Surface free energy of enamel treated with sodium hexametaphosphate, calcium and phosphate

Orthodontic adhesive loaded with different proportions of ZrO2 silver-doped nanoparticles: An in vitro μTBS, SEM, EDX, FTIR, and antimicrobial analysis

Zirconium dioxide silver-doped nanoparticles (ZrO2AgDNPs) impacts the adhesive material in terms of its physical characteristics, antimicrobial properties, degree of conversion (DC), and micro-tensile bond strength (μTBS) of orthodontic brackets to the enamel surface. A comprehensive methodological analysis utilizing a range of analytical techniques, including scanning electron microscopy coupled with energy-dispersive x-ray spectroscopy (EDX), Fourier-transform infrared (FTIR) spectroscopy, DC analysis, and μTBS testing. A light-curable orthodontic adhesive, specifically Transbond XT, was combined with ZrO2AgDNPs at 2.5% and 5%. As a control, an adhesive with no incorporation of ZrO2AgDNPs was also prepared. The tooth samples were divided into three groups based on the weightage of NPs: group 1: 0% ZrO2AgDNPs (control), group 2: 2.5 wt% ZrO2AgDNPs, and group 3: 5 wt% ZrO2AgDNPs. EDX graph demonstrated silver (Ag), Zirconium (Zr), and Oxygen (O2), The antibacterial efficacy of adhesives with different concentrations of NPs (0%, 2.5%, and 5%) was assessed using the pour plate method. The FTIR spectra were analyzed to identify peaks at 1607 cm-1 corresponding to aromatic CC bonds and the peaks at 1638 cm-1 indicating the presence of aliphatic CC bonds. The μTBS was assessed using universal testing machine (UTM) and bond failure of orthodontic brackets was seen using adhesive remanent index (ARI) analysis. Kruskal-Wallis test assessed the disparities in survival rates of Streptococcus mutans. Analysis of variance (ANOVA) and post hoc Tukey multiple comparisons test calculated μTBS values. The lowest μTBS was observed in group 1 adhesive loaded with 0% ZrO2AgDNPs (21.25 ± 1.22 MPa). Whereas, the highest μTBS was found in group 3 (26.19 ± 1.07 MPa) adhesive loaded with 5% ZrO2AgDNPs. ZrO2AgDNPs in orthodontic adhesive improved μTBS and has acceptable antibacterial activity against S mutans. ZrO2AgDNPs at 5% by weight can be used in orthodontic adhesive alternative to the conventional method of orthodontic adhesive for bracket bonding. RESEARCH HIGHLIGHTS: The highest μTBS was found in orthodontic adhesive loaded with 5% ZrO2AgDNPs. ARI analysis indicates that the majority of the failures fell between 0 and 1 among all investigated groups. The colony-forming unit count of S. mutans was significantly less in orthodontic adhesive loaded with nanoparticles compared with control. The 0% ZrO2AgDNPs adhesive showed the highest DC.

Synthesis, Characterization, and Evaluation of the Antimicrobial Effects and Cytotoxicity of a Novel Nanocomposite Based on Polyamide 6 and Trimetaphosphate Nanoparticles Decorated with Silver Nanoparticles

This study aimed to develop a polymeric matrix of polyamide-6 (P6) impregnated with trimetaphosphate (TMP) nanoparticles and silver nanoparticles (AgNPs), and to evaluate its antimicrobial activity, surface free energy, TMP and Ag+ release, and cytotoxicity for use as a support in dental tissue. The data were subjected to statistical analysis (p < 0.05). P6 can be incorporated into TMP without altering its properties. In the first three hours, Ag+ was released for all groups decorated with AgNPs, and for TMP, the release only occurred for the P6-TMP-5% and P6-TMP-10% groups. In the inhibition zones, the AgNPs showed activity against both microorganisms. The P6-TMP-2.5%-Ag and P6-TMP-5%-Ag groups with AgNPs showed a greater reduction in CFU for S. mutans. For C. albicans, all groups showed a reduction in CFU. The P6-TMP groups showed higher cell viability, regardless of time (p < 0.05). The developed P6 polymeric matrix impregnated with TMP and AgNPs demonstrated promising antimicrobial properties against the tested microorganisms, making it a potential material for applications in scaffolds in dental tissues.

Visible light-activated curcumin-doped zinc oxide nanoparticles integrated into orthodontic adhesive on Micro-tensile bond strength, degree of conversion, and antibacterial effectiveness against Staphylococcus Aureus. An investigation using scanning electron microscopy and energy-dispersive X-ray spectroscopy

AIM

To acquire a thorough comprehension of the photoactivated Cur-doped ZnONPs at different concentrations 0%, 2.5%, and 5% on the physical qualities, antibacterial efficacy, degree of conversion, and μshear bond strength between orthodontic brackets and the enamel surface.

MATERIAL AND METHODS

An extensive investigation was carried out utilizing a range of analytical methods, scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDX), Fourier-transform infrared (FTIR) spectroscopy, micro tensile bond strength (μTBS) testing, and evaluation of antibacterial effectiveness. Cur-doped ZnONPs at concentrations of 2.5% and 5% were blended with Transbond XT, a light-curable orthodontic adhesive. A control group without the addition of Cur-doped ZnONPs was also prepared. The tooth samples were categorized into three groups based on the weight percentage of NPs: Group 1 (control) with 0% Cur-doped ZnONPs, Group 2 with 2.5 wt% Cur-doped ZnONPs, and Group 3 with 5 wt% Cur-doped ZnONPs. The SEM technique was employed to analyze the morphological characteristics of Cur-doped ZnONPs and ZnONPs. The composition and elemental distribution of the modified Cur-doped ZnONPs were assessed using energy-dispersive X-ray spectroscopy. The effectiveness of NPs at various concentrations against S.Mutans was gauged through the pour plate method. DC of Cur-doped ZnONPs at a region of 1608 cm-1 to 1636 cm-1 for the cured area, whereas the uncured area spanned the same range of 1608 cm-1 to 1636 cm-1 was assessed. The Adhesive Remnant Index (ARI) approach was utilized to investigate the bond failure of orthodontic brackets, while a Universal Testing Machine (UTM) was utilized to test μTBS. The Kruskal-Wallis test was employed to investigate variations in S.mutans survival rates. To determine the μTBS values, analysis of variance (ANOVA) and the post hoc Tukey multiple comparisons test were used.

RESULTS

The maximum μTBS was given and documented in group 3: 5 wt% Cur-doped ZnONPs (21.21 ± 1.53 MPa). The lowest μTBS was given in group 2: 2.5 wt% Cur-doped ZnONPs (19.58 ± 1.27 MPa). The highest efficacy against S.mutans was documented in group 3 in which 5 wt% Cur-doped ZnONPs (0.39 ± 0.15). The lowest efficacy was seen in group 1 in which no Cur-doped ZnONPs were used (6.47 ± 1.23). The ARI analysis indicated that the predominant failure was between scores 0 and 1 among all experimental groups. Control group 1 which was not modified showed the highest DC (73.11 ± 4.19).

CONCLUSION

Orthodontic adhesive, containing 5% Cur-doped ZnONPs photoactivated with visible light exhibited a favorable impact on μTBS and indicated enhanced antibacterial efficacy against S.mutans. Nevertheless, it was observed that the addition of Cur-doped ZnONPs at different concentrations (2.5%,5%) resulted in a decrease in the monomer-to-polymer ratio compromising DC.

Pomegranate extract in polyphosphate-fluoride mouthwash reduces enamel demineralization

OBJECTIVES

To evaluate the anti-demineralizing effect of a mouthwash comprising pomegranate peel extract (PPE 3%), sodium trimetaphosphate (TMP 0.3%), and fluoride (F 225 ppm) in an in situ study, and to assess its irritation potential in an ex vivo study.

METHODS

This double-blind crossover study was conducted in four phases with 7 days each. Twelve volunteers used palatal appliances containing enamel blocks, which were subjected to cariogenic challenges. The ETF formulation (PPE + TMP + F, pH 7.0), TF formulation (TMP + F, pH 7.0), deionized water (W, pH 7.0), and essential oil commercial mouthwash (CM, 220 ppm F, pH 4.3) were dropped onto the enamel twice daily. The percentage of surface hardness loss, integrated loss of subsurface hardness, calcium, phosphorus, and fluoride in enamel and biofilms were determined. In addition, alkali-soluble extracellular polysaccharide concentrations were analyzed in the biofilms. The irritation potential was evaluated using the hen's egg chorioallantoic membrane test through the vascular effect produced during 300-s of exposure.

RESULTS

ETF was the most efficacious in preventing demineralization. It also showed the highest concentrations of calcium and phosphorus in the enamel and in the biofilm, as well as the lowest amount of extracellular polysaccharides in the biofilm. In the eggs, ETF produced light reddening, whereas CM led to hyperemia and hemorrhage.

CONCLUSIONS

The addition of PPE to formulations containing TMP and F increased its anti-demineralizing property, and this formulation presented a lower irritation potential than the CM.

CLINICAL RELEVANCE

ETF can be a promising alternative alcohol-free mouthwash in patients at high risk of caries.

Influence of bleaching gels formulated with nano-sized sodium trimetaphosphate and fluoride on the physicochemical, mechanical, and morphological properties of dental enamel

OBJECTIVES

To evaluate in vitro the effects of sodium fluoride (F) and nano-sized sodium trimetaphosphate (TMPnano) added to a 35% hydrogen peroxide (H2O2) bleaching gel on the color alteration, enamel mechanical and morphological properties, and H2O2 transamelodentinal diffusion.

MATERIALS AND METHODS

Bovine enamel/dentin discs (n = 180) were divided according to the bleaching gel: 35% H2O2 (HP); 35% H2O2 + 0.1% F (HP/F); 35% H2O2 + 1% TMPnano (HP/TMPnano); 35% H2O2 + 0.1% F + 1% TMPnano (HP/F/TMPnano) and 35% H2O2 + 2% calcium gluconate (HP/Ca). The gels were applied 3 times by 40 min; once each 7-day. The Commission Internationale de l'Eclairage (CIE) L*a*b* total color alteration (ΔE), color alteration by CIEDE2000 (ΔE00), whitening index (ΔWID), surface (SH) and cross-sectional hardness (ΔKHN), surface roughness (Ra), and transamelodentinal diffusion were determined. Enamel surfaces were evaluated by Scanning Electron Microscopy (SEM) and X-ray Dispersive Energy (EDX). Data were submitted to ANOVA, followed by the Student-Newman-Keuls test (p <0.05).

RESULTS

ΔE, ΔE00, and ΔWID were similar among the gels that promoted a bleaching effect after treatment (p <0.001). Mineral loss (SH and ΔKHN), Ra, and H2O2 diffusion were lower for HP/F/TMPnano; the HP and HP/Ca groups presented the highest values (p <0.001). For SEM/EDX, surface changes were observed in all bleached groups, but less intense with TMPnano.

CONCLUSIONS

Gels containing F/TMPnano do not interfere with the bleaching effect and reduce enamel demineralization, roughness, H2O2 diffusion, and morphological changes.

CLINICAL RELEVANCE

Whitening gels containing F/TMPnano can be used as a new strategy to increase safety and maintain clinical performance.

Effect of sodium hexametaphosphate and quercetin, associated or not with fluoride, on dentin erosion in vitro

OBJECTIVE

to investigate the ability of solutions containing sodium hexametaphosphate, fluoride and quercetin, alone or in association, to prevent dentin erosion and to inhibit matrix metalloproteinases -2 and -9 activity using in vitro protocols.

DESIGN

Root dentin blocks (n = 96) were prepared and divided into 8 experimental groups (n = 12/group), according to the solutions to be tested: Placebo; 0.24% sodium fluoride (F); 1.0% sodium hexametaphosphate (HMP); 0.03% quercetin (QC); F+HMP; F+QC; HMP+QC; and F+HMP+QC. Erosive challenges were performed 4×/day for 5 days. Specimens were treated with the respective solutions for one minute, twice a day. Next, dentin loss (profilometry) and integrated hardness area in depth (KHN × µm) were determined. The antiproteolytic potential was assessed by gelatin zymography. Dentin erosion results (log₁₀-transformed) were submitted to one-way ANOVA, followed by Tukey's test. Integrated hardness area in depth data (raw) were submitted to two-way, repeated-measures ANOVA, followed by Holm-Sidak's test (p<0.05).

RESULTS

Dentin erosion was significantly lower for F+HMP+QC than for all other treatments. At the shallowest depths (5-30 µm), blocks treated with F+HMP+QC had the highest integrated hardness area in depth values. All treatments completely inhibited matrix metalloproteinases-2 activity, except for the group QC (77% inhibition). For matrix metalloproteinases-9, all HMP-containing solutions or F+QC promoted total antiproteolytic activity.

CONCLUSION

The association of fluoride, sodium hexametaphosphate, and quercetin must be considered a valuable strategy for novel product formulation for home and professional use, considering its superior protective effects against dentin erosion and its antiproteolytic potential.

New insights into the anti-erosive property of a sugarcane-derived cystatin: different vehicle of application and potential mechanism of action

A new sugarcane-derived cystatin (CaneCPI-5) showed anti-erosive properties when included in solutions and strong binding force to enamel, but the performance of this protein when added to gel formulations and its effect on surface free energy (SFE) requires further studies.

In vitro study on how antioxidant solutions affect enamel surface characteristics and bonding interface of ceramic laminate veneers luting after dental bleaching

PURPOSE

This in vitro study aimed to determine the effect of antioxidant solutions used after dental bleaching on the shear bond strength and adhesive interface sealing of ceramic laminate veneer luting. Additionally, effects on the enamel surface characteristics of hydrogen peroxide neutralization, surface energy, total free interaction energy, morphology, and chemical composition of enamel were assessed.

MATERIAL AND METHODS

Total 127 bovine incisors were divided into experimental groups, according to the surface treatment (unbleached and bleached enamel), antioxidant types (control; 10% ascorbic acid and 10% α-tocopherol), and periods of luting of ceramic laminates (24 h and after 14 days). Shear bond strength was assessed using microtensile test before and after thermal cycling (5760 cycles, 5-55 °C) (n = 6). The sealing of the adhesive interface was assessed using a confocal laser scanning microscope (n = 3). Hydrogen peroxide neutralization analysis was performed using a spectrophotometer (n = 5). The surface energy and total free interaction energy (n = 10) were measured using an automatic goniometer, while enamel morphology and chemical composition were assessed by scanning eletron microscopy (n = 3). Shear bond strength and enamel surface properties data were subjected to ANOVA followed by Tukey's test (α = 0.05). Adhesive interface micrographs were evaluated by the inter-examiner Kappa test and subjected to Kruskal-Wallis and Dunn's tests (α = 0.05).

RESULTS

In general, thermal aging decreased the shear bond strength values of the luting agents to enamel (P < .05). The α-tocopherol solution was able to reverse the oxidizing effect from dental bleaching, increasing the shear bond strength values and preserving the integrity of the adhesive interface sealing (P < .05). Moreover, the α-tocopherol antioxidant agent promoted higher hydrogen peroxide neutralization after dental bleaching (P < .05). Dental bleaching influenced the enamel surface, decreasing the surface energy and total free interaction energy values (P < .05).

CONCLUSION

α-tocopherol was able to reverse the oxidizing effects of dental bleaching, improving the enamel surface properties, as well as the adhesion and interface sealing of ceramic laminate veneer restorations.

Evaluation of bleaching efficacy, microhardness, and trans-amelodentinal diffusion of a novel bleaching agent for an in-office technique containing hexametaphosphate and fluoride

OBJECTIVE

This study evaluated in vitro the effects of calcium gluconate (CaGlu), sodium fluoride (NaF), sodium hexametaphosphate (HMP), and NaF/TMP added to a 35% hydrogen peroxide (H₂O₂) bleaching gel on the color change, enamel hardness, and trans-amelodentinal diffusion.

MATERIALS AND METHODS

Enamel discs/bovine dentin (n = 150) were divided according to the bleaching gel: 35% H₂O₂ (H₂O₂); 35% H₂O₂ + 0.1% NaF (H₂O₂/NaF); 35% H₂O₂ + 1% HMP (H₂O₂/HMP); 35% H₂O₂ + 0.1% NaF + 1% HMP (H₂O₂/NaF/HMP), and 35% H₂O₂ + 2% CaGlu (H₂O₂/Caglu). The bleaching gels were applied three times (40 min/session) at 7-day intervals between each application. Then, color alteration (ΔE), whitening index (ΔWI_D), percentage of surface hardness loss (% SH), cross-sectional hardness (ΔKHN), and trans-amelodentinal diffusion were determined. Data were submitted for analysis of variance (ANOVA), followed by the Student-Newman-Keuls test (p < 0.05).

RESULTS

All bleaching gels showed significant color changes after treatment (p < 0.001). ΔE and ΔWI_D were similar among the evaluated gels. Mineral loss (% SH and ΔKHN) and trans-amelodentinal diffusion of hydrogen peroxide were lower for H₂O₂/NaF/HMP; the H₂O₂/CaGlu group presented the highest values about the other groups (p < 0.001).

CONCLUSION

It is possible to conclude that the addition of NaF/HMP to the in-office bleaching agent did not interfere with the bleaching efficacy and reduced enamel demineralization and H₂O₂ diffusion.

CLINICAL SIGNIFICANCE

The association of NaF/HMP to the bleaching gel can be used as a novel approach for minimizing the adverse effects of H₂O₂ by-products and with similar clinical efficacy.

In vitro Evaluation of Surface Free Energy of Dentin after Treatment with Sodium Trimetaphosphate Associated or Not with Fluoride, Exposed or Not to Calcium

It has been stated that sodium trimetaphosphate (TMP) promotes a more anionic dentin surface inducing greater calcium (Ca) and phosphate precipitation. The aim of the present study was to evaluate in vitro the surface free energy (γs) of dentin after treatment with TMP associated or not with fluoride (F), exposed or not to Ca, as well as the adsorption of TMP, F, and Ca by dentin. Bovine dentin blocks (n = 12 blocks/group) were treated with solutions containing TMP at 0, 1, 3, or 9 (w/v) followed or not by the application of Ca. These solutions were or were not associated to 1,100 ppm F. F, Ca, and TMP were determined in the solutions before and after the treatment to calculate the adsorption by dentin. To analyze the γs of dentin, the apolar (γsLW), and polar (γsAB), components were determined by contact angle measurement. Data were submitted to 2-way ANOVA followed by the Student-Newman-Keuls test (p < 0.05). TMP reduces γs of dentin and increases electron donor sites (γs-). Higher values of γs- led to higher adsorption of Ca (p < 0.001). The F/TMP association did not change γs or γsLW and reduced the values of γs-, but the adsorption of Ca was higher. There was correlation between the adsorption of TMP and γs- (Pearson's r = 0.801; p < 0.001) and F (Pearson's r = 0.871, p < 0.001). It is possible to conclude that TMP increased γs- and Ca adsorption, and reduced γs. The association with F increased the adsorption of TMP without rising γs-; however, there was higher adsorption of Ca.

Surface Free Energy, Interaction, and Adsorption of Calcium and Phosphate to Enamel Treated with Trimetaphosphate and Glycerophosphate

This study aimed to evaluate the surface (γs) and interaction (ΔGiwi) free energy and calcium (Ca2+) and phosphate (PO43-) adsorption to dental enamel treated with sodium trimetaphosphate (TMP) or calcium glycerophosphate (CaGP) that had or had not been exposed to CaPO4-containing solutions. Bovine enamel blocks (n = 192; 24 blocks/group) were treated (2 mL/block; 2 min) with TMP (0%, 1%, 3%, and 9%) and CaGP (0, 0.25, 0.5, and 1%) or exposed to a CaPO4-containing solution. The adsorption of these compounds by enamel was assessed before and after treatment. γs and ΔGiwi and their apolar (γsLW and ΔGiwiLW) and polar (γsAB and ΔGiwiAB) components and acid-base interactions (γs+/γs-) were determined by the contact angles. The data were subjected to ANOVA, followed by the Student-Newman-Keuls test (p < 0.05). The adsorption of TMP was dose dependent (p < 0.001), and it reduced γs and γsAB and increased ΔGiwiAB (ΔGiwi > 0) and γs- when compared with the group without TMP (p < 0.001). The immersion in CaPO4-containing solution increased γs and γsAB and reduced ΔGiwiAB (ΔGiwi > 0) and γs- (p < 0.001). There was a correlation between the adsorption of TMP and Ca2+ (r = 0.916; p < 0.001) and PO43- (r = 0.899; p < 0.001). The adsorption of CaGP on the enamel was dose dependent (p < 0.001), reducing γs, ΔGiwiAB (ΔGiwi < 0), γsLW, and γs- when compared to the group without CaGP (p < 0.001). When exposed to the CaPO4-containing solution, there was an increase in ΔGiwiAB (ΔGiwi > 0), γsLW, and γs- and a decrease in γsAB (p < 0.001) without adsorption of Ca2+ by enamel. It may be concluded that TMP and CaGP were adsorbed onto the enamel, producing hydrophilic and hydrophobic surfaces, respectively. TMP produces electron donor sites that induce Ca2+ adsorption, while CaGP releases Ca2+ into the medium.

In vitro study on how cold plasma affects dentin surface characteristics

PURPOSE

Studies evaluating different features of cold plasma action on dentin surface characteristics are lacking. Thus, this in vitro study aimed to determine the effect of cold plasma under different protocols of exposure time, distance to plasma source, and the association of argon gas with distinct concentrations of oxygen on the wettability, surface energy, total free interaction energy, surface roughness, morphology and chemical composition of dentin.

MATERIAL AND METHODS

One hundred and twenty-five bovine dentin samples were used and divided into twenty-five groups according to the exposure time to plasma (15, 30, or 60 s); distance between plasma source and dentin surface (3 or 6 mm); argon gas without plasma generation; and plasma generated by argon gas and association of argon gas with distinct concentrations of oxygen (2 % or 3 %) (n = 5). Contact angle (θ), surface energy (γs) and total free interaction energy (ΔG) were measured using a goniometer (Krüss), while surface roughness (Ra) was evaluated by a profilometer (Mitutoyo). Representative samples were submitted to scanning electron microscopy (JEOL) to ilustrate the morphology and chemical composition of dentin. Data comparing control group with all experimental groups were submitted to ANOVA followed by Tukey's test (α = .05). Data comparing oxygen gas action at different concentrations and argon gas on dentin characteristics were submitted to non-parametric Kruskal-Wallis test, followed by Dunn test for comparison between the groups and methods (α = 0.05).

RESULTS

In general, argon gas without plasma generation promoted no significant difference on dentin surface characteristics compared to control group (P > .05), differently for the cold plasma that significantly reduced contact angle values and increased total free interaction energy of dentin surface (P < .05). Overall, feeding of oxygen at distinct concentrations promoted significant difference on dentin surface characteristics compared to control group (P < .05). Exposure time and distance protocols interfered with contact angle, surface energy and total free interaction energy analyses for each gas. There was no significant difference on surface roughness (P > .05), morphology and chemical composition of dentin submitted to argon gas, cold plasma, and distinct concentrations of oxygen.

CONCLUSION

In conclusion, plasma generated by argon gas and its feeding with 2 % and 3 % oxygen gas improved the dentin surface characteristics about wettability, surface energy and total free interaction energy. Such treatments preserved the surface roughness, morphology and chemical composition of dentin. The protocols of groups Ar-6mm-15sec, ArO2-3mm-30sec and ArO3-3mm-15sec are recommended for improvement of dentin surface characteristics.

Surface Testing of Dental Biomaterials-Determination of Contact Angle and Surface Free Energy

The key goal of this study was to characterize surface properties of chosen dental materials on the base on the contact angle measurements and surface free energy calculations. Tested materials were incubated in the simulated oral environment and drinks to estimate an influence of conditions similar to those in the oral cavity on wetting and energetic state of the surface. Types of materials were as follows: denture acrylic resins, composite and PET-G dental retainer to compare basic materials used in a prosthetics, restorative dentistry and orthodontics. The sessile drop method was used to measure the contact angle with the use of several liquids. Values of the surface free energies were estimated based on the Owens-Wendt, van Oss-Chaudhury-Good and Zisman's methods. The research showed that surface wetting depends on the material composition and storage conditions. The most significance changes of CA were observed for acrylic resins (84.7° ± 3.8° to 65.5° ± 3.5°) and composites (58.8° ± 4.1° to 49.1° ± 5.7°) stored in orange juice, and for retainers (81.9° ± 1.8° to 99.6° ± 4.5°) incubated in the saline solution. An analysis of the critical surface energy showed that acrylic materials are in the zone of good adhesion (values above 40 mJ/m²), while BIS-GMA composites are in the zone of poor adhesion (values below 30 mJ/m²). Study of the surface energy of different dental materials may contribute to the development of the thermodynamic model of bacterial adhesion, based on the surface free energies, and accelerate the investigation of biomaterial interaction in the biological environment.

Effect of fluoride, casein phosphopeptide-amorphous calcium phosphate and sodium trimetaphosphate combination treatment on the remineralization of caries lesions: An in vitro study

OBJECTIVE

To evaluate the effects of combination of treatments with fluoridated toothpastes supplemented with sodium trimetaphosphate (TMP) and casein phosphopeptide-amorphous calcium phosphate (MI Paste Plus®), on the remineralization of dental enamel.

DESIGN

Enamel blocks with artificial caries were randomly allocated into six groups (n = 12), according to the toothpastes: 1) without F-TMP-MI Paste Plus® (Placebo); 2) 1100 ppm F (1100 F), 3) MI Paste Plus®, 4) 1100 F + MI Paste Plus® (1100 F-MI Paste Plus®), 5) 1100 F + 3% TMP (1100 F-TMP) and 6) 1100 F-TMP + MI Paste Plus® (1100 F-TMP-MI Paste Plus®). Blocks were treated 2×/day with slurries of toothpastes (1 min). Furthermore, groups 4 and 6 received the application of MI Paste Plus® for 3 min. After pH cycling, the percentage of surface hardness recovery (%SHR); integrated loss of subsurface hardness (ΔKHN); profile analysis and lesion depth subsurface through polarized light microscopy (PLM), confocal laser scanning microscopy (LSCM), scanning electron microscopy (SEM), fluoride (F), calcium (Ca), phosphorus (P) concentrations in the enamel were determined. The data were analyzed by ANOVA (1-criterion) and Student-Newman-Keuls test (p < 0.001).

RESULTS

1100 F-TMP-MI Paste Plus® group showed the best results of %SHR, ΔKHN and PLM (p < 0.001). F concentration was similar between the 1100 F, 1100 F-MI Paste Plus®, and 1100 F-TMP-MI Paste Plus® groups (p > 0.001). 1100 F-TMP-MI Paste Plus® group showed the highest concentration of Ca and P in the enamel (p < 0.001).

CONCLUSION

The association of 1100 F-TMP and MI Paste Plus® led to a significant increase in the remineralization of initial carious lesions.

Evaluation of the aesthetic effect, enamel microhardness and trans-amelodentinal cytotoxicity of a new bleaching agent for professional use containing trimetaphosphate and fluoride

This study evaluated the effects of calcium gluconate (CaGlu), sodium fluoride (NaF), sodium trimetaphosphate (TMP), and NaF/TMP when added to a 35% hydrogen peroxide (H₂O₂) bleaching gel on the color change, enamel hardness, penetration and cytotoxicity trans-amelodentinal. Bovine enamel/dentin disks (n = 288) were divided according to the bleaching gel: 35% H₂O₂; 35% H₂O₂ + 0.05% NaF; 35% H₂O₂ + 0.25% TMP; 35% H₂O₂ + 0.05% NaF + 0.25% TMP; 35% H₂O₂ + 0.1% NaF + 1% TMP and 35% H₂O₂ + 2% CaGlu. The bleaching gels were applied thrice (40 min/session) at 7-day intervals between each application. Then, the color change, percentage of surface hardness loss (%SH), cross-sectional hardness (ΔKHN), trans-amelodentinal penetration of H₂O₂, cell viability and morphology (MDPC-23 odontoblast-like cells), alkaline phosphatase activity (ALP) and deposition of mineralization nodules were determined. The data were submitted to ANOVA, followed by the Student-Newman-Keuls test (p < 0.05). All bleaching gels showed significant color changes after treatment (p < 0.001). Mineral loss (%SH and ΔKHN) and H₂O₂ penetration were lower for 35% H₂O₂/0.1% NaF/1% TMP; 35% H₂O₂/2% CaGlu, meanwhile, showed higher values, compared to the other groups (p < 0.001). Cell viability was around 9%, except for the bleaching gel containing 35% H₂O₂/0.1% NaF/1% TMP with 12.8% (p < 0.05). ALP was higher for groups containing TMP compared to other whitening gels (p < 0.05). The formation of mineralization nodules was greater for gels containing NaF/TMP or CaGlu (p < 0.05). The alterations of cell morphology were intense for all bleaching gels. It was concluded that the addition of NaF/TMP in-office bleaching did not interfere in bleaching efficacy, reduced enamel demineralization, H₂O₂ penetration and cytotoxicity.

Evaluation of new compositions of 10% hydrogen peroxide-based bleaching agents containing trimetaphosphate and fluoride on enamel demineralization

This study evaluated the effect on enamel demineralization of 10% hydrogen peroxide (H₂ O₂ ) gels containing different concentrations of sodium trimetaphosphate (TMP) and sodium fluoride (NaF) combined with the daily use of fluoridated or placebo dentifrice. Bovine enamel blocks were selected by surface hardness (n = 72) and randomly assigned to one of the following experimental treatments: 10% H₂ O₂ ; 10% H₂ O₂  + 3% TMP + 0.1% NaF; and 10% H₂ O₂  + 0.3% TMP + 0.05% NaF, each with or without fluoridated dentifrice. H₂ O₂ -based gels were applied for 30 min d^-1 followed by treatment with dentifrice (1 min). Enamels blocks were stored in artificial saliva at 37°C between sessions during the 14 days of experiment. Percentage of surface hardness loss (%SH) was calculated, and the blocks were cut into halves to analyze cross-sectional hardness (ΔKHN). Polarized light microscopy images were obtained of the longitudinal sections of the samples. Enamel treated with fluoridated dentifrice presented lower hardness loss than those treated with placebo dentifrice (%SH and ΔKHN). Use of TMP- and NaF-based gels, regardless of concentration, led to the lowest %SH values. Specimens treated with 10% H₂ O₂ gel had the highest %SH and ΔKHN values. Gels with 10% H₂ O₂  + 3% TMP + 0.1% NaF showed the lowest ΔKHN values. Microscopy images clearly showed that the addition of TMP and NaF to the H₂ O₂ -based gels was effective in reducing the loss of hardness, and the fluoridated dentifrice helped minimize it in all treatments.

Protective Effect of Fluoride Varnish Containing Trimetaphosphate against Dentin Erosion and Erosion/Abrasion: An in vitro Study

This in vitro study evaluated the protective effect of fluoride varnishes containing sodium trimetaphosphate (TMP) against dentin erosion and abrasion. Specimens of coronal dentin were divided into: placebo, 2.5% NaF, 5% NaF, 2.5% NaF + 5% TMP, and 5% NaF + 5% TMP groups (n =24/group). After single application of the varnishes, the samples were immersed in citric acid (0.05 mol/L, pH = 3.2, 5 min) followed or not by brushing, and the dentin wear was assessed after 5 days. Varnishes containing fluoride + TMP led to the lowest wear. TMP varnishes showed a superior effect against dentin erosive wear.

Use of Sodium Hexametaphosphate and Citric Acid Mixture as Depressant in the Flotation Separation of Scheelite from Calcite

The floatability of scheelite and calcite in the presence of single depressant (SHMP or H3Cit) and mixed depressant (SHMP/H3Cit) was studied by microflotation experiments and artificial mixed mineral experiments. Solution chemical calculation, zeta potential tests, thermodynamic analysis and XPS analysis were used to explain the relevant depressive mechanism. Mixed depressant (SHMP/H3Cit) exhibited excellent selective depressive effect on calcite. The optimal molar ratio of SHMP to H3Cit was 1:4. The depressant SHMP and H3Cit can be chemically bonded with Ca2+ to form CaHPO4 and Ca3(Cit)2 at pH 8. The CaHPO4 was more easily formed than Ca3(Cit)2 on the mineral surface, which indicated that the depressive effect of SHMP was stronger than H3Cit. The SHMP and H3Cit of the mixed depressant were co-adsorbed on the calcite surface, while the H3Cit of the mixed depressant was weakly adsorbed on the scheelite surface. The mixed depressant can significantly improve the separation efficiency of scheelite from calcite.