Antibacterial, biocompatible, and mineralization-inducing properties of calcium silicate-based cements.

BACKGROUND: Different pulp capping materials have different origins and compositions, require different preparations, and may vary in their bioactive properties. AIM: The purpose of this study was to evaluate the antibacterial activity, biocompatibility, and mineralization-inducing potential of calcium silicate-based pulp capping materials. DESIGN: Six contemporary calcium silicate-based cements, ProRoot MTA, MTA Angelus, Biodentine, EndoSequence, NeoMTA 2, and NeoPutty, were evaluated. The antibacterial effects of these materials against Streptococcus mutans UA159 and Enterococcus faecalis ATCC 29212 were determined by the agar diffusion assay and the direct culture test. The biocompatibility and mineralization-inducing potential of these materials in preodontoblastic 17IIA11 cells were evaluated by the MTT assay and by Alizarin Red S staining, respectively. RESULTS AND CONCLUSION: In agar diffusion test, only Biodentine showed distinct antibacterial effects against S. mutans. All the tested materials, however, showed antibacterial effects against S. mutans and E. faecalis in the direct culture test, with Biodentine showing the strongest growth inhibition against both S. mutans and E. faecalis. All the tested materials showed acceptable biocompatibility and mineralization-supporting potential in our experimental conditions. In summary, ProRoot MTA, MTA Angelus, Biodentine, EndoSequence, NeoMTA 2, and NeoPutty demonstrated acceptable in vitro antimicrobial, biocompatible, and mineralization-supporting properties.

Impact of corticosteroid administration on the response of exposed dental pulp to capping with bioactive cements-experimental study on mongrel dogs.

BACKGROUND: Corticosteroids are commonly used as a treatment for a variety of pathological conditions, however, systemic corticosteroid administration has adverse effects including impaired immune response and wound healing. Such complications may affect pulp healing after direct pulp capping. The current study evaluated the influence of corticosteroids on the healing ability of exposed dogs' dental pulps after direct pulp capping (DPC) with bioactive materials. METHODS: Ten healthy male dogs were assigned randomly into two groups, 5 dogs each: group I represent the control group which did not receive any medication, and group II was given corticosteroid for 45 days before DPC and till the dogs were euthanized (n = 75 teeth for each group). Following mechanical exposure, the pulps were randomly capped with either Ca(OH)2, MTA, or Biodentine. The pulpal tissues' reaction to the capping materials was evaluated 65 days postoperatively according to the following parameters: calcific bridge formation, pulpal inflammation, pulp necrosis, and bacterial infiltration. RESULTS: The corticosteroid-treated group revealed no significant difference compared to the control group concerning the pulp healing response (P > 0.05). Both Biodentine and MTA-treated specimens revealed significant differences with Ca(OH)2-treated specimens (P < 0.05) which displayed a superior positive effect of both MTA and Biodentine to Ca(OH)2 regarding all the parameters. CONCLUSIONS: Direct pulp capping technique whenever indicated in subjects treated with corticosteroid immunosuppressive drugs like prednisone performed well in aseptic conditions especially when capped with bioactive materials.

Histological evaluation of a novel phosphorylated pullulan-based pulp capping material: An in vivo study on rat molars.

AIM: To evaluate the dental pulp response to a novel mineral trioxide aggregate containing phosphorylated pullulan (MTAPPL) in rats after direct pulp capping. METHODS: Ninety-six cavities were prepared in the maxillary first molars of 56 male Wistar rats. The dental pulps were intentionally exposed and randomly divided into four groups according to the application of pulp capping materials: MTAPPL; phosphorylated pullulan (PPL); a conventional MTA (Nex-Cem MTA, NCMTA; positive control); and Super-Bond (SB; negative control). All cavities were restored with SB and observed for pulpal responses at 1-, 3-, 7- and 28-day intervals using a histological scoring system. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney U-test with Bonferroni's correction, and the level of significance was set at 0.05. DMP1 and CD34 antigen were used to evaluate odontoblast differentiation and pulpal vascularization, respectively. RESULTS: On day 1, mild inflammatory cells were present in MTAPPL and NCMTA groups; fewer inflammatory cells were present in the PPL, whereas SB was associated with a mild-to-moderate inflammatory response. A significant difference was observed between PPL and SB (p < .05). No mineralized tissue deposition was observed. On day 3, moderate-to-severe inflammatory cells were present in PPL and SB, whereas MTAPPL and NCMTA had a mild inflammatory response. Initial mineralized tissue deposition was observed in the NCMTA, MTAPPL and SB. A significant difference was observed between MTAPPL and PPL (p < .05). On day 7, a thin layer of mineralized tissue was observed in all tested groups with no or mild inflammatory response. On day 28, no inflammatory response was observed in MTAPPL, whereas NCMTA, PPL and SB had mild inflammatory responses. A significant difference was observed between MTAPPL and SB (p < .05). Complete mineralized tissue barrier formation was observed in MTAPPL, NCMTA and PPL with no significant difference (p > .05). SB exhibited incomplete mineralized tissue barriers, significantly different from NCMTA, MTAPPL and PPL (p < .05). The staining with CD34 was positive in all the groups on all observation days. CONCLUSION: The favourable pulpal responses and induction of mineralized tissue formation associated with MTAPPL indicate its potential application as a direct pulp capping material.

Physicochemical properties and cytotoxicity of an experimental resin-based pulp capping material containing the quaternary ammonium salt and Portland cement.

AIM: To evaluate in vitro the physicochemical properties, cytotoxicity and calcium phosphate nucleation of an experimental light-curable pulp capping material composed of a resin with antibacterial monomer (MAE-DB) and Portland cement (PC). METHODOLOGY: The experimental material was prepared by mixing PC with a resin containing MAE-DB at a 2 : 1 ratio. Cured pure resin containing MAE-DB served as control resin. ProRoot MTA and Dycal served as commercial controls. The depth of cure, degree of monomer conversion, water absorption and solubility of dry samples, calcium release, alkalinizing activity, calcium phosphate nucleation and the cytotoxicity of materials were evaluated. Statistical analysis was carried out using anova followed by Tukey's HSD test (equal variance assumed) or Tamhane test (equal variance not assumed) and independent-samples t-tests. RESULTS: The experimental material had a cure depth of 1.19 mm, and the mean degree of monomer conversion was 70.93% immediately post-cure and 88.75% at 24 h post-cure. The water absorption of the experimental material was between those of MTA and Dycal, and its solubility was significantly less (P < 0.05) than that of Dycal and higher than that of MTA. The experimental material exhibited continuous calcium release and an alkalinizing power between those of MTA and Dycal throughout the test period. Freshly set experimental material, control resin and all 24-h set materials had acceptable cytotoxicity. The experimental material, MTA and Dycal all exhibited the formation of apatite precipitates after immersion in phosphate-buffered saline. CONCLUSIONS: The experimental material possessed adequate physicochemical properties, low cytotoxicity and good calcium phosphate nucleation.

Injectable Tannin-Containing Hydroxypropyl Chitin Hydrogel as Novel Bioactive Pulp Capping Material Accelerates Repair of Inflamed Dental Pulp.

Conventional pulp capping materials have limited anti-inflammatory capacity. It is necessary to develop more effective pulp capping material for the treatment of inflamed pulps. Tannic acid (TA) is a natural, water-soluble polyphenol with antimicrobial and anti-inflammatory properties. This study aimed to investigate the effects of a tannin-containing hydroxypropyl chitin hydrogel (HPCH/TA hydrogel) as an innovative pulp capping material. The physicochemical properties of the composite hydrogels were characterized. The effects of HPCH/TA hydrogel as a pulp capping material were evaluated in vitro and in vivo. The underlying mechanism of the anti-inflammatory effects of HPCH/TA hydrogel was explored. The HPCH/TA hydrogel demonstrated favorable temperature sensitivity, injectability, and antibacterial properties. In vitro, the HPCH/TA hydrogel effectively promoted the proliferation of human dental pulp cells and inhibited interleukin-1ß, interleukin-6, and tumor necrosis factor-α expression, possibly by suppressing the nuclear factor kappa-B pathway. In vivo, on the fourth day after capping, the HPCH/TA hydrogel group showed lower inflammatory scores compared to the control and iRoot BP Plus (commercial pulp capping material) group. By the sixth week, complete reparative dentin formation was observed in the HPCH/TA hydrogel group, with no difference in thickness compared to the iRoot BP Plus group. Collectively, the HPCH/TA hydrogel holds promise as a bioactive pulp capping material for promoting the repair of inflamed pulp in vital pulp therapy.

Injectable CNPs/DMP1-loaded self-assembly hydrogel regulating inflammation of dental pulp stem cells for dentin regeneration.

Vital pulp preservation, which is a clinical challenge of aseptic or iatrogenic accidental exposure of the pulp, in cases direct pulp capping is the main technology. Human dental pulp stem cells (hDPSCs) play a critical role in pulp tissue repair, but their differentiative ability could be inhibited by the potential infection and inflammatory response of the exposed pulp. Therefore, inflammatory regulation and differentiated promotion of hDPSCs are both essential for preserving living pulp teeth. In this study, we constructed a functional dental pulp-capping hydrogel by loading cerium oxide nanoparticles (CNPs) and dentin matrix protein-1 (DMP1) into an injectable Fmoc-triphenylalanine hydrogel (Fmoc-phe3 hydrogel) as CNPs/DMP1/Hydrogel for in situ drugs delivery. With a view to long-term storage and release of CNPs (anti-inflammatory and antioxidant) to regulate the local inflammatory environment and DMP1 to promote the regeneration of dentin. Results of CCK-8, LDH release, hemolysis, and Live/Dead assessment of cells demonstrated the good biocompatibility of CNPs/DMP1/Hydrogel. The levels of alkaline phosphatase activity, quantification of the mineralized nodules, expressions of osteogenic genes and proteins demonstrated CNPs/DMP1/Hydrogel could protect the activity of hDPSCs' osteogenic/dentinogenic differentiation by reducing the inflammation response via releasing CNPs. The therapy effects were further confirmed in rat models, CNPs/DMP1/Hydrogel reduced the necrosis rate of damaged pulp and promoted injured pulp repair and reparative dentin formation with preserved vital pulps. In summary, the CNPs/DMP1/Hydrogel composite is an up-and-coming pulp-capping material candidate to induce reparative dentin formation, as well as provide a theoretical and experimental basis for developing pulp-capping materials.

A tricalcium phosphate (TCP) and hydroxyapatite (HA) based light-cured biomaterial for vital pulp therapy.

OBJECTIVES: Evaluate a new light-cured material with better properties for vital pulp therapy. METHODS: Light-cured resin materials consisted of polyethylene glycol (600) diacrylate mixed with different ratios of TCP to HA. In addition to the temperature change (n = 5 for each subgroup) were tested, cell viability and Alizarin Red Staining (ARS) assay were also tested in vitro on human dental pulp cells (n = 6 for each subgroup). Lastly, the material was then compared with Biodentine and control groups in the molars of Wistar rats in vivo for histology assessment. RESULTS: The temperature change for the new materials were under 5 degrees Celsius. For the in vitro assessments, there was no significant difference on day 3 and day 7 for cell viability test. ARS assay showed significantly higher mineralized nodule formation when treated without induction medium for Group D and Biodentine on day 10 compared to Group C and control. On the contrary, Biodentine and control groups treated with induction medium showed significant higher mineralization than the new materials. Histology assessments demonstrated higher mineralized content in Group D and Biodentine on week 3 and week 6. The inflammatory cells in the dental pulp complex of the Biodentine group resolved on week 6 while the inflammation resolved in Group D on week 3. SIGNIFICANCE: The new material exhibits low heat production, low cytotoxicity, and good calcium ion release capability. Compared to traditional materials, it has shorter setting time and better aesthetic outcomes, making it highly suitable for use in vital pulp therapy.

The micro-shear bond strength of new endodontic tricalcium silicate-based putty: An in vitro study.

This study aimed to compare in vitro micro-shear bond strength (µSBS) of three different endodontic tricalcium silicate-based materials in contact with a bulk-fill resin-based composite. Thirty cylindrical resin blocks with a hole in the centre (2 mm in depth and 4 mm in diameter) were manufactured with a 3D printer and divided into three groups (n = 10), depending on the calcium silicate cement used: light curing TheraCal LC (Bisco, Schaumburg, IL, USA), liquid-powder NeoMTA 2 (NuSmile Avalon Biomed, Bradenton, FL, USA) and putty NeoPutty (NuSmile, Houston, TX, USA). Each sample was stored for 24 h at 37°C and 100% humidity. Then, after adhesive placement, the restorative material Filtek bulk-fill (3 M ESPE, St. Paul, MN, USA) was placed over the capping material using cylindrical plastic capsules (2 mm height and 2 mm) and polymerised for 20 s. Specimens were then tested in a universal testing machine for the compression load resulting in the µSBS. The data were compared with the one-way ANOVA (Welch) and the Tamhane test. The mean value was significantly higher in the TheraCal LC group than in the other two groups (p < 0.05). There was no significant difference between NeoMTA 2 and NeoPutty groups (p > 0.05). The majority of failure modes for all groups were cohesive within biomaterial. Using TheraCal LC in the pulp capping procedure can result in higher bond strength values to the tested bulk-fill resin-based composite than NeoMTA 2 and NeoPutty.

Anti-Inflammatory and Mineralization Effects of an ASP/PLGA-ASP/ACP/PLLA-PLGA Composite Membrane as a Dental Pulp Capping Agent.

Dental pulp is essential for the development and long-term preservation of teeth. Dental trauma and caries often lead to pulp inflammation. Vital pulp therapy using dental pulp-capping materials is an approach to preserving the vitality of injured dental pulp. Most pulp-capping materials used in clinics have good biocompatibility to promote mineralization, but their anti-inflammatory effect is weak. Therefore, the failure rate will increase when dental pulp inflammation is severe. The present study developed an amorphous calcium phosphate/poly (L-lactic acid)-poly (lactic-co-glycolic acid) membrane compounded with aspirin (hereafter known as ASP/PLGA-ASP/ACP/PLLA-PLGA). The composite membrane, used as a pulp-capping material, effectively achieved the rapid release of high concentrations of the anti-inflammatory drug aspirin during the early stages as well as the long-term release of low concentrations of aspirin and calcium/phosphorus ions during the later stages, which could repair inflamed dental pulp and promote mineralization. Meanwhile, the composite membrane promoted the proliferation of inflamed dental pulp stem cells, downregulated the expression of inflammatory markers, upregulated the expression of mineralization-related markers, and induced the formation of stronger reparative dentin in the rat pulpitis model. These findings indicate that this material may be suitable for use as a pulp-capping material in clinical applications.

Notoginsenoside R1 functionalized gelatin hydrogels to promote reparative dentinogenesis.

Pulp-capping materials are commonly adopted in the clinic to form reparative dentin and thus protect dental pulp tissues from cases of deep caries, accidentally exposed pulps or partial pulpotomy. Some traditional pulp capping materials used in the clinic include calcium hydroxide and mineral trioxide aggregates. However, there are limitations to thin restorative dentin, and a long period of time is needed to cause degenerative changes in dental pulp. In this paper, injectable colloidal gels were developed to induce the formation of reparative dentin through a simple UV method from methacrylic acid functionalized gelatin loaded with notoginsenoside R1 (Gel-MA/NGR1). The results of the physicochemical property examinations showed that the prepared Gel-MA/NGR1 hydrogel possessed an appropriate interconnected porous microarchitecture with a pore size of 10.5 micrometres and suitable mechanical properties with a modulus of 50-60 kPa, enabling cell adhesion and proliferation. The hydrogel remained hydrophilic with sustained drug release performance. In addition, Gel-MA/NGR1 significantly enhanced the odontogenetic differentiation of mouse dental papilla cells by elevating the expression levels of the dentinogenic markers ALP and OCN and extracellular matrix mineralization. In vivo stimulation was carried out by injecting the precursors into the predrilled alveolar cavity of Sprague-Dawley rats followed by immediate in situ UV crosslinking. The results showed that Gel-MA/NGR1 has a strong capacity to promote reparative dentin formation. Haematoxylin& eosin, Masson, and immunohistochemical staining (DMP-1, DSPP, OCN and RUNX2) and micro-CT were employed to illustrate the effectiveness of dentinogenesis, and the relative volumes of calcification were found to have increased ~175-fold. All of the results showed that the Gel-MA/NGR1 hydrogel promoted reparative dentin formation, which suggests that this hydrogel provides great potential as a pulp-capping material to induce dentin formation.

Evaluation of Compressive Strength of Several Pulp Capping Materials.

STATEMENT OF THE PROBLEM: Adequate compressive strength is an important characteristic for an ideal liner. PURPOSE: This study aimed to assess the compressive strength of several commonly used liners. MATERIALS AND METHOD: This in vitro, experimental study evaluated 120 samples fabricated of Dycal, Calcimol LC, Vitrebond, Activa Bioactive, and TheraCal LC (n=24) liners according to the manufacturers' instructions. The samples were fabricated using a cylindrical stainless steel mold with 6±0.1 mm height and 4±0.1 mm internal diameter. Half of the samples in each group (n=12) underwent compressive strength test immediately after completion of their primary setting while the other half (n=12) underwent compressive strength test after 24 h. During this period, the samples were immersed in deionized water (grade 3) and incubated at 37±1°C and 100% humidity for 24 h. The compressive strength was measured using a universal testing machine. Data were analyzed using two-way ANOVA followed by Tukey's post-hoc test. RESULTS: The compressive strength of the five liners was significantly different (p< 0.05). Calcimol LC showed maximum compressive strength both immediately after setting and after 24 h. The compressive strength at 24 h was significantly higher than the primary compressive strength in all groups (p< 0.05). CONCLUSION: Within the limitations of this study, it seems that Calcimol LC, Activa Bioactive Liner, and TheraCal LC have adequate compressive strength and can be used alone to provide adequate support for the restorative materials.

Evaluation of the mechanical properties and biocompatibility of gypsum-containing calcium silicate cements.

Mineral trioxide aggregate (MTA) cement is widely used in the field of endodontic treatment. We herein synthesized calcium silicates from calcium carbonate and silicon dioxide, with the aim of reducing the cost associated with the MTA. Additionally, we prepared gypsum-containing calcium silicate cement to reduce the setting time while enhancing the mechanical strength. We evaluated the physical properties of this cement and investigated the response of human dental pulp stem cells (hDPSCs) grown in culture media containing cement eluate. Our results revealed that calcium silicates could be easily synthesized in lab-scale. Furthermore, we demonstrate that gypsum addition helps shorten the setting time while increasing the compressive strength of dental cements. The synthesized gypsum-containing calcium silicate cement showed minimal cytotoxicity and did not inhibit the proliferation of hDPSCs. These results suggested that the newly developed calcium silicate material could be a promising pulp capping material.

Fabrication of strontium-releasable inorganic cement by incorporation of bioactive glass.

OBJECTIVES: Bioactive glass (BG) is widely used as a bioactive material for various clinical applications, and effective and efficient elemental release and an increase in mechanical strength are expected with further development. The purpose of this study is to clarify the physicochemical and biological characteristics of Sr-doped BG-incorporated glass ionomer cements. METHODS: Sr-doped BGs (45SiO2-6P2O5-24.5Na2O-(24.5-x)CaO-xSrO) (wt%), where × = 0, 6, 12, were prepared, and the particle size, crystallinity, and elemental release profiles were evaluated. The Sr-doped BGs were then incorporated into a glass ionomer cement at a weight ratio of 1:4, and the physicochemical properties (compressive strength, bending strength, hardness, and elemental release profile) were investigated. Cell attachment, cell proliferation, and osteoblastic differentiation were used to evaluate the biological characteristics. RESULTS: The Sr-doped BGs were amorphous phases with a homogeneous particle size and exhibited sustained release of Ca, Si, and Sr. The BG-incorporated cements were able to release these elements while retaining the same mechanical properties as those of the pure glass ionomer cement. In addition, no cytotoxicity of osteoblasts or differences in the cell attachment or proliferation were observed for the BG-incorporated cements. In contrast, the Sr-doped BG-incorporated cements promoted the alkaline phosphatase activities of the osteoblasts without the need for any media supplements for osteoblastic differentiation. SIGNIFICANCE: Sr-releasable inorganic cements with high mechanical properties were successfully fabricated by incorporating Sr-doped BGs in glass ionomer cement. These bioactive materials are promising candidates for bone grafting materials, bone cements, and pulp capping materials.

Evaluation of Pulp Response to Novel Bioactive Glass Pulp Capping Materials.

INTRODUCTION: This study aimed to investigate dental pulp responses to novel bioactive glass (BG) pulp capping materials after direct pulp capping in vivo. METHODS: Novel BG pulp capping materials are composed of powder and fluid. The powder is BG (82.36% SiO2, 15.36% CaO, and 2.28% P2O5), and the fluid is provided in 2 kinds: (1) phosphate buffer solution (BG-PB) and (2) phosphate buffer solution with the addition of 1 wt% sodium alginate (BG-PB-SA). After mixing the powder and fluid, BG-PB and BG-PB-SA were prepared. Cavities with mechanical pulp exposure were prepared on maxillary first molars of Wistar rats. The exposures were randomly capped with BG-PB, BG-PB-SA, or mineral trioxide aggregate (MTA). After 1 (n = 6) and 4 weeks (n = 8), maxillary segments were obtained and prepared for histologic analysis with a scoring system. Statistical analysis was performed using the Kruskal-Wallis and Mann-Whitney U tests with the significance set at .05. RESULTS: After 1 week, few inflammatory cells were present in the BG-PB, BG-PB-SA, and MTA groups. Moreover, a thin layer of newly generated matrix was observed in most specimens. After 4 weeks, all specimens from the 3 groups formed a heavy dentin bridge. BG-PB and BG-PB-SA groups exhibited no or slight inflammatory response, whereas the MTA group exhibited a slight to moderate inflammatory response. No significant difference was observed in pulp inflammation and dentin formation among the 3 groups at either time point (P > .05). CONCLUSIONS: When used as a pulp capping agent, BG-PB and BG-PB-SA had similar favorable cellular and inflammatory pulp responses to those of MTA. Therefore, BG is a promising pulp capping material.

Incorporation of a polymerization catalyst for improved mechanical behavior and physicochemical characteristics of a light-cured pulp capping material / Incorporação de um catalisador de polimerização para aprimorar propriedades mecânicas e fisíco-químicas de um protetor pulpar fotoativável

Objective: To evaluate the influence of the incorporation of a polymerization catalyst to a light-cured pulp capping material on mechanical behavior and physicochemical characteristics. Material and Methods: Different percentages (2 wt%, and 4 wt%) of diphenyliodonium hexafluorophosphate (DPI) were incorporated into the Ultra-Blend Plus, a resin-modified calcium-based cement. The material without incorporation of DPI (0 wt%) served as control. Degree of Conversion (DC), Flexural Strength (FS), Elastic Modulus (EM), Water Sorption (WSp), Solubility (Sl), and pH of eluate at 24-h, 72-h, and 7-day storage times were measured. One-way ANOVA/Tukey posthoc tests were used to analyze the data (p <0.05). Results: For DC, FS, and EM, materials with different % of DPI showed statistically significant differences, so that 0% provided the lowest values and 2% the highest values. Materials with 0% and 2% of DPI provided statistically the lowest WSp, whilst material with 0% of DPI showed statistically the highest Sl. Conclusion: All materials provided statistically similar pH to eluates regardless of storage time, although only materials with DPI at 2% and 4% maintained pH of eluates statistically similar from 72 h to 7 days storage times.(AU)

Objetivo: avaliar a influência nas propriedades mecânicas e físico-químicas da incorporação de um catalisador de polimerização a um protetor pulpar fotoativável. Material e Métodos: foram adicionadas diferentes porcentagens em massa (2% e 4%) de hexafluorofosfato de difeniliodônio (DPI) ao Ultra-Blend Plus, um cimento à base de hidróxido de cálcio modificado por resina. O material sem a adição do DPI (0%) serviu como controle. Foram avaliados: Grau de Conversão (DC), Resistência Flexural (FS), Módulo de Elasticidade (EM), Sorção (WSp), Solubilidade (SI) e o pH do eluato nos tempos de 24h, 72h e 7 dias de armazenamento. ANOVA 1-way com pós-teste de Tukey (p <0.05). Foi utilizado para avaliar os resultados estatisticamente. Resultados: Os materiais com diferentes % de DPI apresentaram diferenças significativas para os testes de DC, FS e EM. A porcentagem em massa de 0% de DPI mostrou valores inferiores a todos os testados e os materiais com adição 2% apresentaram a melhor performance. Materiais com 0% e 2% de DPI apresentaram valores inferiores de WSp; a porcentagem de 0% proporcionou valores estatisticamente maiores para SI. Conclusão: Todos os materiais testados apresentaram pH semelhante nos eluatos independente do tempo de armazenamento, contudo, apenas os materiais com 2% e 4% mantiveram o pH dos eluatos estatisticamente similares nos tempos de estocagem de 72h a 7 dias.(AU)