ABSTRACT Objective: To evaluate the influence of an application technique of a glass-fiber post using self-adhesive resin cements on the push-out bond strength and the presence of bubbles in the root thirds. The cements were either applied according to the manufacturer's instruction or using a commercial delivering system (Centrix), at which the cement pastes were collected and applied after manipulation. Material and Methods: Self-adhesive resin cements (RelyX U200/3M ESPE-U200; Maxcem Elite/Kerr-MAX; Clearfil SA Cement/Kuraray-CSA) and a conventional cement (RelyX ARC/3M ESPE-ARC) were used to cement a post and applied either based on the manufacturer's instructions or using a Centrix syringe to deliver the cements directly onto the post of choice, or directly into canal. The roots were scanned with a micro-computed tomography (μCT) and then sectioned into nine 1-mm thick slices for a push-out bond strength test. The μCT images showed the percentage of bubbles in the root thirds (cervical, medium, and apical). Data were analyzed with three-way ANOVA/Tukey (α=0.05). Results: Triple interaction was not significant (p>0.05). The interaction “material” vs “root third” was not significant. A significant interaction was observed between “material” vs “application technique” (p<0.05). For ARC, U200, and MAX, significantly lower percentages of bubbles were observed when the Centrix syringe delivered the cements. Equivalent percentages of voids were observed for CSA, irrespective of the application technique (p>0.05). Significantly higher bond strength was observed when the self-adhesive resin cements were applied using the Centrix delivery system, in comparison with the manufacturer's instructions (p<0.05). Bond strength varied with the root third: cervical>medium>apical (p<0.05). No correlations were found between the bond strength and voids. Conclusions: Bond strength and voids are negatively influenced by the conventional application technique for luting fiber posts. The delivery system (Centrix) seems to produce better results when cementing fiber posts.

Objective:To investigate the mechanical properties of different classifications of composites indicated for posterior application as functions of the storage condition and of the energy dose.Material and Methods:Specimens (8x2x2 mm) were obtained according to the factors: I) Composites (3M ESPE): Filtek P60, Filtek Z350XT, and Filtek Silorane; II) Syringe storage conditions: room temperature, aged, oven, refrigerator, and freezer; and III) Energy dose: 24 J/cm2 and 48 J/cm2. After photoactivation, the specimens were stored at 37ºC for 24 h. After storage, a three-point bending test was carried out in a universal testing machine at 0.5 mm/min. Flexural strength (S) and flexural modulus (E) were calculated. Data were analyzed by three-way ANOVA and Tukey's test (α=0.05).Results:Different storage conditions significantly affected the silorane composite for S; conversely, no effects were noted in terms of E. The accelerated aging protocol significantly increased the S of Filtek P60 and Filtek Silorane, whereas storage in the oven significantly decreased the S for all of the composites tested. Filtek P60 was the only composite not affected by the lower storage temperatures tested for S, whereas for the silorane this parameter was impacted at the same conditions. The factor "dose" was not statistically significant.Conclusions:The syringe storage at different temperature conditions proved to influence mostly the flexural strength, a clinically important characteristic considering the posterior indication of the materials tested. The silorane composite should not be stored at lower temperatures.

Objective: To evaluate the hardness (KHN), color stability (DE), and superficial micromorphology of two categories of composites after immersion in either distilled water or grape juice for up to 45 days. MATERIAL AND METHODS: Cylindrical specimens (6 mm diameter x 2 mm thick) were obtained according to the factors: composite [Opallis (FGM) and Filtek Z350XT (3M ESPE)]; immersion solution (distilled water and grape juice); and evaluation time: 24 h and 7, 14, 21, 28, and 45 days. After photoactivation, the specimens were stored at 37ºC for 24 h. KHN (50 g/15 s) and ΔE were then repeatedly assessed according to the immersion solutions. Data were analyzed (three-way ANOVA/Tukey's test). Scanning electron microscopy (SEM) topographic analysis was also performed. RESULTS: In general, KHN of both composites reduced after 24 h, irrespective of the immersion solution and time. A significantly lower KHN was noted for Opallis compared with Filtek Z350XT in all parameters. An increase in ΔE over time was noted for both composites, irrespective of the immersion solution. Significantly higher ΔE was noted for Filtek Z350XT immersed in grape juice compared with Opallis, regardless of the evaluation time. The grape juice caused significantly higher DE compared with water in all periods. SEM analysis showed eroded areas for Filtek Z350XT but not for Opallis. CONCLUSIONS: The compositions and immersion solutions influence the composite hardness and the color stability. In spite of the higher hardness, the nanofilled composite is more susceptible to color change than the microhybrid when immersed in an acidic dyed solution.

Objective: To evaluate the influence of solvent evaporation in the kinetics of water diffusion (water sorption-WS, solubility-SL, and net water uptake) and nanoleakage of adhesive systems. Material and Methods: Disk-shaped specimens (5.0 mm in diameter x 0.8 mm in thickness) were produced (N=48) using the adhesives: Clearfil S3 Bond (CS3)/Kuraray, Clearfil SE Bond - control group (CSE)/Kuraray, Optibond Solo Plus (OS)/Kerr and Scotchbond Universal Adhesive (SBU)/3M ESPE. The solvents were either evaporated for 30 s or not evaporated (N=24/per group), and then photoactivated for 80 s (550 mW/cm2). After desiccation, the specimens were weighed and stored in distilled water (N=12) or mineral oil (N=12) to evaluate the water diffusion over a 7-day period. Net water uptake (%) was also calculated as the sum of WS and SL. Data were submitted to 3-way ANOVA/Tukey's test (α=5%). The nanoleakage expression in three additional specimens per group was also evaluated after ammoniacal silver impregnation after 7 days of water storage under SEM. Results: Statistical analysis revealed that only the factor "adhesive" was significant (p<0.05). Solvent evaporation had no influence in the WS and SL of the adhesives. CSE (control) presented significantly lower net uptake (5.4%). The nanoleakage was enhanced by the presence of solvent in the adhesives. Conclusions: Although the evaporation has no effect in the kinetics of water diffusion, the nanoleakage expression of the adhesives tested increases when the solvents are not evaporated.

The influence of curing tip distance and storage time in the kinetics of water diffusion (water sorption-W SP, solubility-W SB, and net water uptake) and color stability of a composite were evaluated. Composite samples were polymerized at different distances (5, 10, and 15 mm) and compared to a control group (0 mm). After desiccation, the specimens were stored in distilled water to evaluate the water diffusion over a 120-day period. Net water uptake was calculated (sum of WSP and WSB). The color stability after immersion in a grape juice was compared to distilled water. Data were submitted to three-way ANOVA/Tukey's test (α = 5%). The higher distances caused higher net water uptake (p < 0.05). The immersion in the juice caused significantly higher color change as a function of curing tip distance and the time (p < 0.05). The distance of photoactivation and storage time provide the color alteration and increased net water uptake of the resin composite tested.

This study evaluated the influence of solvent evaporation conditions of acid-etching adhesives. The medium dentin of thirty extracted human third molars was exposed and bonded to different types of etch-and-rinse adhesives: 1) Scotchbond Multi-Purpose (SBMP) ; water-based; 2) Adper Single Bond 2 (SB) ; ethanol/water-based, and 3) Prime & Bond 2.1 (PB) ; acetone-based. Solvents were evaporated at air-drying temperatures of 21ºC or 38ºC. Composite buildups were incrementally constructed. After storage in water for 24 h at 37ºC, the specimens were prepared for bond strength testing. Data were analyzed by two-way ANOVA and Tukey's test (5%). SBMP performed better when the solvents were evaporated at a higher temperature (p < 0.05). Higher temperatures did not affect the performance of SB or PB. Bond strength at room temperature was material-dependent, and air-drying temperatures affected bonding of the water-based, acid-etching adhesive.

The aim of the present study was to evaluate the fracture resistance of teeth restored with resin composite. Forty-eight maxillary premolar teeth were chosen and randomly divided to six groups: G1 (control): sound teeth; G2: MOD preparation, unrestored; G3: MOD + Adper Single Bond 2/P60; G4: MOD + Adper Easy One/P60; G5: MOD + P90 restorative system; G6: MOD + Adper Easy One/P90 Bond/P90. Specimens were subjected to compressive axial loading (0.5 mm/min). Flexural strength and the modulus of elasticity were also tested (n = 7). The only statistical equivalence with sound teeth was noted for G3 (p < 0.05). Flexural strength and the modulus of elasticity varied among the composites tested (n = 10). The reestablishment of the resistance to fracture in premolars subjected to Class II MOD preparations is restorative-system-dependent. The silorane restorative system is not able to recover the resistance to fracture.

This study examined the immediate bond strength of etch-and-rinse adhesives to demineralized dentin saturated with either water or absolute ethanol. The research hypothesis was that there would be no difference in bond strength to dentin between water or ethanol wet-bonding techniques. The medium dentin of 20 third molars was exposed (n = 5). The dentin surface was then acid-etched, left moist and randomly assigned to be saturated via either water wet-bonding (WBT) or absolute ethanol wet-bonding (EBT). The specimens were then treated with one of the following etch-and-rinse adhesive systems: a 3-step, water-based system (Adper Scotchbond Multipurpose, or SBMP) or a 2-step, ethanol/water-based system (Adper Single Bond 2, or SB). Resin composite build-ups were then incrementally constructed. After water storage for 24 h at 37°C, the tensile strength of the specimens was tested in a universal testing machine (0.5 mm/min). Data were analyzed by two-way ANOVA and Tukey's test (a = 5%). The failure modes were verified using a stereomicroscope (40'). For both adhesives, no significant difference in bond strength was observed between WBT and EBT (p > 0.05). The highest bond strength was observed for SB, regardless of the bonding technique (p < 0.05). No significant interaction between adhesives and bonding techniques was noticed (p = 0.597). There was a predominance of adhesive failures for all tested groups. The EBT and WBT displayed similar immediate bond strength means for both adhesives. The SB adhesive exhibited higher means for all conditions tested. Further investigations are needed to evaluate long-term bonding to dentin mediated by commercial etch-and-rinse adhesives using the EBT approach.

The influence of curing tip distance and storage time on the hardness of a composite was evaluated. Composite samples (Filtek Z250) were polymerized at different distances (5, 10, and 15 mm), compared with a control group (0 mm), and stored in distilled water at 37 ° C for 24 hours. The Knoop-hardness of top and bottom surfaces was assessed (25 g/30 s). Specimens were stored in distilled water for 6 and 12 months and were retested. Hardness was found to be negatively influenced by both curing tip distance and storage time. Despite similar values at 24 hours, differences in hardness values compared with the control group appeared over time. In comparing both surfaces, hardness proved to be greater at the top surface for all groups. Composites with similar initial hardness values can degrade very differently after water storage. The higher the photoactivation distance and storage time, the worse the mechanical property.

OBJECTIVE: To evaluate the microhardness of resin-modified glass-ionomer cements (RMGICs) photoactivated with a blue light-emitting diode (LED) curing light. MATERIAL AND METHODS: Thirty specimens were distributed in 3 groups: Fuji II LC Improved/GC (RM1), Vitremer/3M ESPE (RM2) and Filtek Z250/ 3M ESPE (RM3). Two commercial light-curing units were used to polymerize the materials: LED/Ultrablue IS and a halogen light/XL3000 (QTH). After 24 h, Knoop microhardness test was performed. Data were submitted to three-way ANOVA and Tukey's test at a pre-set alpha of 0.05. RESULTS: At the top surface, no statistically significant difference (p>0.05) in the microhardness was seen when the LED and QTH lights were used for all materials. At the bottom surface, microhardness mean value of RM2 was significantly higher when the QTH light was used (p<0.05). For RM1, statistically significant higher values (p<0.05) were seen when the LED light was used. No statistically significant difference (p>0.05) was seen at the bottom surface for RM3, irrespective of the light used. Top-to-bottom surface comparison showed no statistically significant difference (p>0.05) for both RMGICs, regardless of the light used. For RM3, microhardness mean value at the top was significantly higher (p<0.05) than bottom microhardness when both curing units were used. CONCLUSION: The microhardness values seen when a LED light was used varied depending on the restorative material tested.

The aim of this study was to evaluate the influence of different light sources on the bond strength of indirect resin composite restorations cemented with a dual-cure resin cement. The superficial dentin of human third molars was exposed and acid-etched and an adhesive system was applied (Single Bond 2). Four-mm-thick indirect resin composite restorations (Gradia) were fabricated and cemented using a dual-cure resin cement (Rely X). Four light sources were used to polymerize the cement: QTH - Optilux 401; LED1 - L.E.Demetron 1; LED2 - Optilight CL; and LED3 - Ultralume 5. The teeth were stored for 24 h and then sectioned, yielding stick-shaped specimens for each group with a bonded area of 1.0 mm². The specimens were then tested in a universal testing machine, at a crosshead speed of 1 mm/min. Data were analyzed using ANOVA. Bond strength mean values were: QTH: 22.5 (± 8.4); LED1: 22.7 (± 9.4); LED2: 21.4 (± 10.2); and LED3: 27.3 (± 13.8). No statistically significant difference was observed among the experimental groups. The bond strength values when the cement was polymerized using different LED lights were equivalent to the values when the QTH light was used. It can be concluded that the variety of light sources used in the present study did not influence the bond strength of indirect resin composite restorations cemented with a dual-cure resin cement.

OBJECTIVE: The purpose of this in vitro study was to evaluate the internal adaptation of Class V composite restorations to the cavity walls using three different techniques of polymerization. METHODS: Standard cavities were prepared on the buccal and lingual surfaces of 24 extracted human third molars with margins located above and below the cementoenamel junction. Restorations were placed in one increment using two restorative systems: 3M Filtek A110/ Single Bond (M) and 3M Filtek Z250/ Single Bond (H) in the same tooth, randomly in the buccal and lingual surfaces. Resin composites were polymerized using three techniques: Group 1 - Conventional (60 s - 600 mW/cm²); Group 2 - Soft-start (20 s - 200 mW/cm² , 40 s - 600 mW/cm²); Group 3 - Pulse Activation (3 s - 200 mW/cm², 3-min hiatus, 57 s - 600 mW/cm²). Buccolingual sections were polished, impressions taken and replicated. Specimens were assessed under scanning electron microscopy up to X1000 magnification. Scores were given for presence or absence of gaps (0 - no gap; 1 - gap in one wall; 2 - gap in two walls; 3 - gap in three walls). RESULTS: The mean scores of the groups were (±SD) were: G1M-3.0 (± 0.0); G2M-2.43 (± 0.8); G3M- 1.71 (± 0.9); G1H- 2.14 (± 1.2); G2H- 2.00 (± 0.8); G3H- 1.67 (± 1.1). Data were analyzed using Kruskal-Wallis and Dunnet's tests. No statistically significant difference (p>0.05) was found among groups. Gaps were observed in all groups. CONCLUSIONS: The photocuring technique and the type of resin composite had no influence on the internal adaptation of the material to the cavity walls. A positive effect was observed when the slow polymerization techniques were used.

Avaliou-se a microdureza de uma resina composta para dentes clareados fotoativada com diferentes fontes de luz fotoativadora. Espécimes de resina composta (3M ESPE Filtek Supreme) foram aplicados a cilindros de latão (2 mm de espessura, 5 mm de diâmetro). Três fontes comerciais de luz LED foram utilizadas para polimerizar os espécimes e os resultados foram comparados aos obtidos utilizando-se uma fonte de luz halógena convencional. As fontes de luz utilizadas no presente estudo foram: Demetron Optilux 401 (QTH), 3M ESPE Elipar FreeLight (LED 1); Kerr L.E.Demetron I (LED 2), e ColtoluxLED lights (LED 3). A microdureza das superfícies topo e base foram avaliadas com um microdurômetro digital (Dureza Vickers), sob aplicação de carga. Na superfície base não se observou diferença significante entre as fontes de luz utilizadas (ANOVA, dois critérios). Na superfície topo, a fonte de luz QTH apresentou valores de dureza significantemente maiores quando comparado aos valores apresentados quando LED 1 e LED 3 foram utilizadas. Não houve diferença significante entre QTH e LED 2. Observou-se também diferença significante entre os valores das superfície topo, que foram significantemente superiores, e base. A densidade de potência das fontes de luz fotoativadoras mostrou ser responsável pela dureza da resina composta e não a irradiância.

The microhardness of a bleaching-shade resin composite polymerized with different light-curing units was evaluated. Composite samples (3M ESPE Filtek Supreme) were applied to brass rings (2 mm in thickness, 5 mm in diameter). Three commercial LED lights were used to polymerize the specimens and the results were compared to those of a conventional halogen light. The light sources used in the present study were: Demetron Optilux 401 (QTH), 3M ESPE Elipar FreeLight (LED 1); Kerr L.E.Demetron I (LED 2), and ColtoluxLED lights (LED 3). The microhardness of the top and bottom surfaces was assessed with a digital Vickers hardness-measuring instrument, under load. At the bottom surface, no significant difference among the light sources was observed (two-way ANOVA). At the top surface, the QTH light source presented significantly higher hardness values compared to the values observed when LED 1 and LED 3 were used. There were no significant differences between the QTH and LED 2 light sources. Significantly higher hardness values were also found at the top surface when compared to the values observed at the bottom surface. The power density of the polymerization light sources seemed to be responsible for the observed resin composite hardness, not their irradiance.

O objetivo desse estudo foi investigar o efeito do pH de diferentes sistemas adesivos na polimerização de uma resina composta quimicamente ativada (Adaptic - AD), por meio do teste de resistência à tração. Os sistemas adesivos utilizados foram: ARM, Prime & Bond 2.1 (PB), Scotchbond Multi Purpose (SMP) e Single Bond (SB). Cinco grupos (n=5) foram formados: G1: AD/ARM/AD; G2: AD/PB/AD; G3: AD/SMP/AD; G4: AD/SB/AD; G5: AD/AD (sem interposição de adesivo). Uma matriz de aço inoxidável com abertura central no formato de cone (1 mm de espessura; 4 mm de diâmetro), foi utilizada para obter dois discos de resina composta. A resina AD foi inserida em uma primeira metade da matriz em incremento único. Após a polimerização da resina, uma camada de adesivo foi aplicada na superfície de união e foto-ativada. A segunda metade da matriz foi justaposta à primeira e preenchida com a resina. Após 10 min, o conjunto foi adaptado em uma máquina universal de ensaios para determinar a resistência à tração, com velocidade de 0,5 mm/min. Os dados foram submetidos a ANOVA e teste de Tukey (p<0,05). As médias (kgf) obtidas em cada grupo foram: G1: 15,23 ± 4,1; G2: 0,00 ± 0,0; G3: 16,96 ± 2,4; G4: 10,08 ± 2,7; G5: 15,44 ± 0,9. Houve diferença estatisticamente significante (p<0.05) entre os grupos G2-G1; G2-G3; G2-G4; G4-G1; G4-G3. Os sistemas com pHs mais baixos (PB e SB) apresentaram as menores médias de resistência à tração. Os achados desse estudo in vitro sugerem que o pH dos sistemas adesivos influencia na polimerização e na resistência adesiva de materiais resinosos quimicamente ativados. Os sistemas adesivos simplificados testados, com valores de pH mais baixos, mostraram graus distintos de incompatibilidade com a resina quimicamente ativada, quando comparados aos sistemas adesivos convencionais.

The purpose of this study was to investigate the effect of pH of different adhesive systems on the polymerization of a chemically cured composite resin (Adaptic - AD), by means of tensile bond strength testing. The adhesive systems tested were: ARM, Prime & Bond 2.1 (PB), Scotchbond Multi Purpose (SMP) and Single Bond (SB). Bond strength at the resin/adhesive system/resin interface was assessed. Five groups (n=5) were formed, according to following configuration: G1: AD/ARM/AD; G2: AD/PB/AD; G3: AD/SMP/AD; G4: AD/SB/AD; G5: AD/AD (no adhesive). A two-mold stainless steel matrix with a cone-shaped opening (1-mm-thick; 4 mm in diameter) was used to obtain resin discs. AD resin was inserted into the first mold, left-self curing and an adhesive layer was applied onto resin surface and light-cured. The second mold was assembled over the first and was filled with the resin. After 10 min, this setting was loaded in tension in a universal testing machine running at a crosshead speed of 0.5 mm/min. Data were submitted to one-way ANOVA and Tukey's test (p<0.05). Bond strength means (kgf) were: G1: 15.23 ± 4.1; G2: 0.00 ± 0.0; G3: 16.96 ± 2.4; G4: 10.08 ± 2.7; G5: 15.44 ± 0.9. There were statistically significant differences (p<0.05) between G2-G1; G2-G3; G2-G4; G4-G1; G4-G3. The systems with the lowest pHs (PB and SB) yielded the lowest bond strength. The findings of this in vitro study demostrates that the pH of adhesive systems influences the polymerization and bond strength of chemically cured resin materials. The low pH simplified adhesive systems showed distinct degrees of incompatibility with the chemically cured resin, when compared to the conventional adhesive systems.

O objetivo deste estudo foi mensurar a perda de massa e as alterações de rugosidade superficial de diferentes marcas de resinas compostas "flow" após teste de escovação simulada. A hipótese nula testada foi de que não haveria diferença de massa e rugosidade de superfície após o teste e de que não haveria correlação entre essas variáveis. Os materiais testados foram: Aeliteflo (Bisco), Flow-It (Pentron), Flow-It LF (Pentron), Natural Flow (DFL) e Wave (SDI). As resinas compostas Z100 (3M/ESPE) e Silux Plus (3M/ESPE) foram utilizadas como controle. Doze espécimes (5 mm de diâmetro, 3 mm de espessura) de cada material foram confeccionados de acordo com as instruções do fabricante. O teste foi conduzido em uma máquina de escovação simulada, em todos os espécimes de todos os materiais, totalizando 100.000 ciclos. Antes e depois do teste, a massa e a rugosidade de cada material foram aferidas por uma balança analítica Sartorius de 0,0001 g de precisão e pelo equipamento Hommel Tester T1000, respectivamente. Os valores obtidos foram comparados pelos testes t-pareado e Tukey (p < 0,05). Todos os materiais apresentaram diferenças estatísticas de perda de massa entre os valores iniciais e finais, com exceção da resina Flow-It LF. Entretanto, nenhuma diferença foi observada quando se comparou a porcentagem de perda de massa entre os diferentes materiais testados. Todos os materiais tornaram-se mais rugosos, sendo Wave, estatisticamente, o mais rugoso. As resinas compostas "flow" não demonstraram superioridade em relação aos materiais de controle, devendo-se esperar o desgaste por perda de massa do material e maior rugosidade após a ação da escovação. A hipótese nula antecipada foi parcialmente aceita.

The purpose of this study was to measure mass loss and surface roughness changes of different brands of flowable resin composites after a simulated toothbrushing test. The null hypotheses were that there would be no differences in mass loss and no significant changes in surface roughness after this test and that there would be no correlation between the two variables. The tested materials were Aeliteflo (Bisco), Flow-It (Pentron), Flow-It LF (Pentron), Natural Flow (DFL) and Wave (SDI). Z100 (3M/ESPE) microhybrid and Silux Plus (3M/ESPE) microfilled resin composites were used as control materials. Twelve specimens (5 mm in diameter, 3 mm thick) of each material were prepared according to manufacturers' instructions. Toothbrushing abrasion was performed on all specimens from each of the materials using a simulator. The percentage mass loss and surface roughness were assessed before and after 100,000 brushstrokes, using a Sartorius analytical balance of 0.0001 g accuracy and a Hommel Tester T1000, respectively. The measurements of both properties were statistically compared by paired t-test and Tukey's test (p < 0.05). All materials presented a statistically significant mass loss comparing initial and final values, with the exception of Flow-It LF. However, no difference was revealed when comparing the mass loss of the different tested materials. All materials became rougher and Wave presented statistically higher roughness compared to the other resin composites. Flowable resin composites did not seem to be superior to the control groups, and they can be expected to wear by mass loss and to have an increased roughness of surface after toothbrushing action. The anticipated null hypotheses were partially accepted.