Simonides Consani

University of Campinas, Conceição de Campinas, São Paulo, Brazil

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Publications (190)129.22 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to evaluate the influence of various concentrations of hydrofluoric acid (HF) on the surface/interface morphology and μ-shear bond strength (μSBS) between IPS Empress Esthetic (EST) (Ivoclar Vivadent) and IPS e.max Press (EMX) (Ivoclar Vivadent) ceramics and resin cement. Ceramic blocks were divided into 12 groups for each kind of ceramic. Six different HF concentrations were evaluated: 1%, 2.5%, 5%, 7.5%, 10%, and 15%. All groups were silanated after etching, and half of the specimens within each group received a thin layer of unfilled resin (UR). Three resin cement cylinders were prepared on each ceramic block for μSBS testing. The specimens were stored in distilled water at 37°C for 24 hours. The μSBS test was carried out in a universal testing machine at a crosshead speed of 0.5 mm/min until fracture. The data were submitted to three-way analysis of variance and multiple comparisons were performed using the Tukey post hoc test (p<0.05). The etched surfaces and bonded interfaces were evaluated using scanning electron microscopy. μSBS means (MPa) for 1%, 2.5%, 5%, 7.5%, 10%, and 15% HF concentrations were, respectively, 25.2, 27.2, 30.1, 31.4, 33.3, and 31.8. μSBS means with or without UR application measured 32.24 and 27.4, respectively; EST and EMX measured 29.8 and 29.9, respectively. For the HF concentrations, 10% and 15% showed higher μSBS means than did 1% and 2.5% (p<0.05); 7.5% was higher than 1% (p<0.05); and no statistical differences were found among the other concentrations (p>0.05). When evaluating UR, μSBS mean was significantly higher and better infiltration was observed on the etched surfaces. No statistical difference was found between the ceramics. The HF concentration and UR influenced the bond strength and surface/interface morphology.
    Operative Dentistry 03/2015; DOI:10.2341/14-133-L · 1.27 Impact Factor
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    ABSTRACT: To develop Y-shaped plates with different thicknesses to be used in simulated fractures of the mandibular condyle. Ten plates were developed in Y shape, containing eight holes, and 30 synthetic polyurethane mandible replicas were developed for the study.Material and Methods The load test was performed on an Instron Model 4411 universal testing machine, applying load in the mediolateral and anterior-posterior positions on the head of the condyle. Two-way ANOVA with Tukey testing with a 5% significance level was used.ResultsIt was observed that when the load was applied in the medial-lateral plate of greater thickness (1.5 mm), it gave the highest strength, while in the anteroposterior direction, the plate with the highest resistance was of the lesser thickness (0.6mm). A plate with a thickness of 1.5 mm was the one with the highest average value for all displacements. In the anteroposterior direction, the highest values of resistance were seen in the displacement of 15 mm.Conclusion After comparing the values of the biomechanical testing found in the scientific literature, it is suggested that the use of Y plates are suitable for use in subcondylar fractures within the limitations of the study.
    Journal of Cranio-Maxillofacial Surgery 11/2014; DOI:10.1016/j.jcms.2014.10.029 · 2.60 Impact Factor
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    ABSTRACT: Energy dispersive X-ray spectroscopy microanalysis (EDX), scanning electron microscopy (SEM), and Archimedes' Principle were used to determine the characteristics of inorganic filler particles in five dental alginates, including Cavex ColorChange (C), Hydrogum 5 (H5), Hydrogum (H), Orthoprint (O), and Jeltrate Plus (JP). The different alginate powders (0.5 mg) were fixed on plastic stubs (n = 5) and sputter coated with carbon for EDX analysis, then coated with gold, and observed using SEM. Volume fractions were determined by weighing a sample of each material in water before and after calcining at 450(°)C for 3 h. The alginate materials were mainly composed of silicon (Si) by weight (C-81.59%, H-79.89%, O-78.87%, H5-77.95%, JP-66.88%, wt). The filler fractions in volume (vt) were as follows: H5-84.85%, JP-74.76%, H-70.03%, O-68.31%, and C-56.10%. The tested materials demonstrated important differences in the inorganic elemental composition, filler fraction, and particle morphology.
    BioMed Research International 07/2014; 2014:178064. DOI:10.1155/2014/178064 · 2.71 Impact Factor
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    ABSTRACT: This study investigated the effect of simulated microwave disinfection (SMD) on the linear dimensional changes, hardness and impact strength of acrylic resins under different polymerization cycles.
    Minerva stomatologica 06/2014;
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    ABSTRACT: This study evaluated the effect of adding diphenyliodonium hexafluorphosphate (DPI) as a third component of the free-radical photoinitiator system of model resin cements on their photopolymerization kinetics/stress and fundamental properties. A model resin cement containing a 1:1 mass ratio of 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane and triethyleneglycol dimethacrylate was obtained. Camphorquinone (1mol%) and 2-(dimethylamino)ethyl methacrylate (2mol%) were added to monomer blend. Six mixtures were obtained by incorporation of 0 (control), 0.25, 0.5, 1, 2, or 4mol% of DPI. The cements were loaded with a 60% mass fraction of silanated glass fillers. Polymerization kinetics (using Fourier-transform near-infrared spectroscopy), flexural strength and modulus, water uptake/solubility, and polymerization stress were assessed. Data were statistically analyzed using one-way ANOVA and Student-Newman-Keuls' test (P≤0.05). In the DPI-modified materials, the onset of autodeceleration occurred earlier and at higher conversion compared with the control cement. The addition of DPI also led to a more active early-stage polymerization. The flexural modulus was generally higher for DPI-containing materials. Water uptake and solubility were generally lower for materials with DPI fractions ≥0.5%. Significant increase of polymerization stress was observed only in the group with 1mol% of DPI compared with the control cement. The effect of DPI on the photopolymerization reactivity of the cement is concentration-dependent; the use of DPI could result in better polymerization efficiency of resin-based cements.
    Dental Materials 10/2013; 29:1251-5. DOI:10.1016/j.dental.2013.09.010 · 4.16 Impact Factor
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    ABSTRACT: Objective: The aim of this study was to evaluate the compatibility of commercial dental adhesives to model resin cements (MRCs), using the microshear bond strength (msbs) test. Method: A model Bis­GMA/TEGDMA (1:1 molar ratio) was prepared and diphenyliodonium (DPI) added at different concentrations (0-control, 0.5 or 1 mol%). The MRC were loaded with a 60% mass fraction of silanated Ba­Al­Si glass fillers (Esstech Inc). Twenty-four disc-shaped specimens (6 mm in diameter; 2 mm thick) of each MRC were prepared and randomly divided into 3 groups (n=8), according to the adhesive system used (Scotchbond Multi-Purpouse-SBMP, Singlebond 2-SB2 and ExciTE-EX). For the msbs test, adhesive cylinders were built on the disc surfaces using Tygon tubes (TGY-030, 0.7 mm diameter). The adhesives were light-cured for 10 s, using a light-emitted diode source, with 680 mW/cm2. The bond strength test were carried out in a universal test machine at a crosshead speed of 0.5 mm, using an orthodontic wire loop (0.2mm). The msbs values were submitted to the two-way ANOVA and Tukey’s post-hoc test (a=0.05). Result: SBMP and EX presented similar values of msbs, statistically higher than SB2, regardless of the concentration of DPI. Conclusion: The dental adhesives tested presented are compatible with the resin cements modified by DPI, and the concentration of this component had no influence on the msbs values to the commercial adhesives.
    IADR/AADR/CADR General Session and Exhibition 2013; 03/2013
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    ABSTRACT: Objectives: :To evaluate the effect of different surface treatments on the tensile bond strength of indirect composite. Methods: Fifty caries-free extracted bovine incisors teeth were made flat until the dentin was exposed. The dentin etching was made with 37 % phosphoric acid and the ScothBond Multi-Purpose Plus System (3M ESPE) was applied according to the manufacturer’s instructions. Fifty blocks (5 mm x 5 mm x 2 mm) of indirect composite Sinfony (3M ESPE) were fabricated using a silicone matrix. The blocks were randomly divided into 5 groups (n=10), based on the surface treatment to be performed: (A): abrasion with spherical diamond bur, (B): abrasion with spherical diamond bur + silane + Bond, (C): etching with 10% hydrofluoric acid; (D): etching with 10% hydrofluoric acid + silane + Bond and; (E): no treatment. After surface treatments, the blocks were cemented using Rely-X ARC (3M ESPE). After 24 h, microtensile sticks were made from bonded specimens and loaded in tension until failure. The tensile bond strength tests were carried out using a universal testing machine at cross-head speed of 0.5 mm/minute. The data were submitted to analysis of variance and Tukey's test (5%). Results: Group Mean of tensile bond strength (MPa) A 26.64 C B 28.48 C C 26.62 C D 39.46 A E 33.13 B Conclusions: Group D showed the best results for tensile bond strength. Groups A, B and C showed the lowest results. Group D (control) showed intermediate result.
    IADR/AADR/CADR General Session and Exhibition 2013; 03/2013
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    ABSTRACT: Background/purposePolymerization contraction stress is an undesirable and inevitable characteristic of adhesive restorations. It is important to understand the stress distribution to improve the clinical effectiveness of resin composite restoration. The aim of this study was to evaluate the polymerization shrinkage stress created in tooth photoelastic models using different filling techniques.Materials and methodsTwenty Class II tooth models were obtained. They were distributed into four experimental groups (n = 5) according to the following restorative techniques: resin composite with horizontal insertion, resin composite with oblique insertion, flowable composite + resin composite with horizontal insertion, and flowable composite + resin composite with oblique insertion restoration. Restored photoelastic models were analyzed using a plane polariscope. The stress along seven points of adhesive interface was analyzed from images of each insertion, at the baseline (immediately) and 24 hours after polymerization. Maximum shear stress data were obtained and submitted to two-way ANOVA analysis followed by Tukey's posthoc test at P = 0.05.ResultsHorizontal and oblique techniques have shown differences in stress patterns. No difference between stress values of horizontal and oblique techniques was found. Groups restored with flow composite showed significant higher stress levels than those restored only with universal composite.Conclusion The use of flow composite created higher polymerization stress effects on the class II restoration than does the conventional restoration technique.
    Journal of dental sciences 03/2013; 8(1):53–60. DOI:10.1016/j.jds.2012.01.015 · 0.47 Impact Factor
  • P.H. Freitas, A.B. Correr, S. Consani
    Dental Materials 01/2013; 29:e74. DOI:10.1016/j.dental.2013.08.153 · 4.16 Impact Factor
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    ABSTRACT: Aim: To assess the influence of finishing/polishing procedure on color stability (ΔE ) and surface roughness (Ra ) of composites (Heliomolar and Tetric - color A2) submitted to accelerated artificial aging (AAA). Materials and Methods : Sixty test specimens were made of each composite (12 mm × 2 mm) and separated into six groups (n = 10), according to the type of finishing/polishing to which they were submitted: C, control; F, tip 3195 F; FF, tip 3195 FF; FP, tip 3195 F + diamond paste; FFP, tip 3195 FF + diamond paste; SF, Sof-Lex discs. After polishing, controlled by an electromechanical system, initial color (spectrophotometer PCB 6807 BYK GARDNER) and Ra (roughness meter Surfcorder SE 1700, cut-off 0.25 mm) readings were taken. Next, the test specimens were submitted to the AAA procedure (C-UV Comexim) for 384 hours, and at the end of this period, new color readings and R a were taken. Results: Statistical analysis [2-way analysis of variance (ANOVA), Bonferroni, P < 0.05] showed that all composites demonstrated ΔE alteration above the clinically acceptable limits, with the exception of Heliomolar composite in FP. The greatest ΔE alteration occurred for Tetric composite in SF (13.38 ± 2.10) statistically different from F and FF (P < 0.05). For Ra , Group F showed rougher samples than FF with statistically significant difference (P < 0.05). Conclusion: In spite of the surface differences, the different finishing/polishing procedures were not capable of providing color stability within the clinically acceptable limits.
    Indian journal of dental research: official publication of Indian Society for Dental Research 01/2013; 24(3):363-8. DOI:10.4103/0970-9290.118010
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    ABSTRACT: This study evaluated the temperature variation in the pulp chamber during photoactivation of two restorative composite resins (Filtek P90 silorane-based composite and Heliomolar methacrylate-based composite) with either a quartz-tungsten-halogen (QTH) or light-emitting diodes (LED) light-curing unit (LCU) and using dentin thicknesses (0.5 and 1.0 mm). Standardized cavities (2x2x2 mm) were prepared in 80 bovine incisors, which were randomly assigned to 8 groups according to the photoactivation method and dentin thickness. Filtek P90 and Heliomolar (both in shade A3) were used with their respective adhesive systems (P90 self-etch primer / P90 adhesive bond and Excite adhesive). All experiments were carried out in a controlled environment (37°C). The temperature variations (°C) were recorded using a digital thermometer attached to a K-type thermocouple. The results were analyzed statistically by ANOVA and Tukey's test (α=0.05). For composite/dentin thickness interaction, temperature increase was significantly higher in 0.5 mm dentin thickness (40.07°C) compared with 1.0 mm dentin thickness (39.61°C) for Filtek P90. For composite/LCU interaction, the temperature increase was significantly higher for Filtek P90 (39.21°C - QTH and 40.47°C - LED) compared with Heliomolar (38.40°C - QTH and 39.30°C - LED). The silorane-based composite promoted higher temperature increase in the pulp chamber than the methacrylate-based composite.
    Brazilian dental journal 12/2012; 24(3):258-62. DOI:10.1590/0103-6440201301904
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    ABSTRACT: This study evaluated an alternative method for thermal cycling test on the microleakage and bond strength of the polymer-dentin bond. For the microleakage test the cavities were restored with a TEGDMA+UDMA+bis-EMA composite polymer light cured for 20 s. Samples were immersed in 2% methylene blue solution for 2 h and sectioned. Microleakage scores were submitted to Kruskal-Wallis test. For the shear bond strength test the adhesive was applied to dentin, photoactivated for 10 s and the composite polymer incrementally photoactivated. Samples were submitted to shear bond strength test in a machine with a cross-head speed of 0.5 mm/min and data were submitted to ANOVA and Tukey's test. Studied groups were: 1 - without thermocycling; 2 - thermocycled at 5 ºC and 55 ºC with intermediate bath at 37 ºC; 3 - thermocycled at 5 ºC and 37 ºC; 4 - thermocycled at 37 ºC and 55 ºC; 5 - thermocycled at 5 ºC and 55 ºC (traditional test). Cold baths promoted greater microleakage when compared to control and hot bath, whereas control and hot bath were similar. Cold baths presented significant lower shear bond strength than those submitted to hot bath and control. It was concluded that the alternative method for thermal cycling test showed that cold temperatures increased the microleakage and decreased the bond strength of the polymeric adhesive.
    Materials Research 12/2012; 15(6):1045-1049. DOI:10.1590/S1516-14392012005000114 · 0.48 Impact Factor
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    ABSTRACT: The type IV dental stone is widely used for the fabrication of dyes and master casts for fixed and removable partial prostheses. It is typically normal to wait at least 24 hours for the casts to dry prior to beginning the laboratory procedures. The waiting time has been shown to be greatly reduced by using microwave drying. This study evaluated the influence of drying techniques at room temperature and microwave oven on the linear dimensional change, compressive strength and detail reproduction in type IV dental stones. Three type IV dental stone brands were selected; elite Rock, Shera Premium and Durone IV. Two different drying protocols were tested in 4 groups (n=10); G1 - room temperature (25±4ºC) dried for 2 hours; G2 - room temperature dried for 24 hours; G3 - room temperature dried for 7 days and G4 - microwave oven dried at 800 W for 5 minutes and after 2 hours at room temperature. After drying, the samples were assayed for dimensional charges. The sample surface was submitted to the ImageTool 3.0 software for compressive strength in a universal testing machine with a cell load of 50 KN at a crosshead speed of 0.5 mm/minutes and the detail reproduction was analyzed with a stereomicroscope at 25x magnification. The statistical analysis of the linear dimensional change and compressive strength data were conducted by the ANOVA test followed by the Tukey test (p<0.05). Detailed reproduction values were reported in percentages. For the compressive strength test, Elite Rock and Durone IV did not present significant differences between G2 and G4, while Shera Premium did not present differences between G3 and G4. The best reproduction levels were observed for G3. Dental stone microwave oven drying showed a linear dimensional change similar to after room temperature drying for 24 hours and 7 days. The compressive strength of the stone dried in the microwave oven was similar to those dried at room temperature for 24 hours, with the exception of Shera Premium, which had similar results for microwave and room temperature drying for 7 days. For the microwave drying method the detail reproduction levels for samples dried at room temperature for 24 hours and 7 days were similar, except for the Durone IV.
    Journal of applied oral science: revista FOB 10/2012; 20(5):588-93. DOI:10.1590/S1678-77572012000500016 · 0.80 Impact Factor
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    ABSTRACT: Objectives: Recently, Zn-doped dental adhesives have been advocated to interfere with matrix metalloproteinase-mediated collagen degradation. Nevertheless, there is no information about the effects induced by the inclusion of Zn nitrate on the chemical-physical properties of MDP-based (10-methacryloyloxi-decyl-phosphate) self-etch adhesives. Thus, this investigation aimed at evaluating whether the presence of Zn interfere with the chemical interaction of MDP-based adhesives and dentine. Methods: MDP was solvated in a 1:1-water:ethanol solution. MDP was mixed with 0, 1, 2, 3 or 4 ppm of calcium in presence or absence of zinc. Remaining free-calcium (calcium not chemically bonded to MDP) was measured by atomic absorption spectroscopy (AAS). Further AAS was realized with zinc+MDP following a similar protocol in absence of calcium to evaluate the potential formation of MDP-zinc salt. Three experimental solutions were prepared and analysed for each mixture (n=3). MDP-containing self-etch adhesives Clearfil SE Bond (CSE, primer solution) and Clearfil S3 (S3) (Kuraray Medical, Japan) were doped with 5wt% of zinc. Zinc-doped and zinc-free adhesives were applied following manufacturer’s recommendations to flat dentine surfaces of extracted human third molars and restorations were built up. After 24h immersion in distilled water at 37ºC, the bonded teeth were cut into ~1mm² sticks and submitted to µTBS testing. Data were analysed with ANOVA, paired t-test and Tukey’s test (p<0.05). Results: µTBS showed mean bond strength (MPa) of 39.8±7.3 for CSE, 19.3±4.9 for zinc-doped CSE and 38.3±8.6 for S3. Zinc-doped S3 was not tested because all sticks failed prematurely. AAS showed reduced free-calcium by adding MDP (p<0.001) and an increase in free calcium when adding zinc (p=0.009). Formation of monomer-zinc salt occurred as a reduction of free-zinc by adding MDP (p<0.001). Conclusions: These outcomes showed that zinc may jeopardise the bond strength of MDP-containing adhesives and MDP-calcium salts formation. Addition of zinc should be avoided in this type of self-etch adhesive.
    PER/IADR Congress 2012; 09/2012
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    ABSTRACT: Objective: To evaluate the depth of cure of experimental resin cements (ERC) containing an initiator system with Diphenyliodonium Hexafluorphosphate (DPI) cured with LED (Radii Cal). Method: Experimental resin cements based in Bis-GMA/TEGDMA (1:1 molar ratio) was obtained and DPI added at concentrations of 0 (control), 0.25, 0.5, 1 or 2 mol%, resulting in five ERC. Cylindrical specimens were prepared filling a matrix (13 mm in length and 2 mm Ø) simulating a root canal, and the resin cement was light cured with LED (800 mw/cm2 - 40 J/cm2). After this, the specimens were stored for 24 h, sectioned using a diamond blade at 2, 6, 10 mm and polished with silicon carbide papers #2000. Degree of conversion (DC) was determined by FTIR spectroscopy and results were submitted to the Kruskal-Wallis and Dunn tests. Result: The DC was statistically lower in the cements without DPI (Control) in all depths evaluated, compared to the cements with 0.5; 1 and 2mol% of DPI. Control and 2mol% DPI groups presented reduced DC with 10mm, enabling the evaluation in this depth. The concentrations of 0.25; 0.5 and 1mol% promoted adequate curing even in 10 mm depth. Conclusion: The addition of DPI increased the DC of the ERC even at 10 mm in depth, using the concentrations of 0.25; 0.5 and 1%. The absence of DPI or 2mol% DPI was not capable to produce adequate curing with 10 mm depth.
    IADR General Session 2012; 06/2012
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    ABSTRACT: Objective: The aim of this study was to evaluate the depth of cure of experimental resin cements (ERC) containing an initiator system with Diphenyliodonium Hexafluorphosphate (DPI) (Sigma-Aldrich). Method: A model Bis-GMA/TEGDMA (Sigma-Aldrich) (1:1 molar ratio) was obtained and DPI added at concentrations of 0 (control), 0.25, 0.5, 1 or 2 mol%, resulting in five ERC. The cements were loaded with a 60% mass fraction of silanated Ba-Al-Si glass fillers (Esstech Inc). Cylindrical specimens were constructed filling a matrix (13 mm in length and 2 mm in diameter) to simulate a root canal and light cured with Bluephase LED (Ivoclar-Vivadent) (40 J/cm2). After this, the specimens were stored for 24 h, sectioned using a diamond blade at 2, 6, 10 mm in depth and polished with silicon carbide papers #2000. Degree of conversion (DC) was determined by FTIR spectroscopy and results were submitted to the Kruskal-Wallis and Dunn tests. Result: Control shows a significant decrease of DC after 6 mm, 10 mm could not be tested. ERC containing 0.25 and 2 mol% presented significant decrease of DC after 10 mm. The groups containing 0.5 and 1 mol% were statistically similar and showed the higher values of DC at 10 mm in depth. Conclusion: DPI addition resulted an increase of DC of the ERC even at 10 mm in depth, using the concentrations of 0,5 and 1%.
    IADR General Session 2012; 06/2012
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    ABSTRACT: Objective: To evaluate the effects of four different light-curing protocols on the microtensile bond strength (μTBS), ultimate tensile strength (UTS), Knoop micro-hardness (KH) and cross-link density survey (CLD) of a nanofilled resin composite. Methods: Filtek Supreme XT (3M-ESPE) was used for built ups on flat dentin using the following light-curing approaches: Standard Irradiance (SI); High Irradiance (HI); Pulse-Delay (PD); Soft-Start (SS). After different storage periods (24h or 6 months), the specimens were cut into sticks and submitted to μTBS testing. Hourglass specimens were evaluated for UTS and KH in 24h and 6 months. For cross-link density evaluation, KH of cylindrical specimens was performed before and after immersion in absolute ethanol for 24h. The results were statistically analyzed to ANOVA and Tukey’s test (p<0.05). Results: For KH (KHN), HI (102) obtained the highest top hardness in 24h (p<0.05). After 6 months, SS (35) presented higher bottom hardness than PD (25), but with no statistical difference compared to HI (27) and SI (29) (p>0.05). For UTS (MPa), after 6 months SS (90.2) showed statistical higher results than the other groups (p<0.05). A significant decrease on UTS and KH was observed after 6-months compared to the 24h groups. The μTBS was not affected by the different light-curing approaches (p=0.874) and, no statistical differences were observed between 24h and 6-months storage (p=0.185). The CLD evaluation showed a statistical drop (p<0.001) in KH in the specimens light-cured using PD (21.5%) or SS (20.5%) (step-curing protocols) compared to those light-cured with continuous mode (SI - 12.9%; HI - 12.7%). Conclusion: The SS mode may improve the UTS and KH of nanofilled composite without compromising the μTBS of dentin-bonded specimens. However, both the step-curing protocols may compromise the cross-link density of the polymeric composite.
    IADR General Session 2012; 06/2012
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    ABSTRACT: Objectives To evaluate the effects of four different light-curing protocols on the microtensile bond strength (μTBS), ultimate tensile strength (UTS), Knoop micro-hardness (KH) and cross-link density (CLD) of a nano-filled resin composite. Methods Filtek Supreme XT (3M-ESPE) was used for the entire experiments following four light-curing approaches: ST) Standard irradiance; HI) High irradiance; PD) Pulse delay: SS) Soft Start. The specimens were submitted to different storage periods (24 h or 6 months), cut into match-sticks and subsequently submitted to μTBS testing. Hourglass specimens were also prepared for UTS and KH. Cylindrical specimens were prepared for the CLD evaluation after absolute ethanol challenge. The results were statistically analyzed with a two-way ANOVA and Tukey's test (α=0.05). Results For UTS and KH, continuous irradiance (PD and SS) induced statistically higher results (p < 0.05) both after 24 h and 6 months of water storage compared to ST and HI groups. However, a drop in UTS and KH was obtained after 6 months in all groups. The μTBS was not affected by the different light-curing approaches and, no statistical differences (p > 0.05) were observed between 24 h and 6 months storage. The CLD evaluation showed a statistical drop in KH after 24 h of ethanol storage for PD and SS (step-curing protocols) compared to those attained in continuous mode (ST and HI). Conclusion The soft-start mode may improve the UTS and KH of nano-filled resin composites without compromising the resin-dentin μTBS. However, both the step-curing protocols may reduce the cross-link density of the composite polymeric network. Clinical Significance High irradiances photo-polymerization may be adequate for direct aesthetic restorations such as veneers and onlays. Meanwhile, the soft start protocol would seem more appropriate for the photo-polymerization of high c-factors class I and II restorations.
    Journal of Dentistry 06/2012; · 2.84 Impact Factor
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    ABSTRACT: To evaluate the effects of four different light-curing protocols on the microtensile bond strength (μTBS), ultimate tensile strength (UTS), Knoop micro-hardness (KH) and cross-link density (CLD) of a nano-filled resin composite. Filtek Supreme XT (3M-ESPE) was used for the entire experiments following four light-curing approaches: ST, standard irradiance; HI, high irradiance; PD, pulse delay; SS, soft start. The specimens were submitted to different storage periods (24h or 6 months), cut into match-sticks and subsequently submitted to μTBS testing. Hourglass specimens were also prepared for UTS and KH. Cylindrical specimens were prepared for the CLD evaluation after absolute ethanol challenge. The results were statistically analyzed with a two-way ANOVA and Tukey's test (α=0.05). For UTS and KH, continuous irradiance (PD and SS) induced statistically higher results (p<0.05) both after 24h and 6 months of water storage compared to ST and HI groups. However, a drop in UTS and KH was obtained after 6 months in all groups. The μTBS was not affected by the different light-curing approaches and, no statistical differences (p>0.05) were observed between 24h and 6 months storage. The CLD evaluation showed a statistical drop in KH after 24h of ethanol storage for PD and SS (step-curing protocols) compared to those attained in continuous mode (ST and HI). The soft-start mode may improve the UTS and KH of nano-filled resin composites without compromising the resin-dentine μTBS. However, both the step-curing protocols may reduce the cross-link density of the composite polymeric network. High irradiances photo-polymerization may be adequate for direct aesthetic restorations such as veneers and onlays. Meanwhile, the soft start protocol would seem more appropriate for the photo-polymerization of high c-factors class I and II restorations.
    Journal of dentistry 06/2012; 40(10):802-9. DOI:10.1016/j.jdent.2012.05.014 · 2.84 Impact Factor
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    ABSTRACT: We compared polymerization stress in two commercial composites and three experimental composites made using camphorquinone (CQ) and/or phenylpropanedione (PPD) as photoinitiators. The internal surfaces of photoelastic resin discs with cylindrical cavities were roughened and treated with adhesive. Composites were divided into five groups: two commercial composites (Filtek Silorane and Filtek Z250) and three experimental composites with CQ/amine, CQ/PPD/amine, and PPD/amine. Composites were photopolymerized inside cavities, and subjected to photoelastic analysis immediately and at 24 hours and 7 days later using a plane polariscope. Stress created by Silorane (3.08 ± 0.09 MPa) was similar to that of Z250 (3.19 ± 0.13 MPa) immediately after photopolymerization (p > 0.05). After 24 hours and 7 days, Z250 (3.53 ± 0.15 and 3.69 ± 0.10 MPa, respectively) showed higher stress than Silorane (3.19 ± 0.10 and 3.16 ± 0.10 MPa, respectively). Qualitative analysis immediately after photopolymerization showed composite/CQ promoted higher stress than PPD, but stress levels at other evaluated times were statistically similar, varying between 3.45 ± 0.11 MPa and 3.92 ± 0.13 MPa. At 24 hours and 7 days, Silorane created the lowest stress. All photoinitiators created comparable tensions during polymerization.
    Brazilian oral research 06/2012; 26(3):202-8. DOI:10.1590/S1806-83242012000300004 · 0.77 Impact Factor

Publication Stats

1k Citations
129.22 Total Impact Points

Institutions

  • 1977–2014
    • University of Campinas
      • Faculty of Dentistry from Piracicaba
      Conceição de Campinas, São Paulo, Brazil
  • 2009
    • University of São Paulo
      • Faculdade de Odontologia de Ribeirão Preto (FORP)
      Ribeirão Preto, Estado de Sao Paulo, Brazil
  • 2006
    • Universidade Federal de Pelotas
      São Francisco de Paula, Rio Grande do Sul, Brazil
  • 1994
    • Universidade Federal do Rio Grande do Sul
      Pôrto de São Francisco dos Casaes, Rio Grande do Sul, Brazil