Validation of a Real-Time ISE Methodology to Quantify the Influence of Inhibitors of Demineralization Kinetics in vitro Using a Hydroxyapatite Model System

Huang, Wei-Te; Shahid, Shamsuddin; Anderson, Paul

doi:10.1159/000488597

Cited by 9 publications

(8 citation statements)

References 23 publications

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“…Ion selective electrode investigations are a generally accepted model employed to assess the demineralisation of human enamel in response to varying treatments [ 38 ]. The rate of HAp dissolution with increasing concentrations of γ-PGA was assessed with the aid of porous HAp discs.…”

Section: Resultsmentioning

confidence: 99%

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Microbial Poly-γ-Glutamic Acid (γ-PGA) as an Effective Tooth Enamel Protectant

et al. 2022

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Poly-γ-glutamic acid (γ-PGA) is a bio-derived water-soluble, edible, non-immunogenic nylon-like polymer with the biochemical characteristics of a polypeptide. This Bacillus-derived material has great potential for a wide range of applications, from bioremediation to tunable drug delivery systems. In the context of oral care, γ-PGA holds great promise in enamel demineralisation prevention. The salivary protein statherin has previously been shown to protect tooth enamel from acid dissolution and act as a reservoir for free calcium ions within oral cavities. Its superb enamel-binding capacity is attributed to the L-glutamic acid residues of this 5380 Da protein. In this study, γ-PGA was successfully synthesised from Bacillus subtilis natto cultivated on supplemented algae media and standard commercial media. The polymers obtained were tested for their potential to inhibit demineralisation of hydroxyapatite (HAp) when exposed to caries simulating acidic conditions. Formulations presenting 0.1, 0.25, 0.5, 0.75, 1, 2, 3 and 4% (w/v) γ-PGA concentration were assessed to determine the optimal conditions. Our data suggests that both the concentration and the molar mass of the γ-PGA were significant in enamel protection (p = 0.028 and p < 0.01 respectively). Ion Selective Electrode, combined with Fourier Transform Infra-Red studies, were employed to quantify enamel protection capacity of γ-PGA. All concentrations tested showed an inhibitory effect on the dissolution rate of calcium ions from hydroxyapatite, with 1% (wt) and 2% (wt) concentrations being the most effective. The impact of the average molar mass (M) on enamel dissolution was also investigated by employing commercial 66 kDa, 166 kDa, 440 kDa and 520 kDa γ-PGA fractions. All γ-PGA solutions adhered to the surface of HAp with evidence that this remained after 60 min of continuous acidic challenge. Inductively Coupled Plasma analysis showed a significant abundance of calcium ions associated with γ-PGA, which suggests that this material could also act as a responsive calcium delivery system. We have concluded that all γ-PGA samples tested (commercial and algae derived) display enamel protection capacity regardless of their concentration or average molar mass. However, we believe that γ-PGA D/L ratios might affect the binding more than its molar mass.

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Section: Resultsmentioning

confidence: 99%

“…ISEs have been used to measure the rate of loss of calcium from enamel or HAP discs as a proxy for the rate of demineralisation as described by [ 38 ]. A Ca 2+ ion selective electrode (ISE) was paired with a double-junction lithium acetate reference electrode.…”

Section: Methodsmentioning

confidence: 99%

Microbial Poly-γ-Glutamic Acid (γ-PGA) as an Effective Tooth Enamel Protectant

et al. 2022

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“…Additionally, some limitations have been observed. Micro-CT is an expensive method (due to the cost of the equipment) and requires longer scanning and image processing periods of the sample, resulting in extensive protocols to ensure accurate measurements (Huang et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

“…Regarding demineralization models, several studies have been carried out to observe and measure caries progression (Huang et al, 2018; Magalhães et al, 2009; Shellis et al, 2010). For this task, some methods have been used, such as scanning electron microscopy (SEM), microradiography, microindentation; (Arends et al, 1987; Shellis et al, 2010), transverse microradiography (Magalhães et al, 2009), and micro‐computed tomography (micro‐CT) (González‐Sotelo et al, 2021; Ozgul et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Morphological and porosity changes in primary enamel surface after an in vitro demineralization model

González-Sotelo

Contreras‐Bulnes

Rodríguez‐Vilchis

et al. 2022

Microscopy Res & Technique

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In vitro models are very useful in dentistry, especially to evaluate preventive methods against dental caries. Although they have been used for more than 30 years, specific demineralization models have not been established for primary enamel, which is more prone to demineralization than permanent enamel. This study evaluates porosity changes in primary enamel surface after a demineralization model through a scientifically validated analytical tool. Nine healthy human anterior primary teeth extracted for therapeutic reasons were included in this study, previous informed consent. The samples were randomly assigned to three groups n = 3: G1_2D, G2_4D, and G3_7D. Scanning electron microscopy (SEM) images at ×200 and ×1000 were taken during two stages: before demineralization (BD) and after demineralization (AD). Morphological characterization was observed at ×1000, while porosity (pore count and perimeter) was analyzed by the ImageJ program, using ×200 SEM images previously converted. Several statistical analyses were used to determine differences (p ≤ .05). Morphological characterization AD revealed new pits and cracks on the enamel surface in G1_2D and G2_4D groups. Localized eroded enamel areas were observed in G3_7D. Pore count of enamel surface BD ranged from 64.26 ± 37.62 to 97.93 ± 34.25 and AD ranged from 150.06 ± 64.86 to 256 ± 58.14. AD, G_4D exhibited a decrease in pore perimeter contrary to G_2D and G_7D. Significant differences were observed. Finally, morphological changes were more evident as days of demineralization increased; 7 days of immersion could be employed as an enamel erosive model. The pore count increased after the demineralization model, BD pores perimeter was heterogeneous, and AD varied according to the immersion period. Morphological changes were more evident as days of demineralization increased. Seven days of immersion could be employed as an enamel erosive model. The initial porosity seems to be a determining factor for the final porousness. The pore perimeter of the primary enamel varied according to the immersion period on the demineralization model.

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“…The use of Ion Selective Electrodes (ISE) in dental research has become prevalent to measure real-time ionic transfer processes. The method has been used to measure ion releases from restoratives and adhesives to prevent enamel demineralisation by measuring fluoride ion release [1] and the effect of calcium release from enamel in the presence of a solution containing zinc ions [2]. This method has not been used to measure the penetration of ions through the dentine matrix despite some possible limitations when using these electrodes [3].…”

Section: Introductionmentioning

confidence: 99%

Measurement of Potassium Ion Diffusion through Dentine Using ISE

2022

J Dent Maxillofacial Res

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Objective: To measure the in vitro concentration of potassium ions (K + ) on the opposite side of the dentine samples in real-time, using Potassium Ion Selective Electrodes (K + ISE).Method: An assembly array was designed and different sections (n=4) of dentine were acid etched in 6% citric acid and ultra-sonicated for five minutes. They were subsequently fixed into a polypropylene tube using impression dental material and immersed into simulated dentine fluid (SDF) which consisted of 0.01 mol/dm 3 potassium chloride (KCL) solution. The K + ISE was placed external to the polypropylene tube, to measure changes in the potassium ion concentration [K + ] in the SDF for 60 hrs continuously. Application of potassium nitrate (KNO 3 ) solutions of concentrations between 0.05-3 mol/dm 3 were applied to the exposed dentine samples in separate experiments.Results: Minimal changes in [K + ] (<5 mmol/dm 3 ) in the SDF (the opposite side of the sample) were measured by the K + ISE when applying less than 600 mmol/dm 3 of KNO 3 solutions to the dentine sections. However, significant changes (P<0.05) in [K + ] of 5-25 mmol/dm 3 were measured in the SDF when applying a KNO 3 solution of concentration more than 600 mmol/dm 3 to the dentine samples, indicating greater penetration of K + through the dentine matrix. Conclusion:ISE may be used to measure ionic transfer in dentinal tubules although questions arise due to the sensitivity of the ISE and its suitability. However, it was demonstrated that increasing the concentration of an applied KNO 3 solution to exposed dentine increased the [K + ] in the SDF which was on the opposite side in the dentine disk model and premolar tooth with a cut cavity. This was also the case when the fluid flow was in the opposite direction to diffusion. This study demonstrates that ISE may be suitable for real-time diffusion experiments in dentine for possible future research into dental therapeutics which involve ion exchange.

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Validation of a Real-Time ISE Methodology to Quantify the Influence of Inhibitors of Demineralization Kinetics in vitro Using a Hydroxyapatite Model System

Cited by 9 publications

References 23 publications

Microbial Poly-γ-Glutamic Acid (γ-PGA) as an Effective Tooth Enamel Protectant

Microbial Poly-γ-Glutamic Acid (γ-PGA) as an Effective Tooth Enamel Protectant

Morphological and porosity changes in primary enamel surface after an in vitro demineralization model

Measurement of Potassium Ion Diffusion through Dentine Using ISE

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