ABSTRACT
The aim of this study was to determine the photocatalytic effect of doped-TiO 2 nanoparticles (NPs) on teeth bleaching with an aid of 3% H2O2 and laser irradiation. For the study, Mo-N-TiO2 NPs were prepared. The characteristics of the prepared NPs, NPs morphology and light absorbance, were evaluated. Photocatalytic reactions of NPs were tested using 10 ppm methylene blue (MB) solution. Extracted teeth were pasted using carbomer gel for color differences measurements. Mo-N-TiO2 NPs have close to round shape with some tens nm size. Their absorbance was higher and longer than that of TiO 2 NPs. For MB solution, Mo-N-TiO2 with 3% H2O2 condition showed much decrease in absorbance after laser irradiation for 20 min. Also, regardless of wavelength, Mo-N-TiO2 NPs produced much greater color difference (whitening) on teeth after 3 h than that by 15% H2O2 .
ABSTRACT
This study investigated the effect of the difference in the cooling rates on the optical properties of zirconia during the simulated firing of porcelain, without a porcelain layer on a zirconia core ceramic. No difference was observed in the average transmittance of zirconia with the cooling rate during simulated firing (p>0.05). In all groups, the average transmittance decreased from approximately 44% to approximately 28% (p0.05). In all groups, the translucency decreased from approximately 16 to approximately 5 (p<0.001), while the opalescence increased from approximately 6 to approximately 11 (p<0.001) as the thickness increased from 0.51 mm to 2.00 mm. Thus, the average transmittance and translucency parameter decreased exponentially as the thickness increased in all groups regardless of the cooling rate during simulated porcelain firing, while the opalescence parameter increased in a parabolic manner. Therefore, in this study, even if porcelain is fired at a cooling rate higher or lower than the typical cooling rate when manufacturing a prosthesis with a zirconia core, the optical properties of zirconia are not expected to be significantly affected.
ABSTRACT
In this study, Au-Pt-Pd metal-ceramic alloy was examined by varying cooling rate during simulated porcelain firing cycles to investigate the effect of cooling rate on hardness and related microstructure during simulated firing. The final hardness was different according to the cooling rate after the simulated porcelain firing cycles. The reduction in hardness value was smaller after cooling at the faster cooling rate (Stage 0) than the value after slower rate (Stage 3). In the ice-quenched specimens after oxidation treatment (OXI-IQ), homogenization was slightly occurred, and the hardness decreased apparently compared to that of the as-cast specimens (AS-CAST). In the specimens cooled at Stage 0 and Stage 3 after oxidation, the hardness increased apparently compared to the ice-quenched specimens, even though the hardness decreased later by further firing simulation.The final hardness was lower in the specimen cooled at the slower rate (Stage 3) than the faster rate (Stage 0), and it seems to be due to the coarsening of the microstructure. The matrix and precipitates were consisted of FCC (face-centered-cubic) structure rich in Au. The Au content was higher in the matrix and the Pt content was higher in the precipitates, which corresponded to the Au-Pt binary phase diagram.
ABSTRACT
The purpose of the present study was to assess the temperature change and compressive property of bulk-fill composites (BFCs) by the light curing. Seven resin-based composites (RBCs), including five BFCs, were chosen to evaluate their maximum temperature rise and exothermic heat during and after light curing and compressive strength (CS) and modulus (CM) for 4-mm thick state. Light attenuation coefficients (ACs) showed reasonably high correlation with filler content (vol% and wt%).Except one resin product, AC values of BFCs were lower than those of RBCs tested. All the tested specimens showed temperature rise (9.8-23.6℃) and exothermic heat (4.2-18.3℃) for 4-mm thick case. CS and CM values of the tested specimens ranged approximately 69 to 116 MPa and 1.3 to 2.8 GPa, respectively. The difference of temperature changes and compressive properties (CS and CM) between BFCs and RBCs was not consistent and had no statistically consistent significance.
ABSTRACT
In this study, Au-Pt-Pd metal-ceramic alloy was examined by varying cooling rate during simulated porcelain firing cycles to investigate the effect of cooling rate on hardness and related microstructure during simulated firing. The final hardness was different according to the cooling rate after the simulated porcelain firing cycles. The reduction in hardness value was smaller after cooling at the faster cooling rate (Stage 0) than the value after slower rate (Stage 3). In the ice-quenched specimens after oxidation treatment (OXI-IQ), homogenization was slightly occurred, and the hardness decreased apparently compared to that of the as-cast specimens (AS-CAST). In the specimens cooled at Stage 0 and Stage 3 after oxidation, the hardness increased apparently compared to the ice-quenched specimens, even though the hardness decreased later by further firing simulation.The final hardness was lower in the specimen cooled at the slower rate (Stage 3) than the faster rate (Stage 0), and it seems to be due to the coarsening of the microstructure. The matrix and precipitates were consisted of FCC (face-centered-cubic) structure rich in Au. The Au content was higher in the matrix and the Pt content was higher in the precipitates, which corresponded to the Au-Pt binary phase diagram.
ABSTRACT
The purpose of the present study was to assess the temperature change and compressive property of bulk-fill composites (BFCs) by the light curing. Seven resin-based composites (RBCs), including five BFCs, were chosen to evaluate their maximum temperature rise and exothermic heat during and after light curing and compressive strength (CS) and modulus (CM) for 4-mm thick state. Light attenuation coefficients (ACs) showed reasonably high correlation with filler content (vol% and wt%).Except one resin product, AC values of BFCs were lower than those of RBCs tested. All the tested specimens showed temperature rise (9.8-23.6℃) and exothermic heat (4.2-18.3℃) for 4-mm thick case. CS and CM values of the tested specimens ranged approximately 69 to 116 MPa and 1.3 to 2.8 GPa, respectively. The difference of temperature changes and compressive properties (CS and CM) between BFCs and RBCs was not consistent and had no statistically consistent significance.
ABSTRACT
There has been increasing use of the H₂O₂-based teeth bleaching agents. The purpose of this study was to evaluate the bleaching effectiveness of the laser irradiation combined with nitrogen doped-TiO₂ nanoparticles (NPs) on the stained resin. Nitrogen (N) doped-TiO₂ NPs were prepared under sol-gel method. Light absorbance, X-ray diffraction patterns of NPs, and bleaching of methylene blue and stained resins were evaluated. For bleaching of stained resin, NPs-containing gel was used. For irradiation, light of two different wavelengths was used. Unlike TiO₂, N-TiO₂ showed high absorbance after 400 nm. N-TiO₂, which have used TiN as a precursor, showed a new rutile phase at the TiN structure. For methylene blue solution, N-TiO₂ with 3% H₂O₂ resulted in the greatest absorbance decrease after laser irradiation regardless of wavelength. For stained resin test, N-TiO₂ with 3% H₂O₂ resulted in the greatest color difference after laser irradiation, followed by group that used N-TiO₂ without 3% H₂O₂.
Subject(s)
Methods , Methylene Blue , Nanoparticles , Nitrogen , Tin , Tooth Bleaching Agents , X-Ray DiffractionABSTRACT
In this experiment, the alloy having the composition of 49.5Pd-40Ag-9In-1Ga (wt.%) was used to find the most effective cooling rate for the hardening of alloy during porcelain firing simulation. In each stage of firing simulation, ice-quenching or cooling at the most effective cooling rate for hardening of the alloy was done after firing to observe changes in the hardness and associated microstructures during the firing and subsequent cooling. For this purpose, the firing simulated alloy was characterized by analyzing the changes in hardness, microstructure, crystal structure and the elemental distribution. The hardness of alloy decreased by cooling after oxidation treatment, which was induced by the homogenization of the specimen. In this alloy, the most effective cooling rate for alloy hardening after oxidation treatment was Stage 0. During the porcelain firing simulation until the final firing stage, the cooling rate was set to Stage 0, and the complete firing simulation was performed until the final firing stage, Glaze. As a result, the final hardness of the metal substructure obtained after complete firing simulation was lower than that of the as-cast specimen. The decrease in hardness caused by the porcelain firing simulation results from a reduction in the interface between the precipitates of face-centered tetragonal structures and the matrix of face-centered cubic structures as the precipitates coarsen.
ABSTRACT
The pH of the oral cavity can dynamically change due to diverse foods and beverages served. The purpose of the present study was to evaluate flexural and compressive properties of composite resins after immersion in solutions of different pHs. Four composite resins were cured and immersed in test solutions of different pHs (3, 7.1, and 9) for 2 weeks. Flexural and compressive properties (strength and modulus) were evaluated using universal test machine. After immersion, initial flexural and compressive strength significantly changed to 1.5–30.0% and 0.3–19.6%, respectively; flexural and compressive modulus significantly changed to 4.4–29.0% and 3.5–21.5%, respectively. However, the values obtained from solutions of different pHs were not significantly and consistently different to each other.
Subject(s)
Beverages , Composite Resins , Compressive Strength , Hydrogen-Ion Concentration , Immersion , MouthABSTRACT
The aim of this study was to determine if a 457 nm blue laser could effectively polymerize dental composite resins. After light curing 6 dental composite resins using a laser or a LED light-curing unit at 530 mW/cm2 and 900 mW/cm2, respectively, degree of conversion and microhardness were evaluated. Degree of conversion of specimens by the laser and LED was similar (on top surface 54.4–67.7% and 55.2–67.1%, respectively; on bottom surface 35.1–53.8% and 45.4–53.1%, respectively). Microhardness was also similar (on top surface 28.5–83.6 Hv and 19.1–82.4 Hv, respectively; on bottom surface 22.5–65.4 Hv and 16.8–74.4 Hv, respectively), although, in some cases, laser-treated specimens showed slightly lower microhardness than the LED-treated on bottom surface. The present study shows that the 457 nm laser can polymerize dental composite resins to the same level as LED achieved.
Subject(s)
Composite Resins , Polymerization , PolymersABSTRACT
Flowable resins can be used as a base material during the restoration of deep tooth cavity. The purpose of the present study was to evaluate the mechanical properties of the layered specimens which have flowable resin as a base material. For the study, two composite resins and five flowable resins were chosen for the overlying and base materials, respectively. Flexural and compressive properties of each bulk and ten layered specimens were measured. Layered specimens showed high flexural strength (FS) and flexural modulus (FM) if bulk state FS and FM of the base flowable resin are high. However, compressive strength (CS) was not that case. CS of the layered specimen was not high (251.4~295.3 MPa) whether CS of the bulk state is high or not (259.8~439.8 MPa). FM showed high linear correlation with CM. After all mechanical properties of the layered specimens were not consistently influenced by the mechanical properties of the base flowable resins regardless of the overlying composite resins.
Subject(s)
Composite Resins , Compressive Strength , ToothABSTRACT
The purpose of this study was to examine effects of bioactive glass on Vickers hardness of bleached enamel surface. Enamel specimens were bleached with 15% carbamide peroxide (CP) for 14days. After bleaching, Artificial saliva (AS), 45S5 bioactive glass (BAG) and fluoride varnish (FV) are applied each specimens (n=10). The Vickers hardness of the specimens was measured before and after the bleaching, after the remineralized treatment at 1 day and after 7 and 14 days. The Vickers hardness on enamel surface after bleaching decreased statistically (p < 0.05) compared to before bleached enamel surface. The Vickers hardness increased significantly in the BAG and FV groups compared to the AS group values at 1 day and 7 days after remineralization (P < 0.05). 45S5 bioactive glass rapidly increase Vickers hardness of the bleached enamel surface.
Subject(s)
Dental Enamel , Fluorides , Glass , Hardness , Paint , Saliva, Artificial , UreaABSTRACT
Effect of cooling rate during oxidation treatment on the hardness change by post firing heat treatment of a Pd-Cu-Ga-Zn alloy after simulated porcelain firing was investigated and the following results were obtained. In the firing simulated specimens after quenching during the oxidation treatment, the hardness did not increase by post-firing heat treatment. However, in the firing simulated specimens after slow cooling during the oxidation treatment, post-firing heat treatment for 25 minutes was effective in increasing the hardness (p < 0.05). In the firing simulated specimens after quenching during the oxidation treatment, the significant decrease in hardness during the post-firing heat treatment was attributed to the coarsening of fine precipitates formed in the matrix and plate-like precipitates. In the firing simulated specimens after slow cooling during the oxidation treatment, the increase in hardness during the post-firing heat treatment for 25 minutes was due to precipitation hardening. From these results, it was found that the cooling rate during the oxidation treatment affected the change of hardness by the post-firing heat treatment after the simulated firing. From these results, post-firing heat treatment increased the hardness of the Pd-Cu-Ga-Zn alloy only when the cooling rate during the oxidation treatment was slow.
Subject(s)
Alloys , Dental Porcelain , Fires , Hardness , Hot TemperatureABSTRACT
OBJECTIVE: The aim of this study was to evaluate the mechanical and biological properties of orthodontic bonding agents containing silver- or zinc-doped bioactive glass (BAG) and determine the antibacterial and remineralization effects of these agents. METHODS: BAG was synthesized using the alkali-mediated solgel method. Orthodontic bonding agents containing BAG were prepared by mixing BAG with flowable resin. Transbond™ XT (TXT) and Charmfil™ Flow (CF) were used as controls. Ion release, cytotoxicity, antibacterial properties, the shear bond strength, and the adhesive remnant index were evaluated. To assess the remineralization properties of BAG, micro-computed tomography was performed after pH cycling. RESULTS: The BAG-containing bonding agents showed no noticeable cytotoxicity and suppressed bacterial growth. When these bonding agents were used, demineralization after pH cycling began approximately 200 to 300 µm away from the bracket. On the other hand, when CF and TXT were used, all surfaces that were not covered by the adhesive were demineralized after pH cycling. CONCLUSIONS: Our findings suggest that orthodontic bonding agents containing silver- or zinc-doped BAG have stronger antibacterial and remineralization effects compared with conventional orthodontic adhesives; thus, they are suitable for use in orthodontic practice.
Subject(s)
Adhesives , Dental Cements , Glass , Hand , Hydrogen-Ion Concentration , MethodsABSTRACT
OBJECTIVES: This study evaluated the effects of the resin thickness on the microhardness and optical properties of bulk-fill resin composites. METHODS: Four bulk-fill (Venus Bulk Fill, Heraeus Kulzer; SDR, Dentsply Caulk; Tetric N-Ceram Bulk Fill, Ivoclar vivadent; SonicFill, Kerr) and two regular resin composites (Charisma flow, Heraeus Kulzer; Tetric N-Ceram, Ivoclar vivadent) were used. Sixty acrylic cylindrical molds were prepared for each thickness (2, 3 and 4 mm). The molds were divided into six groups for resin composites. The microhardness was measured on the top and bottom surfaces, and the colors were measured using Commission Internationale d'Eclairage (CIE) L*a*b* system. Color differences according to the thickness and translucency parameters and the correlations between the microhardness and translucency parameter were analyzed. The microhardness and color differences were analyzed by ANOVA and Scheffe's post hoc test, and a student t-test, respectively. The level of significance was set to alpha = 0.05. RESULTS: The microhardness decreased with increasing resin thickness. The bulk-fill resin composites showed a bottom/top hardness ratio of almost 80% or more in 4 mm thick specimens. The highest translucency parameter was observed in Venus Bulk Fill. All resin composites used in this study except for Venus Bulk Fill showed linear correlations between the microhardness and translucency parameter according to the thickness. CONCLUSIONS: Within the limitations of this study, the bulk-fill resin composites used in this study can be placed and cured properly in the 4 mm bulk.
Subject(s)
Humans , Fungi , Hardness , VenusABSTRACT
OBJECTIVES: This study evaluated the effects of the resin thickness on the microhardness and optical properties of bulk-fill resin composites. METHODS: Four bulk-fill (Venus Bulk Fill, Heraeus Kulzer; SDR, Dentsply Caulk; Tetric N-Ceram Bulk Fill, Ivoclar vivadent; SonicFill, Kerr) and two regular resin composites (Charisma flow, Heraeus Kulzer; Tetric N-Ceram, Ivoclar vivadent) were used. Sixty acrylic cylindrical molds were prepared for each thickness (2, 3 and 4 mm). The molds were divided into six groups for resin composites. The microhardness was measured on the top and bottom surfaces, and the colors were measured using Commission Internationale d'Eclairage (CIE) L*a*b* system. Color differences according to the thickness and translucency parameters and the correlations between the microhardness and translucency parameter were analyzed. The microhardness and color differences were analyzed by ANOVA and Scheffe's post hoc test, and a student t-test, respectively. The level of significance was set to alpha = 0.05. RESULTS: The microhardness decreased with increasing resin thickness. The bulk-fill resin composites showed a bottom/top hardness ratio of almost 80% or more in 4 mm thick specimens. The highest translucency parameter was observed in Venus Bulk Fill. All resin composites used in this study except for Venus Bulk Fill showed linear correlations between the microhardness and translucency parameter according to the thickness. CONCLUSIONS: Within the limitations of this study, the bulk-fill resin composites used in this study can be placed and cured properly in the 4 mm bulk.
Subject(s)
Humans , Fungi , Hardness , VenusABSTRACT
OBJECTIVES: This study examined the effects of additional acid etching on the dentin bond strength of one-step self-etch adhesives with different compositions and pH. The effect of ethanol wetting on etched dentin bond strength of self-etch adhesives was also evaluated. MATERIALS AND METHODS: Forty-two human permanent molars were classified into 21 groups according to the adhesive types (Clearfil SE Bond [SE, control]; G-aenial Bond [GB]; Xeno V [XV]; Beauti Bond [BB]; Adper Easy Bond [AE]; Single Bond Universal [SU]; All Bond Universal [AU]), and the dentin conditioning methods. Composite resins were placed on the dentin surfaces, and the teeth were sectioned. The microtensile bond strength was measured, and the failure mode of the fractured specimens was examined. The data were analyzed statistically using two-way ANOVA and Duncan's post hoc test. RESULTS: In GB, XV and SE (pH 0.05). In AU (pH = 3.2), additional etching increased the bond strength significantly (p < 0.05). When adhesives were applied to the acid etched dentin with ethanol-wet bonding, the bond strength was significantly higher than that of the no ethanol-wet bonding groups, and the incidence of cohesive failure was increased. CONCLUSIONS: The effect of additional acid etching on the dentin bond strength was influenced by the pH of one-step self-etch adhesives. Ethanol wetting on etched dentin could create a stronger bonding performance of one-step self-etch adhesives for acid etched dentin.
Subject(s)
Humans , Adhesives , Composite Resins , Dentin , Ethanol , Hydrogen-Ion Concentration , Incidence , Molar , ToothABSTRACT
PURPOSE: The aim was to evaluate the effect of curing mode and different dentin surface pretreatment on microtensile bond strength (microTBS) of self-adhesive resin cements. MATERIALS AND METHODS: Thirty-six extracted human permanent molars were sectioned horizontally exposing flat dentin surface. The teeth were divided into 12 groups (3 teeth/group) according to the dentin surface pretreatment methods (control, 18% EDTA, 10% Polyacrylic acid) and curing mode (self-curing vs. light-curing) of cement. After pretreatment, composite resin blocks were cemented with the following: (a) G-CEM LinkAce; (b) RelyX U200, followed by either self-curing or light-curing. After storage, the teeth were sectioned and microTBS test was performed using a microtensile testing machine. The data was statistically analyzed using one-way ANOVA, Student T-test and Scheffe's post-hoc test at P<.05 level. RESULTS: For G-CEM LinkAce cement groups, polyacrylic acid pretreatment showed the highest microTBS in the self-cured group. In the light-cured group, no significant improvements were observed according to the dentin surface pretreatment. There were no significant differences between curing modes. Both dentin surface pretreatment methods helped to increase the microTBS of RelyX U200 resin cement significantly and degree of pretreatment effect was similar. No significant differences were found regarding curing modes except control groups. In the comparisons of two self-adhesive resin cements, all groups within the same pretreatment and curing mode were significantly different excluding self-cured control groups. CONCLUSION: Selecting RelyX U200 used in this study and application of dentin surface pretreatment with EDTA and polyacrylic acid might be recommended to enhance the bond strength of cement to dentin.
Subject(s)
Humans , Dentin , Edetic Acid , Molar , Resin Cements , ToothABSTRACT
OBJECTIVES: This study examined the color changes of a resin composite with different shades upon exposure to water with different pH. MATERIALS AND METHODS: Nanohybrid resin composites (Filtek Z350XT, 3M ESPE) with four different shades (A2, A3, B1, and B2) were immersed in water with three different pH (pH 3, 6, and 9) for 14 day. The CIE L*a*b* color coordinates of the specimens were evaluated before and after immersion in the solutions. The color difference (DeltaE*) and the translucency parameter (TP) were calculated using the color coordinates. RESULTS: DeltaE* ranged from 0.33 to 1.58, and the values were affected significantly by the pH. The specimens immersed in a pH 6 solution showed the highest DeltaE* values (0.87 - 1.58). The specimens with a B1 shade showed the lowest DeltaE* change compared to the other shades. TP ranged from 7.01 to 9.46 depending on the pH and resin shade. The TP difference between before and after immersion in the pH solutions was less than 1.0. CONCLUSIONS: The resulting change of color of the tested specimens did not appear to be clinically problematic because the color difference was < 1.6 in the acidic, neutral, and alkaline solutions regardless of the resin shade, i.e., the color change was imperceptible.
Subject(s)
Composite Resins , Hydrogen-Ion Concentration , Immersion , WaterABSTRACT
OBJECTIVES: This study examined the influence of the resin thickness on the polymerization of silorane- and methacrylate-based composites. MATERIALS AND METHODS: One silorane-based (Filtek P90, 3M ESPE) and two methacrylate-based (Filtek Z250 and Z350, 3M ESPE) composite resins were used. The number of photons were detected using a photodiode detector at the different thicknesses (thickness, 1, 2 and 3 mm) specimens. The microhardness of the top and bottom surfaces was measured (n = 15) using a Vickers hardness with 200 gf load and 15 sec dwell time conditions. The degree of conversion (DC) of the specimens was determined using Fourier transform infrared spectroscopy (FTIR). Scratched powder of each top and bottom surface of the specimen dissolved in ethanol for transmission FTIR spectroscopy. The refractive index was measured using a Abbe-type refractometer. To measure the polymerization shrinkage, a linometer was used. The results were analyzed using two-way ANOVA and Tukey's test at p < 0.05 level. RESULTS: The silorane-based resin composite showed the lowest filler content and light attenuation among the specimens. P90 showed the highest values in the DC and the lowest microhardness at all depth. In the polymerization shrinkage, P90 showed a significantly lower shrinkage than the rest two resin products (p < 0.05). P90 showed a significantly lower refractive index than the remaining two resin products (p < 0.05). CONCLUSIONS: DC, microhardness, polymerization rate and refractive index linearly decreased as specimen thickness linearly increased. P90 showed much less polymerization shrinkage compared to other specimens. P90, even though achieved the highest DC, showed the lowest microhardness and refractive index.