RESUMEN

INTRODUCTION: Studies have shown that interleukin 6 (IL-6) can regulate stem cell osteogenic differentiation; however, the exact mechanism is not clear. Circular RNAs (circRNAs) are closed circular non-coding RNAs that are involved in the process of stem cell osteogenic differentiation. Therefore, the purpose of this present study was to investigate the effect of IL-6 treatment on osteogenic differentiation of human apical tooth papillae stem cells (hSCAPs), and to detect the difference in circRNA expression using gene microarray technology. METHODS: After extraction and identification of hSCAPs, alkaline phosphatase (ALP) activity, alizarin red staining, and calcium ion quantitative assay were used to determine the changes of ALP enzyme, mineralized nodules, and matrix calcium levels before and after IL-6 treatment of hSCAPs gene microarray technology was used to analyze the changes in circRNA expression levels before and after IL-6 induction of mineralization. The four selected circRNAs were validated by qRT-PCR. Moreover, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were used to predict the potential functions and biological signaling pathways of circRNAs. Finally, these data are integrated and analyzed to construct circRNA-microRNA-mRNA networks. RESULTS: Alp and Alizarin red staining confirmed that IL-6 promoted the osteogenic differentiation of hSCAPs. The gene microarray results identified 132 differentially expressed circRNAs, of which 117 were upregulated and 15 were downregulated. Bioinformatic analysis predicted that the circRNA-406620/miR-103a-3p/FAT atypical cadherin 4 (FAT4) pathway might be involved in regulating IL-6 to promote osteogenic differentiation of hSCAPs. CONCLUSION: Differentially expressed circRNAs might be closely involved in regulating IL-6 to promote osteogenic differentiation of hSCAPs.

Asunto(s)

Interleucina-6 , ARN Circular , Humanos , ARN Circular/genética , ARN Circular/metabolismo , Interleucina-6/farmacología , Osteogénesis/genética , Calcio , Diferenciación Celular/genética , Células Madre/metabolismo

RESUMEN

AIM: The premixed bioceramic sealer iRoot SP that is widely used clinically has been reported to kill bacterial biofilms and promote osteogenic differentiation of human stem cells from the apical papilla (hSCAPs). Although miR-141-3p has been substantiated to be involved in the osteogenic process, the underlying mechanisms remain unclear. The aim of this study was to investigate the role of miR-141-3p in osteogenic differentiation and underlying mechanisms of iRoot SP-treated hSCAPs. METHODOLOGY: hSCAPs were extracted from tissue blocks with enzyme digestion and identified by using immunofluorescence, flow cytometry and alizarin red staining. The mRNA expression level of miR-141-3p in hSCPAs after culture with iRoot SP was examined by quantitative real-time PCR (qRT-PCR) assay. SPAG9 was identified as a downstream target gene of miR-141-3p by dual-luciferase report assay. Alkaline phosphatase (ALP) staining and activity detection, alizarin red staining, calcium concentration assay, qRT-PCR and western blot were used to estimate osteogenic differentiation ability and involved protein expression levels of the osteogenic makers and signalling pathway-related factors in iRoot SP-treated hSCAPs. Data were analysed by one-way anova and post hoc Tukey's test to determine any statistical differences between the experimental groups and the control group. p < .05 was considered statistically significant. RESULTS: Expression of miR-141-3p was reduced in iRoot SP-treated hSCAPs with the increased exposure time up to 7 days, and the western blot and qRT-PCR results revealed that the osteogenic markers osteocalcin (OCN), osterix (OSX), runt-related transcription factor 2 (RUNX2) and dentin sialophosphoprotein (DSPP) were inversely correlated with miR-141-3p. The negative regulatory relationship between miR-141-3p and SPAG9/ mitogen-activated protein kinases (MAPK) signalling axis was validated in this in vitro experiments. CONCLUSIONS: The bioceramic sealer iRoot SP promoted osteogenic differentiation of hSCAPs by inhibiting miR-141-3p following down-regulated SPAG9 expression, and activated MAPK pathway. These findings proposed a novel therapeutic impact of bioceramic sealer iRoot SP inducing bone regeneration in refractory periapical periodontitis.

Asunto(s)

MicroARNs , Osteogénesis , Humanos , Osteogénesis/genética , MicroARNs/metabolismo , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Células Cultivadas , Células Madre/metabolismo , Diferenciación Celular/fisiología , Proteínas Adaptadoras Transductoras de Señales/metabolismo

RESUMEN

OBJECTIVE: The specific objective of this study was to evaluate the effects of atmospheric pressure plasma (APP) in the treatment of experimental periodontitis in Beagle dogs. METHODS: The APP jet was diagnosed using optical emission spectroscopy and laser-induced fluorescence spectroscopy. Six Beagles received stainless steel ligatures to establish experimental periodontitis model. The teeth in the control group were subjected to conventional root surface debridement (RSD) and chlorhexidine irrigation. The APP group also started with RSD and was then subjected to plasma irradiation. Clinical analyses including plaque index, modified sulcus bleeding index, pocket depth and attachment loss (AL), as well as cone-beam computed tomography (CBCT) analysis, were performed at baseline, 4th week, 8th week and 12th week after treatment. RESULTS: The results showed that typical reactive oxygen and nitrogen species were found in the full spectrum and the gas temperature of APP was close to room temperature. The highest concentrations of hydroxide and oxygen were obtained at 5 mm away from the nozzle. In both groups, all values in clinical examinations were significantly lower (P<0.05) at 12th week after treatment than those at baseline. At the 12th week, the AL in clinical examinations and the bone loss in CBCT images in the APP group were significantly lower than those in the control group (P<0.05). The hematoxylin-eosin staining showed more renascent alveolar bone in the APP group than in the control group. CONCLUSION: These findings suggested that APP has profound potential for use as an adjunct approach for periodontitis treatment.

Asunto(s)

Clorhexidina , Periodontitis , Perros , Animales , Clorhexidina/uso terapéutico , Eosina Amarillenta-(YS)/uso terapéutico , Acero Inoxidable , Hematoxilina/uso terapéutico , Periodontitis/diagnóstico por imagen , Periodontitis/terapia , Presión Atmosférica , Oxígeno , Nitrógeno/uso terapéutico

RESUMEN

Objective: We reported the long-term outcomes of transcatheter chemoembolization (TACE) for patients with late-stage or recurrent oral carcinoma. Methods: This retrospective study enrolled 18 patients with late-stage or recurrent oral carcinoma between December 2015 and April 2021. The tumor-feeding artery was catheterized, and cisplatin/oxaliplatin and 5-FU/raltitrexed were infused with embolization using polyvinyl alcohol or gelatin sponge. Computed tomography was performed at about 1, 3, and 6 months after the procedure, and every 6 months after that. During the procedure and follow-up, procedure outcomes, complications, treatment efficacy, and overall survival were analyzed. Results: A total of 31 sessions of TACE were performed, with a technical success rate of 100%. Of 12 patients combined with oral hemorrhage, two patients showed rebleeding 35 and 37 days later, with a clinical efficiency of hemostasis of 88.9%. Mild complications were observed in 11 patients (61.1%). Severe complications or procedure-related deaths were not observed during or after the procedure. The objective response rate and disease control rate were 20.0% and 86.7%, 38.5% and 61.5%, and 25.0% and 50.0% at 1, 3, and 6 months later, respectively. Seventeen patients (94.4%) were followed up, with a median duration of 37.8 months (IQR 22.3-56.8). Nine patients died of tumor progression, one died of massive rebleeding, and one died of severe lung infection. The median overall survival was 23.8 months. Conclusion: TACE is a safe and effective procedure with minimal invasiveness for treating late-stage or recurrent oral carcinoma. TACE can be recommended as a palliative treatment, particularly for patients with oral hemorrhage.

RESUMEN

BACKGROUND: Research shows that nano-bioceramics can modulate the differentiation of dental stem cells. The novel ready-to-use calcium-silicate-based root-canal sealer iRoot SP is widely used in root filling. Accordingly, the aim of this study was to evaluate the effects of iRoot SP on proliferation and osteogenic differentiation in human stem cells from the apical papilla (hSCAPs). METHODS: hSCAPs were isolated and characterized in vitro, then cultured with various concentrations of iRoot SP extract. Cell proliferation was assessed by CCK-8 assay, and scratch-wound-healing assays were performed to evaluate cell-migration capacity. hSCAPs were then cultured in osteogenic medium supplemented with iRoot SP extracts. Alkaline phosphatase (ALP) activity assay was used to evaluate ALP enzyme levels. Alizarin red staining and cetylpyridinium chloride (CPC) assays were performed to assess calcified-nodule formation and matrix-calcium accumulation of hSCAPs. The mRNA and protein expression levels of the osteogenic markers OCN, OSX, Runx2, and DSPP were determined by qRT-PCR and Western blotting. The data were analyzed using one-way ANOVA and LSD-t tests. RESULTS: iRoot SP at low concentrations (2, 0.2, and 0.02 mg/mL) is nontoxic to hSCAPs. iRoot SP at concentrations of 0.02 and 0.2 mg/mL significantly increases cell-migration capacity. In terms of osteogenic differentiation, 0.2 mg/mL iRoot SP promotes intracellular ALP activity and the formation of mineralized nodules. Moreover, the expression of osteogenic markers at the mRNA and protein levels are upregulated by iRoot SP. CONCLUSION: iRoot SP is an effective filling material for periapical bone regeneration.

Asunto(s)

Osteogénesis , Silicatos , Diferenciación Celular , Proliferación Celular , Células Cultivadas , Humanos , Materiales de Obturación del Conducto Radicular , Silicatos/farmacología , Células Madre

RESUMEN

Chondral defects are challenging to repair because of the poor self-healing capacity of articular cartilage. The aim of this study was to compare and investigate the cartilage regeneration of stromal vascular fraction (SVF) cells and adipose-derived stem cells (ASCs) co-cultured with chondrocytes seeding on scaffolds composed of polyhydroxybutyrate (PHB)/poly-(hydroxybutyrate-co-hydroxyhexanoate) (PHBHHx). In this study, the cellular morphologies and proliferation capabilities on scaffolds were evaluated. Next, scaffolds with 1:1 co-culture of ASCs/SVF and chondrocytes were implanted into the full-thickness cartilage defects in rabbit knee for 10 weeks. Cells seeded on the scaffolds showed better adhesion, migration, and proliferation in vitro. Importantly, implantation with scaffolds with SVF and chondrocytes revealed more desirable in vivo healing outcomes. Our results illustrate a one-step surgical procedure for the regeneration of focal cartilage defects using a mixture of SVF from adipose tissue and uncultured chondrocytes.

Asunto(s)

Ácido 3-Hidroxibutírico/química , Tejido Adiposo/citología , Caproatos/química , Cartílago Articular/lesiones , Condrocitos/citología , Hidroxibutiratos/química , Poliésteres/química , Andamios del Tejido/química , Ácido 3-Hidroxibutírico/farmacología , Implantes Absorbibles , Tejido Adiposo/ultraestructura , Animales , Caproatos/farmacología , Cartílago Articular/citología , Adhesión Celular , Movimiento Celular , Proliferación Celular , Células Cultivadas , Técnicas de Cocultivo , Hidroxibutiratos/farmacología , Traumatismos de la Rodilla/terapia , Microscopía Electrónica de Rastreo , Poliésteres/farmacología , Conejos , Regeneración/fisiología , Células del Estroma/citología , Células del Estroma/ultraestructura , Ingeniería de Tejidos/métodos , Cicatrización de Heridas

RESUMEN

OBJECTIVE: Previously, we have shown that miRNA-342-3p was increased during osteogenic differentiation of human umbilical mesenchymal stem cells (hUCMSCs) via regulating the sonic hedgehog (Shh) pathway. In this study, our objective is to further investigate the role of miRNA-342-3p in activation of Shh pathway by targeting suppressor of fused protein (Sufu), a suppressor of transcriptional factor Gli, as well as the potential interaction with transforming growth factor beta (TGF-ß) signaling pathway during osteogenic induction of hUCMSCs. MATERIALS AND METHODS: HUCMSCs that stable overexpression or knockdown of miRNA-342-3p were established by infection with lentiviral vectors. mRNA and protein levels of Hedgehog signaling pathway and osteogenic genes were measured by RT-qPCR and western blot assays. Luciferase reporter assay was performed to test the direct binding site of Sufu 5'UTR targeted by miRNA-342-3p. RESULTS: Overexpression of miRNA-342-3p in hUCMSCs enhanced the expression of osteogenic genes by targeting Sufu. And the potential of osteogenic differentiation of hUCMSCs was inhibited while knocking down miRNA-342-3p. Meanwhile, induced the TGF-ß expression level was also observed upon overexpressing miRNA-342-3p, suggesting activation of TGF-ß signaling pathway was a potential mechanism of miRNA-342-3p-mediated osteogenesis in hUCMSCs. CONCLUSIONS: Our findings provide new mechanistic evidence that miRNA-342-3p might be a valuable therapeutic target in bone regeneration.

Asunto(s)

Proteínas Hedgehog , Células Madre Mesenquimatosas , MicroARNs , Osteogénesis , Proteínas Represoras , Cordón Umbilical , Regeneración Ósea , Diferenciación Celular , Humanos , Transducción de Señal

RESUMEN

Oral submucous fibrosis (OSF) induced by chewing of the areca nut has been considered to be a precancerous lesion with a high probability of developing oral squamous cell carcinoma. Tanshinone (TSN) is the main component extracted from Salvia miltiorrhiza, a traditional Chinese medicine, which was found to have diverse pharmacological effects, such as anti-inflammatory and antitumor. In the current study, we aimed to identify the inhibitory effects and the underlying mechanism of TSN on OSF progress. We found that treatment with TSN inhibited the arecoline-mediated proliferation of primary human oral mucosal fibroblasts and reversed the promotive effects of arecoline on the EMT process. By RNA deep sequencing, we screened two possible targets for TSN: LSD1 and p53. We confirmed that p53 is much lower in OSF than in normal mucous tissues. In addition, p53 and its downstream molecules were decreased by arecoline treatment in oral mucosal fibroblasts, which was reversed by treatment with TSN in a dose-dependent manner. Our results also revealed that arecoline stimulation resulted in hypermethylation of the promoter of TP53 and subsequent downregulation of p53 levels, which was reversed by TSN. Furthermore, we identified that LSD1 could epigenetically activate TP53 by recruiting H3K27me1 and H3K4m2 to its promoter. Our findings provide new insights into the mechanism by which TSN influences arecoline-induced OSF and rationale for the development of clinical intervention strategies for OSF and even oral squamous cell carcinoma.

Asunto(s)

Abietanos/farmacología , Areca/química , Arecolina/toxicidad , Transición Epitelial-Mesenquimal , Mucosa Bucal/patología , Fibrosis de la Submucosa Bucal/patología , Proteína p53 Supresora de Tumor/genética , Animales , Antiinflamatorios no Esteroideos/farmacología , Apoptosis , Proliferación Celular , Células Cultivadas , Agonistas Colinérgicos/toxicidad , Metilación de ADN , Epigénesis Genética , Regulación de la Expresión Génica , Humanos , Masculino , Ratones , Ratones Desnudos , Mucosa Bucal/efectos de los fármacos , Mucosa Bucal/metabolismo , Fibrosis de la Submucosa Bucal/inducido químicamente , Fibrosis de la Submucosa Bucal/metabolismo , Regiones Promotoras Genéticas , Proteína p53 Supresora de Tumor/metabolismo

RESUMEN

BACKGROUND: To investigate the physical properties and the hydration behaviour of the fast-setting bioceramic iRoot FS Fast Set Root Repair Material (iRoot FS) and three other endodontic cements. METHODS: iRoot FS, Endosequence Root Repair Material Putty (ERRM Putty), gray and white mineral trioxide aggregate (G-MTA & W-MTA), and intermediate restorative material (IRM) were evaluated. The setting time was measured using ANSI/ADA standards. Microhardness was evaluated using the Vickers indentation test. Compressive strength and porosity were investigated at 7 and 28 days. Differential scanning calorimetry (DSC) was employed for the hydration test. RESULTS: iRoot FS had the shortest setting time of the four bioceramic cements (p < .001). The microhardness values of iRoot FS, ERRM Putty and MTA increased at different rates over the 28 days period. At day one, ERRM Putty had the lowest microhardness of the bioceramic cements (p < .001), but reached the same level as MTA at 4, 7 and 28 days. The microhardness of iRoot FS was lower than that of W-MTA at 7 and 28 days (p < .05). The porosity of the materials did not change after 7 days (p < .05). The compressive strength values at 28 days were significantly greater for all bioceramic groups compared to those at 7 days (p < .01). ERRM Putty had the highest compressive strength and the lowest porosity of the evaluated bioceramic cements (p < .05), followed by iRoot FS, W-MTA, and G-MTA, respectively. DSC showed that iRoot FS hydrated fastest, inducing an intense exothermic reaction. The ERRM Putty did not demonstrate a clear exothermic peak during the isothermal calorimetry test. CONCLUSIONS: iRoot FS had a faster setting time and hydrating process than the other bioceramic cements tested. The mechanical properties of iRoot FS, G-MTA and W-MTA were relatively similar.

Asunto(s)

Cerámica/química , Materiales de Obturación del Conducto Radicular/química , Compuestos de Aluminio/química , Materiales Biocompatibles , Compuestos de Calcio/química , Fuerza Compresiva , Combinación de Medicamentos , Óxidos/química , Silicatos/química

RESUMEN

INTRODUCTION: The present study aimed to evaluate the antibacterial effect of the combined use of sodium hypochlorite (NaOCl) and root canal sealers on Enterococcus faecalis biofilms using a dentin infection model. METHODS: Cells of E. faecalis were introduced into the dentinal tubules by centrifugation and incubated in brain-heart infusion for 3 weeks. The biofilms in dentin were first subjected to 5% NaOCl or sterile water for 10 minutes followed by an equal thickness of AH Plus (Dentsply International Inc, York, PA), Endosequence BC Sealer (Brasseler USA, Savannah, GA), or MTA Fillapex (Angelus Indústria de Produtos Odontológicos S/A, Londrina, Brazil) placed on the root canal wall of the dentin specimens for 7, 30, and 60 days. Gutta-percha and water were used in a similar manner as controls. The proportions of dead and live bacteria inside the dentinal tubules were assessed by confocal laser scanning microscopy and viability staining. RESULTS: The combined use of NaOCl and sealers (30 and 60 days) killed significantly more bacteria than NaOCl or sealers alone (P < .05). NaOCl + MTA Fillapex was the most effective antibacterial combination by killing 83% bacteria in dentin tubules in 60 days. Thirty and 60 days of exposure to the sealers resulted in significantly more dead bacteria in dentin biofilms than 7-day exposures (P < .05). CONCLUSIONS: The placement of root canal sealer after NaOCl treatment enhanced antibacterial effects against E. faecalis in the dentinal tubules. Little additional effect was obtained after 30 days of exposure to sealers.

Asunto(s)

Antibacterianos/farmacología , Biopelículas/efectos de los fármacos , Dentina/microbiología , Enterococcus faecalis/efectos de los fármacos , Infecciones por Bacterias Grampositivas/tratamiento farmacológico , Materiales de Obturación del Conducto Radicular/farmacología , Hipoclorito de Sodio/farmacología , Dentina/efectos de los fármacos , Dentina/patología , Quimioterapia Combinada , Resinas Epoxi/farmacología , Infecciones por Bacterias Grampositivas/patología , Humanos , Microscopía Confocal , Factores de Tiempo

RESUMEN

AIM: To evaluate the effects of non-equilibrium plasma in the treatment of ligature-induced peri-implantitis in beagle dogs. MATERIALS AND METHODS: Six beagles received 12 implants installed in the position of the fourth mandibular premolars. Ligature-induced peri-implantitis was initiated at 3 months post-implantation. When approximately 40% of the supporting bone was lost, the ligatures were removed. The implants were subjected to the muco-periosteal scaling and chlorhexidine irrigation with or without plasma irrigation. Three months later, clinical, radiographic and microbiological analyses were performed. Block biopsies were prepared for micro-CT and histomorphometric analysis. The primary outcome was the difference in bone healing of peri-implant sites, and the secondary outcomes included changes in clinical parameters (SBI, PD) and bacterial detection. RESULTS: At baseline, no significant differences were observed between the two groups. At 3 months post-treatment, the plasma group showed a significantly higher bone level than the control group (p < 0.05), a significantly decreased detection of bacteria (Porphyromonas gingivalis and Tannerella forsythia) (p < 0.05), and a significant improvement in clinical examination (p < 0.05). CONCLUSIONS: Within the limits of this study, non-equilibrium plasma treatment as an adjunct to the conventional therapy is a feasible approach for the treatment of peri-implantitis.

Asunto(s)

Periimplantitis/terapia , Gases em Plasma/uso terapéutico , Aggregatibacter actinomycetemcomitans/aislamiento & purificación , Animales , Antiinfecciosos Locales/uso terapéutico , Bacteroides/aislamiento & purificación , Biopsia/métodos , Clorhexidina/análogos & derivados , Clorhexidina/uso terapéutico , Implantes Dentales , Modelos Animales de Enfermedad , Perros , Estudios de Factibilidad , Periimplantitis/microbiología , Periimplantitis/patología , Índice Periodontal , Bolsa Periodontal/microbiología , Bolsa Periodontal/patología , Bolsa Periodontal/terapia , Porphyromonas gingivalis/aislamiento & purificación , Curetaje Subgingival/métodos , Irrigación Terapéutica/métodos , Factores de Tiempo , Tomografía Computarizada por Rayos X/métodos , Alveolo Dental/cirugía , Cicatrización de Heridas/fisiología , Microtomografía por Rayos X/métodos

RESUMEN

INTRODUCTION: The cytotoxicity of 2 novel calcium silicate-containing endodontic sealers to human gingival fibroblasts was studied. METHODS: EndoSequence BC (Brasseler, Savannah, GA), MTA Fillapex (Angelus Indústria de Produtos Odontológicos S/A, Londrina, PR, Brazil) and a control sealer (AH Plus; Dentsply DeTrey GmbH, Konstanz, Germany) were evaluated. Human gingival fibroblasts were incubated for 3 days both with the extracts from fresh and set materials in culture medium and cultured on the surface of the set materials in Dulbecco-modified Eagle medium. Fibroblasts cultured in Dulbecco-modified Eagle medium were used as a control group. Cytotoxicity was evaluated by flow cytometry, and the adhesion of the fibroblasts to the surface of the set materials was assessed using scanning electron microscopy. The data of cell cytotoxicity were analyzed statistically using a 1-way analysis of variance test at a significance level of P < .05. RESULTS: Cells incubated with extracts from BC Sealer showed higher viabilities at all extract concentrations than cells incubated with extracts from freshly mixed AH Plus and fresh and set MTA Fillapex, esspecially for the high extract concentrations (1:2 and 1:8 dilutions). Extracts from set MTA Fillapex of 2 weeks and older were more cytotoxic than extracts from freshly mixed and 1-week-old cement. With extract concentrations of 1:32 and lower, MTA Fillapex was no longer cytotoxic. After setting, AH Plus was no longer cytotoxic, and the fibroblast cells grew on set AH Plus equally as well as on BC Sealer. CONCLUSIONS: BC Sealer and MTA Fillapex, the 2 calcium silicate-containing endodontic sealers, exhibited different cytotoxicity to human gingival fibroblasts.

Asunto(s)

Compuestos de Calcio/toxicidad , Materiales de Obturación del Conducto Radicular/toxicidad , Silicatos/toxicidad , Compuestos de Aluminio/química , Compuestos de Aluminio/toxicidad , Compuestos de Calcio/química , Fosfatos de Calcio/química , Fosfatos de Calcio/toxicidad , Adhesión Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Medios de Cultivo , Cementos Dentales/química , Cementos Dentales/toxicidad , Combinación de Medicamentos , Resinas Epoxi/química , Resinas Epoxi/toxicidad , Fibroblastos/citología , Fibroblastos/efectos de los fármacos , Encía/citología , Encía/efectos de los fármacos , Encía/crecimiento & desarrollo , Cementos de Ionómero Vítreo/química , Cementos de Ionómero Vítreo/toxicidad , Humanos , Óxidos/química , Óxidos/toxicidad , Materiales de Obturación del Conducto Radicular/química , Silicatos/química

RESUMEN

INTRODUCTION: The purpose of this study was to evaluate the effect of various degrees of cyclic fatigue on torsional failure and torsional preloading on the cyclic fatigue life of heat-treated K3XF nickel-titanium (NiTi) instruments (SybronEndo, Orange, CA). METHODS: The mean number of cycles until failure (Nf) of K3XF and K3 NiTi instruments was examined in a 3-point bending apparatus with a 7-mm radius and 45° curve. Torque and distortion angles at failure of new instruments and instruments stressed to 25%, 50%, and 75% of the Nf were measured according to ISO 3630-1. Other new files were preloaded at 25%, 50%, and 75% of the mean distortion angles before the fatigue test. After torsional preloading, the Nf was examined. The fracture surface of each fragment was examined with a scanning electron microscope. RESULTS: The fatigue resistance of K3XF instruments was 2 times higher than that of K3 instruments (P < .05). The torque and angle of rotation at fracture of K3XF instruments were similar to those of K3 instruments. The 25%, 50%, and 75% torsional preloading significantly lowered the Nf of both K3 and K3XF instruments (P < .05). In the fatigue prestressed groups, K3 instruments with 75% preloading had significantly lower torque and distortion angles than unused K3 instruments (P < .05). The fractographic patterns corresponded to the pattern defined by the last stage test. CONCLUSIONS: A low amount of torsional preloading reduced the fatigue resistance of K3 and K3XF instruments. A high amount of precycling fatigue significantly reduced the torsional resistance of K3 instruments. The torsional resistance of K3XF instruments was less affected by previous load cycling even after extensive precycling.

Asunto(s)

Equipo Dental , Falla de Equipo , Níquel , Estrés Mecánico , Titanio , Torsión Mecánica

RESUMEN

Bone marrow­derived mesenchymal stem cells (BMSCs) have the potential to form a variety of mesenchymal tissue types, which are a source of cells for bone tissue engineering applications. The present study attempted to establish an effective and convenient method for culturing BMSCs. Total bone marrow cells, which were harvested from rat femurs, were cultured and BMSCs were selected and expanded through passaging in vitro. Furthermore, the biological properties of BMSCs were investigated, specific surface antigen expression was assessed using flow cytometry and the multipotent differentiation potential characteristics were demonstrated using standard in vitro conditions. Monoptychial heterogeneous cells were obtained. A total of 98.4% of cells at passage 3 expressed cluster of differentiation (CD)29 and CD90, but not CD45. The cells were able to differentiate into osteogenic and adipogenic cells. In conclusion, BMSCs that are isolated from the rat bone marrow and exhibit the identified characteristics may be used as seed cells in bone tissue engineering.

Asunto(s)

Células de la Médula Ósea/citología , Células Madre Mesenquimatosas/citología , Adipogénesis , Animales , Diferenciación Celular , Subunidad alfa 1 del Factor de Unión al Sitio Principal/genética , Subunidad alfa 1 del Factor de Unión al Sitio Principal/metabolismo , Factor 2 de Crecimiento de Fibroblastos/genética , Factor 2 de Crecimiento de Fibroblastos/metabolismo , Proteínas Hedgehog/genética , Proteínas Hedgehog/metabolismo , Integrina beta1/metabolismo , Antígenos Comunes de Leucocito/metabolismo , Masculino , Células Madre Mesenquimatosas/metabolismo , Osteogénesis , Fenotipo , Ratas , Ratas Sprague-Dawley , Antígenos Thy-1/metabolismo

RESUMEN

INTRODUCTION: The purpose of this study was to evaluate the antimicrobial activity on Enterococcus faecalis biofilms in dentin canals of short-term and long-term exposure to different endodontic disinfecting solutions by using a dentin infection model and confocal laser scanning microscopy. METHODS: Dentinal tubules in semi-cylindrical dentin blocks were filled with E. faecalis by centrifugation and incubated to form 1-day-old and 3-week-old biofilms. The young and mature biofilms in dentin were subjected to sterile water, 2% chlorhexidine, 2% sodium hypochlorite (NaOCl), and 6% NaOCl for 3, 10, and 30 minutes. After treatments, the proportion of bacteria killed by the disinfectants was analyzed by confocal laser scanning microscopy by using LIVE/DEAD bacterial viability stain. RESULTS: The proportion of killed bacteria was lower after 3 minutes than after 10 and 30 minutes of exposure to the disinfecting agents (P < .05). The killing of bacteria in the E. faecalis biofilms was fastest during the first 3 minutes and slowed down greatly after 10 minutes. Six percent NaOCl was the most effective antibacterial solution against both the 1-day-old and 3-week-old biofilms (P < .05). No significant difference in bacterial killing was detected between 2% chlorhexidine and 2% NaOCl (P > .05). Significantly more cells were killed in young biofilms than in old biofilms in all groups (P < .05). CONCLUSIONS: The killing of bacteria in infected dentin by disinfecting solutions is time-dependent. However, little additional killing is obtained after the first 10 minutes of exposure.

Asunto(s)

Biopelículas/efectos de los fármacos , Cavidad Pulpar/microbiología , Dentina/microbiología , Enterococcus faecalis/efectos de los fármacos , Irrigantes del Conducto Radicular/farmacología , Antiinfecciosos Locales/farmacología , Técnicas Bacteriológicas , Clorhexidina/farmacología , Cavidad Pulpar/ultraestructura , Dentina/ultraestructura , Colorantes Fluorescentes , Humanos , Viabilidad Microbiana/efectos de los fármacos , Microscopía Confocal , Compuestos Orgánicos , Propidio , Distribución Aleatoria , Hipoclorito de Sodio/farmacología , Factores de Tiempo , Agua

RESUMEN

INTRODUCTION: Nonequilibrium plasma has been reported to effectively kill Enterococcus faecalis in endodontic biofilm compared with chlorhexidine digluconate (CHX). The purpose of this study was to evaluate the antimicrobial in vitro activity of modified nonequilibrium plasma with CHX against E. faecalis and multispecies biofilms on bovine dentin discs. METHODS: Sterile bovine dentin discs were incubated with E. faecalis or a mixture of bacteria from human dental root canal infections to form 1- and 3-week-old biofilms. The specimens were subjected to nonequilibrium plasma, modified nonequilibrium plasma with CHX, and 2% CHX for 2- and 5-minute exposure. After treatment, the biofilms were stained with viability dyes and examined by confocal laser scanning microscopy and 3-dimensional reconstruction analysis. The proportions of bacterial cells killed by the treatments were calculated. RESULTS: The 3-dimensional reconstruction images showed that 1- and 3-week-old biofilms adhered to bovine dentin discs. The proportions of dead cells increased significantly with the longer exposure in each treatment group (P < .05). Modified nonequilibrium plasma was the most effective in killing bacteria in E. faecalis and multispecies biofilms at both 2 and 5 minutes (P < .05). No significant difference was detected between nonequilibrium plasma and CHX groups (P > .05). Significantly more cells were killed in 1-week-old biofilms than in 3-week-old biofilms in all groups (P < .05). CONCLUSIONS: The modified nonequilibrium plasma killed more bacteria than conventional nonequilibrium plasma and 2% CHX in E. faecalis and multispecies endodontic biofilms in vitro and thus shows promise as an additional tool in infection control during endodontic treatment.

Asunto(s)

Antiinfecciosos Locales/farmacología , Biopelículas/efectos de los fármacos , Clorhexidina/análogos & derivados , Cavidad Pulpar/microbiología , Enterococcus faecalis/efectos de los fármacos , Gases em Plasma/farmacología , Animales , Adhesión Bacteriana/efectos de los fármacos , Bovinos , Clorhexidina/farmacología , Colorantes , Enfermedades de la Pulpa Dental/microbiología , Dentina/microbiología , Humanos , Procesamiento de Imagen Asistido por Computador/métodos , Imagenología Tridimensional/métodos , Viabilidad Microbiana/efectos de los fármacos , Microscopía Confocal/métodos , Factores de Tiempo

RESUMEN

PURPOSE: The aim of this study was to establish the optimum design and attachment combination to support an overdenture with minimal stress and flexing produced in the alveolar bone surrounding any natural teeth and/or mini dental implants. MATERIALS AND METHODS: Twelve models were included in the study: the six main models (A, B, C, D, E, and F) were categorized according to the support designs of the overdenture prosthesis, and each model was further subdivided according to the attachment combinations into model 1: with Dalbo elliptic and/or O-ring attachments only and model 2: with flexible acrylic attachments. Vertical loads (35 N) and 17.5 N lateral loads under static conditions were applied to the models to simulate the occlusal forces following the concept of lingualized occlusion. All conditions were created using a finite element software program. Maximum von Mises stress at the level of the attachments and at the bone support foundation interfaces were compared in all 12 models. The flexing of the mandible and the attachments were also compared qualitatively. RESULTS: Stress on these models was analyzed after the given loading condition. The results showed that the model with three freestanding mini dental implants and flexible acrylic attachments showed the lowest von Mises stress and flexing, while the models with four freestanding mini dental implants and O-ring attachments showed the highest von Mises stress. CONCLUSION: Three freestanding mini dental implants with flexible acrylic attachment systems supporting an overdenture were better choices than four mini dental implants with O-ring attachment systems, which showed the maximum flexing and stress values in this qualitative comparison.

Asunto(s)

Pilares Dentales , Implantes Dentales , Prótesis Dental de Soporte Implantado , Prótesis de Recubrimiento , Análisis de Elementos Finitos , Imagenología Tridimensional/métodos , Diente/fisiología , Resinas Acrílicas/química , Proceso Alveolar/fisiología , Fuerza de la Mordida , Simulación por Computador , Materiales Dentales/química , Diseño de Prótesis Dental , Diseño de Dentadura , Retención de Dentadura , Dentadura Completa Inferior , Módulo de Elasticidad , Humanos , Mandíbula/fisiología , Modelos Anatómicos , Modelos Biológicos , Plásticos/química , Docilidad , Acero Inoxidable/química , Estrés Mecánico , Titanio/química

RESUMEN

INTRODUCTION: The aim of this study was to evaluate the in vitro antibacterial activity by atmospheric pressure nonequilibrium plasmas (APNPs) as an effective approach against bacterial biofilms in root canal systems during endodontic therapy. METHODS: Sterile cover slips were placed into the wells of tissue culture plates to permit the formation of Enterococcus faecalis biofilms. Biofilms were treated for 5 minutes with APNPs or 2% chlorhexidine digluconate (CHX). The viability of biofilm bacteria was analyzed by staining and confocal laser scanning microscopy. In addition, infected single-rooted teeth were exposed to APNPs or 2% CHX for 5, 10, and 15 minutes. After treatment, the root canals were flushed, and the resulting suspensions were inoculated onto brain-heart infusion agar to assess bacterial survival. Finally, micro-computed tomography scanning was used to observe and verify the root canal systems relative to the antibacterial effects obtained. RESULTS: Treatment for 5 minutes with APNPs or 2% CHX killed the majority of bacteria in the E. faecalis biofilms. Moreover, APNP treatment was as effective as 2% CHX for inactivating bacteria in infected root canals (P > .05). Bacterial survival after treatment with APNPs or 2% CHX remarkably reduced with increasing exposure times (P < .05). There was no significant difference between bacterial survival in complex root canal systems and simple straight canals (P > .05). CONCLUSIONS: APNPs can be an effective adjunct to standard endodontic antimicrobial treatment.

Asunto(s)

Antibacterianos/farmacología , Biopelículas/efectos de los fármacos , Enterococcus faecalis/efectos de los fármacos , Gases em Plasma/farmacología , Antiinfecciosos Locales/farmacología , Técnicas Bacteriológicas , Clorhexidina/análogos & derivados , Clorhexidina/farmacología , Colorantes , Cavidad Pulpar/microbiología , Enterococcus faecalis/fisiología , Helio , Humanos , Ensayo de Materiales , Viabilidad Microbiana/efectos de los fármacos , Microscopía Confocal , Compuestos Orgánicos , Oxígeno , Propidio , Factores de Tiempo , Microtomografía por Rayos X

RESUMEN

Previously, the choice of prosthetic implant-retained overdentures has depended on data from previous studies about the retention-fatigue strength of the attachment system selected. Little or no data have been available on the correlation between the attachment system selected and the overdenture support configuration. The purpose of the present study was to evaluate the retention force and fatigue resistance of three attachment systems and four support designs of overdenture prosthesis. Four lower edentulous acrylic models were prepared and eight combinations of attachments groups were investigated in the study. These included: O-Rings with mini-dental implants (MDIs), Dalbo elliptic with Dalbo Rotex and fabricated flexible acrylic attachments with both MDI and Dalbo Rotex. The study was divided into four test groups: groups A and B, controls, and groups C and D, experimental groups. Control group A contained three overdenture supports: two free standing MDIs in the canine region and at the midline, and one simulated tooth root with Dalbo Rotex screwed in. Control group B contained four overdenture support foundations: two free standing MDIs in the right canine region and the first premolar region, and two simulated tooth roots with Dalbo Rotex screwed in at the same MDI position, but on the left side of the model. Experimental group C contained three overdenture support foundations: two free standing MDIs in the canine region and at the midline, and one simulated tooth root with MDI screwed in. Experimental group D contained four overdenture support foundations: two free standing MDIs in the right canine region and the first premolar region, and two simulated tooth roots with MDIs screwed in at the same MDI position, but on the left side of the model. Each group was further divided into two subgroups according to attachment type used. Five samples were prepared for each group. Retention force (N) values were recorded initially (0 cycles) and after 360, 720, 1440 and 2880 insertion and removal cycles. During the tensile test a cross-head speed of 10 mm/min was applied. Values of absolute force (AF) and relative force (RF) were statistically analyzed by two-way ANOVA and multiple comparison Tukey's tests between groups and cycles periods. The results of fatigue tests showed a 50% reduction in retention force in the subgroups with flexible attachments. A triangular design of overdenture support foundations with O-Ring attachments revealed the lowest value of AF and a relatively high reduction in RF. The four overdenture support designs with flexible acrylic attachments improved the retention force and reduced the fatigue retention. Furthermore, the results of the investigation demonstrate that flexible acrylic attachments for both teeth and implant-supported overdentures offer a wide range of retention forces.

Asunto(s)

Fuerza de la Mordida , Implantes Dentales , Análisis del Estrés Dental/métodos , Prótesis de Recubrimiento , Diente/fisiología , Adhesividad , Análisis de Falla de Equipo , Fricción/fisiología , Humanos , Diseño de Prótesis , Resistencia a la Tracción/fisiología , Diente/cirugía

RESUMEN

Previously,the choice of prosthetic implant-retained overdentures has depended on data from previous studies about the retention-fatigue strength of the attachment system selected.Little or no data have been available on the correlation between the attachment system selected and the overdenture support configuration.The purpose of the present study was to evaluate the retention force and fatigue resistance of three attachment systems and four support designs of overdenture prosthesis.Four lower edentulous acrylic models were prepared and eight combinations of attachments groups were investigated in the study.These included:O-Rings with mini-dental implants (MDIs),Dalbo elliptic with Dalbo Rotex and fabricated flexible acrylic attachments with both MDI and Dalbo Rotex.The study was divided into four test groups:groups A and B,controls,and groups C and D,experimental groups.Control group A contained three overdenture supports:two free standing MDIs in the canine region and at the midline,and one simulated tooth root with Dalbo Rotex screwed in.Control group B contained four overdenture support foundations:two free standing MDIs in the right canine region and the first premolar region,and two simulated tooth roots with Dalbo Rotex screwed in at the same MDI position,but on the left side of the model.Experimental group C contained three overdenture support foundations:two free standing MDIs in the canine region and at the midline,and one simulated tooth root with MDI screwed in.Experimental group D contained four overdenture support foundations:two free standing MDIs in the right canine region and the first premolar region,and two simulated tooth roots with MDIs screwed in at the same MDI position,but on the left side of the model.Each group was further divided into two subgroups according to attachment type used.Five samples were prepared for each group.Retention force (N) values were recorded initially (0 cycles) and after 360,720,1440 and 2880 insertion and removal cycles.During the tensile test a cross-head speed of 10 mm/min was applied.Values of absolute force (AF) and relative force (RF) were statistically analyzed by two-way ANOVA and multiple comparison Tukey's tests between groups and cycles periods.The results of fatigue tests showed a 50％ reduction in retention force in the subgroups with flexible attachments.A triangular design of overdenture support foundations with O-Ring attachments revealed the lowest value of AF and a relatively high reduction in RF.The four overdenture support designs with flexible acrylic attachments improved the retention force and reduced the fatigue retention.Furthermore,the results of the investigation demonstrate that flexible acrylic attachments for both teeth and implant-supported overdentures offer a wide range of retention forces.