The Impact of Citric Acid Solution on Hydraulic Calcium Silicate-Based Sealers and Root Dentin: A Preliminary Assessment

Hydraulic calcium silicate-based (HCS) sealers have recently gained tremendous popularity due to their unique properties. However, their removal during endodontic retreatment is challenging. The solvent, which could chemically deteriorate the material, would be highly desirable for endodontic retreatment procedures. This preliminary study assessed the interplay and dissolving capability of 10% and 20% citric acid, compared to 17% EDTA, on commonly used HCS sealers (AH Plus Bioceramic Sealer, Bio-C Sealer, BioRoot RCS, TotalFill BC Sealer), and evaluated the potential impact of these solutions on root dentin structure. The interaction between tested sealers and irrigating solutions was photographed, and solubility-related mass changes were determined. The surface morphology of treated filling materials and dentin was evaluated using a scanning electron microscope (SEM). One-way analysis of variance (ANOVA) along with Tukey’s test were used to detect the statistically significant differences among groups at the confidence level of 0.95. Intense gas release was observed during the interaction of HCS materials and citric acid, with no evidently visible “bubbling” after the immersion in EDTA. The mass loss of HCS sealers equally confirmed the significantly higher dissolving characteristics of 10% and 20% citric acid solutions compared to EDTA. The surface structural changes, associated with pore and crack formation, were mainly seen for HCS sealers exposed to citric acid. Meanwhile, no severe erosion was detected for dentin after root canal preparation with 10% and 20% citric acid solutions. These findings demonstrate that citric acid has the potential to dissolve HCS sealers with minimal or no negative impact on root dentin, suggesting citric acid as a solvent for HCS sealers in endodontic retreatment procedures

Organic matter flux and reactivity on a South Carolina sandflat: The impacts of pore water advection and macrobiological structures

Study of the flux and fate of reactive organic material (OM) within Debidue Flat, an intertidal sandflat in the North Inlet estuary, South Carolina, demonstrated that this coarse-grained deposit is a dynamic, open system that experiences rapid OM decomposition and exchange of solutes in the top 30 cm of the sediment column. The fluxes of reactive OM through Debidue Flat were high during all seasons (27–170 mmol C m2 d21) and were comparable to fluxes in muddy portions of the North Inlet estuary. Porewater decomposition products were N- and P-rich, the modeled reactivity of organic carbon undergoing decomposition was high (first-order rate constant, k 5 0.02 d21), and abundant extractable chlorophyll a was measured year-round; all properties were consistent with marine algal-derived substrates. Porewater solute profiles were controlled by advective flow that rapidly exchanged porewater with overlying waters to;25 cm depth on timescales of hours. Thus, these sandflats act like an unsteady ‘‘trickling bed filter,’ ’ capturing or generating reactive organic particles, rapidly remineralizing OM, and recycling nutrients. Macrobiological structures within the flat altered the amounts and reaction rates of OM on various spatial and temporal scales. Relatively elevated OM decay rates were associated with the burrows of Callichirus major, a deep-burrowing thalassinid shrimp. Large stingray feeding pits accumulated fine grained OM, locally clogging the ‘‘trick-ling bed filter,’ ’ and inhibiting porewater advection. As illustrated by Debidue Flat, intertidal sands can be sites o

Effect of Calcium Silicate-Based Intracanal Medicament and Calcium Hydroxide on Growth Factor TGF-β1 Release from Root Canal Dentine

Effective root canal disinfection and the subsequent release of natural growth factors from dentin are crucial to the success of regenerative endodontic procedures. This study evaluated the effect of newly introduced calcium silicate-based temporary intracanal medicament Bio-C Temp and calcium hydroxide-based material UltraCal XS on the release of transforming growth factor β1 (TGF-β1) from root canal dentin. Twenty-two intact and fully developed human premolars from patients aged 15–18 were shaped and irrigated according to the current clinical recommendations. The teeth were then gently split in half, and the root canal dentin of paired samples was covered with Bio-C Temp or UltraCal XS. After 3 weeks of incubation, the specimens were conditioned with 17% EDTA and the collected solution was subjected to the quantification of the released TGF-β1 by performing an ELISA. One-way analysis of variance (ANOVA), followed by Tukey’s test, was selected to determine the statistically significant differences between the groups at the 0.95 confidence level. The highest mean value of released TGF-β1 (1993.1 pg/mL) was detected in the control group, where the root canal dentin was conditioned with 17% EDTA alone. Regarding the experimental groups, Bio-C Temp released a statistically significantly higher amount of TGF-β1 (282.14 pg/mL) compared to UltraCal XS (114.28 pg/mL; p = 0.0158). Bio-C Temp affected the release of growth factors from root canal dentin less than UltraCal XS and may therefore serve as an intracanal medicament for regenerative endodontic procedures

Biocompatible upconverting nanoprobes for dual-modal imaging and temperature sensing /

The demand for multimodal nanomaterials has intensified in recent years driven by the need for ultrasensitive bioimaging probes and accurate temperature monitoring in biological objects. Among the different multimodal nanomaterials that have been extensively studied in the past decade, upconverting nanoparticles are among the most promising. In this paper, we report the synthesis of upconverting nanoparticles with complex core-shell compositions, capable of being excited by 808 or 980 nm laser irradiation and exhibiting a good MRI response. The synthesized nanoparticles also demonstrated high colloidal stability in both aqueous and biological media as well as temperature-sensing capabilities, including the physiological range. Furthermore, the upconversion nanoparticles exhibited significantly lower cytotoxicity for HEK293T cells than the commercially available MRI contrast agent Gd-DTPA

Optical Properties of Red-Emitting Rb2Bi(PO4)(MoO4):Eu3+ Powders and Ceramics with High Quantum Efficiency for White LEDs

There are several key requirements that a very good LED phosphor should meet, i.e., strong absorption, high quantum efficiency, high colour purity, and high luminescence quenching temperature. The reported Rb2Bi(PO4)(MoO4):Eu3+ phosphors have all these properties. The Rb2Bi(PO4)(MoO4):Eu3+ phosphors emit bright red light if excited with near-UV radiation. The calculated colour coordinates show good stability in the 77–500 K temperature range. Moreover, sample doped with 50% Eu3+ possesses quantum efficiency close to unity. Besides the powder samples, ceramic disks of Rb2Eu(PO4)(MoO4) specimen were also prepared, and the red light sources from these disks in combination with near-UV emitting LED were fabricated. The obtained results indicated that ceramic disks efficiently absorb the emission of 375 and 400 nm LED and could be applied as a red component in phosphor-converted white LEDs

Biocompatible Upconverting Nanoprobes for Dual-Modal Imaging and Temperature Sensing

The demand for multimodal nanomaterials has intensified in recent years driven by the need for ultrasensitive bioimaging probes and accurate temperature monitoring in biological objects. Among the different multimodal nanomaterials that have been extensively studied in the past decade, upconverting nanoparticles are among the most promising. In this paper, we report the synthesis of upconverting nanoparticles with complex core–shell compositions, capable of being excited by 808 or 980 nm laser irradiation and exhibiting a good MRI response. The synthesized nanoparticles also demonstrated high colloidal stability in both aqueous and biological media as well as temperature-sensing capabilities, including the physiological range. Furthermore, the upconversion nanoparticles exhibited significantly lower cytotoxicity for HEK293T cells than the commercially available MRI contrast agent Gd-DTPA

Luminescence and vacuum ultraviolet excitation spectroscopy of samarium doped SrB4O7

Sm2+ and Sm3+ co-doped SrB4O7 could be utilized in several high-level optical devices and fundamental knowledge about the optical behavior of these materials benefits the development of luminescent applications. Herein, we report luminescence and its vacuum ultraviolet (VUV) excitation spectra in samarium doped SrB4O7. Both, Sm2+ and Sm3+ luminescence centers have been examined and distinguished in the emission and the excitation spectra investigated under synchrotron radiation. The contribution of either Sm2+ or Sm3+ emission lines into the emission spectra heavily depended on the excitation energy, and strong f-f transitions of both Sm2+ and Sm3+ were detected. At 10 K, a broad intrinsic luminescence in the UV range was detected and attributed to the radiative transition of either bound or self-trapped exciton in SrB4O7. The optical behavior, including e.g. inter-configurational f-d transitions of Sm(n+) were elucidated with first-principles calculations. Partial density of states well represents the changes of the electronic states that are related to the samarium doping, which in turn explains the emerging features in excitation spectra. In summary, the obtained results clarify the excitation and emission behavior of samarium doped SrB4O7

Luminescence and vacuum ultraviolet excitation spectroscopy of samarium doped SrB₄O₇

Abstract Sm²⁺ and Sm³⁺ co-doped SrB₄O₇ could be utilized in several high-level optical devices and fundamental knowledge about the optical behavior of these materials benefits the development of luminescent applications. Herein, we report luminescence and its vacuum ultraviolet (VUV) excitation spectra in samarium doped SrB₄O₇. Both, Sm²⁺ and Sm³⁺ luminescence centers have been examined and distinguished in the emission and the excitation spectra investigated under synchrotron radiation. The contribution of either Sm²⁺ or Sm³⁺ emission lines into the emission spectra heavily depended on the excitation energy, and strong f-f transitions of both Sm²⁺ and Sm³⁺ were detected. At 10 K, a broad intrinsic luminescence in the UV range was detected and attributed to the radiative transition of either bound or self-trapped exciton in SrB₄O₇. The optical behavior, including e.g. inter-configurational f-d transitions of Sm(n+) were elucidated with first-principles calculations. Partial density of states well represents the changes of the electronic states that are related to the samarium doping, which in turn explains the emerging features in excitation spectra. In summary, the obtained results clarify the excitation and emission behavior of samarium doped SrB₄O₇