Surface pre‐reacted glass‐ionomer (S‐PRG) technology allows for the release of multiple ions. This study was performed to investigate the remineralization of etched enamel after removal of the bracket using a novel paste containing S‐PRG filler. Surfaces of polished enamel were etched with phosphoric acid and then subdivided into two regions. Bracket bonding resin was thinly applied to one region. After 24‐hr immersion in artificial saliva, the bonding resin on the enamel surfaces was removed by grinding with tungsten carbide bur at low‐speed, followed by polishing with one of four different polishing systems: (a) nonfluoridated paste (NF); (b) fluoridated paste (F); (c) S‐PRG filler‐containing paste (S‐PRG); or (d) nonfluoridated plus S‐PRG filler‐containing paste (NF + S‐PRG) (n = 15). The polished specimens were then immersed in an artificial saliva solution for 7 days. Nanoindentation testing of enamel surfaces was performed and their mechanical properties were compared. Representative specimens were examined with scanning electron microscope. In all specimens, the mechanical properties of the enamel surfaces were markedly degraded by acid etching. However, the mechanical properties of both regions (etched and resin‐infiltrated enamels) showed recovery after polishing and 7‐day immersion. Polishing with NF + S‐PRG paste led to significant recovery of mechanical properties compared to polishing with NF or S‐PRG paste alone, and remineralization was equivalent to that seen with F paste. Porous etched enamel surfaces were filled with a remineralization layer after each polishing procedure and 7‐day immersion in all polishing groups. Polishing using NF + S‐PRG paste can facilitate enamel remineralization after bracket removal.

We investigated the remineralization of demineralized enamel surfaces through the application of bioactive glass (BG) and chitosan nanoparticles (CNPs). BG and CNPs were immersed in artificial saliva for 7 days. The resulting crystals were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Embedded enamel blocks were immersed in demineralization solution and then classified into five treatment groups: (1) No material applied; (2) toothpaste containing NaF (F); (3) CNP hydrogel; (4) distilled water slurry containing BG; and (5) CNP hydrogel containing BG (BG-CNP). The enamel blocks were immersed in an artificial saliva solution for 1 month; each material was applied twice per day. Nanoindentation testing of enamel surfaces was performed during the immersion period. We found that unidirectional rod-shaped crystals formed in the artificial saliva solutions treated with BG and BG-CNP, showing multiple XRD peaks for hydroxyapatite. The mechanical properties of enamel surfaces decreased markedly following immersion in the demineralization solution, and significantly recovered after 1 month of BG-CNP and BG treatment compared to other the specimens. Porous demineralized enamel surfaces were filled with a remineralization layer after immersion in saliva and application of NaF, BG, and CNP-BG. Thus, daily application of CNP-BG or BG facilitates enamel remineralization.

This study demonstrated well-controlled circular polarization switching dual-comb spectroscopy using coherent controllability of combs. Applicability of circular dichroism spectroscopy has been verified using circular polarizers. The developed method realizes high-sensitivity, high-speed, and broadband circular-dichroism characterizations.