Evaluation of the ion-releasing and recharging abilities of a resin-based fissure sealant containing S-PRG filler

Bioactivity of human dental pulp-derived stem cells with boron-controlled S-PRG filler eluate by anion exchange

Surface pre-reacted glass-ionomer (S-PRG) filler is a bioactive glass filler capable of releasing various ions. A culture medium to which was added an S-PRG filler eluate rich in boron was reported to enhance alkaline phosphatase (ALP) activity in human dental pulp-derived stem cells (hDPSC). To clarify the role of boron eluted from S-PRG fillers, the modified S-PRG filler eluate with different boron concentrations was prepared by using an anion exchange material. Therefore, elemental mapping analysis of anion exchange material, adsorption ratio, hDPSCs proliferation and ALP activity were evaluated. For statistical analysis, Kruskal-Wallis test was used, with statistical significance determined at p<0.05. ALP activity enhancement was not observed in hDPSC cultured in the medium that contained the S-PRG filler eluate from which boron had been removed. The result suggested the possibility that an S-PRG filler eluate with controlled boron release could be useful for the development of novel dental materials.

Are S-PRG composites able to resist against erosive and abrasive challenges and protect surrounding enamel in situ?

OBJECTIVES

This study evaluated the resistance of S-PRG (Surface Pre-Reacted Glass-ionomer) composites and other restorative materials against erosive and abrasive challenges and their protective effect on enamel adjacent to the restorations.

MATERIALS AND METHODS

Bovine enamel blocks were prepared and randomized into 12 groups, including 6 types of material, each of them subjected to erosion_e or erosion+abrasion_ea: Beautifil II (S-PRG); Beautifil Bulk Restorative (S-PRG); Filtek Z250 XT; Filtek Bulk Fill; EQUIA Forte; Riva Light Cure. Cavities were prepared in the middle of enamel blocks and restored with the materials. Initial profiling measurement was performed on the material and on adjacent enamel (100, 200, 300, 600 and 700 μm from the restoration margin). Palatal intraoral appliances with the restored enamel blocks were used by the volunteers (n = 10). During 5 days appliances were immersed in 2.5 % citric acid for 2 min; 6 × /day (erosion_e). For ea condition, blocks were brushed for 1 min after each acid immersion. Final profile assessment was performed. Data were analysed by two and three way ANOVA followed by Tukey's test (p < 0.05).

RESULTS

Material wear: Riva Light Cure showed the highest wear followed by EQUIA Forte and then all resin composites, including the ones with S-PRG (p = 0.000). Enamel wear: there was significant interaction among type of restorative material, wear condition and distance (p = 0.014), enamel around materials showed similar wear (p = 0.983) and the enamel subjected to ea exhibited highest wear (p = 0.000).

CONCLUSION

SPRG based composites showed resistance against erosive and abrasive challenges but were not able to protect enamel adjacent to the restorations.

CLINICAL SIGNIFICANCE

S-PRG composites exhibit resistance to material wear comparable to resin composites. However, they have shown an inability to effectively protect the adjacent enamel under in situ erosive-abrasive conditions, despite the presence of mineral-loss-preventing ions surrounding materials.

In Vitro Optical and Physical Stability of Resin Composite Materials with Different Filler Characteristics

The objective of this study was to compare the physical and optical stability of resin composite materials with different filler characteristics. Ninety-six resin composite blocks (6 mm × 6 mm × 2 mm) were prepared using four different types of resin composite, divided into four groups. Specimens from the same material were randomly divided into four groups (n = 6) and allocated for Vickers hardness (VH), water sorption, solubility (WS/SL), and staining and aging challenges tests. One-way ANOVA showed significant differences in microhardness (p = 0.0001), WS (p = 0.0001), and SL (p = 0.003) among the tested groups. Beautifil II LS recorded the highest hardness, and CharmFil^®Flow had the lowest value. Beautifil Injectable X and II LS showed negative WS, whereas the other groups had positive values. All groups showed positive SL. Repeated measures ANOVA showed significant color parameter alteration in the tested groups (p = 0.0001). All groups showed significant color shifting after one week of the staining challenge. Repeated measures ANOVA showed a significant color parameter (p = 0.0001) and weight (p = 0.001) alteration after the aging challenge. The optical and physical stability of resin composites may vary according to filler characteristics. Clinicians should choose the composite as per the desired outcome.

Effects of in vitro erosion on surface texture, microhardness, and color stability of resin composite with S-PRG fillers

OBJECTIVES

To evaluate the effect of acid erosion on different physical properties of resin composite with S-PRG (surface pre-reacted glass) fillers, by conducting simulations of intrinsic and extrinsic sources.

MATERIALS AND METHODS

Cylindrical samples (Ø6 vs. 2 mm) of a conventional nanohybrid resin composite (Forma, Ultradent) and of a nanohybrid resin composite with S-PRG filler (Beautifil II, Shofu) were exposed to erosive cycling (5 days), based on (n=12) remineralizing solution (control); 0.3% citric acid (pH=2.6); or 0.01 M hydrochloric acid (pH=2). Roughness (Ra), microhardness (KHN), and color (CIEL*a*b*, CIEDE2000, and Vita scale (SGU)) factors were analyzed at the initial and final time points, and the general color changes (ΔE_ab, ΔE₀₀, ΔSGU) were calculated. Final images were obtained using scanning electron microscopy (SEM). The data were evaluated by generalized models, Mann-Whitney, Wilcoxon, Kruskal-Wallis, and Dunn tests (α=0.05).

RESULTS

Regarding KHN, there was no difference between the groups or the time periods (p = 0.74). As for Ra, there was a significant increase in the Ra of both composites after cycling with hydrochloric acid, but only the resin composite with S-PRG filler showed a change in Ra after cycling with citric acid (p = 0.003). After cycling with citric and hydrochloric acid, the highest Ra values were found for the resin composite with S-PRG filler (p < 0.0001), corroborating the result of images (SEM) indicating loss of filler and porosities in this material. The resin composite with S-PRG filler showed higher ΔE_ab and ΔE₀₀, in addition to more negative ΔSGU values and lower L* values after exposure to both acids, compared to the control (p < 0.05).

CONCLUSION

The acidic conditions altered the roughness and color stability of the materials tested, pointing out that the resin composite containing S-PRG filler showed greater degradation of its physical properties than the conventional resin composite.

CLINICAL RELEVANCE

Bioactive materials are relevant, considering that their properties interact with dental hard tissues; however, the S-PRG-based resin composite showed greater degradation under acidic conditions than the conventional resin composite.

Effect of a Toothpaste Containing Surface Pre-Reacted Glass-Ionomer Filler on the Remineralization of Artificial Carious Enamel Lesions in situ

This study evaluated the remineralizing effect of a toothpaste containing surface pre-reacted glass-ionomer (S-PRG) filler on demineralized enamel in situ. For this, 180 bovine enamel samples were demineralized by using a microcosm biofilm model for 3 days. Thereafter, the samples were randomly signed to 15 healthy volunteers and to 3 cross-over in situ phases corresponding to the following treatments: (1) toothpaste containing 1,500 ppm F as NaMFP (positive control, Colgate®Cavity Protection), (2) toothpaste containing 5% S-PRG filler (Shofu®), and (3) placebo toothpaste (negative control prepared by Shofu®). Four demineralized enamel blocks were fixed into each palatal appliance per phase. The volunteers wore the appliances for 5 days and were trained to brush their teeth 2 times for 2 min a day, while one drop of the toothpaste's slurry (1:3) was dripped on each sample for the same period. The surface hardness and TMR analyses were done and analyzed by ANOVA/Tukey and t test (p < 0.05). S-PRG filler and Colgate® toothpastes were equally able to improve 2-2.5× enamel remineralization by the analysis of % surface hardness recovery. However, S-PRG toothpaste was the only one able to significantly improve ΔΔZ (the integrated mineral loss recovery: 1,489 ± 503 %vol.μm) compared to placebo (1,050 ± 467 %vol.μm), while Colgate® did not differ from placebo. No differences were seen between the groups with respect to ΔLD. S-PRG filler and Colgate® toothpastes show similar potential to remineralize the lesion surface. However, S-PRG toothpaste is better to recover mineral loss at the subsurface area.

The inhibitory effects of various ions released from S-PRG fillers on dentin protease activity

This study investigates the effect of ions released from S-PRG fillers on host-derived enzymatic degradation of dentin collagen matrices. Dentin beams (n=80) were demineralized and distributed to eight groups following baseline dry mass and total MMP activity assessments. Each group treated with boron, fluoride, sodium, silicone, strontium, aluminium, or S-PRG eluate solutions for 5 min. Untreated beams served as control. After pre-treatment, MMP activity was reassessed, beams were incubated in complete medium for 1 week, dry mass was reassessed. Incubation media were analyzed for MMP and cathepsin-K-mediated degradation fragments. Data were analyzed with ANOVA and Tukey's test. All pretreatment groups showed significant reduction in total MMP activity (p<0.05) that was sustainable after incubation in all groups except for boron and silicone groups (p<0.05). Cathepsin-K activity did not differ between control or treatment groups. The results indicated that ions released from S-PRG fillers have the potential to partly inhibit MMP-mediated endogenous enzymatic activity.

Clinical Evaluation of Low-shrinkage Bioactive Material Giomer Versus Nanohybrid Resin Composite Restorations: A Two-year Prospective Controlled Clinical Trial

This study evaluated the clinical performance of low-shrinkage bioactive resin composite compared with a conventional nanohybrid resin composite. A total of 35 patients (18 males, 17 females; mean age: 29±9 years old) received, randomly, 35 pairs of fillings restored with either low-shrinkage bioactive material employing Giomer filler technology (Beautifil II LS, Shofu Inc, Kyoto, Japan) or conventional nanohybrid resin composite (Clearfil Majesty Posterior, Kuraray, Japan) in Class I and Class II cavities. Two operators made all the restorations using the corresponding adhesive resins: FL-Bond II (Shofu Inc) and Clearfil SE Bond (Kuraray), according to each manufacturer's instructions. Two calibrated operators evaluated the restorations two weeks after placement (baseline), at six months, and at one and two years using FDI criteria (Scores 1-5). Data were analyzed using the McNemar test (α=0.05). Mean observation time was 27.4 ± 4.1 months (min=20.8; max=33.7). In both groups, according to FDI criteria, the restorations were mostly rated with best scores (Score 1 or 2) for biological, functional, and optical parameters. For one filling in the group restored with nanohybrid resin composite, a small and localized secondary caries lesion was observed and monitored at the one- and two-year follow-ups. One restoration in the low-shrinkage Giomer restorative group was accepted as a failure due to retention loss. Over the two-year follow-up, both the Giomer and the nanohybrid resin composite restorations' performance was clinically acceptable.

Comparative Evaluation of Fluoride Release from Glass Ionomer, Compomer, and Giomer Sealants Following Exposure to Fluoride Toothpaste and Fluoride Varnish: An In Vitro Study

Introduction

Applying sealants to the deep pit and fissure area will be an excellent way to stop and slow down tooth caries from developing. Dental sealants that include fluoride are more successful at lowering dental cavities. It is anticipated that exposure to fluoride from dental sealants of various origins may enhance the fluoride release from dental sealants. Therefore, this study's objective was to investigate the amount of fluoride released after using fluoride toothpaste and fluoride varnish from different sealants.

Materials and methods

Using only a fluoride ion selective electrode, the initial release of fluoride was detected every 24 hours for 15 days. After every measurement, the saliva was refreshed. The samples were split into three identical subgroups and given the respective regimes on the 15th day-subgroup A was given fluoride toothpaste every morning and evening, subgroup B was provided fluoride varnish once, and subgroup C was not given any fluoride regime at all. After another 15 days of fluoride exposure, the fluoride release was monitored.

Results

With notable variations across groups over the initial 15 days, glass ionomer sealants (GIS) released more amount of fluoride, second by giomer sealant, and third by resin sealant (p = 0.00). All dental sealants that have been tested released more fluoride when using fluoride toothpaste, with giomer sealants surpassing GIS, followed by resin sealants (p = 0.00). Giomer and resin sealants, fluoride varnish treatment dramatically improves fluoride release in GIS (p = 0.00).

Conclusion

The release of fluoride among all dental sealants is improved by using fluoride toothpaste daily and fluoride varnish just once.

How to cite this article

Senthilkumar A, Chhabra C, Trehan M, et al. Comparative Evaluation of Fluoride Release from Glass Ionomer, Compomer, and Giomer Sealants Following Exposure to Fluoride Toothpaste and Fluoride Varnish: An In Vitro Study. Int J Clin Pediatr Dent 2022;15(6):736-738.

Effect of Surface Pre-Reacted Glass Ionomer Containing Dental Sealant on the Inhibition of Enamel Demineralization

The effect of a surface pre-reacted glass ionomer (S-PRG)-containing sealant on the demineralization inhibition and remineralization of intact enamel adjacent to the sealant material was investigated. BeautiSealant (BTS, S-PRG sealant, Shofu), Teeth Mate F-12.0 (TMF, fluoride-releasing sealant, Kuraray Noritake Dental), and an experimental silica-filler sealant were investigated. After pH cycling for 10 days, the enamel surface adjacent to the sealant material was observed using confocal laser microscopy and scanning electron microscopy. The polymerized sealant disks were immersed in a demineralized solution (pH: 4.3) to measure pH change. The enamel specimens with polymerized sealant disks were additionally immersed in demineralized solution, followed by energy-dispersive X-ray spectroscopy. The demineralized area of BTS was significantly smaller than that of TMF and SS (p < 0.05). The surfaces adjacent to the sealant of TMF and SS were demineralized, while the surface of BTS was comparatively intact. An increase in pH values were observed in the BTS and TMF groups. Enamel surfaces presented an inhibition of demineralization for BTS and TMF, but not for SS. Fluoride uptake from the polymerized sealant was greater for BTS than for TMF. The S-PRG-containing sealant showed a buffering ability, demineralization inhibition, promotion of remineralization, and it can be advised for clinical applications.

Effect of surface prereacted glass ionomer nanofillers on fluoride release, flexural strength, and surface characteristics of polymethylmethacrylate resin

OBJECTIVE

Dentures should have proper fluoride release and physical properties. We evaluated how surface prereacted glass ionomer (S-PRG) nanofillers influenced fluoride release, flexural strength, and surface characteristics of polymethylmethacrylate (PMMA) resin.

MATERIALS AND METHODS

PMMA resin disc (n = 14) and rectangular (n = 5) specimens containing 0, 20 wt% microparticles, and 20 wt% nanoparticles of S-PRG were prepared. Six-disc specimens were examined for surface roughness; eight-disc specimens were immersed in 5 ml of deionized water for 24 h before analyzing the fluoride levels on days 1-3, 12, and 15. They were recharged with 1000 ppm fluoride solution for 24 h and stored in deionized water for five cycles. Fluoride release was examined. The flexural strength of the rectangular specimens was determined using a three-point bending test. Data were analyzed by two-way repeated-measures ANOVA.

RESULTS

S-PRG nanofiller had the highest fluoride exchange rate and did not significantly change the surface roughness compared with the microparticle and control groups; however, the nanofillers agglomerated and reduced the flexural strength to below 65 MPa.

CONCLUSIONS

Incorporating 20 wt% nanofillers into resin enhanced the fluoride exchange property greater than microfillers at the same content, but diminished the mechanical properties of the resin.

CLINICAL SIGNIFICANCE

Incorporating 20 wt% S-PRG nanofillers in resin denture base can improve the fluoride releasing property without affecting the surface roughness.

Efficacy of S-PRG filler varnishes on enamel caries remineralization

OBJECTIVES

To evaluate the remineralizing effect of varnishes containing different concentrations of S-PRG filler or sodium fluoride on enamel caries lesions.

METHODS

Enamel specimens were obtained from bovine incisors, flattened and polished. Half of the surface was protected, and artificial caries lesion was created in the unprotected area. They were assigned into six groups (n=20) according to the varnish applied: four containing S-PRG filler with different concentrations (10%, 20%, 30% and 40% w/w), one containing 5% sodium fluoride (5%NaF) as positive control, and one without treatment as a negative control (NC). Varnishes were applied on specimen's caries-affected surface and removed after 24h. Varnish application and pH cycling (8 days) were performed twice. Cross-sectional microhardness was measured (10-100 µm depth). Knoop microhardness percentage (KHN%) of caries affected/treated area in relation to the sound enamel area at the same depth was calculated. The area under the curve (AUC) and the Δ_AUC were also calculated. Statistical analysis was performed by two-way ANOVA for KHN% and one-way ANOVA for Δ_AUC, followed by Tukey test (α=5%).

RESULTS

Significant differences were found for the factors "treatment" (p=0.0001) and "depth" (p=0001). For the factor "treatment", the results of the Tukey test were: NC-62.2(10.3)a, 10%S-PRG-69.2(9.3)b, 20%S-PRG-71.8(9.7)bc, 30%S-PRG-74.5(9.4)c, 5%NaF-79.6(8.7)d, 40%S-PRG-85.6(8.4)e. In relation to Δ_AUC, significant differences were observed among the groups (p=0.0001) and better results for 40% S-PRG and 5%NaF.

CONCLUSIONS

The varnish containing 40% S-PRG fillers was the most effective to promote the enamel caries remineralization, followed by the one containing 5% sodium fluoride.

CLINICAL SIGNIFICANCE

The varnish containing 40% of S-PRG fillers represents an alternative for initial enamel caries remineralization, since it was more effective than the conventional 5% NaF based product.

Remineralizing Effects of Resin-Based Dental Sealants: A Systematic Review of In Vitro Studies

The incorporation of remineralizing additives into sealants has been considered as a feasible way to prevent caries by potential remineralization through ions release. Thus, this systematic review aimed to identify the remineralizing additives in resin-based sealants (RBS) and assess their performance. Search strategies were built to search four databases (PubMed, MEDLINE, Web of Science and Scopus). The last search was conducted in June 2020. The screening, data extraction and quality assessment were completed by two independent reviewers. From the 8052 screened studies, 275 full-text articles were assessed for eligibility. A total of 39 laboratory studies matched the inclusion criteria. The methodologies used to assess the remineralizing effect included microhardness tests, micro-computed tomography, polarized-light microscopy, ions analysis and pH measurements. Calcium phosphate (CaP), fluoride (F), boron nitride nanotubes (BNN), calcium silicate (CS) and hydroxyapatite (HAP) were incorporated into resin-based sealants in order to improve their remineralizing abilities. Out of the 39 studies, 32 studies focused on F as a remineralizing agent. Most of the studies confirmed the effectiveness of F and CaP on enamel remineralization. On the other hand, BNN and CS showed a small or insignificant effect on remineralization. However, most of the included studies focused on the short-term effects of these additives, as the peak of the ions release and concentration of these additives was seen during the first 24 h. Due to the lack of a standardized in vitro study protocol, a meta-analysis was not conducted. In conclusion, studies have confirmed the effectiveness of the incorporation of remineralizing agents into RBSs. However, the careful interpretation of these results is recommended due to the variations in the studies’ settings and assessments.

Wear Behavior and Surface Quality of Dental Bioactive Ions-Releasing Resins Under Simulated Chewing Conditions

Bioactive materials can reduce caries lesions on the marginal sealed teeth by providing the release of ions, such as calcium, phosphate, fluoride, zinc, magnesium, and strontium. The presence of such ions affects the dissolution balance of hydroxyapatite, nucleation, and epitaxial growth of its crystals. Previous studies mostly focused on the ion-releasing behavior of bioactive materials. Little is known about their wear behavior sealed tooth under mastication. This study aimed to evaluate the wear behavior and surface quality of dental bioactive resins under a simulated chewing model and compare them with a resin without bioactive agents. Three bioactive resins (Activa, BioCoat, and Beautifil Flow-Plus) were investigated. A resin composite without bioactive agents was used as a control group. Each resin was applied to the occlusal surface of extracted molars and subjected to in vitro chewing simulation model. We have assessed the average surface roughness (Ra), maximum high of the profile (Rt), and maximum valley depth (Rv) before and after the chewing simulation model. Vickers hardness and scanning electron microscopy (SEM) also analyzed the final material surface quality). Overall, all groups had increased surface roughness after chewing simulation. SEM analysis revealed a similar pattern among the materials. However, the resin with polymeric microcapsules doped with bioactive agents (BioCoat) showed increased surface roughness parameters. The material with Surface Pre-reacted Glass Ionomer (Beautifil Flow-Plus) showed no differences compared to the control group and improved microhardness. The addition of bioactive agents may influence surface properties, impairing resin composites' functional and biological properties. Future studies are encouraged to analyze bioactive resin composites under high chemical and biological challenges in vitro with pH cycles or in situ models.

S-PRG-based composites erosive wear resistance and the effect on surrounding enamel

This study evaluated Surface Pre-Reacted Glass-ionomer (S-PRG)-based-composites' surface resistance against erosive wear and their protective effect on surrounding enamel. Bovine enamel was randomized into 12 groups (n = 10/group) [erosion (e) or erosion + abrasion (a)]: nanohybrid-S-PRG-based composite (SPRGe/SPRGa), nanohybrid-S-PRG-based bulk-fill (SPRGBFe/SPRGBFa), nanoparticle-composite (RCe/RCa), nanohybrid-bulk-fill (BFe/BFa), Glass Hybrid Restorative System (GHRSe/GHRSa), and resin-modified glass-ionomer-cement (RMGICe/RMGICa). Cavities were prepared and restored. Initial profile assessment was performed on material and on adjacent enamel at distances of 100, 200, 300, 600, and 700 μm from margin. Specimens were immersed in citric acid (2 min; 6×/day for 5 days) for erosion. Erosion + abrasion groups were brushed for 1 min after erosion. Final profile assessment was performed. Two-way ANOVA and Tukey-test showed: for erosion, the GHRSe and RMGICe presented greater material wear compared to the other groups (p = 0.001); up to 300 μm away from restoration, GHRSe and SPRGBFe were able to prevent enamel loss compared to RMGICe and other composite groups (p = 0.001). For erosion + abrasion, none of the materials exhibited a significant protective effect and S-PRG-based groups showed lower wear than RMGICa and GHRSa, and higher wear than composites (p = 0.001). S-PRG-based-composites can diminish surrounding enamel loss only against erosion alone, similarly to GIC, with advantage of being a more resistant material.

Effect of brushing on surface roughness, fluoride release, and biofilm formation with different tooth-colored materials

Background/purpose

Tooth brushing, material mechanical ageing procedure, is the most effective way in removing biofilm. The purpose of this study was to investigate the surface roughness, fluoride-release, and S. mutans biofilm formation on various tooth-colored restorative materials before and after brushing.

Materials and methods

Discs of materials, a nanocomposite (Filtek Z350XT; CO), a giomer (Beautifil II; GIOMER), a resin-modified glass-ionomer material (Fuji II LC; RMGI), and a conventional glass-ionomer material (Fuji IX GP Extra; GI), were prepared, polished with abrasive discs (SofLex), and divided into brushed and not brushed groups. The surface roughness of specimens was observed using a contact profilometer, fluoride-release was measured using a fluoride-specific ion electrode, and S. mutans biofilm formation, biovolume and live/dead cells, was observed under a confocal laser scanning microscope.

Results

Higher roughness was observed on GI and RMGI than on CO and GIOMER. Brushing had no effect on the roughness. The fluoride-release of GI and RMGI was higher than that of GIOMER. The fluoride-release decreased after brushing in all materials. The biovolume of S. mutans was not significantly different between GIOMER, RMGI and GI, while CO showed the highest. Brushing resulted in a higher biovolume for all materials, except CO, which showed no change. After brushing, all the tested materials demonstrated identical biovolumes. There were no significant differences in live/dead cells among all groups.

Conclusion

Brushing demonstrated a negative effect on the fluoride-release and biovolume of S. mutans biofilms for all tested materials except nanocomposites.

Sensitivity Treatments for Teeth with Molar Incisor Hypomineralization: Protocol for a Randomized Controlled Trial

Background

The sensitivity of teeth with molar incisor hypomineralization (MIH) can affect children’s quality of life and is a challenging problem for dentists. Remineralizing agents such as sodium fluoride varnish seem to reduce the sensitivity of teeth with MIH, but long-term clinical trials with large samples are still needed for more evidence about its effectiveness as a desensitizing agent before its clinical recommendation.

Objective

This randomized clinical trial aims to compare three treatment interventions for teeth with MIH and hypersensitivity.

Methods

A total of 60 children aged 6-10 years presenting with at least one first permanent molar with sensitivity and no loss of enamel will be randomly assigned to three groups: the control group (sodium fluoride varnish; Duraphat, Colgate); experimental group I (4% titanium tetrafluoride varnish); and experimental group II (a coating resin containing surface prereacted glass-ionomer filler; PRG Barrier Coat, Shofu). The sodium fluoride varnish and 4% titanium tetrafluoride varnish will be applied once per week for 4 consecutive weeks and the PRG Barrier Coat resin will be applied in the first session and the application will be simulated the following 3 weeks to guarantee the blinding of the study. The primary outcome will be sensitivity level measured at different moments (before each material application, immediately after application or simulation, and 1, 2, 4, and 6 months after the last application/simulation) by one examiner using the Wong-Baker FACES Pain Rating Scale, the Schiff Cold Air Sensitivity Scale, and the FLACC (Face, Legs, Activity, Cry, Consolability) scale. As secondary outcomes, parental satisfaction and child self-reported discomfort after the treatment will be measured with a questionnaire prepared by the researcher. The data will undergo statistical analysis and the significance level will be set at 5%.

Results

The project was funded in 2018, and enrollment was completed in November 2019. The recruitment of participants is currently underway and the first results are expected to be submitted for publication in 2022.

Conclusions

If found effective in reducing the patient’s sensitivity long term, these agents can be considered as a treatment choice, and the findings will contribute to the development of a treatment protocol for teeth with sensitivity due to MIH.

Trial Registration

Brazilian Registry of Clinical Trials Universal Trial Number U1111-1237-6720; https://tinyurl.com/mr4x82k9

International Registered Report Identifier (IRRID)

DERR1-10.2196/27843

S-PRG-based toothpastes compared to NaF toothpaste and NaF varnish on dentin permeability in vitro

Objectives

To analyze the effect of 5 toothpastes containing different percentages of S-PRG fillers compared to NaF toothpaste and NaF varnish on the dentin hydraulic conductance (Lp).

Methodology

Dentin disks (1.0±0.2 mm thickness) were cut from third molars, and their Lp values were evaluated using Flodec. The specimens were allocated into 7 groups (n=8). The minimum (smear layer) and the maximum (after acid etching) Lp values were recorded. Lp was also assessed after treatment with either a 0wt.%, 1wt.%, 5wt.%, 20wt.%, or 30wt.% S-PRG toothpaste, a NaF toothpaste, or a NaF varnish. Toothpastes were applied by brushing for 15 s, allowing it to settle for 1 min, and rinsing with deionized water. The NaF varnish was applied for 4 min and was removed with a probe. Specimens were exposed to citric acid (6%, pH 2.1, 1 min) and their final Lp was recorded. The pH of all products was recorded (n=3) and specimens from each group were analyzed by Laser Scanning Confocal Microscopy (LSCM). Data were subjected to 2-way repeated measures ANOVA and post-hoc Bonferroni (a=0.05).

Results

The highest Lp reduction was noticed for the 5wt.% S-PRG toothpaste, NaF toothpaste, and NaF varnish. However, the toothpastes containing 5wt.%, 20wt.%, and 30wt.% of S-PRG were similar to all toothpastes but differed from the NaF varnish. After erosion, all groups retrieved their maximum Lp values, except for the NaF varnish. The LSCM evidenced deposits on the surface of specimens treated with 5%, 20%, and 30% S-PRG-based toothpastes and NaF toothpaste. Even more deposits were observed for the NaF varnish. After the erosive challenge, the deposits were diminished in all groups.

Conclusion

Toothpastes containing 5wt.%, 20wt.%, and 30wt.% of S-PRG fillers behaved similarly to a conventional NaF toothpaste, even after an erosive challenge. The NaF varnish promoted better reduction of the Lp, but its effect was also diminished after erosion.

Giomer composite compared to glass ionomer in occlusoproximal ART restorations of primary molars: 24-month RCT

BACKGROUND

Occlusoproximal restorations of primary molars usually fail, so it is necessary to investigate new materials that may overcome this challenge. Thus, this trial aimed to evaluate the longevity of occlusoproximal ART restorations in primary molars using a glass ionomer cement - GIC (Equia Forte^® - GC Corp) and a Giomer resin composite - GCR (Beautifil Bulk Restorative^® - Shofu Inc) after 24 months.

METHODS

One hundred and eighty-two (182) children aged from 4 to 8 years were selected and randomly assigned to GIC or GCR. A paediatric dentist treated them in the school setting in Cerquilho, Brazil, and the restorations were assessed after 3, 6, 12, 18 and 24 months. The primary outcome was the restoration survival, evaluated using the Kaplan-Meier and superiority Cox regression analyses. Intention to treat (ITT) was performed as a sensitivity analysis using superiority test P value and confidence interval (CI = 95%). Independent variables included gender, age, molar, jaw, cavity volume and caries experience.

RESULTS

The restoration survival after 24 months was GIC = 58.1% and GCR = 49.1% (HR = 1.24; CI = 0.97-1.59). ITT analysis showed a success of GIC = 61.1% and GCR = 52.2% (RR = 1.17; CI = 0.91-1.52). The superiority hypothesis was not proved in both analyses (P > 0.05).

CONCLUSION

GCR does not have superior longevity than GIC in occlusoproximal ART restorations of primary molars.

Tissue Conditioner Incorporating a Nano-Sized Surface Pre-Reacted Glass-Ionomer (S-PRG) Filler

We aimed to evaluate the properties of a novel tissue conditioner containing a surface pre-reacted glass-ionomer (S-PRG) nanofiller. Tissue conditioners containing 0 (control), 2.5, 5, 10, 20, or 30 wt% S-PRG nanofiller or 10 or 20 wt% S-PRG microfiller were prepared. The S-PRG nanofillers and microfillers were observed using scanning electron microscopy. The ion release, acid buffering capacity, detail reproduction, consistency, Shore A0 hardness, surface roughness, and Candida albicans adhesion of the tissue conditioners were examined. The results indicated that the nanofiller particles were smaller and more homogeneous in size than the microfiller particles. In addition, Al, B, F, and Sr ions eluted from S-PRG were generally found to decrease after 1 day. Acid neutralization was confirmed in a concentration-dependent manner. The mechanical properties of tissue conditioners containing S-PRG nanofiller were clinically acceptable according to ISO standard 10139-1:2018, although the surface roughness increased with increasing filler content. Conditioners with 5-30 wt% nanofiller had a sublethal effect on C. albicans and reduced fungal adhesion in vitro. In summary, tissue conditioner containing at least 5 wt% S-PRG nanofiller can reduce C. albicans adhesion and has potential as an alternative soft lining material.

Bioactive self-etching sealant on newly erupted molars: A split-mouth clinical trial

OBJECTIVES

This randomized clinical trial compares retention, survival rate, and evolution of caries of newly erupted permanent molars sealed with bioactive self-etching sealants with pre-reacted glass ionomer (S-PRG).

METHODS

A split-mouth clinical trial was conducted with 56 permanent second molars in stages 2 and 3 of crown eruption; ICDAS (International Caries Detection and Assessment System) was between 0 and 2. The molars were randomized and blinded in relation to the side (right or left) that would receive the sealants; the conventional resin sealant (FS), Fluroshield (Dentsply), or bioactive self-etch sealant (BS), BeautiSealant with S-PRG (Shofu). The sealants were compared in terms of retention, quality of sealant remnant (anatomical shape, marginal adaptation, surface texture, and marginal discoloration), and development of caries by ICDAS after 1, 6, and 12 months. The Wilcoxon, x² of independence, Kaplan-Meier, and Mantel-Cox survival statistical tests were applied (α = 5%).

RESULTS

The total retention was higher for FS (57.1%) at all periods, and there was no difference in the quality of sealants at all periods. The ICDAS decreased after 6 (p = 0.025) and 12 months (p = 0.027) for both materials. Despite the lower retention of BS, the clinical quality of sealants over 12 months were similar.

CONCLUSION

Teeth sealed with BS presented higher sound teeth predominance (ICDAS 0) compared to FS sealant, even with a higher loss of material.

CLINICAL RELEVANCE

Eruption of permanent molars is a relevant period, and the prevention/management of initial caries is essential in these critical stages. Sealants can be an important prevention strategy. After 12 months of follow-up, there was a major failure of the bioactive sealant but without the development of caries lesions.

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.

Effects of multi-components released from S-PRG filler on the activities of human dental pulp-derived stem cells

Numerous studies have shown that the sustained release of ions from dental restorative materials have acid buffering capacity, prevents tooth enamel demineralization, and inhibits bacterial adhesion. Herein, the release behavior and bioresponsiveness of ions released from surface pre-reacted glass-ionomer (S-PRG) fillers were investigated in different types of media based on human dental pulp-derived stem cell (hDPSC) responses. The hDPSCs were cultured for 1-7 days in S-PRG eluates diluted with varying amounts of cell culture media. S-PRG released several types of ions, such as F^-, Sr²⁺, Na⁺, Al³⁺, BO₃^3-, and SiO₃^2-. The balance of eluted ions differed depending on the dilution and solvent, which in turn affected the cytotoxicity, cell morphology, cell proliferation, and alkane phosphatase activity of hDPSCs, among other properties. The results suggest that tailored S-PRG filler eluates could be designed and prepared for application in dental practice.

Molar incisor hypomineralization: A review and prevalence in Japan

Molar incisor hypomineralization (MIH) is defined as hypomineralization of systemic origin of one to four first permanent molars, and incisors are also frequently affected. This disorder is a serious concern in pediatric dentistry. Teeth affected by MIH have many dental problems, such as hypersensitivity, poor aesthetics, and rapid progression of dental caries. The prevalence of MIH ranges from 2.8% to 21% among studies with more than 1000 subjects in different countries and age groups. The etiology of MIH is unclear, but genetic and environmental factors have been proposed. This review describes the prevalence, etiology, and clinical management of MIH. A detailed description of MIH prevalence in Japan is also provided.

Fabrication and characterization of remineralizing dental composites containing calcium type pre-reacted glass-ionomer (PRG-Ca) fillers

OBJECTIVE

To fabricate and characterize dental composites with calcium type pre-reacted glass-ionomer (PRG-Ca) fillers.

METHODS

PRG-Ca fillers were prepared by the reaction of calcium fluoroaluminosilicate glass with polyacrylic acid. Seven dental composites were produced from the same organic matrix (70/30wt% Bis-GMA/TEGDMA), with partial replacement of barium borosilicate (BaBSi) fillers (60wt%) by PRG-Ca fillers (wt%): E0 (0) - control, E1 (10), E2 (20), E3 (30), E4 (40), E5 (50) and E6 (60). Enamel remineralization was evaluated in caries-like enamel lesions induced by S. mutans biofilm using micro-CT. The following properties were characterized: degree of conversion (DC%), roughness (Ra), Knoop hardness (KHN), flexural strength (FS), flexural modulus (FM), water sorption (W_sp), water solubility (W_sl), and translucency (TP). Data were analyzed to one-way ANOVA and Tukey's HSD test (α=0.05).

RESULTS

All composites with PRG-Ca induced enamel remineralization. E0 and E1 presented similar and highest DC% than E2=E3=E4=E5=E6. Ra and KHN were not influenced by PRG-Ca fillers (p<0.05). The higher the content of PRG-Ca, the lower FS, FM and TP (p<0.05). W_sp increased linearly with the content of PRG-Ca fillers (p<0.05). E6 presented the highest W_sl (p<0.05), while the W_sl of the other composites were not different from each other (p>0.05).

SIGNIFICANCE

Incorporation of 10-40wt.% of PRG-Ca fillers endowed remineralizing potential to dental composites without jeopardizing the overall behavior of their physicochemical properties. Dental composites with PRG-Ca fillers seems to be a good alternative for reinforcing the enamel against caries development.

Preliminary In Vitro Study of Fluoride Release from Selected Ormocer Materials

The purpose of the in vitro study presented in this paper was to determine the long-term release of fluoride ions from selected ormocer materials (Admira (A), Admira Flow (AF), Admira Seal (AS)). The release of fluoride ions from these materials into a saline solution (0.9% NaCl) and deionized water was tested for 14 weeks. In a long-term study the measurements were taken after 1 and 3 h, then 1, 2, and 3 days and then at weekly intervals for 14 weeks. In a short-term study the measurements were made after 3, 24, 48, 72, 69, 168 h, i.e., within 7 days. All materials used in the test showed a constant level of fluoride release. The highest level of cumulative release of fluoride ions into deionized water was found in the AS material (23.95 ± 4.30 μg/mm²), slightly lower in the A material (23.26 ± 4.16 μg/mm²) and the lowest in the AF material (16.79 ± 2.26 μg/mm²). The highest level of cumulative release into saline solution was found in AF (8.08 ± 1.30 μg/mm²), slightly lower in AS (7.36 ± 0.30 μg/mm²) and the lowest in A (6.73 ± 1.10 μg /mm²). After 1 h of immersion of the samples in the saline solution, the highest level of fluoride was released by AF (0.57 ± 0.06 μg/mm²) followed by A (0.20 ± 0.03 μg/mm²) and AS (0.19 ± 0.02 µg/mm²). Moreover, in the 14-week study, the total amount of fluoride release into the saline, which imitates the environment of the oral cavity, was observed as the highest in the AF sample.

The Potential of a Bioactive, Pre-reacted, Glass-Ionomer Filler Resin Composite to Inhibit the Demineralization of Enamel in Vitro

CLINICAL RELEVANCE

A prereacted, glass-ionomer filler fluoride-containing resin composite had lower remineralization potential than glass-ionomer cements but was able to inhibit enamel demineralization; thus, it may be an option for restoring dental surfaces for patients at high risk of caries.

SUMMARY

Evidence is lacking on the use of surface prereacted glass-ionomer filler resin composites to inhibit demineralization and that simulate real clinical conditions. The present laboratory study evaluated the potential of such composites to prevent demineralization and quantified fluoride (F) and other ions released from restorative materials after a dynamic pH-cycling regimen applied to the tooth material interface in vitro. The pH-cycling regimen was assessed by measuring surface hardness (SH) along with energy dispersive X-ray spectroscopy (EDX).

METHODS AND MATERIALS

Ninety blocks of bovine enamel were subjected to composition analysis with EDX, and were further categorized based on SH. The blocks were randomly divided into 6 treatment groups (n=15 each): F IX (Fuji IX Extra; GC Corporation); IZ (Ion Z, FGM); F II (Fuji II LC, GC Corporation); B II (Beautifil II, Shofu); F250 (Filtek Z250 XT, 3M ESPE); and NT (control, no treatment). The blocks were subjected to a dynamic pH-cycling regimen at 37°C for 7 days concurrently with daily alternations of immersion in demineralizing/remineralizing solutions. EDX was conducted and a final SH was determined at standard distances from the restorative materials (150, 300, and 400 μm).

RESULTS

The EDX findings revealed a significant increase in F concentration and a decrease in Ca2+ in the enamel blocks of group B II after the pH-cycling regimen (p<0.05). SH values for groups F IX, IZ, and F II were greater than those for groups B II, F250, and NT at all distances from the materials.

CONCLUSIONS

The results suggest that each of 3 restorative materials, F IX, IZ, and F II, partially inhibited enamel demineralization under a dynamic pH-cycling regimen.

Pulp tissue reaction to a self-adhesive, resin-based direct pulp capping material containing surface pre-reacted glass-ionomer filler

OBJECTIVE

This study aimed to evaluate the effect of direct pulp capping using an experimental self-adhesive resin for direct pulp capping (SRD) containing silica and surface pre-reacted glass-ionomer (S-PRG) filler on pulpal healing and to monitor the dentin bridge formation in rat pulp 2-4 weeks after operation.

METHODS

Five types of SRDs (SRD-0: S-PRG fillers 0 wt%; SRD-1: S-PRG fillers 9.1 wt%; SRD-2: S-PRG fillers 18.4 wt%; SRD-3: S-PRG fillers 27.8 wt%; and SRD-6: S-PRG fillers 57.4 wt%) were prepared, and mineral trioxide aggregate (MTA) was used as control (n = 8). Direct pulp capping was performed on rats that were sacrificed for further evaluation 2 or 4 weeks after the operation. The pulp tissue disorganization (PTD), inflammatory cell infiltration (ICI), and reparative dentin formation were histopathologically evaluated; the data were statistically analyzed using the Kruskal-Wallis and the Mann-Whitney U tests.

RESULTS

The histopathological evaluation of SRD-1-treated test animals 2 weeks post-operation revealed inferior PTD and ICI when compared with that of MTA. Even 4 weeks after the operation in SRD-1- and SRD-2-treated rats, the PTD and ICI were inferior when compared with those of MTA. The dental specimens of SRD-0 and MTA showed orthodentin formation, whereas SRD-treated test animals showed osteodentin formation at a position slightly deeper than the site of the pulpal exposure.

SIGNIFICANCE

The reparative dentin formed by SRD-0 and MTA was genuine, whereas that formed by SRD-3 and SRD-6 was ossified and ectopic. SRD may have the potential to be utilized clinically as a direct pulp capping material.

Antibacterial coating of tooth surface with ion-releasing pre-reacted glass-ionomer (S-PRG) nanofillers

OBJECTIVES

Surface pre-reacted glass-ionomer (S-PRG) fillers release antibacterial borate and fluoride ions. We fabricated nanoscale S-PRG fillers (S-PRG nanofillers) for antibacterial coating of tooth surfaces and assessed the antibacterial effects of this coating in vitro. In addition, we creating a canine model of periodontitis to evaluate the effectiveness of S-PRG nanofiller application on tooth roots and improvement of periodontal parameters.

METHODS

Human dentin blocks were coated with S-PRG nanofiller (average particle size: 0.48 μm) and then characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDX), and ion-releasing test. Antibacterial effects of dentin blocks coated with S-PRG nanofiller were examined using bacterial strains, Streptococcus mutans and Actinomyces naeslundii. Next, we created an experimental model of periodontitis in furcation of premolars of beagle dogs. Then, S-PRG nanofiller coating was applied onto exposed tooth root surfaces. Periodontal parameters, gingival index (GI), bleeding on probing (BOP), probing pocket depth (PPD), and clinical attachment level (CAL), were measured from baseline until 4 weeks. In addition, bone healing was radiographically and histologically examined.

RESULTS

SEM and EDX revealed that S-PRG nanofillers uniformly covered the dentin surface after coating. Dentin blocks coated with S-PRG nanofiller showed ion-releasing property, bacterial growth inhibition, and sterilization effects. In the experimental periodontitis model, S-PRG nanofiller coating significantly reduced clinical inflammatory parameters, such as GI (P < 0.01) and BOP (P < 0.05), compared to uncoated samples. In addition, PPD and CAL significantly decreased by S-PRG nanofiller coating (2 weeks: P < 0.05; 3 and 4 weeks: P < 0.01), suggesting the improvement of periodontitis. Micro-CT and histology revealed that bone healing of furcation defects was enhanced by S-PRG nanofiller coating.

CONCLUSION

S-PRG nanofiller coating provides antibacterial effects to tooth surfaces and improves clinical parameters of periodontitis.

Efficacy of S-PRG filler containing varnishes on enamel demineralization prevention

This study evaluated the efficacy of S-PRG vanishes on preventing enamel demineralization. Bovine enamel specimens were obtained, polished and the baseline Knoop microhardness was evaluated. Specimens were stratified into six groups (n = 15), according to the varnish applied: S10—experimental varnish containing 10% of S-PRG fillers, S20—20% of S-PRG fillers, S30—30% of S-PRG fillers; S40—40% of S-PRG fillers; PC (positive control)—5% of NaF; NC (negative control)—no treatment was performed. Half of enamel surfaces were protected to work as a control and varnishes were applied over the unprotected area. A demineralizing pH-cycling was performed, and surface and cross-sectional microhardness were measured. The percentage of microhardness of the treated area was calculated comparing with the untreated area. Statistical analysis was performed by one-way ANOVA and Tukey’s test (p = 5%). All experimental S-PRG varnishes protected against demineralization in relation to no treatment, but S40 was the most effective on the surface. For all depths, S30 and S40 were superior in enamel demineralization prevention than other S-PRG filler concentrations and 5% NaF. It was concluded that S-RPG filler containing varnishes were effective to prevent enamel demineralization. The higher concentrated products were more effective than 5% sodium fluoride on surface demineralization prevention.

Efficacy of S-PRG filler containing varnishes on enamel demineralization prevention

This study evaluated the efficacy of S-PRG vanishes on preventing enamel demineralization. Bovine enamel specimens were obtained, polished and the baseline Knoop microhardness was evaluated. Specimens were stratified into six groups (n = 15), according to the varnish applied: S10—experimental varnish containing 10% of S-PRG fillers, S20—20% of S-PRG fillers, S30—30% of S-PRG fillers; S40—40% of S-PRG fillers; PC (positive control)—5% of NaF; NC (negative control)—no treatment was performed. Half of enamel surfaces were protected to work as a control and varnishes were applied over the unprotected area. A demineralizing pH-cycling was performed, and surface and cross-sectional microhardness were measured. The percentage of microhardness of the treated area was calculated comparing with the untreated area. Statistical analysis was performed by one-way ANOVA and Tukey’s test (p = 5%). All experimental S-PRG varnishes protected against demineralization in relation to no treatment, but S40 was the most effective on the surface. For all depths, S30 and S40 were superior in enamel demineralization prevention than other S-PRG filler concentrations and 5% NaF. It was concluded that S-RPG filler containing varnishes were effective to prevent enamel demineralization. The higher concentrated products were more effective than 5% sodium fluoride on surface demineralization prevention.

Effects of a surface prereacted glass-ionomer filler coating material on biofilm formation and inhibition of dentin demineralization

OBJECTIVES

This study investigated the ability of a surface prereacted glass-ionomer (S-PRG) coating material to inhibit the biofilm formation and demineralization of dentin.

METHODS AND MATERIALS

Dentin specimens were randomly divided into three groups: (1) no coating (control), (2) S-PRG filler-containing coat, and (3) a nonS-PRG filler-containing coat. Streptococcus mutans biofilms were grown on the dentin surfaces in a microcosm for 20 h. Then, the quantity of bacteria and water-insoluble glucan in the retained biofilm on the dentin surface were measured. Regarding demineralization inhibition test, specimens were demineralized for 5 days then sectioned into halves and observed under confocal laser scanning microscope (CLSM). One-way ANOVA and Tukey's HSD were used for statistical analysis.

RESULTS

The estimated mean surface roughness for specimens in the S-PRG group was statistically significantly higher than the estimates for both the nonS-PRG and the control group specimens. The quantity of bacteria and water-insoluble glucan/mm² revealed that the S-PRG group prevented biofilm formation and bacterial adhesion to the dentin surface compared with the control and nonS-PRG groups. The S-PRG group recorded the highest acid-resistance ability with no surface loss.

CONCLUSION

Application of S-PRG barrier coat on dentin surfaces can inhibit biofilm formation as well as protecting the dentin surface against demineralization.

CLINICAL SIGNIFICANCE

Coating material containing S-PRG fillers might be used for caries prevention, through inhibiting biofilm formation, enhancing mineralization, and reducing acidic attack by cariogenic bacteria.

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.

Protective Effects of GIC and S-PRG Filler Restoratives on Demineralization of Bovine Enamel in Lactic Acid Solution

This study was aimed at investigating the protective effects of glass ionomer cement (GIC) and surface pre-reacted glass ionomer (S-PRG) fillers used as dental restorative materials on demineralization of bovine enamel. GlasIonomer FX ULTRA (FXU), Fuji IX GP Extra (FIXE), CAREDYNE RESTORE (CDR) were used as GICs. PRG Barrier Coat (BC) was used as the S-PRG filler. They were incubated in a lactic acid solution (pH = 4.0) for six days at a temperature of 37 °C. The mineral was etched from the enamel surface, and a large number of Ca and P ions were detected in solution. The Al, F, Na, Sr, and Sr ions were released in GICs and S-RPG fillers. The Zn ion was released only in CDR and the B ion was released only in BC. The presence of apparent enamel prism peripheries was observed after six days of treatment for the group containing only enamel blocks. pH values for the FXU, FIXE, CDR, BC, and enamel block groups after six days were 6.5, 6.6, 6.7, 5.9, and 5.1, respectively. Therefore, the observed pH neutralization effect suppressed progression of caries due to the release of several ions from the restoratives.

Surface Pre-Reacted Glass Filler Contributes to Tertiary Dentin Formation through a Mechanism Different Than That of Hydraulic Calcium-Silicate Cement

The induction of tissue mineralization and the mechanism by which surface pre-reacted glass-ionomer (S-PRG) cement influences pulpal healing remain unclear. We evaluated S-PRG cement-induced tertiary dentin formation in vivo, and its effect on the pulp cell healing process in vitro. Induced tertiary dentin formation was evaluated with micro-computed tomography (μCT) and scanning electron microscopy (SEM). The distribution of elements from the S-PRG cement in pulpal tissue was confirmed by micro-X-ray fluorescence (μXRF). The effects of S-PRG cement on cytotoxicity, proliferation, formation of mineralized nodules, and gene expression in human dental pulp stem cells (hDPSCs) were assessed in vitro. μCT and SEM revealed that S-PRG induced tertiary dentin formation with similar characteristics to that induced by hydraulic calcium-silicate cement (ProRoot mineral trioxide aggregate (MTA)). μXRF showed Sr and Si ion transfer into pulpal tissue from S-PRG cement. Notably, S-PRG cement and MTA showed similar biocompatibility. A co-culture of hDPSCs and S-PRG discs promoted mineralized nodule formation on surrounding cells. Additionally, S-PRG cement regulated the expression of genes related to osteo/dentinogenic differentiation. MTA and S-PRG regulated gene expression in hDPSCs, but the patterns of regulation differed. S-PRG cement upregulated CXCL-12 and TGF-β1 gene expression. These findings showed that S-PRG and MTA exhibit similar effects on dental pulp through different mechanisms.

Chemical and biological properties of new sealant-use cement materials

OBJECTIVES

The aim of this study was to investigate the chemical and biological properties of newly developed bioactive cements, modified such that they are largely composed of calcium, phosphate and fluoride. We investigated whether newly developed bioactive cements have the potential to further protect surrounding hard tissue and enhance remineralization of demineralized tissue by additional ion release.

METHODS

We developed four types of novel GIC based on Fuji VII, modified with phosphate and fluoride and calcium. Compressive strength tests were performed following JIS T6607 methods. Ion release of calcium, phosphate and fluoride after 24 h storage were determined using atomic absorption spectroscopy, colorimetry and an ion-specific electrode. Fluoride releases and recharge were measured at 1, 3, 6, 12, 24 and 168 h. Viability was determined by colony-forming units. Inhibitions of biofilm formation and cell proliferation activity were measured.

RESULTS

The GIC groups showed no significant differences in compressive strength after 1 and 7 days. The rates of fluoride ion release from newly developed GICs were significantly greater than those of Fuji VII, Fuji III and BS. All materials except TM can be recharged with fluoride ions. Compared with the control group, which did not release fluoride ions, all materials showed significantly stronger antibacterial effects. The newly developed GICs and BS showed less biofilm formation than Fuji VII and Fuji III.

SIGNIFICANCE

Three of four newly developed GICs modified with calcium, phosphate and fluoride ions were found to be superior to other sealant materials.

Effectiveness of S-PRG Filler-Containing Toothpaste in Inhibiting Demineralization of Human Tooth Surface

OBJECTIVES

Using an established pH-cycling caries model, the authors evaluated the effectiveness of toothpastes containing Surface Pre-reacted Glass-ionomer filler (S-PRG) in preventing tooth surface demineralization.

MATERIALS AND METHODS

210 tooth blocks were randomly assigned to seven experimental groups (30 blocks/group): no treatment (A), and toothpaste containing either NaF (B), 0 wt% S-PRG (C), 1 wt% S-PRG (D), 5 wt% S-PRG (E), 20 wt% S-PRG (F) or 30 wt% S-PRG (G). Groups were subjected to 14-day demineralization for development of early caries lesions using a pH-cycling caries model. Demineralization was assessed using Quantitative Light-induced Fluorescence (QLF) and Transverse Microradiography (TMR). All pairwise contrasts (between treatments) were tested using Analysis of Variance (ANOVA), and then Tukey's HSD for multiple comparisons. All p-values are considered significant if <0.05.

RESULTS

With QLF, there was a significant (ANOVA; p<0.001) difference in mean percent fluorescence loss (∆F) observed among the groups. Relative to control, all S-PRG-containing toothpastes significantly (Tukey's; p<0.0001) inhibited demineralization at varying percentages (48.6%, 61.3%, 67.4% and 69.8% reduction with S-PRG 1%, 5%, 20% and 30% respectively). Demineralization reduction was not significant with either NaF (15.6% reduction) or 0% S-PRG (-2.5% reduction i.e. 2.5% more demineralization than the Control) when compared to control group. Mineral loss assessed using TMR followed a similar trend as fluorescence loss.

CONCLUSION

Toothpaste containing S-PRG filler can serve as an effective caries control tool. S-PRG filler-containing dentifrice to be more effective in preventing tooth demineralization than 1100 ppm fluoride provided as sodium fluoride.

Clinical evaluation of a surface pre-reacted glass (S-PRG) filler-containing dental sealant placed with a self-etching primer/adhesive

AIMS

To clinically evaluate the retention rates and caries-prevention effect of a resin-based, non-etch and rinse, self-etch primed pit and fissure sealant containing Sealant Pre-reacted Glass Ionomer Cement (S-PRG) fillers, in comparison to a conventional resin-based sealant over an 18-month period.

METHODS

There were 81 children, aged 6-12 years old, who were randomly assigned to one of two sealant-groups, either the self-etch primed sealant (Beautisealant, Shofu) or the conventional etch and rinse sealant (Seal it, Spident). A total of 218 sealants of both groups were placed on first permanent molars with either sound surfaces (The International Caries Detection and Assessment System [ICDAS], code 0) or incipient enamel caries lesions (ICDAS code 1) according to the manufacturers' instructions. Each sealant restoration was independently evaluated in terms of retention and caries status at 6, 12 and 18 months. The data were statistically analysed with the Chi-squared test and z-test and the level of significance was preset at α = 0.05.

RESULTS

The differences between the complete retention rates of the two sealant groups were statistically significant in all periods of evaluation (p < 0.01). Survival rates of each sealant-group were comparable on sound (ICDAS 0) and enamel caries lesions (ICDAS1). Caries prevention effect of the two sealant groups was similar at the end of the evaluation period.

CONCLUSIONS

The clinical performance of the S-PRG filler-containing dental sealant placed with a self-etching primer was poor regarding its retention. Its significantly higher loss did not lead to more carious occlusal surfaces at the 18-month recall.

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.

Application of a direct pulp capping cement containing S-PRG filler

OBJECTIVES

To evaluate new pulp capping cements containing surface pre-reacted glass ionomer (S-PRG) filler and to investigate ion release kinetics and pH shift of eluates from the cement.

MATERIALS AND METHODS

Molars of Wistar rats were directly pulp capped using three kinds of cement containing S-PRG filler and mineral tri-oxide aggregate (MTA) was used as a control. After 1, 2, or 4 weeks, histological evaluation was performed and differences of tertiary dentin formation were analyzed. Release of Sr²⁺, BO₃^3-, SiO₃^2-, Na⁺, and Al³⁺ ions was determined by inductively coupled plasma-atomic emission spectrometry, and F^- ion release was measured using a fluoride ion selective electrode. The pH of the eluate from each cement after mixing was measured with a pH electrode.

RESULTS

One of S-PRG cements promoted tertiary dentin formation to the same extent as the control (p > 0.05) and it showed a tendency of less inflammatory response. This cement released more BO₃^3- and SiO₃^2-, but less Sr²⁺, Na⁺, and F^- than other S-PRG specimens. Each cement recovered nearly neutral compared with glass ionomer cement.

CONCLUSIONS

S-PRG cement induced tertiary dentin formation based on multiple ion releases, suggesting that it is suitable as a pulp capping material.

CLINICAL RELEVANCE

This new material can be an alternative pulp capping agent to MTA.

Evaluation of Ion Release from Four Dental Sealants

The purpose of this study was to determine the ion release from four commercially available pit-and-fissure sealants [3M Clinpro, 3M Concise™, BeautiSealant (BS), and GI FX-II)]. With each brand, 18 specimens were prepared. Their fluoride release in de-ionized water was measured by fluoride electrode, while the release of silicate (Si), aluminum (Al), sodium (Na), calcium (Ca), strontium (Sr), and phosphorus (P) was measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES) on days 1, 3, 7, 14, 21, and 28. The result showed that fluoride was not released from 3M Concise™. GI FX-II displayed the largest fluoride release, which, however, dropped rapidly on day 3. 3M Clinpro exhibited less fluoride release than GI FX-II and BS did. At any time during the 28-day experimental period, GI FX-II released more Na than the other sealants (P<0.001). BS ranked the second in Na release, and a small amount of Na ions was released from the 3M Clinpro and 3M Concise™ samples. Al ions were only detected from BS and GI FX-II, but not from the 3M Clinpro and 3M Concise™. Additionally GI FX-II had the largest Si release among the four brands at any time during the experimental period (P<0.001). Ca ions were detected from 3M Clinpro and 3M Concise™, but not from GI FX-II. BS released more Sr than the other sealants at any time during the experimental period (P<0.001). All the samples released similar amounts of P continuously during these 28 days. In conclusion, based on the type and the amount of ion release, BS is the best pit-and-fissure sealant among the four brands.

Assessment of the inhibitory effects of fissure sealants on the demineralization of primary teeth using an automatic pH-cycling system

In this study, we examined the effects of fissure sealants on inhibition of demineralization of primary teeth using an automatic pHcycling system. Three fissure sealants were used: Teethmate F-1 2.0 (TM), BeautiSealant (BS), and Fuji III LC (IIILC). Using an automatic pH-cycling system, the specimens (n=12) were repeatedly demineralized and remineralized. Specimens were subjected to transverse microradiography (TMR), and changes in integrated mineral loss (IML) and lesion depth (Ld), indicated as ΔIML and ΔLd, respectively, were calculated. In addition, fluoride levels in the enamel were assessed using microparticle-induced gamma-ray emission/particle-induced X-ray emission (n=3). IIILC showed the lowest values for ΔIML and ΔLd, followed by BS and then TM. The highest amount of fluorine in the enamel was observed for IIILC, followed by TM and BS. All fissure sealants inhibited demineralization in primary teeth.

Synthesized mesoporous silica and calcium aluminate cement fillers increased the fluoride recharge and lactic acid neutralizing ability of a resin-based pit and fissure sealant

This study evaluated the effect of different types of filler in a resin-based pit and fissure sealant on fluoride release, recharge, and lactic acid neutralization. Resin-based sealant was incorporated with 5% w/w of the following fillers: calcium aluminate cement (CAC), synthesized mesoporous silica (SI), a CAC and SI mixture (CAC+SI), glass-ionomer powder (GIC), and acetic acid-treated GIC (GICA). Sealant without filler served as control. The samples were immersed in deionized water or a lactic acid solution and the concentration of fluoride in the water, before and after fluoride recharge, and the lactic acid pH change, respectively, were determined. The CAC+SI group demonstrated the highest fluoride release after being recharged with fluoride gel. The CAC+SI group also demonstrated increased lactic acid pH. These findings suggest that a resin-based sealant containing synthesized mesoporous silica and calcium aluminate cement may enhance remineralization due to fluoride release and higher pH.

Long-term release of fluoride from fissure sealants-In vitro study

The intensity of the cariostatic activity of fluoride ions can be attributed to their multidirectional influence on the caries process. They are an irreplaceable factor that helps sustain mineral balance of dental tissues, simultaneously demonstrating antibacterial properties. As a consequence, many manufacturers of fissure sealants include fluoride ions in their products. The aim of this in vitro study was to determine long-term fluoride release from four fissure sealants (Conseal F, Fissurit FX, Delton Fs+, Admira Seal). During a 14-week-long observation, all the materials showed a relatively constant level of F- release; however, it is crucial to mention that within the first 48h, the most significant increase in fluoride release was found for Fissurit and Delton sealants. Based on the overall assessment, the highest total amount of the released fluoride ions was observed for Delton, and the lowest level was reported for Admira Seal.

Structural analysis of strontium in human teeth treated with surface pre-reacted glass-ionomer filler eluate by using extended X-ray absorption fine structure analysis

The bioactive effects of strontium released from surface pre-reacted glass-ionomer (S-PRG) fillers may aid in caries prevention. In this study, the local structure of strontium taken up by teeth was estimated by extended X-ray absorption fine structure analysis. Immersing teeth into S-PRG filler eluate increased the strontium content in enamel and dentin by more than 100 times. The local structure of strontium in enamel and dentin stored in distilled water was the same as that in synthetic strontium-containing hydroxyapatite (SrHAP). Moreover, the local structure of strontium in enamel and dentin after immersion in the S-PRG filler eluate was also similar to that of SrHAP. After immersion in the S-PRG filler eluate, strontium was suggested to be incorporated into the hydroxyapatite (HAP) of enamel and dentin at the calcium site in HAP.

Shear bond strengths of tooth coating materials including the experimental materials contained various amounts of multi-ion releasing fillers and their effects for preventing dentin demineralization

We examined shear bond strengths (SBSs) of various tooth-coating-materials including the experimental materials to dentin and demineralization resistance of a fractured adhesive surface after the SBS testing. Three resin-type tooth-coating-materials (BC, PRG Barrier Coat; HC, Hybrid Coat II; and SF, Shield force plus) and two glass-ionomer-type tooth-coating-materials (CV, Clinpro XT Varnish; and FJ, Fuji VII) were selected. The experimental PRG Barrier Coat containing 0, 17, and 33 wt% S-PRG filler (BC0, BC17, and BC33, respectively) were developed. Each tooth-coating-material was applied to flattened dentin surfaces of extracted human teeth for SBS testing. After storing in water for 32 days with 4000 thermal cycling, the specimens were subjected to the SBS test. Specimens after SBS testing were subjected to a pH cycling test, and then, demineralization depths were measured using a polarized-light microscope. ANOVA and Tukey's HSD test were used for statistical analysis. The SBS value of FJ and CV was significantly lower than those of other materials except for BC (p < 0.01). The lesion depth of FJ was significantly shallower than those of other materials (p < 0.01); that of CV was significantly shallower than those of BC, HC, SF, and the control; and those of BC0 and BC17 were significantly shallower than that of the control (p < 0.05). The resin-type tooth-coating-materials demonstrated significantly higher SBS for dentin than the glass-ionomer-type tooth-coating-materials; however, they were inferior to the glass ionomer-type tooth-coating-materials in regards to the acid resistance of the fractured adhesion surface.