Displaying publications 1 - 20 of 38 in total

  1. Daood U, Yiu CKY
    Dent Mater, 2019 02;35(2):206-216.
    PMID: 30509480 DOI: 10.1016/j.dental.2018.11.018
    OBJECTIVE: To evaluate the transdentinal cytotoxicity and macrophage phenotype response to a novel quaternary ammonium silane (QAS) cavity disinfectant.

    METHODS: NIH 3T3 mouse fibroblasts were cultured in Dulbecco's Modified Eagle's Medium and incubated for 3 days. The cells (3×104) were seeded on the pulpal side of dentine discs and the occlusal side of the discs were treated with different cavity disinfectants: Group 1: de-ionized water (control); Group 2: 2% chlorhexidine (CHX); Group 3: 2% QAS; Group 4: 5% QAS, and Group 5: 10% QAS. Cell morphology of NIH 3T3 cells was examined using scanning electron microscopy (SEM) and cell viability was assessed using Trypan blue assay. The eluates were collected and applied on cells seeded in 24-well plates. The total protein production, alkaline phosphatase activity and deposition of mineralized nodules were evaluated after 7 and 14 days. Immunofluorescence staining was performed on the samples with primary antibodies of CD68+, CD80+, and CD163+ assessing the macrophage M1/M2 phenotypes. The macrophages were imaged using a confocal scanning light microscope with an excitation wavelength of 488nm.

    RESULTS: No significant difference in cell viability (p<0.0001), total protein production (p<0.01) and mineralized nodule production (p<0.05) was found between 2% QAS and the control, which was significantly higher than 2% CHX, 5% and 10% QAS after 14 days. Alkaline phosphatase production of 2% QAS was significantly lower than the control (p<0.001), but higher than 2% CHX at 14 days. The M1/M2 macrophage ratio was also significantly lower in the 2% and 10% QAS groups (p<0.05) compared to the control and 2% CHX groups.

    SIGNIFICANCE: The 2% QAS cavity disinfectant does not have cytotoxic effects on 3T3 NIH mouse fibroblast cells and the predominance of the anti-inflammatory phenotype after its application may stimulate healing and tissue repair.

  2. Daood U, Fawzy AS
    Arch Oral Biol, 2019 Feb;98:195-203.
    PMID: 30502562 DOI: 10.1016/j.archoralbio.2018.10.019
    OBJECTIVE: To investigate effects of HIFU on macrophage phenotype, surface micro-topography and nano-scale surface mechanical properties of dental cementum.

    MATERIALS AND METHODS: Root discs (2 mm thickness) were cut apical to CEJ and sectioned into quadrants. HIFU setup with bowl-shaped piezo ceramic transducer submerged in a water tank was used for exposure on each specimen for 15 s, 30 s or 60 s. The specimens of the control group were left without any HIFU exposure. HIFU was generated with a continuous sinusoidal wave of 120Vpp amplitude, 250 KHZ resonance-frequency and highest ultrasonic pressure of ∼10 bar at the focus. Specimens for SEM were viewed, and micro-topography characterization performed, using AFM and Ra parameter and surface area (SA) calculated by specialized SPM surface analysis software. For nano-indentation testing, experiments were carried out using AFM. Macrophage cell isolation and culturing was performed on cementum to receive the HIFU treatment at different time periods. Raman spectroscopy were scanned to create spectra perpendicular to the cementum substrate to analyze generation of standard spectra for Raman intensity ratio of hydroxyapatite normalized to the peaks ν1 960 cm-1. Data was expressed as means ± standard deviations and analyzed by one-way ANOVA in term of Ra, SA, H and Er. Different points for fluorescence intensity ratio were analyzed by Raman using Wilcoxon rank sum test.

    RESULTS: HIFU exposure at 60 s removed the smear layer and most of cementum appeared smoothened. AFM characterisation, showed a slight decrease in the irregularity of the surface as exposure time increased. Intact macrophages can be identified in control and all experimental HIFU groups. The level of fluorescence for the control and HIFU 15 and 30 s were low as compared to HIFU 60 s.

    CONCLUSION: If HIFU can be successfully implemented, it may be a possible alternative to current methods used in periodontal therapy to achieve smooth root surfaces.

  3. Daood U, Fawzy AS
    Dent Mater, 2020 03;36(3):456-467.
    PMID: 32008748 DOI: 10.1016/j.dental.2020.01.005
    OBJECTIVE: The aim is to investigate the potential significance of combining minimally invasive high-intensity focused ultrasound (HIFU) with hydroxyapatite (HA) nanorods treatment for the remineralization of demineralized coronal dentine-matrix.

    METHODS: HA having nanorods structure were synthetized using ultrasonication with precipitation method. HA nanorods were characterized by TEM for average-size/shape. Following phosphoric acid demineralization, dentine specimens were treated with HA-nanorods with/without subsequent HIFU exposure for 5 s, 10 s and 20 s then stored in artificial saliva for 1-month. Dentine specimens were characterized using different SEM and Raman spectroscopic techniques. In addition, the biochemical stability and HA-nanorods were examined using ATR-FTIR to observe attachment of nanoparticles. Also, surface nanoindentation properties were evaluated using AFM in tapping-mode.

    RESULTS: HA-nanorods displayed well-defined, homogenous plate-like nanostructure. TEM revealed intact collagen-fibrils network structure with high density due to obliteration of interfibrillar spaces with clear evidence of remineralization in combined HA/HIFU treatment. With HA-nanorods treatment collagen-network structure was visible, consisting of fibrils interlaced into a compact pattern with evidence of minerals deposition. AFM investigation revealed clear mineral formation with the increase of HIFU exposure time. Bands associated with inorganic phase dominate well in HIFU exposed specimens with PO stretching within dentine mineral identified at 960 cm-1. Characteristic dentine structure for control and HIFU 20 s specimens is reflected as oscillatory mean Amide-I intensity with measurement giving a precise sinusoidal response of polarization angle β within dentinal tissue. Nanoindentation testing showed a gradual significant increase in elastic-modulus with the increase in HIFU exposure time after 1-month storage. FTIR spectrum of the HIFU exposed dentine displayed bands at 1650 cm-1, 1580 cm-1 and 1510 cm-1 that can be attributed to Amide-I, II and III.

    SIGNIFICANCE: The synergetic effect of HIFU exposure on remineralization potential of demineralized dentine-matrix following nano-hydroxyapatite treatment was revealed. This synergetic effect is dependent on HIFU exposure time.

  4. Daood U, Abduljabbar T, Al-Hamoudi N, Akram Z
    J. Periodont. Res., 2018 Feb;53(1):123-130.
    PMID: 28940417 DOI: 10.1111/jre.12496
    BACKGROUND AND OBJECTIVE: The aim of the present study was to compare clinical periodontal parameters and to assess the release of C-telopeptides pyridinoline cross-links (ICTP) and C-terminal crosslinked telopeptide (CTX) from gingival collagen of naswar (NW) and non-naswar (control) dippers.

    MATERIAL AND METHODS: Eighty-seven individuals (42 individuals consuming NW and 45 controls) were included. Clinical (plaque index, bleeding on probing, probing depth and clinical attachment loss) and radiographic (marginal bone loss) periodontal parameters were compared among NW and control groups. Gingival specimens were taken from subjects in NW and control groups, assessed for ICTP and CTX levels (using ELISA) and analyzed using micro-Raman spectroscopy. The significance of differences in periodontal parameters between the groups was determined using Kruskal-Wallis and Mann-Whitney U tests. The percent loss of dry mass over exposure time and the rate of release of ICTP and CTX from all groups were compared using the paired t-test to examine the effects of exposure time.

    RESULTS: Clinical and radiographic periodontal parameters were significantly higher in the NW group than the control group (P 

  5. Akram Z, Abduljabbar T, Sauro S, Daood U
    Photodiagnosis Photodyn Ther, 2016 Dec;16:142-153.
    PMID: 27619532 DOI: 10.1016/j.pdpdt.2016.09.004
    BACKGROUND: To assess the efficacy of antimicrobial photodynamic therapy (aPDT) or laser therapy (LT) alone as an adjunct to scaling and root planing (SRP) on the gingival crevicular fluid (GCF) inflammatory proteins in periodontal disease.

    METHODS: Databases (MEDLINE via PubMed; EMBASE; Cochrane Central Register of Controlled Trials and Cochrane Oral Health Group Trials Register databases) were searched from 1980 up to and including July 2016. The addressed PICO question was: "What effect does aPDT and/or LT as an adjunct to SRP have on the GCF inflammatory proteins in periodontal disease patients?"

    RESULTS: Eight studies used aPDT while 10 studies used laser alone. Eight cytokines including tumor necrosis factor alpha (TNF-α), interleukin (IL)-1β, IL-6, IL-8, IL-10, interferon gamma (IFN-γ), matrix metalloproteinase (MMP)-8 and granulocyte colony-stimulating factor (GM-CSF) were eligible for qualitative analysis for aPDT and LT studies. Four aPDT studies showed significant reduction in IL-1β while one study showed significant reduction in TNF-α levels after aPDT application at follow-up. One study showed significant reduction of IFN-γ, IL-8 and GM-CSF levels after aPDT at follow-up. IL-1β significantly reduced in 4 LT studies, while one study showed significant decrease for IL-6 and TIMP-1 levels. MMP-8 and TNF-α showed significant reduction in three and one study respectively.

    CONCLUSION: It remains debatable whether adjunctive aPDT or LT is effective in the reduction of GCF inflammatory proteins in periodontal disease due to non-standard laser parameters and short follow up period. These findings should be considered preliminary and further studies with long-term follow up and standardized laser parameters are recommended.

  6. Daood U, Matinlinna JP, Fawzy AS
    Dent Mater, 2019 02;35(2):356-367.
    PMID: 30528297 DOI: 10.1016/j.dental.2018.11.031
    OBJECTIVE: Effect of d-alpha-tocopheryl poly(ethyleneglycol)-1000-succinate (VE-TPGS) with riboflavin-5'-phosphate solution on crosslinking of dentine collagen was investigated to analyze collagen's structural integrity.

    METHODS: VE-TPGS was added to RF-solution, at RF/VE-TPGS (w/w) ratios of 0.125/0.250 and 0.125/0.500. Demineralized dentine beams were used (10wt.% phosphoric acid), rinsed using deionized-water and analysed using ELISA (Human MMP2 ELISA; Human CTSK/Cathepsin-K for MMP2 and Cathepsin K analysis). AFM of dentine collagen-fibrils structure was done before and after dentine specimens' placement in mineralization solution and tested after 14days in artificial saliva/collagenase (AS/Co) solution. The specimens were tested after 24h in mineralization solution for surface/bulk elastic modulus. Nano-indentation was carried out for each specimen on intertubular-dentine with lateral spacing of 400nm. Reduced elastic-modulus and nano-hardness were calculated and collagen content was determined using hydroxyproline-assay. Micro-Raman were performed. TEM was carried out to study structural variations of dentine-collagen in artificial-saliva (collagenase). Data were presented as mean±standard deviation and analyzed by SPSS v.15, by analysis of variance.

    RESULTS: Synergetic effect of VE-TPGS was observed with RF through higher structural integrity of dentine collagen-fibrils shown by TEM/AFM. Superior surface/bulk mechanical stability was shown by nano-indentation/mechanical testing. Improvement in collagenase degradation resistance for hydroxyproline release was observed and lower endogenous-protease release of MMP-2/Cathepsin-K. Raman-analysis analysed chemical interactions between RF and collagen confirming structural-integrity of collagen fibrils after crosslinking. After 24h mineralization, AFM showed mineral depositions in close association with dentine-collagen fibrils with RF/VE-TPGS formulations.

    SIGNIFICANCE: Potential synergetic effect of RF/VE-TPGS was observed by reflection of higher structural integrity and conformational-stability of dentine-collagen fibrils.

  7. Fawzy AS, Daood U, Matinlinna JP
    Dent Mater, 2019 07;35(7):979-989.
    PMID: 31003759 DOI: 10.1016/j.dental.2019.04.001
    OBJECTIVE: This study introduced the potential and proof-of-concept of high intensity focused ultrasound (HIFU) technology for dentin-surface treatment for resin-dentin bonding without acid-aided demineralization. This new strategy could provide a way to enhance interface-integrity and bond-durability by changing the nature of dentin-substrate; bonded-interface structure and properties; and minimizing denuded-collagen exposure.

    METHODS: The interaction between HIFU waves and dentin-surface in terms of structural, mechanical and chemical variations were investigated by SEM, TEM, AFM, nano-indentation and Raman-analysis. The bonding between HIFU-treated dentin and two-step, etch-and-rinse, adhesive was preliminary explored by characterizing dentin-bound proteases activities, resin-dentin interfacial morphology and bond-durability with HIFU exposure at different time-points of 60, 90 and 120 s compared to conventional acid-etching technique.

    RESULTS: With the increase in HIFU exposure-time from 60-to-120 s, HIFU waves were able to remove the smear-layer, expose dentinal-tubules and creating textured/rough dentin surface. In addition, dentin surfaces showed a pattern of interlocking ribbon-like minerals-coated collagen-fibrils protruding from the underlaying amorphous dentin-background with HIFU exposure for 90 s and 120 s. This characteristic pattern of dentin-surface showing inorganic-minerals associated/aligned with collagen-fibrils, with 90-to-120 s HIFU-treatment, was confirmed by the Raman-analysis. HIFU-treated specimens showed higher nano-indentation properties and lower concentrations of active MMP-2 and Cathepsin-K compared to the acid-etched specimens. The resin-dentin bonded interface revealed the partial/complete absence of the characteristic hybrid-layer formed with conventional etch-and-rinse bonding strategy. Additionally, resin-infiltration and resin-tags formation were enhanced with the increase in HIFU exposure-time to 120 s. Although, all groups showed significant decrease in bond-strength after 12 months compared to 24 h storage in artificial saliva, groups exposed to HIFU for 90 s and 120 s showed significantly higher μTBS compared to the control acid-etched group.

    SIGNIFICANCE: The implementation of HIFU-technology for dental hard-tissues treatment could be of potential significance in adhesive/restorative dentistry owing to its ability of controlled, selective and localised combined tissue alteration/ablation effects.

  8. Daood U, Burrow MF, Yiu CKY
    Clin Oral Investig, 2020 Feb;24(2):649-661.
    PMID: 31115692 DOI: 10.1007/s00784-019-02928-7
    OBJECTIVE: Evaluate effect of quaternary ammonium silane (QAS) cavity disinfectant on cariogenic biofilm.

    MATERIALS AND METHODS: Single- (Streptococcus mutans or Lactobacillus acidophilus), dual- (Streptococcus mutans/Lactobacillus Acidophilus), and multi-species (Streptococcus mutans, Actinomyces naeslundii, and Streptococcus sanguis) biofilms were grown on acid-etched dentine discs. Biofilms were incubated (120 min/37 °C) and allowed to grow for 3 days anaerobically. Discs (no treatment) served as control (group 1). Groups II, III, IV, and V were then treated with 2% chlorhexidine, and 2%, 5%, and 10% QAS (20 s). Discs were returned to well plates with 300 μL of bacterial suspension and placed in anaerobic incubator at 37 °C and biofilms redeveloped for 4 days. Confocal microscopy, Raman, CFU, and MTT assay were performed.

    RESULTS: Raman peaks show shifts at 1450 cm-1, 1453 cm-1, 1457 cm-1, 1460 cm-1, and 1462 cm-1 for control, 2% CHX, 2%, 5%, and 10% QAS groups in multi-species biofilms. There was reduction of 484 cm-1 band in 10% QAS group. CLSM revealed densely clustered green colonies in control group and red confluent QAS-treated biofilms with significantly lower log CFU for single/dual species. Metabolic activities of Streptococcus mutans and Lactobacillus acidophilus decreased with increasing QAS exposure time.

    CONCLUSION: Quaternary ammonium silanes possess antimicrobial activities and inhibit growth of cariogenic biofilms.

    CLINICAL SIGNIFICANCE: Available data demonstrated use of QAS as potential antibacterial cavity disinfectant in adhesive dentistry. Experimental QAS can effectively eliminate caries-forming bacteria, when used inside a prepared cavity, and can definitely overcome problems associated with present available cavity disinfectants.

  9. Daood U, Akram Z, Matinlinna JP, Fawzy AS
    Dent Mater, 2019 07;35(7):1017-1030.
    PMID: 31064669 DOI: 10.1016/j.dental.2019.04.005
    OBJECTIVE: The aim of this study was to investigate EDC-assisted collagen crosslinking effect with different concentrations of tiopronin-protected gold (TPAu) nanoparticles on demineralized dentine.

    METHODS: TPAu nanoparticles were fabricated from 0.31-g tetrachloroauric acid and 0.38-g of N-(2-mercaptopropionyl) glycine (2.4-mmol). Then co-dissolved using 35-mL of 6:1 methanol/acetic acid and mixed using NaBH4. EDC (0.3-M) was conjugated to TPAu nanoparticles at TPAU/EDC-0.25:1, and TPAU/EDC-0.5:1 treatment formulations ratios. Dentin specimens treated with 0.3-M EDC solution alone or left untreated were used as control. Nanoparticles formulations were characterized in term of particles morphology and size, Zeta potential, thermogravimetric analysis and small-angle X-ray scattering. Dentin substrates were characterized in term of TEM investigation, dentin proteases characterization, hydroxyproline liberation, elastic modulus measurement, Raman analysis and confocal microscopy viewing.

    RESULTS: TEM evaluation of tiopronin protected gold nanoparticles dispersion revealed nano-clusters formations in both groups. However, based on our TEM measurements, the particle-size was ranging from ˜20 to 50 nm with spherical core-shape which were almost similar for both TPAu/EDC ratios (0.5:1 and 0.25:1). Zeta potential measurements indicate negative nanoparticles surface charge. SAXS profiles for both formulations, suggest a typical profile for uni-lamellar nanoparticles. Superior dentin collagen cross-linking effect was found with the TPAu/EDC nanoparticles formulations compared to the control and EDC treated groups.

    SIGNIFICANCE: Cross-linking of dentin collagen using TPAu coupled with EDC through TPAu/EDC nanoparticles formulations is of potential significance in improving the biodegradation resistance, proteases inhibition, mechanical and structural stability of demineralized dentin substrates. In addition, the cross-linking effect is dependent on TPAu/EDC ratio, whereas higher cross-linking effect was found at TPAu/EDC ratio of 0.5:1.

  10. Daood U, Bandey N, Qasim SB, Omar H, Khan SA
    Acta Odontol Scand, 2011 Nov;69(6):367-73.
    PMID: 21449690 DOI: 10.3109/00016357.2011.569507
    To investigate the failure of 15 dental implants (Paragon/Zimmer) in relation to their surface quality.
  11. Qasim SSB, Nogueria LP, Fawzy AS, Daood U
    AAPS PharmSciTech, 2020 Jun 16;21(5):173.
    PMID: 32548717 DOI: 10.1208/s12249-020-01708-x
    Innovative strategies for periodontal regeneration have been the focus of research clusters across the globe for decades. In order to overcome the drawbacks of currently available options, investigators have suggested a novel concept of functionally graded membrane (FGM) templates with different structural and morphological gradients. Chitosan (CH) has been used in the past for similar purpose. However, the composite formulation of composite and tetracycline when cross-linked with glutaraldehyde have received little attention. Therefore, the purpose of the study was to investigate the drug loading and release characteristics of novel freeze gelated chitosan templates at different percentages of glutaraldehyde. These were cross-linked with 0.1 and 1% glutaraldehyde and loaded with doxycycline hyclate. The electron micrographs depicted porous morphology of neat templates. After cross-linking, these templates showed compressed ultrastructures. Computerized tomography analysis showed that the templates had 88 to 92% porosity with average pore diameter decreased from 78 to 44.9 μm with increasing concentration. Fourier transform infrared spectroscopy showed alterations in the glycosidic segment of chitosan fingerprint region which after drug loading showed a dominant doxycycline spectral composite profile. Interestingly, swelling profile was not affected by cross-linking either at 0.1 and 1% glutaraldehyde and template showed a swelling ratio of 80%, which gained equilibrium after 15 min. The drug release pattern also showed a 40 μg/mL of release after 24 h. These doxycycline-loaded templates show their tendency to be used in a functionally graded membrane facing the defect site.
  12. Qasim SSB, Nogueira LP, Fawzy AS, Daood U
    AAPS PharmSciTech, 2020 Sep 01;21(7):250.
    PMID: 32875436 DOI: 10.1208/s12249-020-01778-x
    The correct spelling of the second author's name is Liebert Parreiras Nogueira.
  13. Akram Z, Daood U, Aati S, Ngo H, Fawzy AS
    Mater Sci Eng C Mater Biol Appl, 2021 Mar;122:111894.
    PMID: 33641897 DOI: 10.1016/j.msec.2021.111894
    We formulated a pH-sensitive chlorhexidine-loaded mesoporous silica nanoparticles (MSN) modified with poly-(lactic-co-glycolic acid) (CHX-loaded/MSN-PLGA) and incorporated into experimental resin-based dentin adhesives at 5 and 10 wt%. Nanocarriers were characterized in terms of morphology, physicochemical features, spectral analyses, drug-release kinetics at varying pH and its effect on dentin-bound proteases was investigated. The modified dentin adhesives were characterized for cytotoxicity, antimicrobial activity, degree of conversion (DC) along with CHX release, micro-tensile bond strength (μTBS) and nano-leakage expression were studied at different pH values and storage time. CHX-loaded/MSN-PLGA nanocarriers exhibited a significant pH-dependent drug release behavior than CHX-loaded/MSN nanocarriers without PLGA modification. The highest percentage of CHX release was seen with 10 wt% CHX-loaded/MSN-PLGA doped adhesive at a pH of 5.0. CHX-loaded/MSN-PLGA modified adhesives exhibited more profound antibiofilm characteristics against S. mutans and more sustained CHX-release which was pH dependent. After 6 months in artificial saliva at varying pH, the 5 wt% CHX-loaded/MSN-PLGA doped adhesive showed excellent bonding under SEM/TEM, higher μTBS, and least nano-leakage expression. The pH-sensitive CHX-loaded/MSN-PLGA could be of crucial advantage for resin-dentin bonding applications especially in reduced pH microenvironment resulting from biofilm formation; and the activation of dentin-bound proteases as a consequence of acid etching and acidic content of bonding resin monomers.
  14. Bhatia S, Nagendrababu V, Peters OA, Fawzy A, Daood U
    Sci Rep, 2021 04 27;11(1):9027.
    PMID: 33907252 DOI: 10.1038/s41598-021-88570-4
    To evaluate structural profiles and mechanical behaviour of WaveOne Gold (WOG), Twisted File Adaptive (TFA) and XP-endo shaper (XPS) instruments after root canal preparation. Standardized in vitro shaping was performed in presence of 5.25% sodium hypochlorite. File morphology was analyzed using scanning electron microscopy; X-ray diffraction analysis was performed before and after use along with Raman spectroscopy. Nanoindentation was carried out to characterize surface topography. Ni2+ release was measured at 1, 3, 5 and 7 days. X-ray photoelectron spectroscopy (XPS) analysis was done before and after use. After allocating scan line shifts like in WOG, mechanical deformation was shown using first order polynomials. XPS file system showed minimal grooves on surface. SEM of WOG instrument showed scraping surface defects. Hardness varied from 8.11 ± 0.99 GPa in TFA system to 6.7 ± 1.27 GPa and 4.06 ± 4.1 GPa in XPS and WOG. Ni2+ concentration from WOG was 171.2 μg/L. Raman peak at 540-545 cm-1 is attributed to Cr2O3. High resolution of Ti 2p spectrum show distinctive peaks with binding energies dominating in WOG, XPS and TFA file system. XRD exhibited NiTi phases with diffraction peaks. WOG files showed more surface deterioration and less passive layer formation as compared to TFA and XPS systems.
  15. Steier L, Sidhu P, Qasim SS, Mahdi SS, Daood U
    Photodiagnosis Photodyn Ther, 2022 Jan 20;38:102732.
    PMID: 35066134 DOI: 10.1016/j.pdpdt.2022.102732
    OBJECTIVE: To evaluate accuracy of caries detection and the application-sensitivity of the new Designs for Vision's REVEAL™ utilizing a fluorescence activating headlight for excitation purpose.

    MATERIALS AND METHODS: REVEAL dental fluorescence loupes and headlight system were used. Occlusal enamel was removed, and mid-coronal dentine was exposed. Carious artificial lesion was created. Streptococcus mutans, Actinomyces naeslundii, and Streptococcus sanguis were used. The assessment was performed using two diagnostic methods: naked eye and Design for Vision Glasses with inter examiner blinding using two calibrated examiners. After 7 days, Raman measurements were made on dentin disc specimens with 785 nm wavelength. The bacterial counts in colony-forming units (CFU) were used to examine the growth kinetics of biofilms. The collagen fibril structure within the discs was performed using Transmission Electron Microscope. Scanning Electron Microscope was used to image samples at various magnifications. FISH was performed with specimens fixed in 4% paraformaldehyde in phosphate-buffered saline. Reproducibility was measured by Cohen kappa scores, values of which range from 0 for less than chance agreement to 1 for almost perfect agreement (p 

  16. Daood U, Tsoi JKH, Neelakantan P, Matinlinna JP, Omar HAK, Al-Nabulsi M, et al.
    Dent Mater, 2018 08;34(8):1175-1187.
    PMID: 29779627 DOI: 10.1016/j.dental.2018.05.005
    OBJECTIVE: Collagen fibrils aid in anchoring resin composite restorations to the dentine substrate. The aim of the study was to investigate effect of non-enzymatic glycation on bond strength and durability of demineralized dentine specimens in a modified two-step etch-and-rinse dentine adhesive.

    METHODS: Dentine surfaces were etched with 37% phosphoric acid, bonded with respective in vitro ethanol and acetone adhesives modified with (m/m, 0, 1%, 2% and 3% ribose), restored with restorative composite-resin, and sectioned into resin-dentine slabs and beams to be stored for 24h or 12 months in artificial saliva. Bond-strength testing was performed with bond failure analysis. Pentosidine assay was performed on demineralized ribose modified dentine specimens with HPLC sensitive fluorescent detection. The structural variations of ribose-modified dentine were analysed using TEM and human dental pulpal cells were used for cell viability. Three-point bending test of ribose-modified dentine beams were performed and depth of penetration of adhesives evaluated with micro-Raman spectroscopy. The MMP-2 and cathepsin K activities in ribose-treated dentine powder were also quantified using ELISA. Bond strength data was expressed using two-way ANOVA followed by Tukey's test. Paired T tests were used to analyse the specimens for pentosidine crosslinks. The modulus of elasticity and dentinal MMP-2 and cathepsin K concentrations was separately analyzed using one-way ANOVA.

    RESULTS: The incorporation of RB in the experimental two-step etch-and-rinse adhesive at 1% improved the adhesive bond strength without adversely affecting the degree of polymerisation. The newly developed adhesive increases the resistance of dentine collagen to degradation by inhibiting endogenous matrix metalloproteinases and cysteine cathepsins. The application of RB to acid-etched dentine helps maintain the mechanical properties.

    SIGNIFICANCE: The incorporation of 1%RB can be considered as a potential candidate stabilizing resin dentine bond.

  17. Neelakantan P, Romero M, Vera J, Daood U, Khan AU, Yan A, et al.
    Int J Mol Sci, 2017 Aug 11;18(8).
    PMID: 28800075 DOI: 10.3390/ijms18081748
    Microbiota are found in highly organized and complex entities, known as biofilms, the characteristics of which are fundamentally different from microbes in planktonic suspensions. Root canal infections are biofilm mediated. The complexity and variability of the root canal system, together with the multi-species nature of biofilms, make disinfection of this system extremely challenging. Microbial persistence appears to be the most important factor for failure of root canal treatment and this could further have an impact on pain and quality of life. Biofilm removal is accomplished by a chemo-mechanical process, using specific instruments and disinfecting chemicals in the form of irrigants and/or intracanal medicaments. Endodontic research has focused on the characterization of root canal biofilms and the clinical methods to disrupt the biofilms in addition to achieving microbial killing. In this narrative review, we discuss the role of microbial biofilms in endodontics and review the literature on the role of root canal disinfectants and disinfectant-activating methods on biofilm removal.
  18. Daood U, Parolia A, Matinlinna J, Yiu C, Ahmed HMA, Fawzy A
    Dent Mater, 2020 12;36(12):e386-e402.
    PMID: 33010944 DOI: 10.1016/j.dental.2020.09.008
    OBJECTIVES: Evaluate a new modified quaternary ammonium silane irrigant solution for its antimicrobial, cytotoxic and mechanical properties of dentine substrate.

    METHODS: Root canal preparation was performed using stainless steel K-files™ and F4 size protaper with irrigation protocols of 6% NaOCl + 2% CHX; 3.5% QIS; 2% QIS and sterile saline. Biofilms were prepared using E. faecalis adjusted and allowed to grow for 3 days, treated with irrigants, and allowed to grow for 7 days. AFM was performed and surface free energy calculated. MC3T3 cells were infected with endo irrigant treated E. faecalis biofilms. Raman spectroscopy of biofilms were performed after bacterial re-growth on root dentine and exposed to different irrigation protocols and collagen fibers analysed collagen fibers using TEM. Antimicrobial potency against E. faecalis biofilms and cytoxicity against 3T3 NIH cells were also. Resin penetration and MitoTracker green were also evaluated for sealer penetration and mitochondrial viability. Data were analysed using One-way ANOVA, principal component analysis and post-hoc Fisher's least-significant difference.

    RESULTS: Elastic moduli were maintained amongst control (5.5 ± 0.9) and 3.5% QIS (4.4 ± 1.1) specimens with surface free energy higher in QIS specimens. MC3T3 cells showed reduced viability in 6%NaOCl+2%CHX specimens compared to QIS specimens. DNA/purine were expressed in increased intensities in control and 6% NaOCl + 2% CHX specimens with bands around 480-490 cm-1 reduced in QIS specimens. 3.5% QIS specimens showed intact collagen fibrillar network and predominantly dead bacterial cells in confocal microscopy. 3.5% QIS irrigant formed a thin crust-type surface layer with cytoplasmic extensions of 3T3NIH spread over root dentine. Experiments confirmed MitoTracker accumulation in 3.5% treated cells.

    SIGNIFICANCE: Novel QIS root canal irrigant achieved optimum antimicrobial protection inside the root canals facilitating a toxic effect against the Enterococcus faecalis biofilm. Root dentine substrates exhibited optimum mechanical properties and there was viability of fibroblastic mitochondria.

  19. Al-Nabulsi M, Daud A, Yiu C, Omar H, Sauro S, Fawzy A, et al.
    Materials (Basel), 2019 Aug 07;12(16).
    PMID: 31394743 DOI: 10.3390/ma12162504
    Objective: To evaluate the effect of a new application method of bulk-fill flowable composite resin material on bond-strength, nanoleakage, and mechanical properties of dentine bonding agents.

    MATERIALS AND METHODS: Sound extracted human molars were randomly divided into: manufacturer's instructions (MI), manual blend 2 mm (MB2), and manual blend 4 mm (MB4). Occlusal enamel was removed and flattened, dentin surfaces were bonded by Prime & Bond universal (Dentsply and Optibond FL, Kerr). For the MI group, adhesives were applied following the manufacturer's instructions then light-cured. For MB groups, SDR flow+ bulk-fill flowable composite resin was applied in 2- or 4-mm increment then manually rubbed by a micro brush for 15 s with uncured dentine bonding agents and the mixture was light-cured. Composite buildup was fabricated incrementally using Ceram.X One, Dentsply nanohybrid composite resin restorative material. After 24-h water storage, the teeth were sectioned to obtain beams of about 0.8 mm2 for 24-h and thermocycled micro-tensile bond strength at 0.5 mm/min crosshead speed. Degree of conversion was evaluated with micro-Raman spectroscopy. Contraction gaps at 24 h after polymerization were evaluated and atomic force microscopy (AFM) nano-indentation processes were undertaken for measuring the hardness across the interface. Depth of resin penetration was studied using a scanning electron microscope (SEM). Bond strength data was expressed using two-way ANOVA followed by Tukey's test. Nanoindentation hardness was separately analyzed using one-way ANOVA.

    RESULTS: Factors "storage F = 6.3" and "application F = 30.11" significantly affected the bond strength to dentine. For Optibond FL, no significant difference in nanoleakage was found in MI/MB4 groups between baseline and aged specimens; significant difference in nanoleakage score was observed in MB2 groups. Confocal microscopy analysis showed MB2 Optibond FL and Prime & Bond universal specimens diffusing within the dentine. Contraction gap was significantly reduced in MB2 specimens in both adhesive systems. Degree of conversion (DC) of the MB2 specimens were numerically more compared to MS1 in both adhesive systems.

    CONCLUSION: Present study suggests that the new co-blend technique might have a positive effect on bond strengths of etch-and-rinse adhesives to dentine.

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