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Dental Materials Journal Oct 2022This study aimed to investigate the effect of N-2-methyl-pyrrolidone (NMP) on the removal of Enterococcus faecalis biofilm. Colony-forming unit (CFU) counting, crystal...
This study aimed to investigate the effect of N-2-methyl-pyrrolidone (NMP) on the removal of Enterococcus faecalis biofilm. Colony-forming unit (CFU) counting, crystal violet staining, and extracellular DNA (eDNA) measurements were performed to analyze removal of the biofilms formed in a bovine root canal. A confocal laser scanning microscope (CLSM) assay was used to measure the volume of the biofilms. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to investigate the biofilm-associated genes. The morphologic feature of the biofilms was observed under a scanning electron microscope (SEM). NMP decreased CFU numbers, eDNA levels, and biofilm biomass significantly compared to control. qRT-PCR showed that NMP increased the expression of some virulence-associated genes, but downregulated genes related to colonization and persistency. SEM showed that the numerous dentinal tubules were exposed as a result of removal of the biofilm. Collectively, NMP has the potential to be used as a vehicle for endodontic intracanal medicaments.
Topics: Animals; Biofilms; Cattle; Dental Pulp Cavity; Enterococcus faecalis; Gentian Violet; Microscopy, Confocal; Pyrrolidinones; Root Canal Irrigants
PubMed: 35768222
DOI: 10.4012/dmj.2022-012 -
Journal of Cellular and Molecular... Sep 2020In addition to bone, the dentin-pulp complex is also influenced by menopause, showing a decreased regenerative capacity. High levels of follicle-stimulating hormone...
In addition to bone, the dentin-pulp complex is also influenced by menopause, showing a decreased regenerative capacity. High levels of follicle-stimulating hormone (FSH) during menopause could directly regulate bone metabolism. Here, the role of FSH in the odontogenic differentiation of the dentin-pulp complex was investigated. Dental pulp stem cells (DPSCs) were isolated. CCK-8 assays, cell apoptosis assays, Western blotting (WB), real-time RT-PCR, alkaline phosphatase activity assays, and Alizarin Red S staining were used to clarify the effects of FSH on the proliferation, apoptosis and odontogenic differentiation of the DPSCs. MAPK pathway-related factors were explored by WB assays. FSH and its inhibitor were used in OVX rats combined with a direct pulp-capping model. HE and immunohistochemistry were used to detect reparative dentin formation and related features. The results indicated that FSH significantly decreased the odontogenic differentiation of the DPSCs without affecting cell proliferation and apoptosis. Moreover, FSH significantly activated the JNK signalling pathway, and JNK inhibitor partly rescued the inhibitory effect of FSH on DPSC differentiation. In vivo, FSH treatment attenuated the dentin bridge formation and mineralization-related protein expression in the OVX rats. Our findings indicated that FSH reduced the odontogenic capacity of the DPSCs and was involved in reparative dentinogenesis during menopause.
Topics: Animals; Apoptosis; Cell Division; Cells, Cultured; Dental Pulp; Dentin; Estrogens; Female; Follicle Stimulating Hormone; Humans; MAP Kinase Signaling System; Menopause; Molar, Third; Odontogenesis; Ovariectomy; Random Allocation; Rats; Rats, Sprague-Dawley; Stem Cells; Tooth Calcification
PubMed: 32725798
DOI: 10.1111/jcmm.15681 -
BMC Oral Health Dec 2022Studies demonstrated the bond strength enhancement and the decrease in degradation of the adhesive interface after applying either self-etch adhesives or two-step,...
BACKGROUND
Studies demonstrated the bond strength enhancement and the decrease in degradation of the adhesive interface after applying either self-etch adhesives or two-step, etch-and-rinse adhesives under an electric field. However, the presence of dentinal fluid driven by the pulpal pressure in vivo is a profounding factor affecting both the sealing ability and bond strength of adhesives. This study aimed to evaluate the effect of three-step etch-and-rinse and two-step self-etch adhesives when applied with iontophoresis under simulated pulpal pressure on the permeability of dentin, resin infiltration, and the sealing ability of resin composite.
METHODS
The experiments were done on 32 recently extracted premolars, randomly assigned into four groups (n = 8) according to two adhesive systems (SBMP and SE), applied following the manufacturer's instructions (control) for two groups or with iontophoresis for the others (SBMPi and SEi). For the iontophoresis, the anodal current was applied at 75 μA for 20 s through the cavity electrode during the bond. The fluid flow rate of dentin was recorded after cavity preparation (smear-layer-covered dentin; T1), bonding (T2), and composite restoration (T3) during the maintained pulpal pressure of 20 mm Hg. The flow rates were expressed as a percentage relative to the initial smear-layer-covered value for each specimen. Results were analyzed using repeated measures ANOVA. Scanning electron microscopy (SEM) was performed to observe the resin/dentin interface.
RESULTS
There were no significant increases in the mean flow rates from T1 to T3 in the SBMP (P = 0.355), while these changes in the SE were significant between T1 (100%) and T2 (166.77%) and T1 and T3 (221.16%) (P = 0.002; one-way RM ANOVA; Holm-Sidak test). For the iontophoresis groups, the mean flow rates decreased significantly from T1 to T2 and T1 to T3 of both SBMPi (T2 = 86.43, and T3 = 79.53; P < 0.001) and SEi groups (T2 = 87.96, and T3 = 81.48; P = 0.004). The iontophoresis of both adhesives produced the optimal resin infiltration with improved quality of the hybrid layer and resin tags.
CONCLUSIONS
SBMP bonded with or without iontophoresis performed better sealing ability than SE under the same condition. Both adhesives applied with anodal iontophoresis significantly decreased the dentin permeability, contributing to the improved resin infiltration.
Topics: Humans; Dentin Permeability
PubMed: 36482395
DOI: 10.1186/s12903-022-02632-1 -
The Journal of Prosthetic Dentistry Nov 2023Layered composite resins may adequately mask discolored substrates. However, whether color changes that occur over time affect masking ability is unclear.
STATEMENT OF PROBLEM
Layered composite resins may adequately mask discolored substrates. However, whether color changes that occur over time affect masking ability is unclear.
PURPOSE
The purpose of this in vitro study was to investigate the effect of layering and water aging on the masking ability of 2 composite resins.
MATERIAL AND METHODS
Disk specimens (1.5 mm-thick and shade A1) from Charisma Diamond (CD) and Filtek Z350XT (Z350) were made according to the composite resin shade combination used in the layering strategies: bilayer for CD (enamel/dentin) and for Z350 (enamel/body and enamel/dentin) and trilayer for Z350 (enamel/body/dentin) (n=5). Color measurements were obtained with a spectrophotometer over an A3.5 ceramic substrate, and the whiteness index for dentistry (WI) was calculated. The specimens were aged in water at 37 °C and evaluated at different times: 24 hours, 1 week, 1 month, 2 months, 6 months, 12 months, 18 months, and 24 months. CIEDE2000 color differences (ΔE) and WI differences (ΔWI) were calculated and interpreted by 50:50% color and whiteness perceptibility and acceptability thresholds. Changes among strategies and aging times were analyzed using the Kruskal-Wallis test (α=.05). Contrasts were made using the Mann-Whitney U test with Bonferroni correction (α=.001).
RESULTS
ΔE decreased from 24 hours to 2 months of aging. From 2 months onwards, ΔE increased for all layering strategies and times, without significant changes in lightness for CD (P>.004). Overall, for the CD restorative system, an increase in ΔWI was observed after 1 month of aging (P<.001), while for the Z350 restorative system, ΔWI decreased after aging (P<.001), except for the Z350 bilayer strategy (enamel + dentin) at 1 week and 2 months (P>.004). For all layering strategies and aging times, color differences were higher than the 50:50% perceptibility threshold for ΔE and, after 6 months, higher than the 50:50% acceptability threshold for ΔE and the 50:50% whiteness acceptability threshold.
CONCLUSIONS
The ability of the tested composite resins to mask a discolored substrate was affected by the layering approach applied and by prolonged water aging.
Topics: Color; Composite Resins; Ceramics; Spectrophotometry; Materials Testing
PubMed: 37730467
DOI: 10.1016/j.prosdent.2023.08.031 -
Biochemical and Biophysical Research... Aug 2021Enhancer of zeste homolog 2 (EZH2) is the catalytic core of polycomb repressive complex 2 (PRC2), which primarily methylates lysine 27 on histone H3 (H2K27me3),...
Enhancer of zeste homolog 2 (EZH2) is the catalytic core of polycomb repressive complex 2 (PRC2), which primarily methylates lysine 27 on histone H3 (H2K27me3), generating transcriptionally suppressed heterochromatin. Since EZH2 suppresses expression of genes involved in dentin formation, we examined the role of EZH2 in tooth development. Intriguingly, microCT analysis of teeth from mice with conditional Ezh2 knockout in uncommitted mesenchymal cells showed hyper-mineralization of enamel, which is produced by the epithelial-lineage cells, ameloblasts. Scanning electron microscopy analysis and nano-indentation of the incisor enamel from knockout mice revealed smaller inter-rod spaces and higher hardness compared to wild type enamel, respectively. Interestingly, expression of the calcium channel subunit gene, Orai2, was decreased compared to its competitor, Orai1, both in knockout mouse incisors and the ex vivo culture of ameloblasts with the surrounding tissues under EZH2 inhibition. Moreover, histological analysis of incisor from knockout mice showed decreased ameloblastin and expedited KLK4 expression in the ameloblasts. These observations suggest that EZH2 depletion in dental mesenchymal cells reduces enamel matrix formation and increases enamel protease activity from ameloblasts, resulting in enamel hyper-mineralization. This study demonstrates the significant role of the suppressive H3K27me3 mark for heterochromatin on enamel formation.
Topics: Animals; Cells, Cultured; Dental Enamel; Enhancer of Zeste Homolog 2 Protein; Mesenchymal Stem Cells; Mice; Mice, Inbred C57BL; Mice, Knockout; Tooth Calcification
PubMed: 34144503
DOI: 10.1016/j.bbrc.2021.06.003 -
Dental Materials : Official Publication... Nov 2021To investigate the effect of novel polymeric nanoparticles (NPs) doped with melatonin (ML) on nano-hardness, crystallinity and ultrastructure of the formed...
OBJECTIVE
To investigate the effect of novel polymeric nanoparticles (NPs) doped with melatonin (ML) on nano-hardness, crystallinity and ultrastructure of the formed hydroxyapatite after endodontic treatment.
METHODS
Undoped-NPs and ML-doped NPs (ML-NPs) were tested at radicular dentin, after 24 h and 6 m. A control group without NPs was included. Radicular cervical and apical dentin surfaces were studied by nano-hardness measurements, X-ray diffraction and transmission electron microscopy. Mean and standard deviation were analyzed by ANOVA and Student-Newman-Keuls multiple comparisons (p < 0.05).
RESULTS
Cervical dentin treated with undoped NPs maintained its nano-hardness values after 6 m of storage being [24 h: 0.29 (0.01); 6 m: 0.30 (0.02) GPa], but it decreased at apical dentin [24 h: 0.36 (0.01); 6 m: 0.28 (0.02) GPa]. When ML-NPs were used, nano-hardness was similar over time [24h: 0.31 (0.02); 6 m: 0.28 (0.03) GPa], at apical dentin. Root dentin treated with ML-NPs produced, in general, high crystallinity of new minerals and thicker crystals than those produced in the rest of the groups. After 6 m, crystals became organized in randomly oriented polyhedral, square polygonal block-like apatite or drop-like apatite polycrystalline lattices when ML-NPs were used. Undoped NPs generated poor crystallinity, with preferred orientation of small crystallite and increased microstrain.
SIGNIFICANCE
New polycrystalline formations encountered in dentin treated with ML-NPs may produce structural dentin stability and high mechanical performance at the root. The decrease of mechanical properties over time in dentin treated without NPs indicates scarce remineralization potential, dentin demineralization and further potential degradation. The amorphous stage may provide high hydroxyapatite solubility and remineralizing activity.
Topics: Apatites; Dentin; Humans; Melatonin; Nanoparticles; Polymers
PubMed: 34544591
DOI: 10.1016/j.dental.2021.09.001 -
Journal of Conservative Dentistry : JCD 2021The aim of this study was to compare the effects of herbal irrigants with conventional irrigants on microhardness and flexural strength of root dentin.
AIM
The aim of this study was to compare the effects of herbal irrigants with conventional irrigants on microhardness and flexural strength of root dentin.
MATERIALS AND METHODS
Sixty extracted permanent maxillary canines were selected. Decoronated roots were sectioned longitudinally into buccal and lingual segments to get 120 specimens. These were embedded in auto polymerizing acrylic resin and further grounded with fine emery papers under distilled water. Of these, 100 root segments without any defects were selected, further divided into four test groups and a control group according to the irrigants used ( = 20). Group 1: 2.5% Sodium hypochlorite, Group 2: Miswak stick extract, Group 3: Cashew leaves extract. Group 4: Mango leaves extract and Group 5: Normal saline (control). All specimens were treated with 5 ml of each irrigant for 10 minutes and rinsed immediately. Dentin microhardness was measured with a Vickers indenter, and the flexural strength test was done using a universal testing machine. The data were analyzed using one-way ANOVA and the intergroup comparison by student -test.
RESULTS
The experimental groups showed a significant reduction in microhardness values when compared with the control group. Intragroup comparison among experimental groups, herbal irrigants showed the least reduction in microhardness values at cervical, middle, and apical thirds. When compared to the control group, the flexural strength values decreased significantly with experimental groups.
CONCLUSION
Within the limitation of this study, it was concluded that herbal irrigants were least detrimental to root dentin microhardness when compared with conventional irrigant. But the flexural strength was equally reduced by both conventional and herbal irrigants.
PubMed: 34475686
DOI: 10.4103/JCD.JCD_426_20 -
Journal of Dental Sciences Apr 2022The bond strength and durability of highly translucent zirconia ceramics to dentin is still unclear. The purpose of this study was to investigate the effect of various...
BACKGROUND/PURPOSE
The bond strength and durability of highly translucent zirconia ceramics to dentin is still unclear. The purpose of this study was to investigate the effect of various surface treatments on the bond strength of self-adhesive resin cements to high-translucent zirconia crowns and dentin.
MATERIALS AND METHODS
A high-transparent zirconia and three self-adhesive resin cements (G-CEM LinkAce (GCL), RelyX U200 (RXU) and TotalCem (TTC)) were used. The zirconia surface was sandblasted with 50 μm alumina particles or coated with an SR Link primer, while a dentin primer (Tetric N-Bond Universal, TBU) was applied to the surface of the dentin. By using three self-adhesive resin cements, zirconia samples were bonded to the dentin surfaces of human teeth. The shear strength of the specimens was measured before and after 10,000-cycle thermocycling or 90-day aging.
RESULTS
When using GCL to bond with the untreated dentin and various zirconia surfaces, the shear bond strength of the sandblasted (Z) and RS Link primer-coated (Z) groups was significantly higher than that of the untreated control group (Zc). However, in the case of TBU-treated dentin, the shear strength of the Z + D group was significantly higher than that of the other groups. After thermocycling and aging, the shear strength of the Z + D group using GCL and RXU cements decreased slightly, while the TTC showed no impact.
CONCLUSION
The zirconia surface pretreated by sandblasting and bonding agent, which was sequentially bonded with a primer-treated dentin by using resin cements, can provide excellent shear bond strength and anti-aging performance.
PubMed: 35756805
DOI: 10.1016/j.jds.2021.12.008 -
Polymers Nov 2021The present study aimed to formulate an experimental adhesive (EA) and reinforce it with 5 wt.% titanium dioxide (TiO) or zirconium oxide (ZrO) to yield 5% TiO and 5%...
The present study aimed to formulate an experimental adhesive (EA) and reinforce it with 5 wt.% titanium dioxide (TiO) or zirconium oxide (ZrO) to yield 5% TiO and 5% ZrO adhesives, respectively, and then analyze the impact of this reinforcement on various mechanical properties of the adhesives. The EA contained a blend of monomers such as bisphenol A glycol dimethacrylate (BisGMA), triethylene glycol dimethacrylate (TEGDMA), 2-hydroxyethyl methacrylate (HEMA), and ethyl 4-dimethylamino benzoate and camphorquinone. The EA included ethyl 4-dimethylamino benzoate and camphorquinone photo-initiators, and diphenyliodonium hexafluorophosphate (DPIHP) was also included to act as an electron initiator. The TiO and ZrO nanoparticles were incorporated into the EA post-synthesis. To characterize the filler nanoparticles, scanning electron microscopy (SEM) and line-energy dispersive X-ray (EDX) spectroscopy were performed. The adhesives were characterized by analyzing their rheological properties, shear-bond strength (SBS), and interfacial failure types. Further, the resin-dentin interface was also analyzed via SEM. The TiO nanoparticles were spherically shaped on the SEM micrographs, while the ZrO nanoparticles were seen as non-uniformly shaped agglomerates. The EDX mapping demonstrated the presence of Ti and oxygen for TiO and Zr and oxygen for the ZrO nanoparticles. Both 5% TiO and 5% ZrO adhesives revealed decreased viscosity as compared with the EA. The 5% TiO adhesive demonstrated higher SBS values for both non-thermocycled (NTC) and thermocycled samples (NTC: 25.35 ± 1.53, TC: 23.89 ± 1.95 MPa), followed by the 5% ZrO adhesive group (NTC: 23.10 ± 2.22, TC: 20.72 ± 1.32 MPa). The bulk of the failures (>70%) were of adhesive type in all groups. The SEM analysis of the resin-dentin interface revealed the development of a hybrid layer and resin tags (of variable depth) for the EA and 5% TiO groups. However, for the 5% ZrO group, the hybrid layer and resin tag establishment appeared compromised. Reinforcement of the EA with TiO or ZrO caused an increase in the adhesive's SBS (with the 5% TiO group demonstrating the highest values) in comparison with the EA (without nanoparticles). However, both nanoparticle-containing adhesives revealed decreased viscosity compared with the EA (without nanoparticles). Further studies investigating the impact of diverse filler concentrations on the properties of adhesives are suggested.
PubMed: 34771351
DOI: 10.3390/polym13213794 -
Clinical Oral Investigations Aug 2021Matrix metalloproteases (MMPs) are a family of enzymes that operate a proteolytic activity at the level of the extracellular matrix. MMPs are regulated by tissue...
OBJECTIVES
Matrix metalloproteases (MMPs) are a family of enzymes that operate a proteolytic activity at the level of the extracellular matrix. MMPs are regulated by tissue inhibitors of metalloproteinases (TIMPs) that can ubiquitously bind different enzyme forms. The study aims to identify a morfo-functional association between TIMP-1 and MMP-2 and -9 in human dentin.
MATERIALS AND METHODS
Proteins were extracted from demineralized human sound dentin powder and centrifuged to separate two aliquots with different molecular weights of proteins, higher and lower than 30 kDa. In each aliquot, the evaluation of the presence of TIMP-1/MMP-2 and TIMP-1/MMP-9 was performed using co-immunoprecipitation/immunoblotting analysis. The distribution of TIMP-1, in association with MMP-2 and -9, was investigated using a double immunohistochemical technique. Furthermore, the activity of TIMP-1 was measured by reverse zymography, where acrylamide gel was copolymerized with gelatin and recombinant MMP-2.
RESULTS
Co-immunoprecipitation/immunoblotting analysis showed the association TIMP-1/MMP-2 and TIMP-1/MMP-9 in human sound dentin. Electron microscopy evaluation revealed a diffuse presence of TIMP-1 tightly associated with MMP-2 and -9. Reverse zymography analysis confirmed that TIMP-1 present in human dentin is active and can bind different MMPs isoforms.
CONCLUSIONS
The strict association of TIMP-1 with MMP-2 and -9 in situ appeared a constant finding in the human sound dentin.
CLINICAL RELEVANCE
Considering the role of TIMP-1, MMP-2, and MMP-9 within the connective tissues, clinically applicable protocols could be developed in the future to increase or decrease the level of TIMPs in human dentin to regulate the activity of MMPs, contributing to reduce caries progression and collagen degradation.
Topics: Dentin; Humans; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Matrix Metalloproteinases; Tissue Inhibitor of Metalloproteinase-1; Tissue Inhibitor of Metalloproteinases
PubMed: 33569677
DOI: 10.1007/s00784-021-03819-6