PURPOSE: The purpose of this study was to compare the accuracy of the implant master cast according to the type (pick-up, transfer) and the length (long, short) of the impression copings. MATERIALS AND METHODS: The metal master cast was fabricated with three internal connection type implant analogs (Osstem GS III analog), embedded parallel and with 10degrees of mesial angulation to the center analog. Four types of impression coping were prepared with different combinations of types (transfer, pick-up) and lengths (long, short) of the coping. The impressions were made using vinyl polysiloxane (one step, heavy + light body) with an individual tray, and 10 impressions were made for each group. Eventually, 40 experimental casts were produced. Then, the difference in the distance between the master cast and the experimental cast were measured, and the error rate was determined. The analysis of variance was performed using the SPSS (v 12.0) program (alpha = .05), and the statistical significance was set at P < .05. RESULTS: The ANOVA showed that the pick-up type impression coping exhibited a significantly lower error rate than the transfer type. However, no significant difference was observed with respect to the length of the impression coping. Additionally, no significant difference was observed between the parallel and mesial angulated groups. CONCLUSION: Within the limitations of this study, the pick-up type impression coping exhibited a more accurate implant master cast than the transfer type in parallel group. The accuracy of the implant master cast did not differ for different lengths of impression coping of at least 11 mm. Additionally, the accuracy of the implant cast was not different for the parallel and 10degrees mesial angulated groups.
Light ; Polyvinyls ; Siloxanes

OBJECTIVES: This study aims to evaluate the size-dependent toxicity of spherical silver nanoparticles (Ag NPs) to an endemic benthic organism, Glyptotendipes tokunagai. METHODS: Ag nanoparticles of three nominal sizes (50, 100, and 150 nm) capped with polyvinyl pyrrolidone (PVP-Ag NPs) were used. Their physicochemical properties, acute toxicity (48 hours), and bioaccumulation were measured using third instar larvae of G. tokunagai. RESULTS: The aggregation and dissolution of PVP-Ag NPs increased with exposure time and concentration, respectively, particularly for 50 nm PVP-Ag NPs. However, the dissolved concentration of Ag ions was not significant compared with the median lethal concentration value for AgNO3 (3.51 mg/L). The acute toxicity of PVP-Ag NPs was highest for the smallest particles (50 nm), whereas bioaccumulation was greatest for the largest particles (150 nm). However, larger PVP-Ag NPs were absorbed and excreted rapidly, resulting in shorter stays in G. tokunagai than the smaller ones. CONCLUSIONS: The size of PVP-Ag NPs significantly affects their acute toxicity to G. tokunagai. In particular, smaller PVP-Ag NPs have a higher solubility and stay longer in the body of G. tokunagai, resulting in higher toxicity than larger PVP-Ag NPs.
Chironomidae ; Ions ; Larva ; Nanoparticles* ; Polyvinyls ; Silver* ; Solubility

OBJECTIVES: This study aims to evaluate the size-dependent toxicity of spherical silver nanoparticles (Ag NPs) to an endemic benthic organism, Glyptotendipes tokunagai. METHODS: Ag nanoparticles of three nominal sizes (50, 100, and 150 nm) capped with polyvinyl pyrrolidone (PVP-Ag NPs) were used. Their physicochemical properties, acute toxicity (48 hours), and bioaccumulation were measured using third instar larvae of G. tokunagai. RESULTS: The aggregation and dissolution of PVP-Ag NPs increased with exposure time and concentration, respectively, particularly for 50 nm PVP-Ag NPs. However, the dissolved concentration of Ag ions was not significant compared with the median lethal concentration value for AgNO3 (3.51 mg/L). The acute toxicity of PVP-Ag NPs was highest for the smallest particles (50 nm), whereas bioaccumulation was greatest for the largest particles (150 nm). However, larger PVP-Ag NPs were absorbed and excreted rapidly, resulting in shorter stays in G. tokunagai than the smaller ones. CONCLUSIONS: The size of PVP-Ag NPs significantly affects their acute toxicity to G. tokunagai. In particular, smaller PVP-Ag NPs have a higher solubility and stay longer in the body of G. tokunagai, resulting in higher toxicity than larger PVP-Ag NPs.
Chironomidae ; Ions ; Larva ; Nanoparticles* ; Polyvinyls ; Silver* ; Solubility

The purpose of this study was to compare the accuracy of currently used elastomeric impression materials for complete arch impression taking. Five elastomers (Impregum, Permlastic, Express, Extrude, Examix) and one Irreversible hydrocolloid (Aroma-fine) were tested. For each material, 5 impressions were made of stainless steel model to which five tapered posts were attached. Custom trays were used for polyether and polysulfide impression materials, and putty/wash two step technique was used for addition polyvinylsiloxane impression materials. Improved stone models were poured to all impressions. Accuracy of the materials was assessed by measuring ten distances on stone dies poured from impressions of the master model. All measurements for master and improved stone models were with three dimensional measuring machine. The results were as follows 1. The dimensional accuracy of polyether, extrude, and examix were significantly superior to polysulfide, exress, and alginate in reproducing full arch mode (p<0.05). 2. There were no statistical differences in dimensional accuracy for full arch impression between polyether, extrude and examix (p>0.05). 3. there were no statistical differences in dimensional accuracy between polysulfide, express, and alginate (p>0.05). 4. There were no statistical differences between addition polyvinyl siloxane materials (p>0.05). 5. There were no statistical differences between anterior-posterior and lateral dimensional changes of all impression materials (p>0.05).
Colloids ; Elastomers* ; Polyvinyls ; Siloxanes ; Stainless Steel

PURPOSE: Comparing the accuracy of casts produced from digital workflow to that of casts produced from conventional techniques. MATERIALS AND METHODS: Whole arch alginate (ALG) and polyvinyl siloxane (PVS) impressions were taken with stock trays and custom trays, respectively. The ALG impressions were poured with type III dental stone, while the PVS impressions were poured with type IV dental stone. For the digital workflow, IOS impressions were taken and physical casts were produced by 3D printing. In addition, 3D printed casts were produced from images obtained from a laboratory scanner (LS). For each technique, a total of 10 casts were produced. The accuracies of the whole arch and separated teeth were virtually quantified. RESULTS: Whole arch cast accuracy was more superior for PVS followed by LS, ALG, and IOS. The PVS and ALG groups were inferior in the areas more susceptible to impression material distortion, such as fossae and undercut regions. The LS casts appeared to have generalized errors of minor magnitude influencing primarily the posterior teeth. The IOS casts were considerably more affected at the posterior region. On the contrary, the IOS and LS casts were more superior for single tooth accuracy followed by PVS and ALG. CONCLUSION: For whole arch accuracy, casts produced from IOS were inferior to those produced from PVS and ALG. The inferior outcome of IOS appears to be related to the span of scanning. For single tooth accuracy, IOS showed superior accuracy compared to conventional impressions.
Jupiter ; Polyvinyls ; Printing, Three-Dimensional ; Siloxanes ; Tooth

Poly (p-phenylene vinylene) (PPV) was synthesized from p-xylylene bis(tetrahydrothiophenium chloride) using the Wessling route and characterized by Fourier Transform Infra-Red (FTIR) and UV-visible (UV-VIS) spectroscopic techniques. The significance of thermal treatment along with evolution of precursor polymer to polymer PPV was also studied through these spectroscopic techniques. Thermally Stimulated Current (TSC) measurements indicated the presence of crystallization, sulphonium group which occurred through the evolution from precursor polymer to polymer PPV during thermal treatment.
Polymers/analysis ; Polymers/*chemical synthesis ; Polyvinyls/analysis ; Polyvinyls/*chemical synthesis ; Spectroscopy, Fourier Transform Infrared

PURPOSE: To evaluate the usefulness of new liquid embolic materials for portal vein embolization (PVE). MATERIALS AND METHODS: The liquid embolic material, Embol, was obtained by hydrolytic reaction of polyvinyl acetate (PVAc). Several Embols with a different hydrolysis ratio and polymer concentration were prepared and named, an example was Embol-78-12. These were percutaneously injected through a 5-Fr catheter into the left portal vein of six pigs, and radio-opacity under X-ray fluoroscopy and the possibility of reflux were evaluated. RESULTS: The radio-opacity of Embol-78-8, Embol-73-10, and Embol-73-12 was too low to recognize reflux, but was excellent when Embol-78-12 or (Embol-78-12 + Lipiodol) was used; it was still difficult to prevent reflux, however. With the use of a balloon catheter, however, complete embolization became possible. CONCLUSION: Embol-78-12 injection through a balloon catheter seems to be useful for clinical PVE.
Animals ; Catheters ; Fluoroscopy ; Hydrolysis ; Polymers ; Polyvinyls ; Portal Vein* ; Swine*

Selective arterial embolization can reduce the size and pressure whtihin the nidus of the arteriovenous malformations(AVMS) and diminish the number of feeding pedicles, making subsequent surgical excision technically easier and safer, especially in those AVM patients whose lesions are judged to be inoperable or respectable with major risk. Authors have successfully and repeatedly performed selective arterial embolizations with polyvinyl alcoholfoam(PVA foam) and isobutyl-2-cyanoacrylate(IBCA) to a large AVM at the left basal ganglia, thalamus and lateral ventricles, and a large cortical AVM near right motor strip.
Arteriovenous Malformations* ; Basal Ganglia ; Humans ; Lateral Ventricles ; Polyvinyls ; Thalamus

Demodex is easily found from eyelashes and suggested as the one of the causes of some eye diseases. This study was to investigate the occurence rate, and classification of Demodex from eyelashes, and its relationship with blepharitis. The data of this study were compiled from 27 blepharitis patients and 173 patients without blepharitis (control group) who had visited St. Paul's Hospital from October 1981 to December 1981. Three eyelashes from each eyelid-total 12 lashes from a patient-were extracted under the slit lamp, located on a slide glass and fixed with polyvinyl lactophenol mounting medium. (countinued..)
Blepharitis ; Classification ; Eye Diseases ; Eyelashes* ; Glass ; Humans ; Polyvinyls

The key materials for bioartificial liver (BAL) construction include biomaterials and scaffolding materials. The former mainly refers to hepatocytes, nonparenchymal cells, etc. The latter mainly refers to films and other scaffolding materials, the properties of which correlate directly with hepatocyte growth and functions, and thus are related to the support effects of BAL. Several kinds of scaffolding materials frequently used for BAL construction in recent years are reviewed in this article.
Biocompatible Materials ; Liver, Artificial ; Membranes, Artificial ; Polyurethanes ; Polyvinyls ; Tissue Engineering