Abstract
White spot lesions (WSL) that occur on teeth after orthodontic appliances have been attached are caused by bacterial demineralization of the enamel surface. This study investigated the anti-demineralization effect of orthodontic resins containing mesoporous bioactive glass nanoparticles (MBN) doped with gallium, which has antibacterial activity, as well as MBN with increased calcium and phosphate contents as these ions can remineralize enamel. Resins (CF, CharmFill Flow, Dentkist, Seoul, South Korea) containing 1%, 3%, and 5% Ga-doped MBN (GaMBN) were characterized using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and isothermal tests, and their physical properties were measured in terms of Vickers microhardness, bracket retention force, and adhesive remnant index (ARI). Cell viability in the resins was confirmed by testing human dental pulp stem cells (hDPSCs), and ion release tests were performed after 1, 7, and 14 days to determine whether the resins released Ga3+, Ca2+, and PO43–. After 14 days, antibacterial activity was determined using Streptococcus mutans (S. mutans)—the bacteria that causes tooth decay—and the chemical remineralization effect was investigated using a cycle of acid–base solutions. The microhardness of the resins increased with GaMBN concentration whereas their bracket retention force, ARI, and cell viability remained unchanged. The bacterial activity of the 5%-GaMBN resin decreased after 24 and 48 h; however, the change in activity was not statistically significant. Anti-demineralization testing demonstrated that the degree of enamel demineralization decreased as the GaMBN concentration increased, which indicates that resins containing 5%-GaMBN may be viable orthodontic adhesives for preventing WSLs.
Highlights
White spot lesions (WSLs) on enamel around orthodontic brackets is a common side effect of orthodontic treatment because cariogenic bacteria such as Streptococcus mutans (S. mutans) colonize plaque deposited around the brackets and produce acids such as lactic acid, which demineralize the enamel surface [1,2,3]
The adhesive remaining on teeth that were separated from their bracket was assessed using the adhesive remnant index (ARI): (1) All of the adhesive remained on the tooth; (2) more than 90% of the adhesive remained on the tooth; (3) 10–90% of the adhesive remained on the tooth; (4) less than 10% of the adhesive remained on the tooth; and (5) no adhesive remained on the tooth
This study of Ga-doped MBN (GaMBN)-containing resins demonstrated that these resins exhibit the physical and biological properties required for safe clinical use, as well as the ability to prevent demineralization
Summary
White spot lesions (WSLs) on enamel around orthodontic brackets is a common side effect of orthodontic treatment because cariogenic bacteria such as Streptococcus mutans (S. mutans) colonize plaque deposited around the brackets and produce acids such as lactic acid, which demineralize the enamel surface [1,2,3]. White spot legions on anterior teeth are considered unaesthetic as the demineralized enamel is often whiter than the surrounding enamel [6]; clinicians have made several attempts to prevent the formation of WSLs [7]. Researchers have attempted to incorporate antibacterial agents in orthodontic adhesives in order to reduce the causative bacteria and prevent WSLs caused by orthodontic devices [8,9,10,11]. According to a study by Valappil et al, Ga-doped
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