Stem su8230

Two dentin specimens from each tooth, which represents 10 specimens from each tested material, were prepared for SEM and EDX analyses. The same specimens were used for both analyses. The samples were dried in a graded ethanol series (50–100%), and then sputter-coated with gold. SEM was performed under high-vacuum conditions (Hitachi SU8230 STEM). Two photomicrographs were captured for each section to observe details at the tooth-restoration interface (the intimate adaptation of the adhesive-resin layer to the dentine, the hybrid layer) and the materials’ structures. The photomicrographs were analyzed by a single examiner (LB) using a blinded protocol, and measurements of the hybrid layers and resinous tags penetrating the dentin were performed using ImageJ software. EDX was performed using a Hitachi SU8230 STEM under the following conditions: 30 kV acceleration voltage, 10 µA extraction current, 15 mm working distance, Oxford Instruments EDS detector placed inside the sample chamber, and AZtec Software. Measurements were performed at the same magnifications of similar surfaces (three ROIs) for all samples: the healthy tooth, the added restorative material, and the transition material between the healthy tooth and the restorative material. Ten measurements for each material were averaged to provide a single mean value for each parameter for each specimen.

The morphology and diameters of silica and silica gold particles were determined using a scanning transmission electron microscope (STEM SU8230, Hitachi, Tokyo, Japan) and a scanning electron microscope (SEM JXA—8530F, JEOL, Tokyo, Japan). The diameters of the AuNPs were obtained by measuring at least 50 particles from STEM images with Image J software bundled with Java 8 (Stapleton, NY, USA).

The morphology and diameters of AuNPs were determined using a scanning transmission electron microscope (STEM SU8230, Hitachi, Tokyo, Japan). The diameters of the AuNPs were obtained by measuring at least 50 particles with Image J software [30 (link)]. DLS and Z potential were performed using a Zetasizer Nano ZS (Malvern Panalytical, Worcestershire, UK). Infrared absorption spectra of dried AuNPs and lyophilized extracts were recorded using Fourier-transformed infrared (FT-IR) equipment (Spectrometer Spectrum Two, PerkinElmer, Waltham, MA, USA). The X-ray pattern of the AuNPs was obtained with an X-ray diffractometer (Dmax 2100 Rigaku Americas, The Woodlands, TX, USA) that has a CuKα radiation generator (k = 1.5418° A), from 5 to 50 °, on a 2θ scale, with a step size of 0.02° [31 (link)]. The thermal analysis of the AuNPs was carried out using a TGA-50, Shimzadu thermogravimetric analyzer (Shimzadu Corp., Kyoto, Japan) by increasing the temperature from 25 to 800 °C at the rate of 5 °C/min, and nitrogen gas flow rate of 10 mL/min.