PURPOSE: The aim of this study was to compare the film thicknesses of several resin cements as a function of time after mixing and to examine the effect of working time on the film thicknesses. MATERIALS AND METHODS: The film thickness (microm) of 4 resin cements (n=10), 1 composite resin (Panavia F 2.0), 3 self-adhesive resin (Clearfil SA luting, Zirconite, RelyX U200) cements was measured at 20-second intervals after mixing of the cements up to 200 seconds under a load of 50 N. Linear regression was fitted to verify the effect of working time on the film thickness of each cement. Data were compared to the working time recommended by manufacturers using Wilcoxon test (alpha=.05). RESULTS: All of the materials showed a positive linear correlation between the film thickness and working time. There was no statistically significant difference between the working time based on our results and the values recommended by the manufacturers even though there was a discrepancy between those two values. CONCLUSION: The film thickness of resin cements could increase with the increase of working time. Working time to meet the ISO standard of 50-microm maximum film thickness could be different from the manufacturer's recommended value.
Linear Models ; Resin Cements ; Resins, Synthetic*

We surveyed the literatures domestic and abroad, and summarized the physical and chemical characterizations as well as preparation and applications of macroporous resin. The research of physical parameter and chemical parameter includes the measurement of the organic residue, the application research includes the separation and purification methods of the phytochemical ingredients. Macroporous resin show its advantages in the field of phytochemical studies, traditional Chinese medicine development and production, but there exist some disadvantages in its performance and application. It's necessary to establish the quality standard and the technical specifications to promote the standardization of the research and the application of the macroporous resin.
Resins, Synthetic ; chemistry ; standards ; Technology, Pharmaceutical ; methods

PURPOSE: The aim of this study was to compare the fracture toughness of currently available resin cements for zirconia restorations and evaluate the effect of water storage on fracture toughness of those resin cements. MATERIALS AND METHODS: Single-edge notched specimens (3 mm x 6 mm x 25 mm) were prepared from three currently available dual cure resin cements for zirconia restorations (Panavia F 2.0, Clearfil SA luting and Zirconite). Each resin cement was divided into four groups: immersed in distilled water at 37degrees C for 1 (Control group), 30, 90, or 180 days (n=5). Specimens were loaded in three point bending at a cross-head speed of 0.1 mm/s. The maximum load at specimen failure was recorded and the fracture toughness (K(IC)) was calculated. Data were analyzed using one-way ANOVA and multiple comparison Scheffe test (alpha=.05). RESULTS: In control group, the mean KIC was 3.41 +/- 0.64 MN.m(-1.5) for Panavia F, 2.0, 3.07 +/- 0.41 MN.m(-1.5) for Zirconite, 2.58 +/- 0.30 MN.m(-1.5) for Clearfil SA luting respectively, but statistical analysis revealed no significant difference between them. Although a gradual decrease of K(IC) in Panavia F 2.0 and gradual increases of KIC in Clearfil SA luting and Zirconite were observed with storage time, there were no significant differences between immersion time for each cement. CONCLUSION: The resin cements for zirconia restorations exhibit much higher K(IC) values than conventional resin cements. The fracture toughness of resin cement for zirconia restoration would not be affected by water storage.
Immersion ; Resin Cements ; Resins, Synthetic* ; Water*

OBJECTIVEThe aim of this study was to determine the metameric color differences between natural teeth and three brands of commercially available resin teeth.

METHODSThe spectral reflectance and color coordinates of natural teeth and three brands of commercially available resin teeth of A2 shade were measured with a spectrophotometer (PR-650) according to the CIE L*, a*, b* and CIE XYZ color scale relative to illuminant D65, A, cool white fluorescent (CWF) and ultraviolet (UV), and the metameric indices were calculated to determine the metameric color differences between natural teeth and resin teeth.

RESULTSCIE L*, a*, b* values were influenced by the type of illuminants in both natural teeth and resin teeth. The pattern of spectral reflectance curves for natural teeth and resin teeth of A2 shade were different, while there were more than three crossing points among each curves, which meant the color of natural teeth and resin teeth of A2 shade might be the same under certain illuminant. The metameric indices between natural teeth and resin teeth of A2 shade were 3.48, 2.52 and 3.36 under illuminant A; 1.21, 1.90, and 2.79 under illuminant CWF; 1.59, 2.07, and 4.07 under illuminant UV. The metameric indices between resin teeth of different brand were 1.08, 0.10, and 1.01 under illuminant A; 1.46, 2.23, and 0.94 under illuminant CWF; and 2.55, 2.69, and 4.64 under UV.

CONCLUSIONChanges in optical properties of resin teeth of A2 shade relative to the different illuminants were different from those of natural teeth, the metameric effect between natural teeth and resin teeth of A2 shade were significant. Therefore, shade matching between natural teeth and resin teeth should be performed under more than one illuminant.

OBJECTIVETo analyze the use situation of finished resin teeth for the different location, and to provide reference for manufacturers of finished resin teeth and all the buyers.

METHODSTo analyze the use situation of finished resin teeth in the Dental Laboratory of the Affiliated Hospital of Stomatology of Chongqing Medical University from January 2006 to December 2008 by using statistic methods.

RESULTSDuring the use of 55,787 finished resin teeth, the study found some rules. (1) The top use of finished resin teeth was D6 with the percentage of 5.31%, and the lowest use of finished resin teeth was D3 with the percentage of 1.94%. (2) Except the maxillary canines and the mandibular lateral incisors, there was no significant difference between the usage of other same name finished resin teeth (P > 0.05). (3) Among all finished resin teeth, the usage of section B exceeded section A, and the usage of maxillary finished resin teeth exceeded mandibular finished resin teeth (P < 0.05). (4) The use of the complete denture and single complete denture was about 1/3 of the total usage of finished resin teeth. (5) Except the use situation of complete denture and single complete denture, the frequency of simultaneously using mandibular left and right central incisors was the most with the percentage of 81.46%, for the frequency of simultaneously using maxillary left and right canines was 43.26% of the total, which was the lowest.

CONCLUSIONThere is significant difference in the use frequency of finished resin teeth for different location. For such reason, the manufacturers should produce finished resin teeth pro rata as well as the buyers for their purchase.

OBJECTIVETo prepare novel electrospun porphyrinated polyimide nanofibrous membrane for rapid detection of trace amount of methanol vapor.

METHODSPorphyrin chromophore was copolymerized into polyimide backbones and the porphyrinated polyimide nanofibrous membrane was prepared by electrospinning technique. By optimizing the processing parameters, such as solution concentration and electrospinning voltage, nanofibrous membrane with three dimensional and large surface-to-area ratio structure was fabricated for trace amount of methanol vapor sensing applications.

RESULTSThe obtained nanofibrous membrane preserved typical photophysical properties of porphyrin chromophores with uniformly fine and smooth fiber diameter. When exposed to methanol vapor, a red-shift of the absorption spectra and decrease in the emission intensities was observed, while no significant changes were seen when the membrane contacting with other common alcohols. After five times of 150 ppm methanol vapor quenching and nitrogen gas regeneration, the fluorescence of the membrane remained unchanged, indicating a good reversibility.

CONCLUSIONCombining the specific optical properties of porphyrin with large surface-area-to-volume ratio of nanofibrous membranes, a porphyrinated polyimide nanofibrous membrane has been facilely fabricated for trace methanol vapor detection. The sensing membrane exhibits good sensitivity, selectivity and reproducibility.

OBJECTIVETo investigate necessity of the further processing for adsorptive resin material.

METHODSAccording to GB/ T 16886.4, coagulation tests, haematology tests, in vitro spontaneous platelet-adhesion test and complement activation tests were conducted respectively to assess the in vitro blood compatibility of adsorptive resin material.

RESULTSIn comparison with polypropylene, he adsorptive resin material appears to be a very slight activator to the endogenous blood coagulation system, it can inhibited the exogenous blood coagulation system very significantly (P < 0.01), it can adhere to fibrinogen, red blood cells, reticulocytes very significantly (P < 0.01), and platelet significantly (P < 0.05). The adsorptive resin material is also revealed to be a very significant activator (P < 0.01) to the complement system.

CONCLUSIONSThe in vitro blood compatibility assessment witnesses that it is very necessary for the adsorptive resin material to go through the certain special processing(such as the surface modification and the microencapsulation technology, etc) before its application to human being.

Conventional dental resins for crown and bridge fulfill ISO 10477 and ISO 10993 before clinical application. Although 3D printing or rapid prototyping (RP) for the fabrication of temporary crown and bridge have been proposed, a little studies were reported for 3D printing resin for temporary crown and bridge. The purpose of this study was to evaluate the physical properties (such as water sorption and solubility, color stability and flexural strength) of the various 3D printing temporary crown and bridge resin following the ISO 10477:2018 and estimate the effect of chemical composition of resin on the physical properties. Four resins approved by KFDA and 4 experimental resins developed by different manufacturer were tested in this study. Samples were prepared with DLP typed 3D Printer (G-Printer) and post-cured using UV-light Cure Unit (Cure M). Proper 3D printing and post-curing conditions were selected for different 3D printing resins. Each test was performed according to the ISO 10477 and results were statistically analyzed using Tukey-multiple comparison test (p=0.05). Only group-B did not satisfied the ISO requirement (< 40 µg/ mm³) in water sorption test, but 3 groups (C, E and F) showed high solubility which exceeds the ISO requirement (< 7.5 µg/mm³). For color stability, the color difference were detected at 5 groups (A, E, F, G and H). Group-D and F showed the low flexural strength and some building direction did not satisfied the ISO requirement (> 60 MPa). Resin components may affect the flexural strength, then user should check the components of 3D printing resin. Deficient degree of polymerization may lead to large water sorption, water solubility and color changes. Further study should be done comparison between specimens printed with specific 3D printer recommended by manufacturer and specimens used in this study.
Crowns ; Polymerization ; Polymers ; Printing, Three-Dimensional ; Resins, Synthetic ; Solubility ; Water

OBJECTIVE: The purpose of this study was to investigate the degree of conversion (DC) and mechanical properties of a microhybrid Filtek Z250 (3M ESPE) resin composite after aging. METHOD: The specimens were fabricated using circular molds to investigate Vickers microhardness (Vickers hardness number [VHN]) and DC, and were prepared according to ISO 4049 for flexural strength testing. The initial DC (%) of discs was recorded using attenuated total reflectance-Fourier transforming infrared spectroscopy. The initial VHN of the specimens was measured using a microhardness tester under a load of 300 g for 15 seconds and the flexural strength test was carried out with a universal testing machine (crosshead speed, 0.5 mm/min). The specimens were then subjected to thermocycling in 5°C and 55°C water baths. Properties were assessed after 1,000–10,000 cycles of thermocycling. The surfaces were evaluated using scanning electron microscopy (SEM). Data were analyzed using 1-way analysis of variance followed by the Tukey honest significant difference post hoc test. RESULTS: Statistical analysis showed that DC tended to increase up to 4,000 cycles, with no significant changes. VHN and flexural strength values significantly decreased upon thermal cycling when compared to baseline (p < 0.05). However, there was no significant difference between initial and post-thermocycling VHN results at 1,000 cycles. SEM images after aging showed deteriorative changes in the resin composite surfaces. CONCLUSIONS: The Z250 microhybrid resin composite showed reduced surface microhardness and flexural strength and increased DC after thermocycling.
Aging ; Baths ; Composite Resins ; Fungi ; Hardness ; Methods ; Microscopy, Electron, Scanning ; Polymerization ; Resins, Synthetic* ; Spectrum Analysis ; Water

PURPOSE: The purpose of this study was to evaluate the effect of surface treatment on the shear bond strength of zirconia ceramic to 3 resin cements. MATERIALS AND METHODS: A total of 143 disk-shaped Zirconia blocks (HASS Co., Gangneung, Korea) were randomly divided into three treatment groups: (1) only 50 microm Al2O3 sandblasting, (2) 50 microm Al2O3 sandblast and zircona liner, (3) 50 microm Al2O3 sandblasting and Rocatec (3M ESPE, Seefeld, Germany). Bistite II (Tokuyama Dental Co., Japan), Panavia F (Kuraray Medical, Japan), and Superbond C&B (Sun Medical, Japan) were used to cement onto the zirconia. After 24h of storage in distilled water, shear bond strength was evaluated. High value group was re-tested after thermocycling at 5,000 cycles(5-55degreesC). Shear bond strength data were analyzed with one-way ANOVA, two-way ANOVA test and Post Hoc Test (alpha=.05). Shear bond strength data before and after thermocycling were analyzed with Independent sample T test (alpha=.05). RESULTS: Super-bond C&B treated with Rocatec showed the most high shear bond strength. Super-bond C&B groups resulted in significantly higher than other cement groups (P<.05). Rocatec groups resulted in significantly higher than other surface treatment groups (P<.05). Shear bond strength has increased in Panavia F treated with Zirconia liner (P<.05). After thermocycling, shear bond strength was increased in Super-bond C&B treated with Rocatec but decreased in other groups (P<.05). CONCLUSION: Super-bond C&B cement resulted the highest shear bond strength and Rocatec system enhanced the shear bond strength. After thermocycling, shear bond strength has decreased in most resin cements except Super-bond C&B treated with Rocatec.
Boron Compounds ; Ceramics ; Dental Cements ; Methacrylates ; Methylmethacrylates ; Resin Cements ; Resins, Synthetic ; Water ; Zirconium