RESUMEN
The aim of this study was to verify the effect of finishing and polishing procedures and glaze application on biaxial strength and surface properties of milled feldspathic ceramic blocks. Forty disc-shaped samples (14 mm diameter, 1.2 mm thickness) were divided in four groups (n = 10): C (control): no finishing and polishing; FP: finishing and polishing; G: glaze; and GFP: finishing and polishing + glaze. The specimens were subject to surface gloss (glossmeter) and roughness (profilometer) tests followed by biaxial flexural strength (universal testing machine) and Vickers hardness (microhardness tester) tests. The surface morphological analysis was performed by scanning electron microscopy (n = 3). Data were submitted to normality tests with Shapiro-Wilk, and one-way ANOVA followed by Tukey's post hoc test (α = 0.05). Group C showed the lowest gloss. For the hardness test, groups C, FP, and GFP obtained the highest values without significant differences between them. Regarding the biaxial strength test, group C showed the lowest mean value. Both finishing and polishing methods (FP and GFP) showed surface properties similar or better than the control, and with higher biaxial strength.
Asunto(s)
Pulido Dental , Porcelana Dental , Porcelana Dental/química , Ensayo de Materiales , Pulido Dental/métodos , Diseño Asistido por Computadora , Cerámica/química , Propiedades de SuperficieRESUMEN
AIM: To evaluate possible modifications in root canal sealers subjected to a variety of heating conditions using vibrational spectroscopy and analysis of physical and chemical properties. METHODOLOGY: EndoSequence BC Sealer HiFlow, Bio-C Sealer, BioRoot RCS and AH Plus were analysed chemically using Raman spectroscopy (25-220 °C) and Fourier-transform infrared spectroscopy (FT-IR) (37-100 °C ). For FT-IR, the materials were tested individually and mixed with root dentine powder. Scanning electron microscopy (SEM) and coupled energy dispersive spectroscopy (EDS) were used to evaluate surface and chemical elements. ISO 6876-2012 and ASTM-C266-07 specifications were followed to evaluate flow, setting time (moist and dry), solubility and radiopacity. Also, pH analysis at 37 and 100 °C was performed. Shapiro-Wilk and Mixed ANOVA (within and between the effects of the subjects), Levene, and a post hoc analyses with Bonferroni correction were performed (P < 0.05). RESULTS: Vibrational spectroscopy revealed peaks of tricalcium silicate, dicalcium silicate and zirconium dioxide. Chemical changes in the Raman spectra during heating were discrete, as the inorganic content predominated the signalling for all root canal sealers. FT-IR analysis exhibited spectral changes in water absorption for EndoSequence BC Sealer HiFlow and Bio-C Sealer, probably related to dehydration. For BioRoot RCS and AH Plus, no significant chemical changes were observed. Bio-C Sealer exhibited a band of polyethylene glycol only after heating to 100 °C, probably related to its thermal decomposition. SEM/EDS analysis corroborated the composition results observed in vibrational spectroscopy for all materials. Heating to 100 °C significantly changed the flowability of all calcium silicate-based sealers with a wide variation in setting times at both temperatures, along with solubility levels above ISO standards. For all tested sealers, radiopacity fulfilled the requirements, and pH exhibited alkaline values. CONCLUSIONS: The tested calcium silicate-based sealers were affected by heating. Calcium silicate-based root canal sealers had high solubility which is a concern for their clinical use. AH Plus was the only root canal sealer that was stable after heating.
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Calefacción , Materiales de Obturación del Conducto Radicular , Compuestos de Calcio , Resinas Epoxi , Humanos , Ensayo de Materiales , Silicatos , Espectroscopía Infrarroja por Transformada de FourierRESUMEN
AIM: To evaluate the influence of different enamel etching times on the bond strength of two self-adhesive resin cements (RCs) with and without thermocycling (TMC). METHODS: One hundred twenty bovine teeth were used. Blocks of enamel (8×4×2mm) were obtained, polished, and randomly divided into two groups, according to the RC used: MaxCem Elite or RelyX U200. Groups were subdivided into four groups (n=16), according to the etching time: Control (0 seconds), 5 seconds, 10 seconds, and 20 seconds. Three RC cylinders (1-mm diameter) were built on each enamel block. The specimens were submitted to two storage conditions: 24 hours in distilled water or TMC (5000 cycles/5°C-55°C). Afterward, the specimens were submitted to the shear bond strength (SBS) test. The failure modes and adhesive interfaces were analyzed by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Data were analyzed with three-way analysis of variance (ANOVA) and Tukey test (α=0.05). RESULTS: Etching increased the SBS for both the RCs,especially forthe groups etched for 5 and 10 seconds. TMC affected negatively the SBS of the control groups (p<0.05). No resin tags were observed in control groups, and the formation of tags was time dependent. CONCLUSION: The 10 seconds etching time was more effective in increasing the enamel-resin bond strength. TMC negatively affected bond strength in specimens without acid etching.
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Recubrimiento Dental Adhesivo , Cementos de Resina , Grabado Ácido Dental , Animales , Bovinos , Cementos Dentales , Esmalte Dental , Cementos de Resina/químicaRESUMEN
This study aimed to quantify the concentration of hydrogen peroxide into the pulp chamber in the presence or absence of adhesive enamel restorations and to analyze the resin-dentin interface of bleached groups. Bovine incisors (120) were randomly divided into three groups according to enamel treatment (n=40 each): (1) enamel without restoration (control); (2) enamel cavities (3 mm diameter × 1.5 mm depth) restored with a silorane-based (SB) system; or (3) enamel cavities (3 mm diameter × 1.5 mm depth) restored with a dimethacrylate-based (DB) system. Restorations were thermocycled, and all groups were submitted to one application of 35% hydrogen peroxide (HP) agent for 45 minutes and subjected to four light activation methods (n=10 each): without light, light-emitting diode (LED), LED/diode laser, or halogen light. Acetate buffer solution was placed into the pulp chamber before bleaching, and this solution was collected to spectrophotometrically determine the concentration of HP that reached the pulp chamber after bleaching. Rhodamine B was added to the HP agent and applied on additional enamel samples of each group for 24 hours. Samples were sectioned mesiodistally, and the bleaching agent was traced using confocal microscopy. According to two-way analysis of variance and Tukey test (α=0.05), the HP concentration in the pulp chamber of the control group was significantly lower than that of the SB group (p<0.05), regardless of light activation. No differences were observed between DB and SB groups and between control and DB groups, except for the DB halogen light activated group, which exhibited higher HP intrapulpal concentration (p<0.05). Confocal microscopy exhibited HP diffusion through the interface of the SB and DB restored groups as well as enamel prisms in the control group. The SB restorative system increased the HP diffusion into the pulp chamber, but HP was able to diffuse even in the absence of enamel restorations.
Asunto(s)
Resinas Compuestas/farmacología , Permeabilidad del Esmalte Dental , Cavidad Pulpar/efectos de los fármacos , Peróxido de Hidrógeno/farmacología , Cementos de Resina/farmacología , Resinas de Silorano/farmacología , Animales , Bovinos , Restauración Dental Permanente , Técnicas In Vitro , Ensayo de Materiales , Microscopía Confocal , Rodaminas , Blanqueamiento de DientesRESUMEN
AIM: To evaluate the effects of two methods to simulate physiological pulpal pressure on the dentine bonding performance of two all-in-one adhesives and a two-step self-etch silorane-based adhesive by means of microtensile bond strength (µTBS) and nanoleakage surveys. METHODOLOGY: The self-etch adhesives [G-Bond Plus (GB), Adper Easy Bond (EB) and silorane adhesive (SIL)] were applied to flat deep dentine surfaces from extracted human molars. The restorations were constructed using resin composites Filtek Silorane or Filtek Z350 (3M ESPE). After 24 h using the two methods of simulated pulpal pressure or no pulpal pressure (control groups), the bonded teeth were cut into specimens and submitted to µTBS and silver uptake examination. Results were analysed with two-way anova and Tukey's test (P < 0.05). RESULTS: Both methods of simulated pulpal pressure led statistically similar µTBS for all adhesives. No difference between control and pulpal pressure groups was found for SIL and GB. EB led significant drop (P = 0.002) in bond strength under pulpal pressure. Silver impregnation was increased after both methods of simulated pulpal pressure for all adhesives, and it was similar between the simulated pulpal pressure methods. CONCLUSIONS: The innovative method to simulate pulpal pressure behaved similarly to the classic one and could be used as an alternative. The HEMA-free one-step and the two-step self-etch adhesives had acceptable resistance against pulpal pressure, unlike the HEMA-rich adhesive.