Addition Of CHX Research Articles

Antimicrobial activity of intracanal dressings composed by natural products associated to chlorhexidine and its influence on dentinal colour change

Purpose: The aim of study was to evaluate the antimicrobial activity of intracanal dressings and their influence on dentinal colour changes. Material and methods: Eighty samples were divided into eight groups (n=10) according to intracanal dressing protocols: G1–distilled water (DW); G2–2% chlorhexidine gel (CHX); G3–calcium hydroxide (Ca[OH]2)+DW; G4–grape seed extract (GSE)+DW; G5–ginger extract (GE)+DW; G6–Ca(OH)2+CHX; G7–GSE+CHX; and G8–GE+CHX. The antimicrobial activity was evaluated by colony-forming units (CFUs) counting and dentinal colour changes was evaluated by digital spectrophotometry. Data were statistically analysed by specific tests (α=0.05). Results: The highest bacterial reduction was observed in groups 4, 6, 7 and 8, with no significant difference between them (p<0.05). Groups 4 and 7 showed the highest medians of dentinal colour change (p<0.05). Conclusion: The addition of CHX improved the antimicrobial activity of GE-based intracanal dressing, with no effect in GSE-based intracanal dressing; moreover, these protocols induced significant dentinal colour changes.

Surface morphology and in vitro leachability of soft liners modified by the incorporation of antifungals for denture stomatitis treatment.

Objective To evaluate the surface morphology and in vitro leachability of temporary soft linings modified by the incorporation of antifungals in minimum inhibitory concentrations (MIC) for Candida albicans biofilm.Methodology Specimens of soft lining materials Softone and Trusoft were made without (control) or with the addition of nystatin (Ny), miconazole (Mc), ketoconazole (Ke), chlorhexidine diacetate (Chx), or itraconazole (It) at their MIC for C. albicans biofilm. The surface analyses were performed using Confocal laser scanning microscopy after 24 h, 7 days, or 14 days of immersion in distilled water at 37ºC. In vitro leachability of Chx or Ny from the modified materials was also measured using Ultraviolet visible spectroscopy for up to 14 days of immersion in distilled water at 37ºC. Data (μg/mL) were submitted to ANOVA 1-factor/Bonferroni (α=0.05).Results Softone had a more irregular surface than Trusoft. Morphological changes were noted in both materials with increasing immersion time, particularly, in those containing drugs. Groups containing Chx and It presented extremely porous and irregular surfaces. Both materials had biexponential release kinetics. Softone leached a higher concentration of the antifungals than Trusoft (p=0.004), and chlorhexidine was released at a higher concentration than nystatin (p<0.001).Conclusions The surface of the soft lining materials changed more significantly with the addition of Chx or It. Softone released a higher concentration of drugs than Trusoft did, guiding the future treatment of denture stomatitis.

LncRNA FAM83H-AS1 contributes to the radioresistance, proliferation, and metastasis in ovarian cancer through stabilizing HuR protein

Ovarian cancer (OC) is a major cause of cancer-related deaths in women all over the world. The easy metastasis of OC and the problem of radioresistance are serious issues remaining to be overcome. Thus, research on molecular mechanisms underlying is in urgent demand. Long non-coding RNAs (lncRNAs) are a class of RNAs without protein coding potential, which has been reported to participate in the regulation on multiple biological process in cancers, including cell radiosensitivity and metastasis. Present study aimed to explore the role of lncRNA FAM83-AS1 in radioresistance and metastasis of ovarian cancer. First of all, the obvious upregulation of FAM83H-AS1 was identified by qRT-PCR in OC tissues, especially in metastatic tissues, as well as in OC cell lines. Importantly, we confirmed the correlation of FAM83H-AS1 levels with both ovarian cancer cells and normal ovarian cells. And Kaplan-Meier analysis indicated FAM83H-AS1 as a potential target of poor prognosis of OC. Through loss-of-function assays, we validated the inductive effect of FAM83H-AS1 in OC cell metastasis and radioresistance. Through mechanism research on FAM83H-AS1, we confirmed its interaction with HuR using pull-down assay and RNA immunoprecipitation (RIP), and verified the stabilization of HuR protein by FAM83-AS1 through western blot with the addition of CHX. Finally, rescue assays showed that overexpression of HuR rescued the suppression on radioresistance and metastasis in OC cell caused by the silencing of FAM83H-AS1. In conclusion, present study proved that FAM83H-AS1 contributes to the radioresistance and cell metastasis in ovarian cancer through stabilizing HuR protein.

Inhibition of secondary caries in vitro by addition of chlorhexidine to adhesive components

ObjectiveTo investigate secondary caries inhibition after dentine pre-treatment with 2% CHX, experimental addition of CHX in primer and adhesive of a 3-step adhesive system, and industrial addition od CHX in a 2-step adhesive system. Materials and methodSixty Class-V cavities were restored according to the adhesive protocol (n=12): 1) control group, Scotchbond Multi-Purpose, 3M (CTRL), 2) 2% CHX dentine pre-treatment (DENT), 3) 0.1% CHX in primer (PRIM), 4) 0.1% CHX in bonding agent (BOND), 5) Peak Universal Bond including 0.2% CHX (PEAK). Specimens were thermocycled (10,000 cycles) and inserted into a Streptococcus mutans biofilm artificial mouth (caries model). The 10-day biological loading protocol consisted of consecutive phases of demineralisation (1h) and remineralisation (5h). Evaluation under a fluorescence microscope (demineralisation) and an SEM (marginal gap) followed, at restoration margins, and at 0.3mm and 0.5mm distance from the margins, in enamel and in dentine. Total demineralization was calculated as the sum of demineralisation and substance loss due to demineralisation. ResultsPRIM (p=0.007, mod. LSD), BOND (p=0.012, mod. LSD) and PEAK (p=0.008, mod. LSD) exhibited significantly higher total demineralisation values in enamel margins than CTRL. No significant differences were noted for total demineralisation in dentine. Regarding marginal gaps, DENT exhibited significantly lower enamel gap values compared to all other groups (p=0.001). Conclusions2% CHX as dentine pre-treatment, 0.1% or 0.2% CHX added in adhesives did not provide any antibacterial effect regarding secondary caries in dentine. On the other hand, 2% CHX dentine pre-treatment managed to limit marginal gap formation in enamel compared to the other adhesive protocols in the study.

Interaction of intracanal medicaments with apical papilla stem cells: quantitative cytotoxicity assessment by methyl thiazolyl tetrazolium, trypan blue and lactate dehydrogenase.

Chemical residues often have cytotoxic effects on the stem cells. This study aimed to assess the cytotoxic effects of intracanal medicaments on stem cells of the apical papilla (SCAPs) using methyl thiazolyl tetrazolium (MTT), trypan blue exclusion (TBE) and lactate dehydrogenase release (LDHR) assays. SCAPs were cultured and exposed to 0.125, 0.25, 1, 5 and 10 mg/mL concentrations of modified triple antibiotic paste (mTAP)/distilled water (DW), mTAP/chlorhexidine (CHX), calcium hydroxide(Ca(OH)2)/CHX and Ca(OH)2/DW. Cell viability was quantitatively analyzed using the MTT, LDHR and TBE assays. Data were analyzed using one-way ANOVA and Tukey's test. All three assessment methods yielded the same results. Ca(OH)2/ DW resulted in the highest and mTAP/CHX resulted in the lowest cell viability. In contrast to Ca(OH)2, mTAP decreased cell viability in a dose-dependent manner. Also, addition of CHX to mTAP and Ca(OH)2 increased their cytotoxicity. In contrast to the proliferative effects of Ca(OH)2, even low concentrations of mTAP have cytotoxic effects on SCAPs.

Effect of the addition of chlorhexidine and miswak extract on the clinical performance and antibacterial properties of conventional glass ionomer: an in vivo study.

Antibacterial restorations can increase the success rate of minimum invasive dentistry especially in young permanent molars with deep carious lesions as an attempt to preserve maximum dental structure and avoid pulp exposure. Further research is warranted to evaluate different antibacterial agents. This study aimed to evaluate the efficacy of adding chlorhexidine gluconate (CHX) or aqueous miswak (Salvadora persica) extract on the clinical performance and in vivo antibacterial activity of conventional anhydrous glass ionomer cement (GIC). The study was a randomized clinical trial. Sixty young permanent molars, with deep carious lesions in 6- to 9-year-old children were included. After randomization, atraumatic restorative treatment (ART) or stepwise excavation was performed followed by bacterial sampling from the center of the remaining carious dentine in the floor of the pulp. GIC powder was mixed with 0.5% chlorhexidine gluconate liquid in group I; with 100% aqueous miswak in group II; and with deionized water in group III (control). Clinical performance for all groups was assessed at 3, 6, and 9 months. After 9 months, restorations were removed and a second bacterial sample was collected for Streptococcus mutans (S. mutans) quantification and analysis by real-time polymerase chain reaction (PCR) test. Results showed no statistically significant difference in the success rate of the three groups at the 3-month interval. At 6 and 9 months, however, restoration success was 75% then 60% in group I, 100% then 90% in group II, and 95% then 85% in control group. Group II and the control group showed statistically significant higher survival rates than group I. All groups showed reduction in S. mutans counts in underlying dentine, but the percent reduction was significantly higher in group I. (P < 0.001). The addition of CHX and miswak to GIC showed superior antibacterial properties than conventional GIC, without seriously affecting the clinical performance of the restoration until the 6-month follow-up, but failure significantly increased in terms of marginal defects at 9 months with CHX (group 1).

Effect of incorporating antifungals on the water sorption and solubility of interim resilient liners for denture base relining

Statement of problemIncorporating antifungals into interim denture resilient liners has been proposed to prolong their clinical longevity and to treat denture stomatitis. However, information is lacking on the effect of this addition on water sorption and solubility. PurposeThe purpose of this in vitro study was to evaluate the addition of minimum inhibitory concentrations (MICs) of antifungals for Candida albicans biofilm on the water sorption (WS) and solubility of interim denture resilient liners. Material and methodsDisk-shaped specimens (n=10; 50×0.5 mm) of tissue conditioner (Softone) and resilient liner (Trusoft) were created either without (control) or with the incorporation of 1 of the 3 following drugs at MICs (g of drug per g of resilient material powder): nystatin (Ny, 0.032g/g), chlorhexidine diacetate (Chx, 0.064g/g), and ketoconazole (Ke, 0.128g/g). Specimens were dried; immersed in water for 24 hours and 7 or 14 days; weighed, dried, and weighed again. Data (μg/mm3) were analyzed by 3-way ANOVA followed by the Tukey-Kramer honest significant differences test (α=.05). ResultsAt the 14-day interval, only the addition of Chx (483.0 ±61.0 μg/mm3) increased the WS of the tissue conditioner compared with the control group (244.0 ±42.0 μg/mm3; P<.001). For all periods, the solubility of both materials increased with the addition of Chx (27.7 ±6.1 μg/mm3) and Ke (30.9 ±5.3 μg/mm3) compared with the control group (22.5 ±6.0 μg/mm3; P<.001). ConclusionsAfter 14 days, the addition of Ny and Ke at MICs in both Softone and Trusoft and addition of Chx in Trusoft did not affect WS. The solubility of the 2 interim materials was not altered by the addition of Ny for up to 14 days.

Two-year clinical evaluation of chlorhexidine incorporation in two-step self-etch adhesive

ObjectivesThe aim of this 24-month double-blind randomized paired-tooth clinical study was to evaluate the 2-year clinical performance of two self-etch adhesives containing or not chlorhexidine digluconate (CHX) in non-carious cervical lesions (NCCLs). MethodsTwenty-two patients, with at least four NCCLs, participated in this study. After sample size calculation, 126 restorations were assigned to one of the following groups: CSE – Clearfil SE Bond (Kuraray); CSE/CHX – Clearfil SE Bond+CHX; ADS – AdheSE (Ivoclar Vivadent); and ADS/CHX – AdheSE+CHX. The composite resin Filtek Z-250 composite (3M ESPE) was placed incrementally by one expert operator. The restorations were evaluated at baseline and after 2 years using the modified USPHS criteria. Statistical analyses were performed with Friedman repeated measures ANOVA by rank and Fisher exact test for significance in each pair (α=0.05). ResultsNo significant difference was observed between baseline and 2-year for any criteria when adhesives with and without the addition of CHX were compared (p>0.05). ADS and ADS/CHX resulted in lower retention rates (82% on average) than CSE and CSE/CHX (97%) (p=0.02). ConclusionsThe inclusion of CHX into the primer of both self-etch systems did not add clinical advantages over the 2-year period. Clearfil SE Bond resulted in better retention rate than AdheSE. Clinical significanceIt is more important to choose a gold standard self-etch adhesive, like a Clearfil SE Bond, than to consider the inclusion of CHX in the self-etch adhesives.

Addition of chlorhexidine gluconate to a glass ionomer cement: a study on mechanical, physical and antibacterial properties.

The objective of this work was to determine the effect of different concentrations of chlorhexidine digluconate (CHX) on setting time, surface hardness, maximum tensile bond strength and antibacterial activity of a glass ionomer cement (GIC). The material used as control was Ketac Molar Easymix GIC. CHX was incorporated into the GIC during its manipulation at concentrations of 0.5, 1.0 and 2.0%. Antimicrobial activity against S. mutans and L. acidophilus was evaluated by means of agar diffusion test. Tensile bond strength data were analyzed statistically using Analysis of variance and Tukey's test. Setting time, Vickers hardness and agar diffusion test were analyzed using Kruskal-Wallis and Mann-Whitney tests at a significance level of 5%. It was observed that adding CHX at concentrations of 1% and 2% increased significantly the setting time of the material (p=0.012 and p=0.003, respectively). There was no significant difference between control and 0.5% CHX groups regarding the setting time. Addition of 2% CHX decreased significantly the surface hardness in relation to the control group (p=0.009), followed by the 1% CHX group (p=0.009). The tensile bond strength of the material also decreased significantly after adding CHX at a concentration of 2% (p=0.001). Addition of CHX promoted formation of an inhibition halo in both bacterial strains for all concentrations. The results showed that the best option for clinical use of GIC with CHX is at 0.5% concentration, since antibacterial activity increased and the physical-mechanical properties remained unchanged.

Effects of chlorhexidine-containing adhesives on the durability of resin–dentine interfaces

ObjectivesThis study evaluated the effect of addition of diacetate CHX in different concentrations into two simplified etch-and-rinse (ER) adhesive systems (XP Bond [XP] and Ambar {AM}) on the ultimate tensile strength (UTS), degree of conversion (DC), 60-day cumulative water sorption (WS), solubility (SO) and CHX release (CR) as well as the immediate (IM) and 1-year (1Y) resin–dentine bond strength (μTBS) and nanoleakage (NL). MethodsTen experimental adhesive systems were formulated according to the addition of CHX diacetate (0 [control], 0.01, 0.05, 0.1 and 0.2%) in the two ER. For UTS and DC, specimens were constructed and tested after 24h. For WS, SO and CR, after specimens build-up, they were stored in water and the properties measured after 60 days. The occlusal enamel of fifty molars was removed and the adhesives were applied in dentine surface after 37% phosphoric acid etching. After composite resin build-ups, specimens were longitudinally sectioned to obtain resin–dentine bonded sticks (0.8mm2). Specimens were tested in tension at 0.5mm/min in the IM or 1Y. For NL, 2 bonded sticks from each tooth were prepared and analyzed under SEM. The data were submitted to appropriate statistical analysis (α=0.05). ResultsThe addition of CHX did not influence UTS, DC, WS and SO (p<0.05). Higher CR was observed in adhesives with higher concentration of CHX (p<0.05). After 1Y, significant reductions of μTBS and increases of NL were observed in the control groups (p<0.05). Reductions of μTBS and increase of NL over time were not observed (AM) for CHX-containing adhesives or it was less pronounced than the control (XP) regardless of the CHX concentration. ConclusionsThe addition of CHX diacetate in concentrations until 0.2% in the simplified ER adhesive systems may be an alternative to increase the long-term stability of resin–dentine interfaces, without jeopardizing the adhesives’ mechanical properties evaluated.

Assessment of the cytotoxicity of chlorhexidine by employing an in vitro mammalian test system

Background/purposeChlorhexidine (CHX), a chlorophenyl biguanide with broad antibacterial action, has been widely used in dentistry. The initial uses of CHX in dentistry were to wash operation site and to disinfect root canals. Recently, the addition of CHX into many dental materials has improved the overall therapeutic efficacy. The aim of this study was to evaluate the potential toxicological implications of CHX employing an in vitro mammalian test system. Materials and methodsCytotoxicity, mode of cell death, and generation of superoxide anion were performed to elucidate the toxic effects of CHX on Chinese hamster ovary cells. Cytotoxicity was judged using tetrazolium bromide reduction assay. The mode of cell death was determined by flow cytometry. Superoxide anion generation was determined by the superoxide dismutase-inhibitable reduction of ferricytochrome c. ResultsCHX demonstrated a cytotoxic effect on Chinese hamster ovary cells in a dose-dependent and time-dependent manner (P < 0.05). The mode of cell death changed from apoptosis to necrosis as the concentrations of CHX elevated. CHX demonstrated a significant superoxide anion generation in a dose-dependent manner (P < 0.05). The addition of superoxide dismutase decreased the cytotoxicity induced by CHX (P < 0.05). ConclusionCHX was demonstrated to exhibit cytotoxicity that could disrupt the stable cellular redox balance, resulting in increasing levels of free radical generation and subsequent cell death. CHX has significant potential for cytotoxicity.

Casein Kinase 2 Regulates the mRNA-destabilizing Activity of Tristetraprolin

Tristetraprolin (TTP) is an AU-rich element-binding protein that regulates mRNA stability. We previously showed that TTP acts as a negative regulator of VEGF gene expression in colon cancer cells. The p38 MAPK pathway is known to suppress the TTP activity. However, until now the signaling pathway to enhance TTP function is not well known. Here, we show that casein kinase 2 (CK2) enhances the TTP function in the regulation of the VEGF expression in colon cancer cells. CK2 increased TTP protein levels and enhanced VEGF mRNA decaying activity of TTP. TTP was not a direct target of CK2. Instead, CK2 increased the phosphorylation of MKP-1, which led to a decrease in the phosphorylation of p38 MAPK. Inhibition of MKP-1 by siRNA attenuated the increase in TTP function and the decrease of p38 phosphorylation induced by CK2α overexpression. TGF-β1 increased the expressions of CK2 and TTP and the TTP function. The siRNA against CK2α or TTP reversed TGF-β1-induced increases in the expression of CK2 and TTP and the TTP function. Our data suggest that CK2 enhances the protein level and activity of TTP via the modulation of the MKP-1-p38 MAPK signaling pathway and that TGF-β1 enhances the activity of CK2.

In TNF-stimulated Cells, RIPK1 Promotes Cell Survival by Stabilizing TRAF2 and cIAP1, which Limits Induction of Non-canonical NF-κB and Activation of Caspase-8

RIPK1 is involved in signaling from TNF and TLR family receptors. After receptor ligation, RIPK1 not only modulates activation of both canonical and NIK-dependent NF-κB, but also regulates caspase-8 activation and cell death. Although overexpression of RIPK1 can cause caspase-8-dependent cell death, when RIPK1(-/-) cells are exposed to TNF and low doses of cycloheximide, they die more readily than wild-type cells, indicating RIPK1 has pro-survival as well as pro-apoptotic activities. To determine how RIPK1 promotes cell survival, we compared wild-type and RIPK1(-/-) cells treated with TNF. Although TRAF2 levels remained constant in TNF-treated wild-type cells, TNF stimulation of RIPK1(-/-) cells caused TRAF2 and cIAP1 to be rapidly degraded by the proteasome, which led to an increase in NIK levels. This resulted in processing of p100 NF-κB2 to p52, a decrease in levels of cFLIP(L), and activation of caspase-8, culminating in cell death. Therefore, the pro-survival effect of RIPK1 is mediated by stabilization of TRAF2 and cIAP1.

Effect of a calcium hydroxide–based paste associated to chlorhexidine on RAW 264.7 macrophage cell line culture

The objective of this study was to evaluate the effect of a calcium hydroxide Ca(OH)(2)-based paste (Calen) associated or not to 0.4% chlorhexidine digluconate (CHX) on RAW 264.7 macrophage cell line culture. The cell viability (MTT assay), immunostimulating properties (NO dosage), and anti-inflammatory properties (NO, TNF-alpha, and IL-1alpha dosage) were evaluated after cell exposure to the materials. Data were analyzed statistically by Kruskal-Wallis test at 5% significance level. There was low immunostimulating activity of the Calen paste associated or not to 0.4% CHX in the different materials' concentrations evaluated (P > .05). Anti-inflammatory activity with inhibition of NO and cytokine (TNF-alpha and IL1-alpha) release was observed only with Ca(OH)(2) + CHX at the highest concentration (25 microg/mL). As the Calen paste associated to 0.4% CHX did not alter cell viability or the immunostimulating and anti-inflammatory properties, the addition of CHX brought no benefits to the Ca(OH)(2)-based paste with regard to the tested parameters.

Two Point Mutations of RPE65 from Patients with Retinal Dystrophies Decrease the Stability of RPE65 Protein and Abolish Its Isomerohydrolase Activity

RPE65 is the isomerohydrolase in the retinoid visual cycle essential for recycling of 11-cis retinal, the chromophore for visual pigments in both rod and cone photoreceptors. Mutations in the RPE65 gene are associated with inherited retinal dystrophies with unknown mechanisms. Here we show that two point mutations of RPE65, R91W and Y368H, identified in patients with retinal dystrophies both abolished the isomerohydrolase activity of RPE65 after a subretinal injection into the Rpe65-/- mice and in the in vitro isomerohydrolase activity assay, independent of their protein levels. Further, the R91W and Y368H mutants showed significantly decreased protein levels but unchanged mRNA levels when compared with the wild-type RPE65 (wtRPE65). Protein stability analysis showed that wtRPE65 is a fairly stable protein, with an apparent half-life longer than 10 h, when expressed in 293A cells. Under the same conditions, mutants R91W and Y368H both showed substantially decreased protein stabilities, with half-lives less than 2 and 6 h, respectively. Subcellular fractionation and Western blot analysis demonstrated that wtRPE65 predominantly exists in the membrane fraction, while both of the mutants are primarily distributed in the cytosolic fraction, suggesting that these mutations disrupt the membrane association of RPE65. However, palmitoylation assay showed that wtRPE65 and both of the mutants were palmitoylated. These results suggest that these mutations may result in critical structural alterations of RPE65 protein, disrupt its membrane association, and consequently impair its isomerohydrolase activity, leading to retinal degeneration.

Differential action of cycloheximide and activation stimuli on transcription of tumor necrosis factor-alpha, IL-1 beta, IL-8, and P53 genes in human monocytes.

In the present study we have analyzed superinduction of TNF-alpha mRNA and enhancement of TNF-alpha gene transcription by cycloheximide (Chx) in human blood monocytes isolated by continuous Percoll gradient and activated in vitro. In the same monocyte cultures, we have compared the rate of gene transcription of TNF-alpha, IL-1 beta, IL-8, and the P53-antioncogene under the influence of plastic adherence, Staphylococcus aureus Cowan 1 (SAC), and Chx added at different times of monocyte culture. It was shown that the cytokine genes have low or negligible transcriptional activity in freshly isolated monocytes, whereas P53 gene transcription was constant in freshly isolated and in vitro-stimulated cells. Transcription of the IL-1 beta and IL-8 genes was induced by adherence and was not more enhanced by SAC. Transcription of the TNF-alpha gene was not induced by adherence. Chx added at the beginning of the monocyte culture did not block TNF-alpha or IL-1 beta gene transcription. IL-8 gene transcription, however, was abrogated by Chx. Addition of SAC to monocyte culture containing Chx caused significant enhancement of TNF-alpha gene transcription. Addition of Chx after 2.5 or 4 h of SAC activation caused "superinduction" of TNF-alpha mRNA and enhancement of TNF-alpha gene transcription. The data imply that TNF-alpha gene transcription in activated human monocytes might be regulated by both positive and negative regulatory factors that differ in their stability and protein synthesis dependence. In addition, results demonstrate that TNF-alpha, IL-1 beta, IL-8, and p53 genes in human monocytes are differently regulated.

Homologation of small alkanes on Pt, Pd and Ni catalysts. Contribution of intermediate carbenes to skeletal isomerisation

Chain lengthening homologation of propane,n-butane,2-methylpropane,2-methylbutane and 2,2-dimethylpropane has been investigated over Pt, Pd and Ni catalysts. With both Pd and Ni the chain lengthening selectivity was observed to be commensurable to the isomerisation one. Addition of CHx onto the β-carbon atom in n-butane and propane as well as chain lengthening of 2-methylpropane and 2-methylbutane were observed. The mechanism of the skeletal rearrangement is discussed in terms of CHx addition.