Surface Reaction-type Pre-reacted Glass-ionomer Research Articles

In vitro remineralization assessment of enamel subsurface lesions using different percentages of surface reaction-type pre-reacted glass-ionomer containing gum-based material

ObjectiveTo identify the remineralization activity of enamel subsurface lesions using different percentages of surface pre-reacted glass-ionomer (S-PRG) filler containing gum-base material. MethodsGum extracts from gum-base materials containing 0wt%, 5wt%, and 10wt% S-PRG filler were prepared as GE0, GE5, and GE10, respectively. A total of 50 bovine enamel specimens were used, and the polished enamel surface of a 3 × 3 mm2 window area was exposed. The specimens were then subjected to a demineralization solution for seven days to create a subsurface enamel lesion. Remineralization was then conducted for seven days using a protocol whereby the specimens were immersed three times a day in prepared gum extracts (0wt%, 5wt%, and 10wt%) and artificial saliva of pH 7 (Control) for 20 min at 37 °C. Thereafter, remineralization assessment was performed by using Swept Source Optical Coherence Tomography (SS-OCT) and micro-computed tomography (μCT). Surface morphology and elemental analysis were conducted by scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDS). ResultsThe depths of the demineralized lesions in the GE5 and GE10 groups were significantly lower than those of the Control and the GE0 groups. SEM observations of the enamel surface morphology of the GE5 and GE10 groups indicated remineralization with S-PRG filler-related elements present. ConclusionThe GE5 and GE10 S-PRG filler containing gum-base materials showed significantly improved surface remineralization and reduced demineralization of the enamel lesions. EDS analysis suggested that the released ions from the S-PRG filler might be responsible for surface remineralization. Clinical significanceThe S-PRG filler containing gum-base material may have a significant remineralization effect and improve the surface morphology of enamel subsurface lesions.

Effects of a co-stimulation with S-PRG filler eluate and muramyl dipeptide (MDP) on matrix metalloproteinase-1 production by human dental pulp fibroblast-like cells.

The present study investigated the effects of a co-stimulation with surface reaction-type pre-reacted glass-ionomer (S-PRG) filler eluate and muramyl dipeptide (MDP) on matrix metalloproteinase (MMP)-1 production by human dental pulp fibroblast-like cells (hDPFs). S-PRG filler eluate contains 6 ions (F, Na, Al, B, Sr, and Si) released from S-PRG filler. Each S-PRG filler eluate and MDP stimulation enhanced MMP-1 production by hDPFs. The co-stimulation with S-PRG filler eluate and MDP enhanced MMP-1 production more than the MDP stimulation alone. A similar stimulation induced the phosphorylation of ERK 1/2. The increased secretion of MMP-1 and enhanced phosphorylation of ERK 1/2 by the co-stimulation with S-PRG filler eluate and MDP were suppressed by the selective and potent CaSR antagonist NPS 2143. Since strontium binds to CaSR, these results suggest that the enhanced production of MMP-1 by the co-stimulation with S-PRG filler eluate and MDP was due to the effects of strontium.

The bleaching effect of office bleaching agents containing S-PRG filler evaluated by pH value and electron spin resonance.

Surface reaction-type pre-reacted glass-ionomer (S-PRG) filler releases six types of ions with a neutralizing ability. This study evaluated the effect of S-PRG filler incorporation in an H2O2-based bleaching material on the bleaching efficacy, pH, and reaction state. The experimental bleaching material was formulated by the addition of 5% or 10% S-PRG fillers to the powder part. The stained bovine teeth were treated with the prepared bleaching paste. Commission internationale de l'éclairage (CIE) L*a*b* color space values were recorded before and after bleaching, and the color difference (ΔE) and whiteness index (WID) were calculated. Moreover, the used bleaching formulations were assessed for their pH values and reaction state by evaluating the oxidation state of manganese (Mn+2) using electron spin resonance (ESR). The results of ΔE and WID showed that the addition of S-PRG filler increased the bleaching effect, but there was no significant difference between the groups with 5% and 10% S-PRG filler. A significant increase in pH in S-PRG filler groups (5% pH 6.7, 10% pH 6.8) was found compared to the 0% group (pH 4.8). ESR measurements showed that the signal emitted from Mn+2 decreased over time. The S-PRG filler groups showed a significantly higher reduction in Mn+2 compared to the 0% group, with no significant difference between the 5% and 10% S-PRG groups. S-PRG filler addition resulted in improved bleaching efficacy, higher reaction rate, and pH values that are close to neutral. S-PRG filler addition may be effective on thebleachingoutcome of H2O2-based materials.

Evaluation of the anti-inflammatory effects of surface-reaction-type pre-reacted glass-ionomer filler containing root canal sealer in lipopolysaccharide-stimulated RAW264.7 macrophages.

A prototype surface-reaction-type pre-reacted glass-ionomer (S-PRG) filler containing root canal sealer (S-PRG sealer) exhibits bioactive potential by releasing multiple ions. This study explored the suppressive effects and modes of action of S-PRG sealer extracts on proinflammatory cytokine expression in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Expression of proinflammatory cytokines was evaluated by RT-qPCR and ELISA. Expression of phosphorylated nuclear factor-kappa B (p-NF-kB) p65 was evaluated by western blotting. S-PRG sealer extracts significantly downregulated mRNA expression levels of interleukin (IL)-1α, IL-6, and TNF-α in LPS-stimulated RAW264.7 cells; the extracts also reduced the levels of IL-6 protein and p-NF-kB. In order to verify that Zn2+ was responsible for downregulation of proinflammatory cytokine expression, N,N,N',N'-tetrakis(2-pyridylmethyl) ethylenediamine (TPEN) was used as a heavy metal chelator with strong affinity for Zn2+. These effects were mitigated by TPEN. The application of ZnCl2 reproduced the actions of S-PRG sealer extracts. These data suggest that S-PRG sealer has anti-inflammatory potential involving heavy metal ions such as Zn2+.

Effects of S-PRG filler eluate on MMP-1 and MMP-3 secretion by human gingival fibroblasts.

The aim of this study was to investigate the effects of surface reaction-type pre-reacted glass-ionomer (S-PRG) filler eluate on Matrix metalloproteinase (MMP)-1 and MMP-3 secretion by human gingival fibroblasts (HGF). The S-PRG filler eluate contains 6 ions (F, Na, Al, B, Sr and Si) released from the S-PRG filler. The S-PRG filler eluate stimulation induced a slight secretion of MMP-1 and MMP-3 by HGF. It also enhanced the phosphorylation of p38 and ERK. The increase in MMP-1 and MMP-3 secretion by the inflammatory cytokine TNF-α was suppressed by the S-PRG filler eluate. TNF-α-induced increases in the phosphorylation of ERK were slightly enhanced by S-PRG filler eluate. These findings may prompt the development of new therapeutic agents for oral inflammation with materials composed of S-PRG filler eluate.

Dentin anti-demineralization potential of surface reaction-type pre-reacted glass-ionomer filler containing self-adhesive resin cement.

To investigate the anti-demineralization potential of a newly developed surface reaction-type pre-reacted glass-ionomer (S-PRG) filler containing self-adhesive resin cement against acidic attacks on the dentin surface. A total of 32 bovine teeth were used. Cavities were prepared on crown dentin slaps and filled with three self-adhesive resin cement: (1) S-PRG-based cement, (2) Si-based cement, and (3) RelyX cement. Specimens were then subjected to pH cycling for 28days, and the depth of demineralization was assessed using swept-source optical coherence tomography (SS-OCT) after 7, 14, 21, and 28days. Sixty-four root dentin blocks were divided into four groups and then subjected to a pH cycling procedure with the aforementioned three material blocks and one negative control. The mineral loss was observed using transverse microradiography (TMR), and the surface microhardness (SMH) test was conducted to investigate the mechanical properties of treated dentin surfaces. The depth of demineralization for the S-PRG-based cement was significantly lower than that of the Si-based cement after 7, 21, and 28days. Conversely, the RelyX cement was not significantly different from the Si-based cement after 7, 14, and 21days (p < 0.05). Regarding the TMR and SMH test, the S-PRG-based cement showed the least mineral loss with the highest resistance to acidic challenge. The S-PRG filler containing resin cement can reduce mineral loss and promote remineralization of dentin substrate and has the potential to preserve dentin integrity and resist acidic attack. Clinical significance Self-adhesive resin cement containing S-PRG fillers maintained the surface integrity of dentin after exposure to 28days of acidic challenge with a significant anti-demineralization effect.

A Novel Bioactive Endodontic Sealer Containing Surface-Reaction-Type Prereacted Glass-Ionomer Filler Induces Osteoblast Differentiation.

Surface-reaction-type prereacted glass-ionomer (S-PRG) fillers exhibit bioactive properties by the release of multiple ions. This study examined whether a novel endodontic sealer containing S-PRG fillers (PRG+) has the capacity to induce osteoblast differentiation. Kusa-A1 osteoblastic cells were cultured with extracts of PRG+, PRG− (an experimental sealer containing S-PRG-free silica fillers), AH Plus (an epoxy-resin-based sealer), and Canals N (a zinc-oxide noneugenol sealer). Cell viability and mineralized nodule formation were determined using WST-8 assay and Alizarin red staining, respectively. Osteoblastic-marker expression was analyzed with RT-qPCR and immunofluorescence. Phosphorylation of extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (MAPK) was determined with Western blotting. Extracts of freshly mixed PRG+, PRG−, and AH Plus significantly decreased cell growth, but extracts of the set samples were not significantly cytotoxic. Set PRG+ significantly upregulated mRNAs for alkaline phosphatase and bone sialoprotein (IBSP) compared to set PRG−, and upregulation was blocked by NPS2143, a calcium-sensing receptor antagonist. Set PRG+ significantly accelerated IBSP expression, mineralized nodule formation, and enhanced the phosphorylation of ERK and p38 compared with set PRG−. In conclusion, PRG+ induced the differentiation and mineralization of Kusa-A1 cells via the calcium-sensing receptor-induced activation of ERK and p38 MAPK.

Optimal dilutions of S-PRG filler eluate for experiments on human gingival fibroblasts in vitro.

The present study attempted to identify the optimal dilution at which at which the effects of surface reaction-type pre-reacted glass-ionomer (S-PRG) filler eluate on human gingival fibroblasts (HGF) may be safely examined in vitro. S-PRG filler is a material that releases six ions and exerts strong caries-suppressing effects. We prepared S-PRG filler eluate in which S-PRG filler and α-MEM were mixed as a medium for HGF. This eluate contains six ions that are released from S-PRG filler. All cells died in proliferation experiments on HGF using S-PRG filler eluate, which demonstrated that unless S-PRG filler eluate was diluted, the ion concentration was strongly cytotoxic. S-PRG filler eluate diluted by 1/100 or more with the addition of 2% or more of FBS was safe for use. We herein successfully established the optimal dilution of S-PRG filler eluate at which HGF may be safely examined in vitro.

Effects of pastes containing ion-releasing particles on dentin remineralization

We investigated the effects of the weekly application of pastes containing a surface reaction-type pre-reacted glass-ionomer (S-PRG) filler on dentin remineralization. Human dentin blocks were demineralized and polished using pastes containing S-PRG filler (0, 5, and 30%), and then immersed in remineralizing solution for 1 month. Nanoindentation testing was carried out during the immersion period, and the dentin surfaces were examined using scanning electron microscopy. A nano-hydroxyapatite-containing paste was used for comparison. Immersion in demineralization solution had a marked negative effect on the mechanical properties in all specimens. The mechanical properties of specimens polished with S-PRG filler-containing pastes recovered significantly after immersion in remineralization solution for 1 month compared with the other specimens. After remineralization, the open dentinal tubules were filled with a remineralization layer in specimens polished with S-PRG filler-containing and nano-hydroxyapatite-containing pastes. S-PRG filler-containing pastes can aid dentin remineralization.

Effect of a coating material containing surface reaction-type pre-reacted glass-ionomer filler on prevention of primary enamel demineralization detected by optical coherence tomography.

We used optical coherence tomography to examine the effect of a coating material containing surface reaction-type pre-reacted glass-ionomer (S-PRG) filler on primary enamel demineralization in 18 extracted human primary teeth. The pulp was removed, and each tooth was ultrasonically cleaned with distilled water. Six teeth were treated with 0.1-M lactic acid buffer solution (De group). In the second group (n = 6), a thin film of coating material was applied before demineralization (PRG group). A third group (Control group; n = 6) was maintained in artificial saliva. Using optical coherence tomography, we measured peak signal intensity (dB) and width at 1/e2 (µm) at predetermined locations on the enamel surface and calculated integrated values. All data were analyzed with ANOVA and the Tukey-Kramer test (α = 0.05). Although changes in integrated values differed between groups, there was a small but significant increase in the Control group and a small but significant decrease in the De group. In the PRG group, integrated values were significantly higher at 7 days after the start of the experiment and significantly increased thereafter. Our findings indicate that a coating material containing S-PRG fillers may prevent primary enamel demineralization.

Effect of topical fluoride application on enamel after in‐office bleaching, as evaluated using a novel hardness tester and a transverse microradiography method

This study evaluated the effect of topical fluoride application on enamel hardness after in-office bleaching. Twelve human incisors were cut along the long axis, resulting in 24 halves used in four treatment groups (n = 6 in each group): (i) untreated group (C); (ii) in-office bleaching material (B); (iii) treatment with surface reaction-type prereacted glass-ionomer varnish after in-office bleaching (B+PRG); and (iv) treatment with acidulated phosphate fluoride solution after bleaching (B+F). All specimens were subjected to pH-cycling for 4 wk. Knoop hardness was measured using a Cariotester. The decalcification of enamel was assessed quantitatively by measuring the integrated mineral loss (ΔIML). Games-Howell analysis was used to assess statistical significance of between-group differences. The Knoop hardness decreased significantly after bleaching for all groups. In treatment groups B+PRG and B+F, the Knoop hardness returned to the original unbleached values after the first pH cycle and did not change afterwards. In treatment groups C and B there was a gradual decrease in the Knoop hardness until the fourth pH cycle. The integrated mineral loss, ΔIML, was significantly higher in treatment group B+F after 2 wk than in the other treatment groups. After 4 wk, the ΔIML in treatment group B was significantly higher than in treatment group B+PRG. The application of fluoride-containing materials after bleaching results in recuperation of hardness to levels similar to those of unbleached enamel.

The effects of single application of pastes containing ion-releasing particles on enamel demineralization.

We investigated single application of pastes containing a surface reaction-type pre-reacted glass-ionomer (S-PRG) filler on enamel demineralization. Human enamel blocks were polished using pastes containing S-PRG filler (0, 5, and 30%) and immersed in demineralizing solution for 5 days with daily change of solutions. The pH measurement and nanoindentation testing was carried out during the immersion period, and the enamel surfaces were examined using scanning electron microscopy and atomic force microscopy. A non-fluoride paste and a hydroxyapatite-containing paste were used for comparison. The specimens polished with the S-PRG filler-containing paste exhibited acid-neutralizing properties, which became stronger with an increasing S-PRG filler content. Following immersion in the demineralizing solution, specimens polished with the S-PRG filler-containing paste exhibited significantly greater hardness and elastic modulus values than those polished with the other pastes and exhibited a smoother surface than did the other specimens. Pastes containing S-PRG filler inhibits the demineralization of enamel.

Caries Prevention After Surface Reaction-Type Prereacted Glass Ionomer Filler-Containing Coating Resin Removal from Root Surfaces

Caries Prevention After Surface Reaction-Type Prereacted Glass Ionomer Filler-Containing Coating Resin Removal from Root Surfaces

Effects of pre-reacted glass-ionomer cement on the viability and odontogenic differentiation of human dental pulp cells derived from deciduous teeth

Surface reaction-type pre-reacted glass-ionomer (PRG) fillers have the ability to slowly release various ions. This study investigated the effects of cement-containing surface reaction-type PRG filler (PRG cement) on the viability and differentiation of human dental pulp cells derived from deciduous teeth (hDPC-Ds). Other materials generally used for pulp capping, Dycal and Fuji glass-ionomer cement Type II, were also tested by culturing hDPC-Ds with the extract of each material. The viability of hDPC-Ds was measured by methyl-thiazol-tetrazolium [3-(4, 5-di-methylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide] assay. Odontogenic differentiation of hDPC-Ds was evaluated by alkaline phosphatase (ALP) activity and immunocytochemistry. The concentration of each ion in the extract was assessed by ion pair chromatography, inductively coupled plasma, and fluoride ion meter. Based on the results of ion analysis, a medium containing fluoride (F) and aluminum (Al) ions was reconstituted. Human DPC-Ds were cultured in this medium, followed by 3-(4, 5-di-methylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assays and measurement of ALP activity. PRG cement extracts were found to significantly enhance the viability, ALP activity, ALP staining in the extracellular matrix of hDPC-Ds, and release of F and Al ions. These ions, in turn, enhanced the viability and differentiation of hDPC-Ds. Taken together, these results indicate that the proliferation and differentiation of hDPC-Ds was enhanced by PRG cement and that F and Al, which elute from the PRG filler, were most likely involved in the proliferation and differentiation of hDPC-Ds. These findings suggest that PRG cement is potentially useful as a pulp capping agent.

Effect of an experimental adhesive resin containing multi-ion releasing fillers on direct pulp-capping.

The purpose of this study was to evaluate pulpal healing and reparative dentin formation after 14 and 28 days in exposed rat pulp directly capped with an experimentally developed all-in-one adhesive containing surface reaction-type pre-reacted glass-ionomer (S-PRG) filler. The four experimental groups and the control group were compared using the Kruskal-Wallis test, followed by the Steel-Dwass post-hoc test to compare the histopathological score. The Mann-Whitney U test was used to compare the histopathological score at 14 and 28 days for each observation item. All experimental adhesives containing S-PRG fillers developed for direct pulp capping showed no pulpal inflammation. After 14 days, the experimental adhesives containing S-PRG fillers and the control group formed tertiary dentin around the exposed pulp. After 28 days, the experimental adhesives containing 13 and 27 wt% of S-PRG fillers formed dentin bridge equal to the control.

Reduction of Candida biofilm adhesion by incorporation of prereacted glass ionomer filler in denture base resin

ObjectivesThis study investigated the influence of surface reaction-type prereacted glass ionomer (S-PRG) fillers on Candida albicans adhesion on denture base resin. MethodsDiscs were prepared by incorporating the S-PRG filler into the polymer powder of a polymethyl methacrylate (PMMA)-based, heat-polymerizing resin at 0 (control), 5%, 10%, and 20% (w/w). The surface roughness of all disc surfaces was measured. Elemental analysis of released Na+, Sr2+, SiO32−, Al3−, BO33−, and F− was performed after water immersion. Each disc was placed in a well with artificial saliva to form acquired pellicle, incubated, washed with phosphate-buffered saline, and immersed in a C. albicans (JCM2085) cell suspension standardized at 104 cells/ml. After aerobic incubation at 37°C for 24h, the metabolic mitochondrial activity, total biofilm biomass, and biofilm thickness were evaluated. The morphogenetic transition of C. albicans in the early culture stage (1 and 3h) was observed. ResultsThere was a slight but significant increase in the surface roughness with an increase in the filler content. The metabolic activity and total biomass volume were significantly lower in all filler groups than in the control group, although there were no significant differences among the filler groups. Groups with at least 5% filler content exhibited a thinner biofilm compared with the control group. All filler groups showed hyphal forms at 3h, with the length of the hyphae being lesser than those in the control group. ConclusionsAlthough the incorporation of S-PRG filler slightly increases the surface roughness of denture base resin, it reduces the adhesion of C. albicans. Clinical significanceThe S-PRG filler has the potential to reduce Candida albicans adhesion on denture base resin and may lower the risk of denture stomatitis. However, filler incorporation can increase the surface roughness of heat-polymerizing denture base resin.

Effects of surface reaction-type pre-reacted glass ionomer on oral biofilm formation of Streptococcus gordonii.

Streptococcus gordonii, a bacterium involved in the initial colonization of tooth surfaces, contributes to dental biofilm formation and is an important cause of infective endocarditis. This study aimed to investigate the influence of surface reaction-type pre-reacted glass ionomer (S-PRG) filler on oral bacterial growth and aggregation of S. gordonii. The effect of various concentrations of S-PRG eluate on the growth and the biofilm formation of S. gordonii and other oral microorganisms (Streptococcus mutans, Streptococcus oralis, Lactobacillus acidophilus, and Candida albicans) was assessed. In addition, the effect of S-PRG eluate on coaggregation of S. gordonii with both S. oralis and Fusobacterium nucleatum was assessed. The effect of S-PRG eluate treatment on autoaggregation of S. gordonii was also evaluated. Our results indicate that S-PRG eluate treatment reduced both for the growth and for biofilm of all organisms in a dose-dependent manner. Coaggregation of S. gordonii with both S. oralis and F. nucleatum was inhibited by S-PRG eluate, whereas autoaggregation of S. gordonii increased at certain concentrations of S-PRG eluate. These results indicate that the S-PRG filler possesses antimicrobial activity that is mediated by inhibiting growth and biofilm of oral microorganisms, and by suppressing coaggregation of S. gordonii. In addition, these findings indicate that coaggregation of S. gordonii with other bacteria is inhibited by increased autoaggregation of S. gordonii.

Effects of immersion in solution of an experimental toothpaste containing S-PRG filler on like-remineralizing ability of etched enamel.

This study investigated the like-remineralizing ability of experimental toothpaste containing surface reaction-type pre-reacted glassionomer (S-PRG) filler on etched enamel. Human enamel blocks were etched with 35% phosphoric acid and immersed in 5-mL distilled water, fourfold diluted solution of NaF-containing toothpaste, or S-PRG filler-containing experimental toothpaste. Nanoindentation testing was carried out during immersion and the enamel surfaces were observed by scanning electron microscopy. Elemental analysis of the ions in each solution was performed using inductively coupled plasma atomic emission spectroscopy and fluoride electrode. After 1 month of immersion, the hardness and elastic modulus of the specimen immersed in S-PRG filler-containing toothpaste showed significantly greater values than those of the specimen immersed in NaF-containing toothpaste. Considerable amounts of Al, B, Na, Si, Sr, F ions were detected in the solution of S-PRG filler-containing toothpaste. Experimental S-PRG filler-containing toothpaste may enhance the like-remineralizing ability of etched enamel surfaces due to its ion-releasing ability.

Effects of Ion-Releasing Tooth-Coating Material on Demineralization of Bovine Tooth Enamel

We compared the effect of a novel ion-releasing tooth-coating material that contained S-PRG (surface-reaction type prereacted glass-ionomer) filler to that of non-S-PRG filler and nail varnish on the demineralization of bovine enamel subsurface lesions. The demineralization process of bovine enamel was examined using quantitative light-induced fluorescence (QLF) and electron probe microanalyzer (EPMA) measurement. Ion concentrations in demineralizing solution were measured using inductively coupled plasma atomic (ICP) emission spectrometry and an ion electrode. The nail varnish group and the non-S-PRG filler group showed linear demineralization. Although the nail varnish group and the non-S-PRG filler group showed linear demineralization, the S-PRG filler group did not. Further, plane-scanning by EPMA analysis in the S-PRG filler group showed no changes in Ca ion distribution, and F ions showed peak levels on the surface of enamel specimens. Most ions in the demineralizing solution were present at higher concentrations in the S-PRG filler group than in the other two groups. In conclusion, only the S-PRG filler-containing tooth-coating material released ions and inhibited demineralization around the coating.

Evaluation of the effects of fluoride-releasing varnish on dentin demineralization using optical coherence tomography

Effects of a fluoride-releasing varnish containing surface reaction-type prereacted glass ionomer (S-PRG) filler on dentin demineralization were examined using optical coherence tomography. Bovine incisors that were sliced and treated with undersaturated 0.1 M lactic acid buffer solution (DE group). A thin film of varnish-containing S-PRG filler was applied before demineralization (PRG group). Control was maintained in artificial saliva. Using optical coherence tomography of selected locations on the dentin surface, peak intensity (dB) and width (μm) at 1/e(2) were obtained and integrated values calculated. Although alterations in integrated values were different in each group, there was a slight but not significant increase in those for the control group and a slight but significant increase for the De group. For the PRG group, integrated values were doubled seven days after experiment initiation, followed by a significant increase. Fluoride-releasing varnish containing S-PRG fillers prevented dentin demineralization as detected by optical coherence tomography.