In order to develop questionnaire estimating vinyl chloride monomer(VCM) exposure levels, to reset selection criteria for detailed tests, to measure current VCM exposure levels, to evaluate the mutagenic effects of VCM exposures and to develop multiphasic screening method of PVC- or VCM-handling workers, VCM concentrations of work environments were measured and tentative self-administrative questionnaire, physical examination, sister chromatid exchange(SCE) test and some clinical chemical test were applied to 195 men who had been handling VCM or PVC(Exposed Group) and 37, in the same factories without exposure to VCM or in polyethylene- or polypropylene-related factories(Control Group). Mean VCM concentrations of work environments were 0.268+/-0.183 ppm under PVC synthesis processes, 0.160+/-0.200 ppm under VCM synthesis process, 0.076+/-0.111 ppm under PVC pipe producing processes, 0.090+/-0.108 ppm under PVC wall paper, sheet, or film producing processes, 0.071+/-0.051 ppm under PVC floor producing processes, 0.243+/-0.250 ppm under PVC sash producing processes, and 0.020+/-0.031 ppm under triming process. VCM levels of work environments under manual resin mixing processes (0.209+/-0.168 ppm)were higher than those of the others (0.209+/-0.168 ppm) (p-value<0.05). There was no VCM-related symptoms, the positive response rates of which were higher in the Exposed Group. Overall abnormal rate in clinical chemistry test of the Exposed Group was higher than that of the Control Group, but due to extermely low exposure level of exposure group and to small sample size of the Control Group, no statistical significance was found(p-value>0.05). SCE frequencies of the Exposed Group were significantly higher than those of Contorl Group(p-value<0.05) and those of test-abnormal persons were higher than those of test-normal persons. SCE frequencies linearly increased with not only current but also cumulative VCM exposure levels(p-value<0.05). These results suggest that adverse health effect may ensue from VCM exposure to as low as 1 ppm. But SCE frequencies had no statistically significant correlation with drinking amounts, smoking amoutns, or radiation dose equivalents. Questionnaire was revised by referring to these results and formula estimating cumulative VCM exposure levels based on occupational history in questionnaire were made. In addition, were presented methods evaluating work environments and multiphasic screening test for PVC workers.
Chromatids ; Clinical Chemistry Tests ; Drinking ; Humans ; Male ; Multiphasic Screening* ; Patient Selection ; Physical Examination ; Polyvinyl Chloride* ; Polyvinyls* ; Questionnaires ; Sample Size ; Siblings ; Sister Chromatid Exchange ; Smoke ; Smoking ; Vinyl Chloride*

OBJECTIVES: The study was performed to investigate the changes of urinary thiodiglycolic acid (TDGA) concentration in workers exposed to vinyl chloride monomer (VCM) according to the time of sampling urine. METHODS: The personal exposure to airborne VCM was assessed and urinary TDGA concentration was sampled in 31 workers employed in a VCM and polyvinyl chloride (PVC) manufacturing factory. Urinary TDGA was sampled three times: before the start of the shift after 3 days off (TDGA1), after the end of the first-day shift (TDGA2) and before starting the following day shift after completing the oneday shift (TDGA3). Urinary TDGA in 30 workers who had not been exposed to airborne VCM was sampled after the end of the shift. A gas chromatography/pulsed flame photometric detector (GC/PFPD) was utilized to analyze TDGA concentration in urine after the urine was methylated with trimethylsilyldiazomethane(2.0M in diethyl ether). RESULTS: The creatinine level was 0.179+/-0.271 mg/g in the control workers and 0.218+/-0.443 mg/g in the workers before the start of the shift after 3 days off (TDGA1), showing no significant difference (p=0.7035). Urine samples were compared according to sampling time in order to investigate the change of urinary TDGA concentration in the case of continuous exposure to airborne VCM. In VCM-exposed workers, urinary creatinine concentration was 0.434+/-0.623 mg/g in TDGA2 and 0.767+/-1.056 mg/g in TDGA3, which indicated a gradual but significant increase (p=0.024). In terms of the statistical correlation between airborne VCM and urinary TDGA to evaluate exposure dose per day, of the three urinary TDGA concentrations, TDGA3 showed the highest degree of regression (R(2)=0.4215) with 8h-TWA airborne VCM concentration. CONCLUSION: Based on this result, the excretion half-life of urinary TDGA was assumed to be less than 3 days, because the concentration of urinary TDGA at 3 days after exposure to airborne VCM was decreased to the level of urinary TDGA concentration in the control workers. The concentration of urinary TDGA increased in the case of continuous shift, due to the accumulation of residual metabolites of TDGA. It was considered that TDGA3 can be applied as a useful biological index to evaluate the exposure dose of airborne VCM during one day because TDGA3 showed the highest correlation with the exposure dose of airborne VCM in the previous shift day.
Creatinine ; Half-Life ; Humans ; Polyvinyl Chloride ; Vinyl Chloride*

OBJECTIVES: Fast-setting pozzolan cement (Endocem, Maruchi) was recently developed. The aim of this study was to investigate the effects of various root canal irrigants on the washout of Endocem in comparison to the previously marketed mineral trioxide aggregate (ProRoot; Dentsply) in a furcal perforation model. MATERIALS AND METHODS: ProRoot and Endocem were placed into acrylic molds on moist Oasis. Each mold was then immediately exposed to either physiologic saline, 2.5% sodium hypochlorite (NaOCl), or 2% chlorhexidine (CHX) under gentle shaking for five minutes. Washout testing was performed by scoring scanning electron microscope (SEM) images. RESULTS: Endocem exhibited higher washout resistance compared to ProRoot, especially in the NaOCl group. CONCLUSIONS: These results suggest that Endocem can be considered a useful repair material for furcal perforation, especially in a single-visit scenario.
Acrylic Resins ; Aluminum Compounds ; Calcium Compounds ; Chlorhexidine ; Dental Pulp Cavity* ; Drug Combinations ; Fungi ; Oxides ; Pyrroles ; Root Canal Irrigants* ; Silicates ; Sodium Hypochlorite ; Vinyl Compounds

The purpose of this study was to measure the polymerization shrinkage and hygroscopic expansion of resin-based temporary filling materials and to evaluate microleakage at the interface between the materials and cavity wall. Five resin-based temporary filing materials were investigated: Fermit (Vivadent), Quicks (Dentkist), Provifil (Promedica), Spacer (Vericom), Clip (Voco). Caviton (GC) was also included for comparison. Polymerization shrinkage of five resin-based temporary filling materials was measured using the bonded disc method. For the measurement of hygroscopic expansion, the discs of six cured temporary filling materials were immersed in saline and a LVDT displacement sensor was used to measure the expansion for 7 days. For estimating of microleakage, Class I cavities were prepared on 120 extracted human molars and randomly assigned to 6 groups of 20 each. The cavities in each group were filled with six temporary filling materials. All specimens were submitted to 1000 thermo-cycles, with temperature varying from 5degrees C/55degrees C. Microleakage was determined using a dye penetration test. The results were as follows: 1. Fermit had significantly less polymerization shrinkage than the other resin-based temporary filling materials. Fermit (0.22 %) < Spacer (0.38 %) < Quicks (0.64 %), Provifil (0.67 %), Clip (0.67 %) 2. Resin-based temporary filling materials showed 0.43 - 1.1 % expansion in 7 days. 3. Fermit showed the greatest leakage, while Quicks exhibited the least leakage. 4. There are no correlation between polymerization shrinkage or hygroscopic expansion and microleakage of resin-based temporary filling materials.
Calcium Sulfate ; Dental Cements ; Displacement (Psychology) ; Humans ; Molar ; Polymerization ; Polymers ; Polymethacrylic Acids ; Root Canal Filling Materials ; Vinyl Compounds ; Zinc Oxide

OBJECTIVES: The purpose of this study was to evaluate the microleakage of 4 temporary materials in teeth with Class II-type endodontic access preparations by using a glucose penetration model. MATERIALS AND METHODS: Glucose reaction test was performed to rule out the presence of any reaction between glucose and temporary material. Class II-type endodontic access preparations were made in extracted human premolars with a single root (n = 10). Each experimental group was restored with Caviton (GC), Spacer (Vericom), IRM (Dentsply-Caulk), or Fuji II(GC). Microleakage of four materials used as temporary restorative materials was evaluated by using a glucose penetration model. Data were analyzed by the one-way analysis of variance followed by a multiple-comparison Tukey test. The interface between materials and tooth were examined under a scanning electron microscope (SEM). RESULTS: There was no significant reaction between glucose and temporary materials used in this study. Microleakage was significantly lower for Caviton and Spacer than for Fuji II and IRM. SEM observation showed more intimate adaptation of tooth-restoration interfaces in Caviton and Spacer than in IRM and Fuji II. CONCLUSIONS: Compared to IRM and Fuji II, Caviton and Spacer can be considered better temporary sealing materials in Class II-type endodontic access cavities.
Bicuspid ; Calcium Sulfate ; Dental Cements ; Electrons ; Glass Ionomer Cements ; Glucose ; Humans ; Root Canal Filling Materials ; Tooth ; Vinyl Compounds ; Zinc Oxide

The purpose of this study was to compare the sealing abilities of four endodontic temporary restorative materials using a methylene blue dye penetration test under dynamic loading. Standardized access cavities were prepared in forty-four intact human permanent molar teeth, and the cavities were restored with Caviton, MD-Temp, IRM, or ZOE. After thermocycling, an intermittent load of 98 N at 1 Hz was applied for 1,000 cycles to the long axis of the functional cusp of each of the teeth, which were immersed in a 1% methylene blue solution. The teeth were split in half, and the linear depth of dye penetration was evaluated according to the criteria. The results were analyzed using one-way ANOVA (p = 0.05) and Duncan's multiple range test. The results demonstrated that Caviton and MD-Temp showed significantly lower microleakage than IRM and ZOE. It was concluded that Caviton and MD-Temp exhibited better sealing ability than IRM and ZOE under dynamic loading.
Axis, Cervical Vertebra ; Calcium Sulfate ; Dental Cements ; Humans ; Methylene Blue ; Molar ; Root Canal Filling Materials ; Tooth ; Vinyl Compounds ; Zinc Oxide

The asialoglycoprotein receptor (ASGPR) was used to mediate drug carrier for hepatic targeted drug delivery, this article showed the enzyme-catalyzed esterification of galactose and vinyl stearate and a kind of ASGPR ligand-targeted which was used to insert the surface of liposome has been synthesized. The structure of product has been confirmed by TLC, ESI-MS and 1H NMR. The factors of types and quantity of enzyme, organic solvents, molar ratio of substrate, temperature and time of reaction have been studied. Results showed when using acetone as reaction medium, the quantity of Novozym 435 immobilized lipase was 30 mg mL(-1), molar ratio of galactose to vinyl stearate was 1:5, and reacted at 60 degrees C for 12 h, the transformation of vinyl stearate reached more than 70%. This study provides a novel and efficient route to the synthesis of ligand-targeted modifier.
Acetone ; chemistry ; Asialoglycoprotein Receptor ; chemical synthesis ; Catalysis ; Esterification ; Galactose ; chemistry ; Ligands ; Lipase ; chemistry ; Stearates ; chemistry ; Temperature ; Vinyl Compounds ; chemistry

To study the application characteristics of copovidone (PVP-S630) in Xinyueshu extracts during the spray drying process, and its effect on such pharmaceutical properties as micromeritics and drug release behavior. PVP-S630 was added into Xinyueshu extracts to study on the spray drying, the effect of different dosages of PVP-S630 against the wall sticking effect of the spray drying, as well as the power property of Xinyueshu spray drying power and the dissolution in vitro behavior of the effective component of hyperoside. The results showed that PVP-S630 revealed a significant anti-wall sticking effect, with no notable change in the grain size of the spray drying power, increase in the fluidity, improvement in the moisture absorption and remarkable rise in the dissolution in vitro behavior of hyperoside. It was worth further studying the application of PVP-S630 in spray drying power of traditional Chinese medicine.
Absorption ; Desiccation ; methods ; Drug Compounding ; methods ; Drugs, Chinese Herbal ; chemistry ; Porosity ; Powders ; Pyrrolidines ; chemistry ; Vinyl Compounds ; chemistry ; Wettability

PURPOSE: Tracheal intubation in a hemorrhagic airway is a difficult procedure because the visibility can be obscured by blood or vomitus. Several devices and methods have been developed to overcome such obstacles, but they are not available at all practical sites. Therefore, this study was conducted to assess the time and success rate of tracheal intubation according to the type of suction tip used in a hemorrhagic airway manikin model. METHODS: This study was a randomized crossover manikin simulation study. We recruited 18 emergency physicians to perform intubation with suction using a Yankauer suction tip and a polyvinyl chloride (PVC) catheter suction tip in a hemorrhagic airway manikin model. We then measured the time and success rate of intubation for each suction tip. RESULTS: The mean intubation time using the Yankauer suction tip was 42.3 seconds, and the mean intubation time using the PVC catheter suction tip was 91.1 seconds (p < 0.001). Two cases of esophageal intubation occurred when the PVC catheter suction tip was used (success rate, 88.9%). In contrast, there was no esophageal intubation when the Yankauer suction tip was used (success rate, 100%) (p=0.217). CONCLUSION: Intubation of a hemorrhagic airway manikin model can be performed in a shorter time when a Yankauer suction tip is used than when a PVC catheter suction tip is used.
Catheters ; Emergencies ; Hemorrhage ; Intubation ; Manikins ; Polyvinyl Chloride ; Polyvinyls ; Suction

OBJECTIVES: This in vitro study investigated whether short-term application of calcium hydroxide in the root canal system for 1 and 4 wk affects the fracture strength of human permanent teeth. MATERIALS AND METHODS: Thirty two mature human single rooted mandibular premolars in similar size and dentin thickness without decay or restorations were hand and rotary instrumented and 16 teeth vertically packed with calcium hydroxide paste and sealed coronally with caviton to imitate the endodontic procedure and the other 16 teeth was left empty as a control group. The apicies of all the samples were sealed with resin, submerged in normal saline and put in a storage box at 37degrees C to mimic the oral environment. After 1 and 4 wk, 8 samples out of 16 samples from each group were removed from the storage box and fracture strength test was performed. The maximum load required to fracture the samples was recorded and data were analysed statistically by the two way ANOVA test at 5% significance level. RESULTS: The mean fracture strengths of two groups after 1 wk and 4 wk were similar. The intracanal placement of calcium hydroxide weakened the fracture strength of teeth by 8.2% after 4 wk: an average of 39.23 MPa for no treatment group and 36.01 MPa for CH group. However there was no statistically significant difference between experimental groups and between time intervals. CONCLUSIONS: These results suggest that short term calcium hydroxide application is available during endodontic treatment.
Bicuspid ; Calcium ; Calcium Hydroxide ; Calcium Sulfate ; Dental Cements ; Dental Pulp Cavity ; Dentin ; Hand ; Humans ; Hydrazines ; Hydroxides ; Root Canal Filling Materials ; Tooth ; Vinyl Compounds ; Zinc Oxide