44 research outputs found

    d-(+)-Galactose-Conjugated Single-Walled Carbon Nanotubes as New Chemical Probes for Electrochemical Biosensors for the Cancer Marker Galectin-3

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    d-(+)-Galactose-conjugated single-walled carbon nanotubes (SWCNTs) were synthesized for use as biosensors to detect the cancer marker galectin-3. To investigate the binding of galectin-3 to the d-(+)-galactose-conjugated SWCNTs, an electrochemical biosensor was fabricated by using molybdenum electrodes. The binding affinities of the conjugated SWCNTs to galectin-3 were quantified using electrochemical sensitivity measurements based on the differences in resistance together with typical I-V characterization. The electrochemical sensitivity measurements of the d-(+)-galactose-conjugated SWCNTs differed significantly between the samples with and without galectin-3. This indicates that d-(+)-galactose-conjugated SWCNTs are potentially useful electrochemical biosensors for the detection of cancer marker galectin-3

    Correlation study between distal caries in the mandibular second molar and the eruption status of the mandibular third molar in the Korean population

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    Objectives The purpose of this study was to analyze the correlation parameters between the distal caries of the mandibular second molars (M2Ms) and the eruption status of the mandibular third molars (M3Ms). Study design The records of 786 patients who had their M3Ms extracted from 2002 to 2007 at Samsung Medical Center were reviewed. The distal caries of M2Ms, age, gender, angulations, impaction degree, and distance between M2M and M3M were assessed. Results Among 883 M2Ms, 152 had distal caries (17.2%, caries group). In the caries group, 79.6% of M3Ms exhibited mesial angulation between 40° and 80° and 82.2% of M3Ms exhibited an impaction level in which the most coronal aspect of the M3M was located superior to the occlusal surface of the M2M. The distance between M2M and M3M (between cemontoenamel junctions) was 7-9 mm for 57.2% of the caries group. Conclusions The M3Ms under eruption status as described here could be considered for preventive extraction

    Analysis of heavy metal contents in gray and white MTA and 2 kinds of Portland cement: a preliminary study

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    Objective: The levels of 10 heavy metals (arsenic, bismuth, cadmium, chromium, copper, iron, lead, manganese, nickel, and zinc) in gray Portland cement (GPC), white Portland cement (WPC), gray MTA (GMTA), and white MTA (WMTA) were analyzed by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Study design: One gram of each material was digested with 80°C "aqua-regia" (7 mL of 60% HNO3 and 21 mL of 35% HCl), filtered, and analyzed by ICP-AES. The analysis was performed 6 times and the data were analyzed statistically. Results: Arsenic and lead concentrations were the highest in GPC (P < .05). GPC had much more of 7 heavy metals than the other 3 cements (P < .05). GMTA and WMTA had higher purity than GPC and WPC (P < .05), particularly when arsenic content was considered. Conclusion: If a clinician is considering using Portland cement versus MTA, the differences in purity may be considered

    In vitro evaluation of the sealing ability of newly developed calcium phosphate-based root canal sealer

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    This study compared the sealing ability of newly developed calcium phosphate–based root canal sealers (CAPSEAL I, CAPSEAL II) with other calcium phosphate–based sealer (Sankin Apatite Root Canal Sealer: SARCS I, SARCS III), a resin-based sealer (AH Plus), a ZOE-based sealer (Pulp Canal Sealer EWT), and a calcium hydroxide–based sealer (Sealapex) by using an anaerobic bacterial leakage model with Prevotella nigrescens during a 90-day observation period (n = 15/group). SARCS I and III had significantly greater leakage with P. nigrescens than all other groups (P < .05). There was no other statistical difference between the sealers. Field emission–scanning electron microscope observations showed that both CAPSEAL I and II sealers were well-adapted to the canal wall and infiltrated into the dentinal tubules.This study was supported by a grant of the Korea Health 21 R&D Project, Ministry of Health & Welfare, Republic of Korea (01-PJ5- PG1-01CH12-0002)

    Analysis of heavy metal contents in gray and white MTA and 2 kinds of Portland cement: a preliminary study

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    Objective. The levels of 10 heavy metals (arsenic, bismuth, cadmium, chromium, copper, iron, lead, manganese, nickel, and zinc) in gray Portland cement (GPC), white Portland cement (WPC), gray MTA (GMTA), and white MTA (WMTA) were analyzed by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Study design. One gram of each material was digested with 80°C aqua-regia (7 mL of 60% HNO3 and 21 mL of 35% HCl), filtered, and analyzed by ICP-AES. The analysis was performed 6 times and the data were analyzed statistically. Results. Arsenic and lead concentrations were the highest in GPC (P .05). GPC had much more of 7 heavy metals than the other 3 cements (P .05). GMTA and WMTA had higher purity than GPC and WPC (P .05), particularly when arsenic content was considered. Conclusion. If a clinician is considering using Portland cement versus MTA, the differences in purity may be considered

    Effects of short-term chemical disinfection of GP cone: identification of affected microbes and alterations in surface texture and physical properties

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    The aims of this study were to identify microorganisms on the surface of gutta-percha (GP) cones using a polymerase chain reaction (PCR) and to evaluate the sterilization effect of 5.25% sodium hypochlorite (NaOCl), 2% chlorhexidine (CHX), and ChloraPrep on these bacteria. Alterations of the surface texture and physical properties of GP cone after chemical sterilization were compared. A total of 150 GP cones were randomly selected in endodontic clinics, and a PCR assay was performed to identify the contaminating microorganisms. After inoculation with the same microorganisms followed by drying for 1 day, the GP cones were immersed in the three chemical disinfectants. The sterilization effects were assessed by measuring the turbidity and through subculturing. The changes in surface texture were observed by scanning electron microscopy, and Instron 5500 (Instron Corp, Canton, MA) was used to measure the tensile strength and elongation rate of the GP cones after chemical sterilization. Statistical analysis was performed. Results indicate that 19.4% of GP cones from the clinic were contaminated, and all the species belonged to the genus Staphylococcus. Three chemical disinfectants were all effective in the rapid disinfection of GP cones against Staphylococcus spp, and 1-minute immersion of the GP cones was adequate for disinfection. Microphotographs of the NaOCl-soaked cone showed a cluster of cuboidal crystals. The tensile strength between the NaOCl- and CHX-soaked groups was significantly different (p 0.05), but there was no significant difference between the NaOCl- and ChloraPrep-soaked groups (p 0.05). All disinfectants significantly increased the elongation rate of the GP cones compared with fresh GP cones (p 0.05), especially in the ChloraPrep (Medi-flex, Leawood, KS). These results show that the three chemical disinfectants are effective agents for the rapid sterilization of GP cones. However, further research will be needed to determine the clinical relevance of the changes in physical properties. (J Endod 2007;33:594–598

    Evaluation of three obturation techniques in the apical third of mandibular first molar mesial root canals using micro-computed tomography

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    Background/purpose Recent studies have demonstrated a high incidence of isthmuses in mandibular first molar mesial roots, and intratubular mineralization following mineral trioxide aggregate obturation. This study assessed the filling quality of three obturation techniques in the apical 5 mm of mandibular first molar mesial root canals. Materials and methods Sixty extracted human mandibular first molar mesial roots with two separate canals that had interconnecting isthmuses, were prepared to an apical size of 40/0.06. They were allocated to three groups of 20 roots for obturation by either cold lateral compaction (CLC) or the continuous wave of condensation (CW) that used gutta-percha and AH Plus sealer, or by an orthograde canal obturation using OrthoMTA. The obturated roots were scanned by micro-computed tomography and assessed for the volumetric ratio (%) of gutta-percha, sealer, and OrthoMTA within the main canals or isthmuses in the apical 5 mm area. Measurements were analyzed statistically for differences among three obturation techniques. Results In the main canals, filled volume ratios were not significantly different among groups. Within isthmuses, the filled volume ratio for CLC was lower than in CW (P = 0.025) or OrthoMTA (P = 0.002). In isthmuses, the gutta-percha volume ratio in CLC was lower than in CW (P = 0.005), although the sealer volume ratio was higher than in CW (P = 0.049). Conclusion CLC demonstrated lower filling densities in isthmuses in the apical region than either CW or OrthoMTA. Orthograde MTA obturation showed comparable filling quality to gutta-percha with sealer

    Evaluation of the safety and efficiency of novel metallic implant scaler tips manufactured by the powder injection molding technique

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    Abstract Background Although many studies have compared the properties of ultrasonic scaling instruments, it remains controversial as to which is most suitable for implant scaling. This study evaluated the safety and efficiency of novel metallic ultrasonic scaler tips made by the powder injection molding (PIM) technique on titanium surfaces. Methods Mechanical instrumentation was carried out using four types of metal scaler tips consisting of copper (CU), bronze (BR), 316 L stainless steel (316 L), and conventional stainless steel (SS) tips. The instrumented surface alteration image of samples was viewed with scanning electron microscope (SEM) and surface profile of the each sample was investigated with confocal laser scanning microscopy (CLSM). Arithmetic mean roughness (Ra) and maximum height roughness (Rmax) of titanium samples were measured and dissipated power of the scaler tip was estimated for scaling efficiency. Results The average Ra values caused by the 316 L and SS tip were about two times higher than those of the CU and BR tips (p < 0.05). The Rmax value showed similar results. The efficiency of the SS tip was about 3 times higher than that of CU tip, the 316 L tip is about 2.7 times higher than that of CU tip, and the BR tip is about 1.2 times higher than that of CU tip. Conclusions Novel metallic bronze alloy ultrasonic scaler tip minimally damages titanium surfaces, similar to copper alloy tip. Therefore, this bronze alloy scaler tip may be promising instrument for implant maintenance therapy
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