurable leucite crystallization in any of the porcelains examined in this study., Significance: The crystallization of leucite during a dilatometer heating run can be ruled out as a possible interference with the determination of the coefficient of thermal expansion of dental porcelain.
- Published
- 1996
- Full Text
- View/download PDF
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