BACKGROUND AND OBJECTIVE

Endocrine Disrupting Chemicals (EDCs) are ubiquitously found as low-level contaminants and pose serious threat to women’s health. EDCs may result in various reproductive disorders, fetal birth and developmental abnormalities, and endocrine and metabolic disorders. EDCs can be detected in body fluids of exposed individuals including blood and urine. This study aimed to detect four EDCs — Methyl Paraben (MP), 2,4-Dichlorophenoxyacetic acid (2,4-D), Monobutyl Phthalate (MBP), and Bisphenol A (BPA) in urine samples of women using Ultra-Performance Liquid Chromatography – Quadrupole Time-of-Flight (UPLC-QTOF) mass spectrometry.

Sequential steps of enzymatic deconjugation, liquid-liquid extraction, solid phase extraction, and liquid chromatography separation and mass spectrometry detection were optimized in urine samples. The method was used to analyze 70 urine samples from women of reproductive age.

The sample preparation method showed a recovery ranging from 86.6% (MBP) to 100 % (2,4-D). The method demonstrated limits of quantitation ranging from 1.52 ng/m(MP) to 6.46 ng/mL(2,4D). Intra-day precisions expressed as relative standard deviation were all below 15% while accuracy was shown to range from 67.10% (2,4-D) to 102.39% (MBP). MP was detected in nine samples (12.86%) with a geometric mean value of 10.15 ng/ml (range: 3.62-52.39 ng/ml). MBP was detected in 68 samples (97.14%) with a geometric mean value of 97.62 ng/ml (range: 15.32-698.18 ng/ml). BPA was detected only once (9.58 ng/ml) while 2, 4-D was not detected in all samples.

A UPLC-QTOF mass spectrometry method to detect four EDCs at parts per billion level (ng/ml) was adapted and applied for analysis of urine samples. This method can find applicability in routine testing of clinical specimens as well as surveillance and other epidemiological studies.

Teeth that have short clinical crown, which are not alone enough to support the definitive restoration can be best treated using the post and core system. The advantages of fiber post over conventional metallic post materials have led to its wide acceptance. In addition to that the combination of aesthetic and mechanical benefits of fiber post has provided it with a rise in the field of dentistry. Also the results obtained from some clinical trials have encouraged the clinicians to use the fiber posts confidently. Fiber posts are manufactured from pre-stretched fibers impregnated within a resin matrix. The fibers could that be of carbon, glass/silica, and quartz, whereas Epoxy and bis-GMA are the most widely used resin bases. But recently studies are also found to be going on for polyimide as possible material for the fiber post resin base as a substitute for the conventional materials.
Bisphenol A-Glycidyl Methacrylate ; Carbon ; Crowns ; Dentin ; Dentistry ; Quartz ; Tooth

OBJECTIVES: The aim of this study was to investigate the effect of monomer and filler compositions on the rheological properties related to the handling characteristics of resin composites. METHODS: Resin matrices that Bis-GMA as base monomer was blended with TEGDMA as diluent at various ratio were mixed with the Barium glass (0.7 um and 1.0 um), 0.04 um fumed silica and 0.5 um round silica. All used fillers were silane treated. In order to vary the viscosity of experimental composites, the type and content of incorporated fillers were changed. Using a rheometer, a steady shear test and a dynamic oscillatory shear test were used to evaluate the viscosity (eta) of resin matrix, and the storage shear modulus (G'), the loss shear modulus (G"), the loss tangent (tandelta) and the complex viscosity (eta*) of the composites as a function of frequency omega = 0.1-100 rad/s. To investigate the effect of temperature on the viscosity of composites, a temperature sweep test was also undertaken. RESULTS: Resin matrices were Newtonian fluid regardless of diluent concentration and all experimental composites exhibited pseudoplastic behavior with increasing shear rate. The viscosity of composites was exponentially increased with increasing filler volume%. In the same filler volume, the smaller the fillers were used, the higher the viscosities were. The effect of filler size on the viscosity was increased with increasing filler content. Increasing filler content reduced tandelta by increasing the G' further than the G". The viscosity of composites was decreased exponentially with increasing temperature.
Barium ; Bisphenol A-Glycidyl Methacrylate ; Glass ; Rheology ; Silicon Dioxide ; Viscosity

The purpose of this study was to compare the microtensile bond strength in Class I cavities associated with different light curing modes of same light energy density. Occlusal enamel was removed to expose a flat dentin surface and twenty box-shaped Class I cavities were prepared in dentin. Single Bond (3M Dental product) was applied and Z 250 was inserted using bulk technique. The composite was light-cured using one of four techniques; pulse delay (PD group), soft-start (SS group), pulse cure (PC group) and standard continuous cure (CC group). The light-curing unit capable of adjusting time and intensity (VIP, Bisco Dental product) was selected and the light energy density for all curing modes was fixed at 16 J/cm2. After storage for 24 hours, specimens were sectioned into beams with a rectangular cross-sectional area of approximately 1 mm2. Microtensile bond strength (microTBS) test was performed using a universal testing machine (EZ Test, Shimadzu Co.). The results were analyzed using oneway ANOVA and Tukey's test at significance level 0.05. The microTBS of PD group and SS group was higher than that of PC group and CC group. Within the limitations of this in vitro study, modification of curing modes such as pulse delay and soft start polymerization can improve resin/dentin bond strength in Class I cavities by controlling polymerization velocity of composite resin.
Bisphenol A-Glycidyl Methacrylate ; Collodion ; Dental Enamel ; Dentin ; Light ; Polymerization ; Polymers

PURPOSE: The aim of this study was to determine differences in shear bond strength to human dentin using immediate dentin sealing (IDS) technique compared to delayed dentin sealing (DDS). MATERIAL AND METHODS: Forty extracted human molars were divided into 4 groups with 10 teeth each. The control group was light-cured after application of dentin bonding agent (Excite(R) DSC) and cemented with Variolink(R) II resin cement. IDS/SE (immediate dentin sealing, Clearfil(TM) SE Bond) and IDS/SB (immediate dentin sealing, Adapter(TM) Single Bond 2) were light-cured after application of dentin bonding agent (Clearfil(TM) SE Bond and Adapter(TM) Sing Bond 2, respectively), whereas DDS specimens were not treated with any dentin bonding agent. Specimens were cemented with Variolink(R) II resin cement. Dentin bonding agent (Excite(R) DSC) was left unpolymerized until the application of porcelain restoration. Shear strength was measured using a universal testing machine at a speed of 5 mm/min and evaluated of fracture using an optical microscope. RESULTS: The mean shear bond strengths of control group and IDS/SE group were not statistically different from another at 14.86 and 11.18 MPa. Bond strength of IDS/SE group had a significantly higher mean than DDS group (3.14 MPa) (P < .05). There were no significance in the mean shear bond strength between IDS/SB (4.11 MPa) and DDS group. Evaluation of failure patterns indicates that most failures in the control group and IDS/SE groups were mixed, whereas failures in the DDS were interfacial. CONCLUSION: When preparing teeth for indirect ceramic restoration, IDS with Clearfil(TM) SE Bond results in improved shear bond strength compared with DDS.
Bisphenol A-Glycidyl Methacrylate ; Ceramics ; Collodion ; Dental Porcelain ; Dentin ; Humans ; Molar ; Resin Cements ; Shear Strength ; Tooth

PURPOSE: The purpose of this study was to research the properties of some chemically cured methacrylate polymers such as MMA, HEMA, TEG-DMA, bis-GMA, GMA. MATERIAL AND METHOD: 5 kinds of methacrylates were selected and added 2% tertiary amine and benzoyl peroxide to make a chemically curable polymer. 25 micron crushed silicas which are treated with silane were selected as filler, they were added into methacrylate monomer until the consistency did not changed by the load of 500gram. All of the experimental resins were 5 kinds, and a serial test was done with 3 kinds of items including the filler contents, the tensile strength, and the bond strength. The number of specimen were 10 for each group. Filler contents were obtained by reducing the specimens to ashes at 600 degrees C for 1 hour. The specimens with the dimension of 6mm in diameter and 3mm thick were immersed in 37+/-1degrees C distilled water for 24 hours before test, and tensile strength were measured with cross-head speed 1mm/min. Shear bond strength were measured on the specimens attached to bovine enamel etched with 37% phosphoric acid for 1 minute. RESULTS: 1. Maximum filler incorporation was the highest as 75.5% on MMA, and the least as 53.4% on bis- GMA(p<0.0001). 2. The tensile stregth were MMA 141.3, GMA 154.3, TEG-DMA 157.4, bis-GMA 161.4 MPa, and HEMA showed the highest value, 226.9MPa(p=0.0004). 3. The bond strength were GMA 10.1, TEG-DMA 11.7, HEMA 12.2, bis-GMA 13.3 MPa, and MMA showed the highest value, 15.3MPa, however statistical significances were not (p=0.3838). 4. TEG-DMA and HEMA were not different on the aspect of maximum filler contents and shear bond strength(p>0.05). CONCLUSION: HEMA can be used as an another diluent substituting TEG-DMA with the increased strength and with the constant bond strength and the constant filler contents.
Benzoyl Peroxide ; Bisphenol A-Glycidyl Methacrylate ; Dental Enamel ; Methacrylates ; Polymers* ; Silicon Dioxide ; Tensile Strength ; Water

OBJECTIVES: The purpose of this study was to compare the microshear bond strength (microSBS) and bonding interfaces of two-step total-etching and self-etching adhesive systems to three etch types of dentin either the acid etched, laser etched or laser and acid etched. MATERIALS AND METHODS: The occlusal dentinal surfaces of thirty human molars were used. They were divided into six groups: group 1, 37% H3PO4 + Single Bond 2 (3M ESPE); group 2, Er:YAG laser (KEY Laser 3, KaVo) + Single Bond 2; group 3, Er:YAG laser + 37% H3PO4 + Single Bond 2; group 4, Clearfil SE Primer + Bond (Kuraray); group 5, Er:YAG laser + Clearfil SE Bond; group 6, Er:YAG laser + Clearfil SE Primer + Bond. The samples were subjected to microSBS testing 24 hr after bonding. Also scanning microscopic evaluations were made on the resin-dentin interfaces of six specimens. RESULTS: The microSBS of group 2 was significantly lower than that of groups 1 and 3 in Single Bond 2 (p < 0.05). There were significant differences among the uSBS of groups 4, 5, and 6 in Clearfil SE Bond (p < 0.05). Very short and slender resin tags were observed in groups 2 and 5. Long and slender resin tags and lateral branches of tags were observed in groups 3 and 6. CONCLUSIONS: Treatment of dentin surface using phosphoric acid or self-etching primer improved the adhesion of Er:YAG lased dentin.
Adhesives ; Bisphenol A-Glycidyl Methacrylate ; Dentin ; Humans ; Molar ; Phosphoric Acids ; Resin Cements

This study was undertaken to compare by Atomic Force Microscope the effects of various finishing and polishing instruments on surface roughness of filling and veneering composite resins. Seven composite resins were studied : Silux Plus (3M Dental Products, U.S.A.), charisma (Heraeus Kulzer, Germany), Prisma THP (L.D.Caulk, Dentsply, U.S.A.), Photoclearfil (Kuraray, Japan), Cesead (Kuraray, Japan), Thermoresin LC (GC, Japan), Artglass (Heraeus Kulzer, Germany), samples were placed and polymerized in holes (2mm thick and 8.5mm in diameter) machined in Teflon mold under glass plate, ensuring excess of material and moulded to shape with polyester matrix strip, Except control group (polyester mztrix strip), all experimental groups were finished and polishied under manufacturer's instructions. The finishing and polishing procedure were : carbide bur (E.T. carbide set 4159, Komet, Germany), diamond bur (composite resin polishing bur set, GC, Japan), aluminum-oxide disc (Sof-Lex Pop-On, 3M Dental Products, U.S.A.), diamond-particle disc (Dia-Finish, Renfert Germany), white stone bur & rubber point(composite finishing kit, EDENTA, Swiss), respectively. Each specimens were evaluated for the surface roughness with Atomic Force Microscope (AutoProbe CP, Park Scientific Instruments, U.S.A.) under contact mode and constant height mode. The results as follows : 1. Except Thermoresin LC, all experimental composite resin groups showed more rougher than control group after finishing and polishing(p<0.1). 2. A surface as smooth as control group was obtained by Al2O3 disc all filling composite resin groups except Charisma and all veneering composite resin groups except Thermoresin LC(p<0.05). 3. In case of Thermoresin LC, there were no statistically significant differences before and after finishing and polishing(p>0.1). 4. Carbide bur, diamond bur showed rough surfaces in all composite resin groups, so these were inappropriate for the final poslishing instruments.
Bisphenol A-Glycidyl Methacrylate ; Composite Resins* ; Dental Instruments ; Fungi ; Glass ; Polyesters ; Polymers ; Polytetrafluoroethylene ; Rubber

The purpose of this study was to evaluate the influence of sodium ascorbate on microtensile bond strengths of total-etching adhesive system to pulp chamber dentin treated with NaOCl. Pulp chambers of extracted human non-caries permanent molars were treated as follows: group 1, with 0.9% NaCl; group 2, with 5.25% NaOCl; group 3, with 5.25% NaOCl and 10% sodium ascorbate for 1min; group 4, with 5.25% NaOCl and 10% sodium ascorbate for 1 min and 10ml of water; group 5, with 5.25% NaOCl and 10% sodium ascorbate for 5 min; group 6, with 5.25% NaOCl and 10% sodium ascorbate for 5 min and 10ml of water; group 7, with 5.25% NaOCl and 10% sodium ascorbate for 10 min; group 8, with 5.25% NaOCl and 10% sodium ascorbate for 10 min and 10ml of water. Treated specimens were dried, bonded with a total-etching adhesive system (Single bond), restored with a composite resin(Z250) and kept for 24h at 100% humidity to measure the microtensile bond strength. NaOCl-treated group (group 2) demonstrated significantly lower strength than the other groups. No significant difference in microtensile bond strengths was found between NaCl-treated group (group 1) and sodium ascorbate-treated groups (group 3-8). The results of this study indicated that dentin treated with NaOCl reduced the microtensile bond strength of Single bond. Application of 10% sodium ascorbate restored the bond strength of Single bond on NaOCl-treated dentin. Application time of sodium ascorbate did not have a significant effect.
Adhesives ; Ascorbic Acid ; Bisphenol A-Glycidyl Methacrylate ; Dental Pulp Cavity ; Dentin ; Humans ; Humidity ; Molar ; Sodium ; Water

OBJECTIVES: This study investigated the effect of the strength and wetting characteristics of adhesives on the bond strength to dentin. The experimental adhesives containing various ratios of hydrophobic, low-viscosity Bis-M-GMA, with Bis-GMA and TEGDMA, were made and evaluated on the mechanical properties and bond strength to dentin. MATERIALS AND METHODS: Five experimental adhesives formulated with various Bis-GMA/Bis-M-GMA/TEGDMA ratios were evaluated on their viscosity, degree of conversion (DC), flexural strength (FS), and microtensile bond strength (MTBS). The bonded interfaces were evaluated with SEM and the solubility parameter was calculated to understand the wetting characteristics of the adhesives. RESULTS: Although there were no significant differences in the DC between the experimental adhesives at 48 hr after curing (p > 0.05), the experimental adhesives that did not contain Bis-GMA exhibited a lower FS than did those containing Bis-GMA (p < 0.05). The experimental adhesives that had very little to no TEGDMA showed significantly lower MTBS than did those containing a higher content of TEGDMA (p < 0.05). The formers exhibited gaps at the interface between the adhesive layer and the hybrid layer. The solubility parameter of TEGDMA approximated those of the components of the primed dentin, rather than Bis-GMA and Bis-M-GMA. CONCLUSIONS: To achieve a good dentin bond, a strong base monomer, such as Bis-GMA, cannot be completely replaced by Bis-M-GMA for maintaining mechanical strength. For compatible copolymerization between the adhesive and the primed dentin as well as dense cross-linking of the adhesive layer, at least 30% fraction of TEGDMA is also needed.
Adhesives ; Benzhydryl Compounds ; Bisphenol A-Glycidyl Methacrylate ; Chimera ; Dentin ; Methacrylates ; Polyethylene Glycols ; Polymethacrylic Acids ; Solubility ; Viscosity