Effect of microwave disinfection on the hardness and adhesion of two resilient liners

Statement of problem. Microwave irradiation has been suggested for denture disinfection. However, the effect of this procedure on the hardness and bond strength between resilient liners and denture base acrylic resin is not known.Purpose. This study evaluated the effect of water storage time and microwave disinfection on the hardness and peel bond strength of 2 silicone resilient lining materials to a heat-polymerized acrylic resin.Material and methods. Acrylic resin (Lucitone 199) specimens (75 X 10 X 3 mm) were stored in water at 37 degrees C (2 or 30 days) before bonding (n = 160). The resilient lining materials (GC Reline Extra Soft and Dentusil) were bonded to the denture base and divided into the following 4 groups (n = 10): Tests performed immediately after bonding (control); specimens immersed in water (200 mL) and irradiated twice, with 650 W for 6 minutes; specimens irradiated daily for 7 total cycles of disinfection; specimens immersed in water (37 degrees C) for 7 days. Specimens were submitted to a 180-degree peel test (at a crosshead speed of 10 mm/min) and the failure values (MPa) and mode of failure were recorded. Pretreatment and posttreatment hardness measurements (Shore A) of the resilient materials were also performed. Three-way analysis of variance, followed by the Tukey HSD test, was performed (alpha=.05).Results. The analysis revealed that, for all conditions, the mean failure strengths of GC Reline Extra Soft (0.95-1.19 MPa) were significantly higher (P<.001) than those of Dentusil (0.45-0.50 MPa). The adhesion of the liners was not adversely affected by water storage time of Lucitone 199 or microwave disinfection. All peel test failures were cohesive. There was a small but significant difference (P<.001) between the pretreatment (34.33 Shore A) and posttreatment (38.69 Shore A) hardness measurements.Conclusion. Microwave disinfection did not compromise the hardness of either resilient liners or their adhesion to the denture base resin Lucitone 199.

EFFECT of METAL PRIMERS on BOND STRENGTH of RESIN CEMENTS TO BASE METALS

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of light-curing units on microleakage under dental composite resins

The aim of this study was to determine the effect of two light-curing units (QTH and LED) on microleakage of Class II composite resin restorations with dentin cavosurface margins. Twenty extracted mandibular first premolars, free of caries and fractures were prepared two vertical slot cavities in the occluso-mesial and -destal surfaces (2 mm buccal-lingually, 2 mm proximal-axially and cervical limit in enamel) and divided into 4 equal groups (n = 8): GI and GII: packable posterior composite light-activated with LED and QTH, respectively; GIII and GIV: micro-hybrid composite resin light-activated with LED and QTH, respectively. The composite resins were applied following the manufacturer's instructions. After 24 h of water storage specimens were subjected to thermocycling for a total of 500 cycles at 5 and 55A degrees C and the teeth were then sealed with impermeable material. Teeth were immersed in 0.5% Basic fuchsin during 24 h at room temperature, and zero to three levels of penetration score were attributed. The Mann-Whitney and Kruskal-Wallis tests showed significant statistically similar (P > 0.05) from GI to GII and GIII to GIV, which the GII (2.750) had the highest mean scores and the GIII and GIV (0.875) had lowest mean scores. The use of different light-curing units has no influence on marginal integrity of Class II composite resin restorations and the proprieties of composite resins are important to reduce the microleakage.

Desenvolvimento de plantas de ervilha (Pisum sativum L.), submetidas à diferentes potenciais da água no solo: índices fisiológicos

A ervilha é cultivada no Brasil Central, durante o inverno seco, exigindo para o pleno êxito da cultura o uso da irrigação. Assim, o presente trabalho se propõe a avaliar os efeitos do potencial da água no solo nos índices fisiológicos da análise quantitativa de crescimento de plantas de ervilha (Pisum sativum L.). O experimento foi montado em casa de vegetação, em solos de textura argilosa, com delineamento experimental inteiramente casualizado, com quatro tratamentos decorrentes de potenciais mínimos da água no solo (-33, -100, -200 e -1500 kPa) em três repetições, cada qual contendo duas plantas de ervilha, cultivar Caprice. Os resultados obtidos evidenciaram que a redução do potencial água no solo, induziu o decréscimo na área foliar, sem interferir no comportamento da razão de massa foliar, razão de área foliar, taxa assimilatória líquida e taxa de crescimento relativo.

Aerobic biodegradation of butanol and gasoline blends

This work aimed to assess the aerobic biodegradation of butanol/gasoline, blends (5; 10; 15 and 20% v/v), being the latter compared to the ethanol/gasoline blend (20% v/v). Two experimental techniques were employed, namely the respirometric method and the redox indicator DCPIP test. in the former, experiments simulating the contamination of natural environments (addition of 50 mL of fuel kg(-1) of soil from a non-contaminated site and 20 mL of fuel L(-1) of water from a river) were carried out in biometer flasks (250 mL), used to measure the microbial CO(2) production. The DCPIP test assessed the capability of four inocula to biodegrade the blends of 20%. The addition of butanol at different concentrations enhanced the biodegradation of gasoline in soil. However, no practical gains were observed for concentrations of butanol above 10%. Ethanol showed to have a much faster biodegradation rate than butanol, particularly in water, and the following order of biodegradability was found: ethanol > butanol > gasoline. The addition of the alcohols to the gasoline resulted in positive synergic effects on the biodegradation of the fuels in soil and water matrices. Furthermore, results suggest that, in soil, butanol better enhanced the biodegradation of gasoline than ethanol. (C) 2009 Elsevier Ltd. All rights reserved

Aerobic biodegradation of butanol and diesel oil blends

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Germination performance of congeneric Styrax species from the Cerrado sensu lato areas and their distribution pattern in different physiognomies

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Leaf gas exchange and fruit yield in sweet orange trees as affected by citrus variegated chlorosis and environmental conditions

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Respostas fisiológicas ao déficit hídrico em duas cultivares enxertadas de seringueira (RRIM 600 e GT 1) crescidas em campo

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of conditioning methods on the microtensile bond strength of phosphate monomer-based cement on zirconia ceramic in dry and aged conditions

The objective of this study was to evaluate the durability of bond strength between a resin cement and aluminous ceramic submitted to various surface conditioning methods. Twenty-four blocks (5 X 5 X 4 mm 3) of a glass-in filtrated zirconia-alumina ceramic (inCeram Zirconia Classic) were randomly divided into three surface treatment groups: ST1-Air-abrasion with 110-mu m Al2O3 particles + silanization; ST2-Laboratory tribochemical silica coating method (110-mu m Al2O3, ilO-PM Silica) (Rocatec) + silanization; ST3-Chairside tribochemical silica coating method (30-mu m SiOx) (CoJet) + silanization. Each treated ceramic block was placed in its silicone mold with the treated surface exposed. The resin cement (Panavia F) was prepared and injected into the mold over the treated surface. Specimens were sectioned to achieve nontrimmed bar specimens (14 sp/block) that were randomly divided into two conditions: (a) Dry-microtensile test after sectioning; (b) Thermocycling (TC)-(6,000X, 5-55 degrees C) and water storage (150 days). Thus, six experimental groups were obtained (11 = 50): Gr1-ST1 + dry; Gr2-ST1 + TC. Gr3-ST2 + dry; Gr4-ST2 + TC; Gr5-ST3 + dry; Gr6ST3 + TC. After microtensile testing, the failure types were noted. ST2 (25.1 +/- 11) and ST3 (24.1 +/- 7.4) presented statistically higher bond strength (MPa) than that of STI (17.5 +/- 8) regardless of aging conditions (p < 0.0001). While Gr2 revealed the lowest results (13.3 +/- 6.4), the other groups (21.7 +/- 7.4-25. 9 +/- 9.1) showed statistically no significant differences (two-way ANOVA and Tukey's test, a 0.05). The majority of the failures were mixed (82%) followed by adhesive failures (18%). Gr2 presented significantly higher incidence of ADHESIVE failures (54%) than those of other groups (p = 0.0001). Both laboratory and chairside silica coating plus silanization showed durable bond strength. After aging, airabrasion with 110-mu m Al2O3 + silanization showed the largest decrease indicating that aging is fundamental for bond strength testing for acid-resistant Arconia ceramics in order to estimate their long-term performance in the mouth. (c) 2007 Wiley Periodicals, Inc.

Does Adhesive Resin Application Contribute to Resin Bond Durability on Etched and Silanized Feldspathic Ceramic?

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Evaluation of interface characterization and adhesion of glass ceramics to commercially pure titanium and gold alloy after thermal- and mechanical-loading

Objectives. This study evaluated the effect of thermal- and mechanical-cycling on the shear bond strength of three low-fusing glassy matrix dental ceramics to commercial pure titanium (cpTi) when compared to conventional feldspathic ceramic fused to gold alloy.Methods. Metallic frameworks (diameter: 5 min, thickness: 4 mm) (N = 96, n = 12 per group) were cast in cpTi and gold alloy, airborne particle abraded with 150 mu m aluminum oxide. Low-fusing glassy matrix ceramics and a conventional feldspathic ceramic were fired onto the alloys (thickness: 4mm). Four experimental groups were formed; Gr1 (control group): Vita Omega 900-Au-Pd alloy; Gr2: Ticeram-cpTi; Gr3: Super Porcelain Ti-22-cpTi and G4: Vita Titankeramik-cpTi. While half of the specimens from each ceramic-metal combination were randomly tested without aging (water storage at 37 C for 24h only), the other half were first thermocycled (6000 cycles, between 5 and 55 C, dwell time: 13 s) and then mechanically loaded (20,000 cycles under SON load, immersion in distilled water at 37 C). The ceramic-alloy interfaces were loaded under shear in a universal test machine (cross-head speed: 0.5 mm/min) until failure occur-red. Failure types were noted and the interfaces of the representative fractured specimens from each group were examined with stereo microscope and scanning electron microscope (SEM). in an additional study (N = 16, n = 2 per group), energy dispersive X-ray spectroscopy (EDS) analysis was performed from ceramic-alloy interfaces. Data were analyzed using ANOVA and Tukey's test.Results. Both ceramic-metal combinations (p < 0.001) and aging conditions (p < 0,001) significantly affected the mean bond strength values. Thermal- and mechanical-cycling decreased the bond strength (MPa) results significantly for Gr3 (33.4 +/- 4.2) and Gr4 (32.1 +/- 4.8) when compared to the non-aged groups (42.9 +/- 8.9, 42.4 +/- 5.2, respectively). Gr1 was not affected significantly from aging conditions (61.3 +/- 8.4 for control, 60.7 +/- 13.7 after aging) (p > 0.05). Stereomicroscope images showed exclusively adhesive failure types at the opaque ceramic-cpTi interfacial zone with no presence of ceramic on the substrate surface but with a visible dark titanium oxide layer in Groups 2-4 except Gr1 where remnants of bonder ceramic was visible. EDS analysis from the interfacial zone for cpTi-ceramic groups showed predominantly 34.5-85.1% O(2) followed by 1.1-36.7% Aland 0-36.3% Si except for Super Porcelain Ti-22 where a small quantity of Ba (1.4-8.3%), S (0.7%) and Sn (35.3%) was found. In the Au-Pd alloy-ceramic interface, 56.4-69.9% O(2) followed by 15.6-26.2% Si, 3.9-10.9% K, 2.8-6% Na, 4.4-9.6% Al and 0-0.04% Mg was observed.Significance. After thermal-cycling for 6000 times and mechanical-cycling for 20,000 times, Triceram-cpTi combination presented the least decrease among other ceramic-alloy combinations when compared to the mean bond strength results with Au-Pd alloy-Vita Omega 900 combination. (c) 2008 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Bond strength durability of a resin composite on a reinforced ceramic using various repair systems

Objectives. This study compared the durability of repair bond strength of a resin composite to a reinforced ceramic after three repair systems.Methods. Alumina-reinforced feldspathic ceramic blocks (Vitadur-alpha(R)) (N=30) were randomly divided into three groups according to the repair method: PR-Porcelain Repair Kit (Bisco) [etching with 9.5% hydrofluoric acid + silanization + adhesive]; CJ-CoJet Repair Kit (3M ESPE) [(chairside silica coating with 30 mu m SiO2 + silanization (ESPE(R)-Sil) + adhesive (Visio(TM)-Bond)]; CL-Clearfil Repair Kit [diamond surface roughening, etching with 40% H3PO4 + Clearfil Porcelain Bond Activator + Clearfil SE Bond)]. Resin composite was photo-polymerized on each conditioned ceramic block. Non-trimmed beam specimens were produced for the microtensile bond strength (mu TBS) tests. In order to study the hydrolytic durability of the repair methods, the beam specimens obtained from each block were randomly assigned to two conditions. Half of the specimens were tested either immediately after beam production (Dry) or after long-term water storage (37 degrees C, 150 days) followed by thermocyling (12,000 cycles, 5-55 degrees C) in a universal testing machine (1 mm/min). Failure types were analyzed under an optical microscope and SEM.Results. mu TBS results were significantly affected by the repair method (p=0.0001) and the aging conditions (p=0.0001) (two-way ANOVA, Tukey's test). In dry testing conditions, PR method showed significantly higher (p < 0.001) repair bond strength (19.8 +/- 3.8 MPa) than those of CJ and CL (12.4 +/- 4.7 and 9.9 +/- 2.9, respectively). After long-term water storage and thermocycling, CJ revealed significantly higher results (14.5 +/- 3.1 MPa) than those of PR (12.1 +/- 2.6 MPa) (p < 0.01) and CL (4.2 +/- 2.1 MPa) (p < 0.001). In all groups when tested in dry conditions, cohesive failure in the composite accompanied with adhesive failure at the interface (mixed failures), was frequently observed (76%, 80%, 65% for PR, CJ and CL, respectively). After aging conditions, while the specimens treated with PR and CJ presented primarily mixed failure types (52% and 87%, respectively), CL group presented mainly complete adhesive failures at the interface (70%).Significance. Hydrolytic stability of the repair method based on silica coating and silanization was superior to the other repair strategies for the ceramic tested. (C) 2009 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Effect of Cement Shade and Light-curing Unit on Bond Strength of a Ceramic Cemented to Dentin

Purpose: To evaluate the effect of cement shade, light-curing unit, and water storage on tensile bond strength (a) of a feldspathic ceramic resin bonded to dentin.Materials and Methods: The dentin surface of 40 molars was exposed and etched with 37% phosphoric acid, then an adhesive system was applied. Forty blocks of feldspathic ceramic (Vita VM7) were produced. The ceramic surface was etched with 10% hydrofluoric acid for 60 s, followed by the application of a silane agent and a dual-curing resin cement (Variolink II). Ceramic blocks were cemented to the treated dentin using either A3 or transparent (Tr) shade cement that was activated using either halogen or LED light for 40 s. All blocks were stored in 37 degrees C distilled water for 24 h before cutting to obtain non-trimmed bar-shaped specimens (adhesive area = 1 mm(2) +/- 0.1) for the microtensile bond strength test. The specimens were randomly grouped according to the storage time: no storage or stored for 150 days in 37 degrees C distilled water. Eight experimental groups were obtained (n = 30). The specimens were submitted to the tensile bond strength test using a universal testing machine at a crosshead speed of 1 mm/min. The data were statistically analyzed using ANOVA and Tukey's post-hoc tests (alpha = 0.05).Results: The mean bond strength values were significantly lower for the corresponding water stored groups, except for the specimens using A3 resin cement activated by halogen light. There was no significance difference in mean bond strength values among all groups after water storage.Conclusion: Water storage had a detrimental effect under most experimental conditions. For both cement shades investigated (Tr and A3) under the same storage condition, the light-curing units (QTH and LED) did not affect the mean microtensile bond strengths of resin-cemented ceramic to dentin.

Opaque Layer Firing Temperature and Aging Effect on the Flexural Strength of Ceramic Fused to Cobalt-Chromium Alloy

Purpose: To evaluate the effect of the opaque layer firing temperature and mechanical and thermal cycling on the flexural strength of a ceramic fused to commercial cobalt-chromium alloy (Co-Cr). The hypotheses were that higher opaque layer temperatures increase the metal/ceramic bond strength and that aging reduces the bond strength.Materials and Methods: Metallic frameworks (25 x 3 x 0.5 mm(3); ISO 9693) (N = 60) were cast in Co-Cr and airborne-particle abraded (Al(2)O(3): 150 mu m) at the central area of the frameworks (8 x 3 mm(2)) and divided into three groups (N = 20), according to the opaque layer firing temperature: Gr1 (control)-900 degrees C; Gr2-950 degrees C; Gr3-1000 degrees C. The opaque ceramic (Opaque, Vita Zahnfabrick, Bad Sackingen, Germany) was applied, and the glass ceramic (Vita Omega 900, Vita Zahnfabrick) was fired onto it (thickness: 1 mm). While half the specimens from each group were randomly tested without aging (water storage: 37 degrees C/24 hours), the other half were mechanically loaded (20,000 cycles; 50 N load; distilled water at 37 degrees C) and thermocycled (3000 cycles; 5 degrees C to 55 degrees C, dwell time: 30 seconds). After the flexural strength test, failure types were noted. The data were analyzed using 2-way ANOVA and Tukey's test (alpha = 0.05).Results: Gr2 (19.41 +/- 5.5 N) and Gr3 (20.6 +/- 5 N) presented higher values than Gr1 (13.3 +/- 1.6 N) (p = 0.001). Mechanical and thermal cycling did not significantly influence the mean flexural strength values (p > 0.05). Increasing the opaque layer firing temperature improved the flexural bond strength values (p < 0.05). The hypotheses were partially accepted.Conclusion: Increasing of the opaque layer firing temperature improved the flexural bond strength between ceramic fused to Co-Cr alloy.