Rigolac

After the acid challenge, each sample was washed with xylene. After carbon vapor deposition was performed for the analyte sample surface, the tooth surface was observed using a scanning electron microscope (SU6600, HITACHI Ltd., Tokyo, Japan) at an accelerating voltage of 15 kV. The samples were then embedded in polyester resin (Rigolac, Nisshin EM, Tokyo, Japan) to prepare polished sections, and the cross-sections were observed.

The imaging conditions and analysis method were based on those by Sato et al., with reference to Angmar’s formula [16 (link),17 (link)]. The samples were embedded in a polyester resin (Rigolac, Nisshin EM, Tokyo, Japan) to prepare 100 µm thick polished sections. Soft X-ray imaging was performed (CMR-3, Softex, Tokyo, Japan) with a 20 µm Ni filter and light microscopy at 200× magnification using a glass plate (High Precision Photo Plate, HRP-SN-2; Konica Minolta, Tokyo, Japan). Imaging was performed using a tube voltage, tube current, and radiation time of 15 kV, 3 mA, and 15 min, respectively. The resulting images were analyzed using the Image Pro Plus software (version 6.2; Media Cybernetics Inc., Silver Spring, MD, USA) and image analysis system (HC-2500/OL; OLYMPUS Corp., Tokyo, Japan) to obtain the concentration profile. Mineral loss value (ΔZ) and lesion depth (Ld) were determined to compare the extent of demineralization. ΔZ was calculated using a formula, and Ld was defined as the distance from the enamel surface to the lesion location with a mineral content higher than 95% compared to that of sound enamel.

Following pH-cycling, each sample was rinsed with xylene, and carbon vapor deposition was applied to the surface of the analyte sample. The tooth surfaces were examined under a scanning electron microscope (SU6600; HITACHI Ltd., Tokyo, Japan) at an accelerating voltage of 15 kV. The samples were then embedded in a polyester resin (Rigolac, Nisshin EM, Tokyo, Japan) to create polished sections, and the cross-sections were observed.

The samples were subjected to carbon deposition during pre-measurement preparation using a vacuum deposition device (VC-100S; Vacuum Device Co., Ltd., Ibaraki, Japan). The samples were embedded in polyester resin (Rigolac; Nisshin EM Co., Ltd., Tokyo, Japan), mirror-polished, and observed in cross sections. The surfaces of their samples were observed using an SEM (SU6600; Hitachi Co., Ltd., Tokyo, Japan) at a voltage of 15 kV. The photographing magnification was 10,000× for surface observation and 5000× for cross-sectional observation.

After the pH cycling, each sample was washed with xylene and then subjected to carbon vapor deposition on its surface. The tooth surfaces were examined using a scanning electron microscope (SU6600; HITACHI Ltd., Tokyo, Japan) with an acceleration voltage of 15 kV. The samples were then embedded in polyester resin (Rigolac, Nisshin EM, Tokyo, Japan) to create polished sections, which were then observed.