OBJECTIVETo study the mechanical properties of two kinds of composite resins reinforced by preimpregnated glass fibers.

METHODSSinfony and belleGlass composite resins were used to make standard samples (25 mm x 2 mm x 2 mm) with and without glass fibers. After all specimens were stored for 24 hours in distilled water at (37 +/- 1) degrees C, the flexural strength and flexural modulus were measured on a universal test machine.

RESULTSBoth flexural strength and flexural modulus of Sinfony composite reinforced by the glass fibers became significantly increased, which were (555.76 +/- 67.31) MPa and (12.59 +/- 3.06) GPa respectively, and 4.5 and 2.5 times much more than those of the specimens without glass fibers (P = 0); the flexural modulus of belleGlass composite became significantly increased, which was (14.10 +/- 2.88) GPa, and 0.9 time much more than the specimens without glass fibers (P = 0), but the improvement of flexural strength was not significant.

CONCLUSIONGlass fibers can improve the mechanical properties of composite resins, but the reinforcement effect is different between different resins.

Composite Resins ; chemistry ; Glass ; chemistry ; Materials Testing

OBJECTIVETo determine the rheological properties of the photo-polymerized composite resin reinforced with retentive filler (RF) and its rheological difference with normal filler (NF) composite resin.

METHODSRheological properties of the composite resins, such as viscosity, shear stress and creep compliance, were measured with dynamic stress rheometer at room temperature (25 degrees C).

RESULTSThe viscosity of the composite resin reinforced with RF is higher than that of NF composite resin (P < 0.01); at the beginning, the viscosity of the former has little change with the rising of shear stress and the latter decreases, then the viscosities of the two composite resins increase with the rising of shear stress as soon as over 203.18 Pa of shear stress; the creep compliance of the composite resin reinforced with RF is significant smaller than that of NF composite resin (P < 0.01).

CONCLUSIONSThe rheological properties of the two composite resins have significant difference, so they have different clinical using properties.

Composite Resins ; chemistry ; Dental Restoration, Permanent ; Viscosity

Dental resin composites (DRCs) are popular materials for repairing caries or dental defect, requiring excellent properties to cope with the complex oral environment. Filler/resin interface interaction has a significant impact on the physicochemical/biological properties and service life of DRCs. Various chemical and physical modification methods on filler/resin interface have been introduced and studied, and the physical micromechanical interlocking caused by the modification of fillers morphology and structure is a promising method. This paper firstly introduces the composition and development of DRCs, then reviews the chemical and physical modification methods of the filler/resin interface, mainly discusses the interface micromechanical interlocking structures and their enhancement mechanism for DRCs, finally give a summary on the existing problems and development potential.
Composite Resins/chemistry* ; Surface Properties ; Materials Testing

OBJECTIVETo evaluate the potential corrosive effect of topical fluoride agents used for professional treatments at dental prophylaxis on the polished surfaces of five composite resins.

METHODSA total of 125 specimens were fabricated from micro hybrid composite, nano-combined composite, nanocomposite, compomer and ormocer in a phi 6 mm x 3 mm cavity with 25 specimens for each composite group. The flat surfaces of the specimens were smoothed and polished, then applied respectively with four topical fluoride agents and distilled water, and stored at 37 degrees C 100% relative humidity for 30 min. The changes in morphologic features of the surfaces were assessed by scanning electron microscopy (SEM). The disintegrated surface was further analysed under a confocal laser scanning microscope (CLSM).

RESULTSAll fluorides showed reaction to all composites except nanocomposite. The aggressiveness of the fluorides arranged sequentially as F (Elmex fluid) > G (Elmex gelée) > D (Duraphat) > B (Bifluorid 12). The treated surfaces were generally rough. F and G caused the overall surface corrosion, whereas etching on the surface by D and B was sporadic confined. The destructive effects demonstrated a large number of craters on the surface somewhat like an atoll owing to filler dissolution. Crack formation resulted in destruction of the filler-matrix interface was observed. Ormocer was severely affected after F and G treatment. Instead of crater glass filler protruding from the bumpy surface indicated the excessively disintegrated matrix of ormocer. Topography under CLSM exhibited the roughening of the composite surface, roughness parameters for profile (Sa, Sz, Smax) increased when the surface was treated. Surface change in nanocomposite specimens was neither visually nor numerically discerned.

CONCLUSIONSTopical application of highly concentrated fluoride prophylactic agents leaded to surface degradation and porosity of composite, nanocomposite was, however, chemically resistant. Isolation of the composite surface should be considered in clinical application of topical fluoride.

Composite Resins ; chemistry ; Corrosion ; Fluorides, Topical ; chemistry ; In Vitro Techniques

Acrylic Resins ; chemistry ; Composite Resins ; chemistry ; Dental Research ; Dental Stress Analysis ; Polymerization ; Polyurethanes ; chemistry

OBJECTIVEThis study aims to investigate the color stability of ceromer with different thicknesses and different types of resin adhesive materials after accelerated aging and provide references for clinical application and selections.

METHODSNine groups of experimental samples were used, and each group contained five samples. We made joint samples with ceromer having three different thicknesses (1.00, 0.75, 0.50 mm) combined with three different resin adhesive materials (RelyX Veneer, RelyX Unicem, Filtek Z350 Flow), respectively. All samples were placed into Xenon Lamp Aging Instrument to implement accelerated aging. Spectrophotometer was used to measure the lightness (L*), red green color value (a*), and blue yellow color value (b*) of all samples before and after accelerated aging. The change of lightness (ΔL), red green color value (Δa), blue yellow color value (Δb), and color variation (ΔE) were also calculated. We investigated the influence of ceromer veneer thicknesses and resin adhesive material types on color variation by two-factor analysis of variance.

RESULTSThe thickness and type factors showed significant influence on ΔE values, and exhibited interactions (P < 0.05). The ΔE values of all experimental groups were lower than 3.3. After the accelerated aging process, all L*, a*, and b* values of the experimental groups decreased and the ΔL values were lower than 2.0.

CONCLUSIONCeromer veneer thickness and resin adhesive material types could affect the color stability of ceromer veneer and resin adhesive materials. The changes in lightness and color in ceromer veneer and resin adhesive materials are considered clinically acceptable after accelerated aging.

Ceramics ; Color ; Composite Resins ; Dental Cements ; chemistry ; Light ; Resin Cements

OBJECTIVETo study the monomolecular coverage of the silane coupling agent gamma-methacryloxypropyltrimethoxysilane (gamma-MPS) on the barium glass filler surface.

METHODSKubelka-Munk (K-M) function values of the isolated OH-groups on the barium glass filler surface, which were based on the change of gamma-MPS concentrations, were measured using the quantitative analysis of the diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. When all of the isolated OH-groups on the filler surface disappeared (where the K-M function values was zero), the monomolecular coverage of the gamma-MPS molecules on the filler surface was indicated by the linear regression analysis.

RESULTSThe relationship tallied with negative linear correlation between the K-M function values of the isolated OH-groups on the barium glass surface and the concentrations of gamma-MPS. Each gamma-MPS molecule occupied 0.21 nm(2) when the monomolecular coverage was formed on the barium glass surface.

CONCLUSIONSThe result of this study indicated the optimal amount of silane coupling agent on silanated barium glass filler during the production of resin composite.

Barium Compounds ; chemistry ; Composite Resins ; chemistry ; Dental Materials ; chemistry ; Methacrylates ; chemistry ; Silanes ; chemistry ; Silicon Dioxide ; chemistry

OBJECTIVETo analyze the color parameters and translucency of four frequently-used veneer materials.

METHODSForty disc specimens[(1.00±0.01) mm in thickness, 10 mm in diameter] were fabricated according to the manufacturer's instructions with IPS Empress(®) CAD[A2, high translucency (HT)], IPS e.max(®) Press(A2, HT), IPS e.max(®) CAD (A2, HT) and VITABLOCS(®) Mark II (A2) respectively and were divided into Groups A, B, C, D. All of the specimens were ground and polished on a grinding machine. Then color parameters (L*, a*, b*) and transmittance (τ) were measured using spectrocolorimeter and transmissivity testing device. The color parameters of the specimens were compared to the color parameters of A2 shade of Ivoclar Vivadent A-D shade guide. The data were analyzed with one-way analysis of variance (ANOVA), and mean values were compared by the Tukey's test (α = 0.05).

RESULTSThere was no statistical difference between the color parameters L*, a*, b* and C*ab of Group A and Group D (P > 0.05). But the color parameters of those two ceramic materials were statistically different from the color parameters of Group B and Group C (P < 0.05). There was no statistical difference between color parameters b* and C*ab of Group B and Group C(P > 0.05). However, the color parameters L* and a* of the two materials were statistically different(P < 0.05). The color differences (ΔE) between Group A, B, C, D and standard A2 were 6.05±0.12, 5.11±0.27, 3.73±0.27, 6.30±0.38 respectively. The transmittances of Group A, B, C, D were (29.69±0.31)%, (25.83±0.36) %, (28.92±0.47)% and (26.94±0.33)% respectively.

CONCLUSIONSThe color parameters of these four materials are different. Their transmittance are relatively high but statistically different. The color difference (ΔE) between IPS e.max(®) CAD (A2, HT) and standard A2 is lowest among all the groups.

Acrylic Resins ; chemistry ; Ceramics ; chemistry ; Color ; Composite Resins ; chemistry ; Dental Porcelain ; chemistry ; Dental Veneers ; Optical Phenomena ; Polyurethanes ; chemistry

OBJECTIVETo evaluate the effect of bleaching agents on the color of indirect and direct composite resins.

METHODSFive resin composite materials were tested in this in vitro study. The five composites were as follow: two indirect composite resins (Adoro SR, Ceramage) and three direct composite resins (Filtek Z350, Clearfil Majesty Esthetic, and Gradia Direct Anterior). For each material, twenty disk-shaped specimens were prepared and randomly divided into five groups according to the color parameters of specimens before bleaching treatment. The composite resin specimens were treated by one of five sample solutions which were at-home bleaching agents (10% and 15% carbarmide peroxide), in- office bleaching agents (38% H(2)O(2) and 35%H(2)O(2)) and deionized water (control group). The color parameters of specimens were measured by spectrophotometer at baseline and after bleaching treatments. The color differences (ΔE values) between baseline and post-treatments were calculated. The data of color differences were evaluated statistically using two-way analysis with a significance level of 0.05.

RESULTSThe color changes of the resin composites were less than 2.0 after bleaching agent treatment, therefore were not perceptible. Slight increase of L(*) values and decrease of C(*)ab values in color parameters of specimens were observed. There were statistically significant differences in ΔE values for different bleaching treatments and resin materials (P = 0.001).

CONCLUSIONSThe bleaching agents did not affect the color of indirect and direct composite resins tested.

Bleaching Agents ; chemistry ; Color ; Composite Resins ; chemistry ; Hydrogen Peroxide ; Materials Testing ; Peroxides ; Silicates

OBJECTIVETo prepare a new synthetic macromolecular resin class of denture adhesive (named Comfort-DA).

METHODSTwelve different formulae for denture adhesive were designed by orthogonal design. Each factor affecting tensile bond strength of adhesive was analyzed by ANNOVA to select the best formula. Then the chemical and physical properties, such as tensile bond strength, pH value, and viscosity, were evaluated and compared with Fittydent in vitro also.

RESULTSThe effect of content of polyvinyl acetate and cellulose ether on tensile bond strength exhibited no statistical significance (P > 0.05), while ethyl alcohol and CMC-Na showed statistical significance and mutual action (P < 0.05). Results of testing viscosity and shearing stress showed that there was no significant difference between Fittydent and Comfort-DA (P > 0.05), while Fittydent exhibited a significantly lower tensile bond strength than the prepared one (P < 0.05). The prepared adhesive demonstrated a neutral or slightly basic pH.

CONCLUSIONSThe generally favorable in vitro performance of the prepared adhesive (Comfort-DA) formulation indicated that it might be efficacious denture adhesive.

Adhesives ; chemistry ; Composite Resins ; chemistry ; Dental Bonding ; Denture Retention ; methods ; Humans ; Hydrogen-Ion Concentration ; Tensile Strength