Strontium Carbonate and Strontium-Substituted Calcium Carbonate Nanoparticles Form Protective Deposits on Dentin Surface and Enhance Human Dental Pulp Stem Cells Mineralization

Abstract

Strontium acetate is applied for dental hypersensitivity treatment; however, the use of strontium carbonates for this purpose has not been described. The use of Sr-carbonate nanoparticles takes advantage of both the benefits of strontium on dentin mineralization and the abrasive properties of carbonates. Here in, we aimed to synthesize strontium carbonate and strontium-substituted calcium carbonate nanoparticles and test them as potential compounds in active dentifrices for treating dental hypersensitivity. For this, SrCO3, Sr0.5Ca0.5CO3, and CaCO3 nanoparticles were precipitated using Na2CO3, SrCl2, and/or CaCl2 as precursors. Their morphology and crystallinity were evaluated by electron microscopy (SEM) and X-ray diffraction, respectively. The nanoparticles were added to a poly (vinyl alcohol) gel and used to brush dentin surfaces isolated from human third molars. Dentin chemical composition before and after brushing was investigated by infrared spectroscopy (FTIR) and X-ray dispersive energy spectroscopy. Dentin tubule morphology, obliteration, and resistance of the coatings to acid attack were investigated by SEM and EDS. The cytotoxicity and ability of the particles to trigger the mineralization of hDPSCs in vitro were studied. Dentin brushed with the nanoparticles was coated by a mineral layer that was also able to penetrate the tubules, while CaCO3 remained as individual particles on the surface. FTIR bands related to carbonate groups were intensified after brushing with either SrCO3 or Sr0.5Ca0.5CO3. The shift of the phosphate-related FTIR band to a lower wavenumber indicated that strontium replaced calcium on the dentin structure after treatment. The coating promoted by SrCO3 or Sr0.5Ca0.5CO3 resisted the acid attack, while calcium and phosphorus were removed from the top of the dentin surface. The nanoparticles were not toxic to hDPSCs and elicited mineralization of the cells, as revealed by increased mineral nodule formation and enhanced expression of COL1, ALP, and RUNX2. Adding Sr0.5Ca0.5CO3 as an active ingredient in dentifrices formulations may be commercially advantageous since this compound combines the well-known abrasive properties of calcium carbonate with the mineralization ability of strontium, while the final cost remains between the cost of CaCO3 and SrCO3. The novel Sr0.5Ca0.5CO3 nanoparticles might emerge as an alternative for the treatment of dental hypersensitivity.

Ca substitution in Ca1‐xSrxTi0.8Fe0.2O3‐δ perovskites for oxygen transport membranes: A promising strategy to improve CO2 tolerance

“…Hence, the diminished intensity of the two reflections may be related either to a reduced formation of SrCO 3 compared to STF82, or to the appearance of a mixed strontium-calcium carbonate phase characterized by a lower diffraction intensity. 39 However, in this latter case the peaks should be slightly displaced to higher angles due to the lower ionic radius of Ca than Sr, 40 which we did not observe in our patterns. Moreover, thermogravimetric analysis performed on CSTF1982 indicated a lower mass uptake in CO 2 with respect to STF82 (see Figure 3), which is consistent with a decreased formation of carbonate phases.…”

“…According to the Ellingham theory, both strontium and calcium carbonate (SrCO 3 and CaCO 3 ) are stable for p CO2 ∼ 10 5 Pa and T ≤ 770°C, that is, the experimental conditions of the treatment performed on the powders. Hence, the diminished intensity of the two reflections may be related either to a reduced formation of SrCO 3 compared to STF82, or to the appearance of a mixed strontium‐calcium carbonate phase characterized by a lower diffraction intensity 39 . However, in this latter case the peaks should be slightly displaced to higher angles due to the lower ionic radius of Ca than Sr, 40 which we did not observe in our patterns.…”

Application of Zeolites and Zeolitic Imidazolate Frameworks in Dentistry—A Narrative Review

“…It can promote dentin remineralization. Strontium ions (Sr 2+ ) can replace Ca 2+ in the apatite structure in the dental hard tissue and bone tissue to promote the proliferation and differentiation of human dental pulp stem cells [28].…”

Antibacterial Activity and Cell Viability of Biomimetic Magnesian Calcite Coatings on Biodegradable Mg

“…Recently, Ca(Mg)CO 3 coatings providing a much improved corrosion resistance in isotonic physiological fluids containing chloride ions were grown on pure Mg [ 13 ] and on AZ91 Mg alloy [ 14 ] via simple green conversion methods in aqueous solution; on Mg2Zn0.2Ca alloy via hydrothermal method [ 12 , 15 ]; and on Mg-Nd alloy by ultrasound-assisted chemical conversion [ 17 ]. CaCO 3 does not pose a threat to any species and is therefore greatly biocompatible [ 18 ] and widely used as a biomaterial in many products, such as toothpaste [ 19 ] and cosmetics [ 20 ], as a vector to deliver drugs, genes, and enzymes [ 21 ], and for controlled degradability in vivo [ 22 ]. Therefore, the availability of simple, green, synthetic methods for protective carbonate coatings on Mg and alloys opens up the possibility of their application in Mg-based resorbable implants, which could allow the use of synthetic scaffolds for regeneration and restoration of bone function [ 23 ] or of resorbable fixation screws without the need for a second surgery for extraction [ 24 ], which are current topics in biomaterials research.…”