Abstract
White spot lesions (WSLs), due to enamel demineralization, occur frequently in orthodontic treatment. We recently developed a novel rechargeable dental composite containing nanoparticles of amorphous calcium phosphate (NACP) with long-term calcium (Ca) and phosphate (P) ion release and caries-inhibiting capability. The objectives of this study were to develop the first NACP-rechargeable orthodontic cement and investigate the effects of recharge duration and frequency on the efficacy of ion re-release. The rechargeable cement consisted of pyromellitic glycerol dimethacrylate (PMGDM) and ethoxylated bisphenol A dimethacrylate (EBPADMA). NACP was mixed into the resin at 40% by mass. Specimens were tested for orthodontic bracket shear bond strength (SBS) to enamel, Ca and P ion initial release, recharge and re-release. The new orthodontic cement exhibited an SBS similar to commercial orthodontic cement without CaP release (P>0.1). Specimens after one recharge treatment (e.g., 1 min immersion in recharge solution repeating three times in one day, referred to as “1 min 3 times”) exhibited a substantial and continuous re-release of Ca and P ions for 14 days without further recharge. The ion re-release did not decrease with increasing the number of recharge/re-release cycles (P>0.1). The ion re-release concentrations at 14 days versus various recharge treatments were as follows: 1 min 3 times>3 min 2 times>1 min 2 times>6 min 1 time>3 min 1 time>1 min 1 time. In conclusion, although previous studies have shown that NACP nanocomposite remineralized tooth lesions and inhibited caries, the present study developed the first orthodontic cement with Ca and P ion recharge and long-term release capability. This NACP-rechargeable orthodontic cement is a promising therapy to inhibit enamel demineralization and WSLs around orthodontic brackets.
Highlights
IntroductionWhite spot lesions (WSLs) have been reported as a prevailing and challenging problem in fixed orthodontic therapy
White spot lesions (WSLs) have been reported as a prevailing and challenging problem in fixed orthodontic therapy.1–4 The irregular surfaces of brackets, bands, wires and other attachments provide areas for biofilm/plaque build-up that are difficult to clean.1–3 These conditions promote the colonization of cariogenic bacteria, which produce acids to induce enamel demineralization and can lead to WSLs.5–7 It was reported that 50%–70% of patients with fixed orthodontic therapy had WSLs,8–9 and that it took only 1 month to develop WSLs.10 Extensive efforts were made to improve the properties of dental materials, including the use of anti-bacterial agents,11–15 reducing polymerization stresses,16–19 enhancing adhesive systems,20–22 and improving clinical operating methods.23–24 Previous efforts included methods to combat WSLs in orthodontic treatment
We recently developed a novel rechargeable dental composite containing nanoparticles of amorphous calcium phosphate (NACP) with long-term calcium (Ca) and phosphate (P) ion release and caries-inhibiting capability
Summary
White spot lesions (WSLs) have been reported as a prevailing and challenging problem in fixed orthodontic therapy.. The irregular surfaces of brackets, bands, wires and other attachments provide areas for biofilm/plaque build-up that are difficult to clean.. The irregular surfaces of brackets, bands, wires and other attachments provide areas for biofilm/plaque build-up that are difficult to clean.1–3 These conditions promote the colonization of cariogenic bacteria, which produce acids to induce enamel demineralization and can lead to WSLs.. It was reported that 50%–70% of patients with fixed orthodontic therapy had WSLs, and that it took only 1 month to develop WSLs.. Extensive efforts were made to improve the properties of dental materials, including the use of anti-bacterial agents, reducing polymerization stresses, enhancing adhesive systems, and improving clinical operating methods.. Previous efforts included methods to combat WSLs in orthodontic treatment.
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