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AIM: The purpose of this study was to quantify the effect of five different root canal preparation instruments on Substance P (SP), Calcitonin gene-related peptide (CGRP) and their receptors expression in healthy human periodontal ligament. METHODOLOGY: STROBE guidelines were used to design a study using 60 periodontal ligament samples obtained from healthy lower premolars where extraction was indicated for orthodontic reasons. Prior to extraction 40 of these premolars were equally divided into four groups and root canals were prepared using different systems: Mtwo, Reciproc Blue, HyFlex EDM and Plex-V. Ten premolars were prepared with hand files and served as a positive control group. The remaining 10 premolars where extracted without treatment and served as a negative control group. All periodontal ligament samples were processed to measure the expression of SP, CGRP and their receptors by radioimmunoassay. Kruskal-Wallis and Duncan tests were performed to determine statistically significant differences between the groups for each variable. RESULTS: Greater expression of all the peptides measured were found in the hand-file preparation group, followed by the Reciproc Blue, Mtwo, HyFlex EDM and Plex-V groups. The lower SP, CGRP and their receptors values were for the intact teeth control group. Kruskal-Wallis test showed statistically significant differences amongst groups (p < .001). Dunn post-hoc tests showed statistically significant differences in SP, CGRP and their receptors expression between the intact teeth and the hand-file and Reciproc Blue groups. Hand-file group showed significant differences with the other groups, except with Reciproc Blue, where no differences were observed in any of the peptides measured. Finally, no differences were observed between Plex-V and HyFlex in any of the peptides measured. CONCLUSIONS: Root canal preparation with hand files and Reciproc Blue generates the highest expression of SP, CGRP, NK1 and CGRP1R in human periodontal ligament, whilst Plex-V and HyFlex maintain the basal expression of neuropeptides and their receptors. Mtwo showed intermediate results between Reciproc Blue and HyFlex.

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In this study, the effect of the recycling process and copper particle incorporation on virgin and recycled pellet HDPE were investigated by thermo-chemical analysis, mechanical characterization, and antibacterial analysis. Copper particles were added to pellet HDPE, virgin and recycled, using a tabletop single screw extruder. Some copper particles, called copper nano-particles (Cu-NPs), had a spherical morphology and an average particle size near 20 nm. The others had a cubic morphology and an average particle size close to 300 nm, labeled copper nano-cubes (Cu-NCs). The thermo-chemical analysis revealed that the degree of crystallization was not influenced by the recycling process: 55.38 % for virgin HDPE and 56.01% for recycled HDPE. The degree of crystallization decreased with the addition of the copper particles. Possibly due to a modification in the structure, packaging organization, and crystalline ordering, the recycled HDPE reached a degree of crystallization close to 44.78% with 0.5 wt.% copper nano-particles and close to 36.57% for the recycled HDPE modified with 0.7 wt.% Cu-NCs. Tensile tests revealed a slight reduction in the tensile strength related to the recycling process, being close to 26 MPa for the virgin HDPE and 15.99 MPa for the recycled HDPE, which was improved by adding copper particles, which were near 25.39 MPa for 0.7 wt.% copper nano-cubes. Antibacterial analysis showed a reduction in the viability of E. coli in virgin HDPE samples, which was close to 8% for HDPE containing copper nano-particles and lower than 2% for HDPE having copper nano-cubes. In contrast, the recycled HDPE revealed viability close to 95% for HDPE with copper nano-particles and nearly 50% for HDPE with copper nano-cubes. The viability of S. aureus for HDPE was lower than containing copper nano-particles and copper nano-cubes, which increased dramatically close to 80% for recycled HDPE with copper nano-particles 80% and 75% with copper nano-cubes.

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Background: The purpose of this study was to quantify the effect of moderate and severe orthodontic forces on Calcitonin gene-related peptide (CGRP) expression in the healthy human periodontal ligament (PDL) and its possible relationship with the human dental pulp. Material and Methods: Ninety human periodontal ligament samples were obtained from healthy premolars where extraction was indicated for orthodontic reasons. Prior to extraction, teeth were divided in 3 groups of 30 samples each: I) Untreated teeth control group; II) Moderate force group: A 56 g force was applied to the premolars for 24 hours; and III) Severe force group: A 224 g force was applied to the premolars for 7 days. All periodontal ligament samples were processed and CGRP was measured by radioimmunoassay. Results: Greater CGRP expression was found in the severe force group, followed by the moderate force group. The lower CGRP values were for the untreated teeth. Kruskal-Wallis test showed statistically significant differences between groups (p<0.001). LSD post hoc tests showed statistically significant differences in CGRP expression between the untreated teeth and the severe forces group (p<0.001). Differences between the moderate and severe force groups were statistically significant (p<0.001). There was no statistically significant differences between the untreated teeth and the moderate forces group (p<0.261). Conclusions: CGRP expression in human periodontal ligament increases when teeth are submitted to severe orthodontic forces. This elevated expression of CGRP, which is proportional to the applied force, may affect the way the dental pulp responds to different stimuli from the orthodontic forces. Key words:Calcitonin gene-related peptide, orthodontic force, human periodontal ligament, neurogenic inflammation.

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BACKGROUND: Current treatment of immature necrotic permanent teeth with a periapical lesion is regenerative endodontics, which is based on tissue engineering under the triade of stem cells, scaffolds and bioactive molecules. OBJECTIVES: This Umbrella Review was aimed to evaluate the success of scaffold and regenerative materials used for the treatment of these teeth, in terms of apical closure, tooth length increase, widening of root canal walls, tissue vitality and periapical lesion repair. METHODS: An extensive literature research was carried out in the Medline, ISI Web of Science, and Scopus databases for relevant systematic reviews matching the keyword search strategy. Based on inclusion and exclusion criteria, reviewers independently rated the quality of each study to determine their level of evidence. Methodological quality assessment of each article was obtained using A Measurement Tool to Assess Systematic Reviews (AMSTAR)-2 tool, and risk of bias was assessed with the Risk of Bias in Systematic Reviews (ROBIS) tool. RESULTS: After removing duplicates, 155 articles were found; from which 133 were excluded for being non-relevant and 15 other due to exclusion criteria. One more was discarded after methodological quality evaluation, for a total of six articles remaining. The most common scaffold used was the blood clot, others used were poly lactic-co-glycolic acid and platelet-rich fibrin matrix. The most common regeneration material used was Mineral Trioxide Aggregate (MTA), followed by Biodentine. An increase in tooth length and widening of root canal walls were reported in all selected studies with different proportions, as well as periapical lesion repair. ROBIS analysis showed that only one article had low bias, two were classified as unclear bias, while the remaining three had high risk of bias. DISCUSSION: An exhaustive literature search was carried out applying language filters, high-quality indexed journals, year of publication, which ensures the best quality articles were included. Blood clot was the most used scaffold as is the most easy to place inside the canal and does not require to extract blood from the patient. The use of MTA and Biodentine as sealing materials has been associated with thickening of canal walls, apical closure and reduced signs and symptoms of apical periodontitis. However, most of the included reviews assessed were case reports and only in a few of them were clinical trials included. There is also a lack of risk of bias analysis in most reviews. CONCLUSION: The blood clot is the most common scaffold used for inducing regeneration during the treatment of immature necrotic teeth. Tooth length increase and widening of root canal walls are the most common criteria used in the studies as success indicators. MTA and Biodentine did not show differences in the results analysed. Quality assessment and bias risk evaluation showed that it is necessary to design better studies with rigorous methodology to recommend a trustable and predictable protocol for the treatment of immature necrotic permanent teeth with periapical lesions. REGISTRATION: International Prospective Register of Systematic Reviews (PROSPERO) CRD42021248404.

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The influence of pH on the electrochemical behavior of hydrogen peroxide in the presence of Pseudomonas aeruginosa was investigated using electrochemical techniques. Cyclic and square wave voltammetry were used to monitor the enzymatic activity. A modified cobalt phthalocyanine (CoPc) carbon electrode (OPG), a known catalyst for reducing O2 to H2O2, was used to detect species resulting from the enzyme activity. The electrolyte was a sterilized aqueous medium containing Mueller-Hinton (MH) broth. The open-circuit potential (OCP) of the Pseudomonas aeruginosa culture in MH decreased rapidly with time, reaching a stable state after 4 h. Peculiarities in the E / I response were observed in voltammograms conducted in less than 4 h of exposure to the culture medium. Such particular E/I responses are due to the catalase's enzymatic action related to the conversion of hydrogen peroxide to oxygen, confirming the authors' previous findings related to the behavior of other catalase-positive microorganisms. The enzymatic activity exhibits maximum activity at pH 7.5, assessed by the potential at which oxygen is reduced to hydrogen peroxide. At higher or lower pHs, the oxygen reduction reaction (ORR) occurs at higher overpotentials, i.e., at more negative potentials. In addition, and to assess the influence of bacterial adhesion on the electrochemical behavior, measurements of the bacterial-substrate metal interaction were performed at different pH using atomic force microscopy.

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BACKGROUND: The aim of this study was to measure the dental pulp inflammatory response through neuropeptides (SP and CGRP) as a response to occlusal trauma, orthodontic movements and a combination of both, as well as the angiogenic defense mechanism through VEGF expression, which could be the initial step to mineralized tissue formation. METHODS: Forty human dental pulp samples were collected from healthy first premolars with extraction indicated due to orthodontic reasons from a sample of 20 patients. Patients were divided into four groups with 10 premolars each (1 mandibular and 1 maxillary premolar from each patient): healthy pulp control group, occlusal trauma group, moderate orthodontic forces group; and occlusal trauma plus moderate orthodontic forces group. Stimuli were applied for 24 h before tooth extraction in all experimental groups. All samples were processed, and SP, CGRP, and VEGF were measured by radioimmunoassay. The Kruskal-Wallis test was performed to assess significant differences among groups and Mann-Whitney's U post hoc pairwise comparisons were also performed. RESULTS: The highest increase in SP, CGRP, and VEGF expressions was found in the occlusal trauma plus orthodontic forces group, followed by the moderate orthodontic forces, the occlusal trauma and the control groups, with statistically significant differences between all groups for each of the 3 peptides analyzed (Kruskal-Wallis p < 0.001). All possible pairwise post-hoc comparisons were also significant for each peptide analyzed (Mann-Whitney's U p < 0.001). CONCLUSION: SP, CGRP, and VEGF expressions significantly increase in human dental pulps when stimulated by occlusal trauma combined with moderate orthodontic forces, as compared with these two stimuli applied independently. Name of the registry: Importance of Neurogenic Inflammation in the Angiogenic Response of the Dental Pulp as a Defensive Response. TRIAL REGISTRATION NUMBER: NCT03804034. Date of registration: 01/15/2019 Retrospectively registered. URL of trial registry record: https://clinicaltrials.gov/ct2/show/NCT03804034?term=NCT03804034&draw=2&rank=1 .

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BACKGROUND: The purpose of this study was to evaluate the changes in canal volume after root canal preparation in vivo with 3 different single-file techniques (Reciproc-Blue®, WaveOne-Gold® and XP-EndoShaper®), with a new method using CBCT and 3D reconstruction. METHODS: In this prospective study, thirty human lower premolars from healthy patients were used, in which extraction was indicated for orthodontic reasons. All the teeth used were caries- and restoration-free with complete root development, without signs of periodontal disease or traumatic occlusion, and with only one straight canal (up to 25º curvature). Teeth were randomly divided into three different groups: Reciproc-Blue, WaveOne-Gold and XP-EndoShaper. CBCT scans before root canal preparation were used to create a 3D reconstruction with RHINOCEROS 5.0 software to assess the initial canal volume, and then compared with 3D reconstructions after canal preparation to measure the increase in canal volume. Student's t test for paired data were used to determine statistically significant differences between the before and after canal volumes. Anova test was used to determine statistically significant differences in the percentage of canal volume increase between the groups and Tukey's post-hoc test were used to paired comparison. RESULTS: Reciproc-Blue showed the higher increase in canal volume, followed by WaveOne-Gold and XP-EndoShaper (p = 0.003). XP-EndoShaper did not show a statistically significant increase in canal volume after root canal preparation (p = 0.06). CONCLUSION: With this model, Reciproc-Blue showed higher increase in root canal volume, followed by WaveOne-Gold, while XP-EndoShaper did not significantly increase root canal volume during preparation.

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BACKGROUND: Proper oxygen balance in the dental pulp is essential for cell metabolism. Angiogenesis in the pulp is a constant process during the life of the tooth. Hypoxia indicators in a tissue, such as HIF-1α, as well as vascular destabilization markers, such as ANG2 and its receptor TIE2, are necessary for angiogenesis. Therefore the purpose of this study is to evaluate the expression of HIF-1α, ANG1, ANG2 and TIE2 in dental pulp as early angiogenesis indicators in teeth with complete and incomplete root development. METHODS: Forty human dental pulps were obtained from freshly extracted third molars divided into two groups: incomplete (n = 20) and complete (n = 20) root development. Dental pulps were stored at - 80 °C, defrosted in an ice bath and re-frozen with their respective thaws to disintegrate the tissue. Three sonication cycles were performed until the tissues were homogenized, then thaw were centrifuged and the supernatant was collected for the detection of the markers to be studied. The samples were processed for the ELISA test using the ELISA-sandwich principle. Student t and Mann-Whitney U tests were performed to determine statistically significant differences between groups. RESULTS: In the complete root development, HIF-1α, ANG1, ANG2 and TIE2 expressions were significantly higher than their expression in the incomplete root development group. CONCLUSIONS: The angiogenic process seems to be a physiological process in the dental pulp. Angiogenic activity is higher in teeth with mature than immature apex teeth.

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Resumen: De acuerdo a la información disponible, los pacientes pediátricos con COVID-19 tendrían una me nor frecuencia, se presentarían en su mayoría con un cuadro clínico de leve a moderado, y con una baja tasa de morbimortalidad asociada5. Sin embargo, es incierto el comportamiento real que tendrá el SARS-CoV-2 en Chile, así como tampoco sabemos el impacto que tendrá su interacción con otros virus respiratorios en el desenlace clínico. Asumiendo que los pacientes pediátricos que requieran hospitalización por sospecha o confirmación de COVID-19 necesitarán de diferentes niveles de so porte respiratorio, hemos elaborado recomendaciones transversales fundamentadas en el óptimo manejo del apoyo respiratorio pediátrico, basados en los principios de calidad y eficiencia en la en trega del soporte, en parámetros de bioseguridad y en el uso apropiado de recursos6. Estos elementos que se encuentran relacionados al armado y filtrado de los aerosoles producidos por algunos equipos de soporte ventilatorio, son recomendados en esta guía con el fin de unificar criterios técnicos que permitan entregar un apoyo óptimo al paciente pediátrico, manteniendo la mayor bioseguridad po sible para el paciente y el equipo de salud.

Abstract: According to the available information, pediatric cases of COVID-19 would present less frequently, most of them with mild to moderate clinical picture, and low associated morbidity and mortality5. However, we do not know the actual behavior that SARS-CoV-2 will have in Chile, nor the impact that its interaction with other respiratory viruses will have on the clinical outcome. On the assump tion that pediatric patients requiring hospitalization due to suspicion or confirmation of COVID-19 will need different levels of respiratory support, we have developed wide-range recommendations based on the optimal management of pediatric respiratory support according to the principles of quality and efficiency in the delivery of support, biosafety parameters, and appropriate use of resou rces6. These elements, which are related to assembling and filtering the aerosols produced by some respiratory support equipment, are recommended in this guide in order to unify technical criteria that allow optimal support for the pediatric patient while maintaining the highest possible biosafety for the patient and the health team.

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Ti-6Al-4V alloy has been widely investigated for biomedical applications due to its low density, high specific strength, and favorable corrosion resistance. However, some reported failures have imposed a challenge to improve bone regeneration and fixation, as well as antibacterial properties. A further opportunity for solving this problem is the introduction of porosity. However, this can induce metallic release and corrosion product formation. In this work, a Ti-6Al-4V alloy was exposed to Hank's solution, sterilized and inoculated with Staphylococcus aureus at 37 °C. Surface analysis was carried out by SEM-EDS and XPS. Electrochemical measurements were also performed using chronopotentiometry at open circuit potential, polarization curves, and electrochemical impedance spectroscopy. After exposure, FE-SEM showed some colonies of S. aureus on the sample with 22% porosity. However, XPS analysis revealed that the presence of bacterium influenced the composition of the oxide layer, even more drastically with the increase in added porosity. Moreover, the impedance analysis showed De Levie's behavior, revealing a reduction of pore resistance and modulus of the impedance in the low frequency range in inoculated medium, and polarization curves showed that the passivity potential range was decreased, whereas the passivity current increased in the presence of the S. aureus.

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(25R)-spirost-5-en-3ß-ol, also known as diosgenin (DSG), exerts antiproliferative activity on diverse cell lines, induces apoptosis, and acts as a chemopreventative agent. However, the relationship between DSG glycosides and apoptotic, necrotic, and antiproliferative activity remains unclear. It is in this regard that we report the antiproliferative, necrotic, and apoptotic activities of DSG and its glycoside derivatives: (25R)-spirost-5-en-3ß-yl O-ß-D-glucopyranoside (3GD), (25R)-spirost-5-en-3ß-yl O-α-L-rhamnopyranosyl-(1 â†’ 4)-ß-D-glucopyranoside (3GRD); and (25R)-spirost-5-en-3ß-yl O-α-L-rhamnopyranosyl-(1 â†’ 2)-O-[α-L-rhamnopyranosyl-(1 â†’ 4)]-ß-D-glucopyranoside), also known as dioscin (DSC), in in vitro assays of cervical HeLa and CaSki cancer cells. The results demonstrated that DSG glycosidic derivatives preserved their antiproliferative activity. However, in both cancer cell lines, 3GD and 3GRD were less potent than DSG, while DSC was more potent than DSG. With respect to necrotic activity, all tested compounds showed no or low activity on the two cervical cancer cell lines. Regarding apoptosis, the results showed that DSG glycosides were better apoptosis-inducers than DSG, suggesting that glucose and rhamnose residues play a central role in enhancing the apoptotic activity of DSG. Finally, DSG and its glycosidic derivatives were shown to affect the proliferative potential of lymphocytes (non-tumour cells) to a lesser extent than cancer cells, suggesting that these compounds have selective action. In conclusion, the results indicate that DSG and its glycosidic derivatives are promising anticancer compounds since they are compounds with low necrotic activity and selective action.

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Numerous chemical compounds isolated from medicinal plants have anti-tumor properties, the effects of which on human cancer cells are currently under study. Here, the chemical transformation of glaucolide B were performed to produce a hirsutinolide. The antiproliferative and cytotoxic activity of 5ß-hydroxy-hirsutinolide and its ability to induce apoptosis in tumor and non-tumor cells (lymphocyte cultures and the normal HaCaT cell line) (1a) are reported. We ascertained that compound 1a exerts an inhibitory effect on the proliferation of SK-Lu-1, MDA-MB-231 and CaSki cells in a dose-dependent manner at IC50 values of 15, 18 and 30 µg/ml, respectively. The proliferation of lymphocyte cells treated with 1a was inhibited at a range from 14 to 28%, but the HaCaT cell line was not affected, suggesting that compound 1a has a selective action. Cytotoxic activity was evaluated by detecting the lactate dehydrogenase enzyme in supernatants from tumor and non-tumor cells. The 1a compound exhibited low or null cytotoxic activity in both cell types. The presence of apoptotic bodies and active caspase-3 in tumor cell lines treated with compound 1a are suggestive of apoptotic cell death. Notably, flow cytometry evaluation did not detect the presence of active caspase-3 on lymphocytes treated with this compound. Our results suggest that 5ß-hydroxy-hirsutinolide is a molecule with antiproliferative activity and low cytotoxic activity in tumor and non-tumor cells; this induces apoptotic cell death in tumor cell lines through selective action. Hence, this lactone could be considered a molecule worthy of study as an anti-tumor agent with therapeutic potential.

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Quercetagetin and patuletin were extracted by the same method from two different Tagetes species that have multiple uses in folk medicine in Mexico and around the globe, one of which is as an anticancer agent. Their biological activity (IC50 and necrotic, apoptotic and selective activities of these flavonols) was evaluated and compared to that of quercetin, examining specifically the effects of C6 substitution among quercetin, quercetagetin and patuletin. We find that the presence of a methoxyl group in C6 enhances their potency.

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Identification of a new class of antitumor agent capable to induce apoptosis without triggering necrotic cell death event is challenging. The present communication describes the multicomponent synthesis of seven new (1S,4S)-2,5-diazabicyclo[2.2.1]heptane-dithiocarbamates and their in vitro antiproliferative activity on cervical cancer cell line (CaSki), breast cancer cell line (MDA-MB231), lung cancer cell line (SK-Lu-1) and human lymphocytes. Among the synthesized dithiocarbamates, compound 9e displayed significant antiproliferative activity without inducing any necrotic cell death (both on tumour cells and lymphocytes) and induced apoptosis in tumor cells by the caspase dependent apoptotic pathway. The compound 9e also exhibited greater tumor selectivity than human lymphocytes. In silico ADME predictions revealed that compound 9e has the potential to be developed as a drug candidate. Rapid chemical modifications of this lead are thus highly necessary for further investigation as a drug like safer antitumor candidate and also to achieve compounds with better activity profile.

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Steroidal sapogenins have shown antiproliferative effects against several tumor cell lines; and their effects on human cancer cells are currently under study. Changes in the functionality on the steroidal structure make it possible to modify the biological activity of compounds. Herein, we report the synthesis and in vitro antitumor activity of two steroidal oxime compounds on cervical cancer cells. These derivatives were synthesized from the steroidal sapogenin diosgenin in good yields. The in vitro assays show that the steroidal oximes show significant antiproliferative activity compared to the one observed for diosgenin. Cell proliferation, cell death, and the cytotoxic effects were determined in both cervical cancer cells and human lymphocytes. The cancer cells showed apoptotic morphology and an increased presence of active caspase-3, providing the notion of a death pathway in the cell. Significantly, the steroidal oximes did not exert a cytotoxic effect on lymphocytes.

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PURPOSE: Tumor cells are known to secrete cytokines that modify their microenvironment in order to favor their survival and continuous proliferation. In this work, we evaluated if TGF-ß secreted in vitro by cervical cancer cells could interfere with the proliferation and survival of lymphocytes. METHODS: Lymphocytes were obtained from peripheral blood of healthy human volunteers, and isolated by density gradient centrifugation and cultured in 96-well plates. Lymphocyte proliferation was induced with phytohemaglutinin and co-cultured with conditioned media (CM) from cervical cancer cell lines, and the inhibition of proliferation was evaluated after 72 h by the incorporated radioactivity and a CFSE-labeling assay. TGF-ß quantification on these CM was evaluated by ELISA. Non-apoptotic cellular death was evaluated through disruption of cell membrane integrity by measuring the liberation of lactate dehydrogenase. The apoptosis process was evaluated by annexin-V and active caspase-3. The presence of CD4+ or CD8+ lymphocytes was evaluated by flow cytometry using specific antibodies. RESULTS: It was found that the conditioned media from these cells significantly inhibited the proliferation of lymphocytes and induced them to go into apoptosis. Antibodies against TGF-ß almost completely blocked this activity, suggesting that this cytokine is responsible for the inhibitory activity. When the induced apoptosis on subpopulations of lymphocytes was evaluated, it was detected that the CD4+ cells were specifically targeted. CONCLUSIONS: Cervical cancer cells secrete TGF-ß that inhibits lymphocyte proliferation and induces apoptosis in CD4+, but not in CD8+ lymphocytes.

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INTRODUCTION: Many in vitro studies have debated over the ability of different irrigant delivery and/or agitation systems to reach the apical third of curved root canals; however, little is known about irrigant penetration in vivo. Therefore, the purpose of this study was to compare the efficacy of the conventional endodontic irrigation needle, passive ultrasonic irrigation (PUI), and a negative pressure system for irrigant delivery to working length (WL) of mesial canals of mandibular molars. METHODS: Thirty mesial canals of 30 vital mandibular first or second molars were randomly assigned into 3 groups (n = 10): (1) Monoject syringe with 27-gauge needle; (2) PUI with IrriSafe tip; and (3) EndoVac system. All canals were treated following the same preparation protocol to size 35/0.04 by using 5.25% NaOCl as irrigant during preparation procedure. Before obturation, canals were irrigated with 1 mL of a radiopaque solution by using the assigned irrigation system, and a digital radiograph was taken by using a parallel technique. With the aid of image editing software the distance between WL and maximum irrigant penetration was measured. RESULTS: Mean distances for Monoject, PUI, and EndoVac groups were 1.51 mm, 0.21 mm, and 0.42 mm, respectively. Analysis of variance test showed statistically significant differences between groups (P < .001). Tukey honestly significant difference test showed statistically significant differences between the Monoject group and the other 2 groups (P < .001) but no significant differences between PUI and EndoVac groups (P = .06). CONCLUSIONS: PUI and EndoVac are more effective than the conventional endodontic needle in delivering irrigant to WL of root canals.

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INTRODUCTION: The purpose of this study was to quantify the effect of moderate and severe orthodontic forces on calcitonin gene-related peptide (CGRP) expression in healthy human dental pulp. METHODS: Thirty human dental pulp samples were obtained from healthy premolars in which extraction was indicated for orthodontic reasons. Before extraction, teeth were divided into 3 groups of 10 premolars each: (1) the control group: healthy premolars without application of orthodontic forces; (2) the moderate force group: a 56-g force was applied to the premolars for 24 hours; and (3) the severe force group: a 224-g force was applied to the premolars for 24 hours. All dental pulp samples were processed, and CGRP was measured by radioimmunoassay. RESULTS: Greater CGRP expression was found in the severe force group followed by the moderate force group. The lower CGRP values were for the control group. The Kruskal-Wallis test showed statistically significant differences between groups (P < .0001). Least significant difference (LSD) post hoc tests showed statistically significant differences in CGRP expression between the control group and the severe force group (P < .0001) but not with the moderate force group (P = .06). Differences between the moderate and severe force groups were statistically significant (P < .0001). CONCLUSIONS: CGRP expression in human dental pulp increases when teeth are submitted to severe orthodontic forces.

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INTRODUCTION: The purpose of this study was to quantify the effect of occlusal trauma experimentally induced with occlusal interferences on substance P (SP) expression in healthy human dental pulp and periodontal ligament. METHODS: Twenty-eight human dental pulp and periodontal ligament samples were obtained from healthy premolars in which extraction was indicated for orthodontic reasons. Before extraction, occlusal trauma was induced with experimental occlusal interferences in half of these premolars by placing a resin block over their occlusal surface and submitting patients to chew gum for 30 minutes. The remaining healthy premolars were extracted without occlusal trauma and served as a control group. All dental pulp and periodontal ligament samples were processed, and SP was measured by radioimmunoassay. RESULTS: There was 45% and 120% greater SP expression in dental pulp and periodontal ligament, respectively, of teeth with experimentally induced occlusal trauma. Paired t test showed statistically significant differences for both human dental pulp and periodontal ligament (P = .02 and P < .001, respectively) of teeth submitted to occlusal trauma when compared with control group values. CONCLUSIONS: SP expression in human dental pulp and periodontal ligament increases when teeth are submitted to occlusal trauma experimentally induced with occlusal interferences.

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INTRODUCTION: The purpose of this study was to quantify the effect of three different rotary root canal preparation systems on substance P and calcitonin gene-related peptide expression in healthy human periodontal ligament. METHODS: Fifty periodontal ligament samples were obtained from healthy premolars in which extraction was indicated for orthodontic reasons. Before extraction, 40 of these premolars were equally divided into four groups, and root canals were prepared using four different systems: the ProTaper Universal rotary system, the RaCe rotary system, the Mtwo rotary system, and the hand instrumentation technique. The remaining 10 healthy premolars that were extracted without treatment served as a negative control group. All periodontal ligament samples were processed, and SP and CGRP were measured by radioimmunoassay. RESULTS: Greater SP and CGRP expression were found in the ProTaper Universal group followed by the hand instrumentation group, the RaCe, and the Mtwo groups. The lower SP and CGRP values were for the negative control group. The Kruskal-Wallis test showed statistically significant differences between groups (p < 0.0001). Post hoc Least Significant Difference (LSD) tests showed statistically significant differences in SP and CGRP expression between the negative control group and all the other groups except the Mtwo group. Hand instrumentation also showed statistically significant differences with all the other groups, except the ProTaper Universal group. Differences between the three rotary systems were also statistically significant. CONCLUSION: SP and CGRP expression in periodontal ligament increases when teeth are prepared with ProTaper Universal and RaCe rotary instrumentation systems as well as with hand instrumentation. Mtwo maintains SP and CGRP levels.

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