RESUMO
OBJECTIVE: The study addresses the long-standing challenge of insufficient length in vascularized fibular flaps when reconstructing large mandibular defects that require dual-barrel grafts. Employing personalized 3D-printed osteotomy guides, the study aims to optimize fibular utilization and minimize the required graft length. MATERIAL AND METHODS: Two reconstruction methods for distal bone defects were compared: a fold-down (FD) group that employed a specialized osteotomy guide for folding down a triangular bone segment, and a traditional double-barrel (DB) group. Metrics for comparison included defect and graft lengths, as well as the graft-to-defect length ratio. Postoperative quality of life was assessed using the University of Washington Quality of Life questionnaire (UW-QoL). RESULT: Both FD and DB groups achieved successful mandibular reconstruction. Despite larger defects in the FD group (117 ± 31.35 mm vs 84 ± 35.34 mm, p = 0.028), the used fibula length was not statistically longer in the FD group. The median ratio of graft-to-defect length was also lower in the FD group (1.327 vs 1.629, p = 0.024), suggesting that FD required only 82.47% of the graft length needed in the DB approach. Quality of life scores post-surgery were comparable between the groups. CONCLUSION: Personalized 3D-printed osteotomy guides enhance fibula graft efficacy for reconstructing larger mandibular defects, necessitating shorter graft lengths while preserving postoperative quality of life. CLINICAL RELEVANCE: This study confirms the utility of 3D printing technology as an effective and precise tool in orthopedic surgery, particularly for complex reconstructions like large mandibular defects. It suggests a viable alternative that could potentially revolutionize current practices in bone grafting.
Assuntos
Retalhos de Tecido Biológico , Reconstrução Mandibular , Fíbula/cirurgia , Qualidade de Vida , Mandíbula/cirurgia , Retalhos Cirúrgicos , Reconstrução Mandibular/métodos , Transplante Ósseo/métodos , OsteotomiaRESUMO
Lignin nanoparticles, the innovative achievements in the development and utilization of lignin, combine the structural characteristics of nanomaterials and lignin molecules and have a wide range of applications. In this review, we summarize the methods for preparing lignin nanoparticles by solvent exchange method, mechanical method, biological enzymatic method, interface polymerization/crosslinking method, and spray freezing method, and emphatically introduce the application prospects of lignin nanoparticles in ultraviolet protection, antibacterial, nano-filler, drug delivery, and adsorption, aiming to provide a certain reference direction for additional high-value applications of lignin nanoparticles.
Assuntos
Nanopartículas , Nanoestruturas , Fenômenos Químicos , Lignina/química , Nanopartículas/química , PolimerizaçãoRESUMO
BACKGROUD: Root caries in aging population was prevalent worldwide. Due to the absence of enamel and specific structure of dentine, bacteria are able to penetrate further into dentine at an earlier stage of lesion development. The aim of this study was to investigate the effect of adding of a strontium-doped bioactive glass-ceramic (HX-BGC) to a fluoride-free toothpaste on prevention of formation of artificial dentine caries. METHODS: Thirty-six human tooth specimens were allocated to three groups (n = 12 per group). Group 1 treated with slurry containing a fluoride-free toothpaste and 5% HX-BGC, Group 2 was treated with fluoride-free toothpaste slurry, and Group 3 received deionized water as a negative control. The specimens were subjected to four cycles (15 h demineralization and 8 h remineralization for one cycle) of biochemical cycling. A mixed suspension of five bacteria species (Streptococcus mutans, Streptococcus sobrinus, Lactobacillus acidophilus, Lactobacillus rhamnosus, and Actinomyces naeslundii) were prepared in brain heart infusion broth with 5% sucrose and used as acidic challenge in biochemical cycling. Subsequently, surface morphology of the dentine lesion was assessed by scanning electron microscopy, while the lesion depths and mineral loss were assessed by micro-computed tomography. RESULTS: The mean lesion depths in dentine in Groups 1 to 3 were 87.79 ± 16.99 µm, 101.06 ± 10.04 µm and 113.60 ± 16.36 µm, respectively (p = 0.002). The mean amounts of mineral loss in Groups 1 to 3 were 0.82 ± 0.10 g/cm3, 0.89 ± 0.09 g/cm3 and 0.96 ± 0.11 g/cm3, respectively (p = 0.016). No obvious differences in the surface morphology were seen among the groups. CONCLUSION: Addition of strontium-doped bioactive glass-ceramic to fluoride-free toothpaste has potential to reduce formation of dentine lesions.
Assuntos
Cárie Dentária , Cremes Dentais , Idoso , Cariostáticos/farmacologia , Cerâmica/uso terapêutico , Cárie Dentária/prevenção & controle , Suscetibilidade à Cárie Dentária , Dentina , Fluoretos/farmacologia , Humanos , Minerais/farmacologia , Estrôncio/farmacologia , Estrôncio/uso terapêutico , Remineralização Dentária/métodos , Cremes Dentais/uso terapêutico , Microtomografia por Raio-XRESUMO
Constructing a high-performance ultraviolet shielding film is an effective way for addressing the growing problem of ultraviolet radiation. However, it is still a great challenge to achieve a combination of multifunctional, excellent mechanical properties and low cost. Here, inspired by the multiscale structure of biomaterials and features of lignin, a multifunctional composite film (CNF/CMF/Lig-Ag) is constructed via a facile vacuum-filtration method by introducing micron-sized cellulose fibers (CMF) and lignin-silver nanoparticles (Lig-Ag NPs) into the cellulose nanofibers (CNF) film network. In this composite film, the microfibers interweave with nanofibers to form a multiscale three-dimensional network, which ensures satisfactory mechanical properties of the composite film. Meanwhile, the Lig-Ag NPs are employed as a multifunctional filler to enhance the composite film's antioxidant, antibacterial and ultraviolet shielding abilities. As a result, the prepared CNF/CMF/Lig-Ag composite film demonstrates excellent mechanical properties (with tensile strength of 133.8 MPa and fracture strain of 7.4 %), good biocompatibility, high thermal stability, potent antioxidant and antibacterial properties. More importantly, such composite film achieves a high ultraviolet shielding rate of 98.2 % for ultraviolet radiation A (UVA) and 99.4 % for ultraviolet radiation B (UVB), respectively. Therefore, the prepared CNF/CMF/Lig-Ag composite film shows great potential in application of ultraviolet protection.
Assuntos
Lignina , Nanopartículas Metálicas , Lignina/química , Celulose/química , Prata/química , Antioxidantes , Raios Ultravioleta , Nanopartículas Metálicas/química , AntibacterianosRESUMO
Adhesives are used extensively in the wood industry. As resource and environmental issues become increasingly severe, the development of green and sustainable biomass-based adhesives has attracted increasing attention. In this work, a green wood adhesive is developed from poly(vinyl alcohol) and lignin with molecular designs of lignin extending beyond those in nature. The lignin undergoes extraction from corncob residue, aldehydration, and phenolisation (phenol, resorcinol, and catechol) to significantly increase the phenolic hydroxyl groups (over 7.92 mmol/g), which has the effect of enhancing the hydrogen bonding force between the adhesive and the wood, thereby greatly improving adhesive performance. Compared with pure PVA, polyphenol lignin-containing PVA showed improved adhesion strength and hydrophobicity. PVA/resorcinol-lignin has the significantly improved wood lap shear strength (6.27 MPa, 77.6 % improvement) and hydrophobicity (almost 100 % increase in wet shear strength). This research not only provides a green and high-performance alternative raw material for wood adhesives but also broadens the path for large-scale application of biomass.
Assuntos
Lignina , Polifenóis , Polifenóis/análise , Lignina/química , Álcool de Polivinil , Adesivos/química , Madeira/química , Fenóis/química , Metanol , Cloreto de Polivinila , ResorcinóisRESUMO
Carbon dots (CDs) have emerged as a promising subclass of optical nanomaterials with versatile functions in multimodal biosensing. Howbeit the rapid, reliable and reproducible fabrication of multicolor CDs from renewable lignin with unique groups (e.g., -OCH3, -OH and -COOH) and alterable moieties (e.g., ß-O-4, phenylpropanoid structure) remains challenging due to difficult-to-control molecular behavior. Herein we proposed a scalable acid-reagent strategy to engineer a family of heteroatom-doped multicolor lignin carbon dots (LCDs) that are functioned as the bimodal fluorescent off-on sensing of metal-ions and glutathione (GSH). Benefiting from the modifiable photophysical structure via heteroatom-doping (N, S, W, P and B), the multicolor LCDs (blue, green and yellow) with a controllable size distribution of 2.06-2.22 nm deliver the sensing competences to fluorometric probing the distinctive metal-ion systems (Fe3+, Al3+ and Cu2+) under a broad response interval (0-500 µM) with excellent sensitivity and limit of detection (LOD, 0.45-3.90 µM). Meanwhile, we found that the addition of GSH can efficiently restore the fluorescence of LCDs by forming a stable Fe3+-GSH complex with a LOD of 0.97 µM. This work not only sheds light on evolving lignin macromolecular interactions with tunable luminescent properties, but also provides a facile approach to synthesize multicolor CDs with advanced functionalities.
Assuntos
Carbono , Pontos Quânticos , Carbono/química , Lignina/química , Pontos Quânticos/química , Metais , Corantes Fluorescentes/química , Íons , GlutationaRESUMO
Lignin has been regarded as a potential natural sun screening agent. However, the dark color of traditional industrial lignin hinders its application in the field of skincare. In this study, a green and facile approach was developed to extract light-colored lignin. p-Toluenesulfonic acid (p-TsOH) was used to separate lignin and fibers from Kenaf stalks. During the isolation of lignin, formaldehyde was added to preserve the ß-O-4 bonds of lignins in the form of stable acetals. The obtained lignin was further employed to prepare nanoparticles (LNPs) as sunscreen additives. After adding 4 wt% LNPs, the SPF values of the cream increased from 7.05 to 27.84. The residual fibers from the Kenaf stalks can be utilized for papermaking as the raw materials. by mixing them with softwood pulp to reduce the consumption of commercial pulp. With the addition of 5 wt% residual fibers in commercial softwood pulp, the produced paper showed better mechanical properties. The ring crush strength index and tear index of the samples increased from 2.49 N·m/g and 4.63 mN·m2/g to 2.62 N·m/g and 4.75 mN·m2/g, respectively. This study paved a way for the comprehensive utilization of Kenaf stalks towards not only papermaking but also daily chemical products.
Assuntos
Hibiscus , Lignina , Lignina/química , Protetores Solares/química , Hibiscus/química , Alimentos , IndústriasRESUMO
Templating polymeric membranes with micro-nano-scaled solid materials is an effective method to simultaneously improve the water flux and retention ratio. However, the fabrication of a green, recyclable, and size-controlled template material remains a challenge. Here, a new green pore-forming agent, lignin particles (LP), was developed to prepare porous polysulfone (PSF) membranes via the phase inversion technique. A series of LP have uniform sizes from ~200 nm to ~1800 nm. The performances of the templated PSF membranes cast at different sizes and contents of LP were examined for their surface and crosssection morphologies. The LP-templated PSF membranes displayed a remarkable enhancement in flux, porosity, and moisture content. Particularly, the PSF membranes cast with LP from ~200 to 1800 nm broke the traditional trade-off to a certain degree, which possessed stable retentions of bovine serum albumin (> 85 %) and significantly improved water flux (174.275 to 254.775 L m-2 h-1). In addition, the LP pore-forming agent is low-cost and environmentally friendly as it was prepared from industrial by-products and can be easily recycled. Overall, this study shows that lignin particles are green pore-forming agents that can be used for the fabrication of porous polymeric membranes with improved performance for water treatment.
Assuntos
Lignina , Membranas Artificiais , Polímeros , SulfonasRESUMO
The chemical compositions of lignin, hemicellulose and cellulose are so far unascertained to various lignocellulose in respect to effect of cellulose enzymatic hydrolysis. The novel and environment-friendly gluconic acid (GA) pretreatment technology showed impressive results on the enzymatic hydrolysis of cellulose in various agricultural straws. However, only few of the main reasons or critical issues pertaining to this reaction are known. Therefore, the novel GA pretreatment was carried out to remove hemicellulose from the three representative waste straws under different conditions. Next, for the enzymatic hydrolysis of the residual cellulose fraction in the pretreated straws, some mathematical correlations have been investigated between enzyme accessibility, hemicellulose removal rate, and cellulose crystallinity index. Both linear and nonlinear models were compared using five-parameter logic curve, four-parameter logic curve, and Deming regression. Hemicellulose removal was logically ascribed to be the trigger for cellulose saccharification efficiency during GA pretreatment of these waste straws.
Assuntos
Celulose , Lignina , Agricultura , Gluconatos , HidróliseRESUMO
As a new and green type of nanomaterials, lignin nanoparticles (LNPs) have been considered as high-value renewable materials for application in many fields. However, the industrialization of LNPs faces many challenges, such as high manufacturing costs and small-scale production. Here, a simple but rapid and reversible approach for the fabrication of LNPs was provided via switching pH environments. The LNPs were regularly shaped in the acetonitrile/water system, and their size appeared to be very homogeneous. The alternation of forming and dissolving of LNPs could be repeated many times simply by alternately adding acid and alkaline solutions. There was little difference in the molecular structures between the original and regenerated LNPs. In addition, the consumption of solvents for LNPs production was only 200â mL g-1 , reduced by more than 10 times compared with conventional solvent exchange methods. The concentration of LNPs in the solution also improved to 5.0â g L-1 . This study not only provides a new, simple, and effective strategy for the fabrication of LNPs but also paves the way towards their real green production and application.
Assuntos
Lignina , Nanopartículas , Ácidos , Concentração de Íons de Hidrogênio , Lignina/química , Nanopartículas/química , Solventes/químicaRESUMO
Lignin nanoparticles (LNPs), as a new type of green nanomaterial, initiate many promising applications in polymer composites. However, their heterogeneity, dissolution in organic solvents, and poor compatibility in the polymer matrix greatly limited the applications of LNPs fillers. Herein, we proposed an antisolvent precipitation of the fractionations by combining a hydrothermal treatment-assisted synthesis to fabricate self-crosslinked LNPs (ScLNPs), which have good stability in the organic solvent and controllable sizes. After surface grafting modification with d-lactide, ScLNPs-graft-poly(d-lactide) (ScLNPs-g-PDLA) exhibited excellent dispersion and compatibility in PLLA matrix. Using the rational design and addition of ScLNPs-g-PDLA fillers, the strength and toughness of the generated PLLA composite reached 31.6 MPa and 396 % (the highest value among the PLLA materials), respectively. Furthermore, the mechanical performance can also be well-tuned by the sizes and amounts of LNPs fillers. This strategy involving only green and recyclable materials provides an effective route to producing sustainable polymeric plastics with integrated strength and super-toughness.
Assuntos
Lignina , Poliésteres , PolímerosRESUMO
The rationally-designed lignocellulose valorization that promotes a novel "waste-treats-pollutant" standpoint is highly desired yet still challenging for the spread of biomass industry. At this point, a cascade technique with the assistance of deep eutectic solvent (DES) fractionation is tailored to dually valorize wheat straw into fluorescent lignin carbon dots (LCDs) and bimetallic Mg-Fe oxide-decorated biochar (MBC) via solvothermal engineering and co-precipitation/pyrolysis respectively. Benefitting from the abundance of ß-aryl ether and hydroxyl groups in DES-extracted lignin, the photoluminescence LCDs emit blue color in a wide excitation span, which can be adopted to selectively detect ferric ions (Fe3+) in a broad dosage scale with a highly linear correlation of 10-50 µM. Taking advantages of the MBC-aided persulfate activation, we propose the efficient arbidol removal system with a universal concentration of 20-200 ppm in the scalable pH ranging from 3 to 11. The dominate migration pathways involving with active oxygen species and surface electron transfer are comprehensively studied via electron paramagnetic resonance, radical-quenching experiments, and theoretical arithmetic. With the endeavor of biorefineries, this full-scale platform ignites the dazzling wildfire from dual lignocellulose valorization that will also seek its accurate position in the kingdoms of functional materials and wastewater restoration.
Assuntos
Poluentes Ambientais , Lignina , Carbono , Carvão Vegetal , FerroRESUMO
Lignin, as the most abundant aromatic biopolymer, is being widely studied to replace phenol and some other petroleum-based materials in the polymer industry. However, the low substitution of lignin and high levels of additives greatly limited the applications of lignin-based materials. Herein, we first propose a simple but effective hydrothermal method assisted synthesis for the fabrication of self-crosslinked lignin-based hydrogels (Lig-Scgel) with super-high-contents (75 wt%) of lignin and controllable mechanical properties. The self-crosslink mechanism was inspired by the repolymerization of lignins under a hydrothermal environment. The employment of self-condensation of lignin subunits in the synthesis of Lig-Scgel can significantly improve the degree of crosslinking, thereby greatly reducing the addition of toxic crosslinkers. The appearances, microstructures, crosslink densities, and mechanical properties of Lig-Scgels can be well controlled by simply altering the hydrothermal temperatures. This strategy not only promotes green and large-scale applications of lignin but also provides insights in the development of environment-friendly polymeric materials.
Assuntos
Hidrogéis , Lignina , Biopolímeros , Fenômenos Químicos , Hidrogéis/química , Lignina/química , Polímeros/químicaRESUMO
OBJECTIVES: The presentation-assimilation-discussion (PAD) class is a novel teaching method in which half the class time is allocated for the instructor's presentation and the other half for student's assimilation and discussion. This study evaluates and compares the teaching outcomes of the PAD class and traditional lecture-based method in oral pathology courses in School of Stomatology, Kunming Medical University. MATERIALS AND METHODS: The experimental and control groups included 88 undergraduates from Class 2017 and 72 undergraduates from Class 2016, respectively. The PAD method was applied on the experimental group in 2019, whereas the traditional lecture-based method was applied on the control group in 2018. The two groups' teaching outcomes were compared using final theory tests, biopsy diagnostic tests, and questionnaires. The Mann-Whitney U-test and independent-sample t-test were adopted for statistical analysis. RESULTS: In five multiple-choice questions examining the same knowledge point from final theory tests, the distribution of the final scores showed a statistically significant difference between the two groups (p < 0.05). In the biopsy diagnostic tests, the experimental group scored higher than the control group (p < 0.05). In the questionnaires, there was no statistically significant difference for the "enhancing knowledge mastery" item (p > 0.05). However, the experimental group showed significant superiority in the remaining nine items (p < 0.05). [Correction added on August 30, 2021, after first online publication: The data value p was corrected in the last sentence of result section.] CONCLUSIONS: Compared with the traditional lecture-based teaching, the PAD class stimulated a passion for learning among students and results in improved teaching outcomes. Therefore, the application of PAD class in oral pathology teaching should be recommended.
Assuntos
Aprendizagem , Patologia Bucal , Humanos , Estudantes , Inquéritos e Questionários , Ensino , UniversidadesRESUMO
The application of industrial kraft lignin is limited by its low molecular weight, dark color, and low solubility. In this work, an efficient crosslinking reaction with N,N-Dimethylformamide (DMF) and 1,6-dibromohexane was proposed for adjusting the molecular weight and color of lignin. The chemical structure of alkylation lignin was systematically investigated by gel permeation chromatography (GPC), ultraviolet spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and 2D heteronuclear single quantum correlation nuclear magnetic resonance (HSQC NMR) spectra. After the alkylation modification, the molecular weights of the lignin were increased to 1643%. The resinol (ß-ß), ß-aryl ether (ß-O-4), and phenylcoumaran (ß-5) linkages were still the main types of the linkages. The formation of ß-ß linkage would be inhibited at high temperatures. The color reduction of lignin can be attributed to the low content of chromophores and low packing density. This alkylation lignin will be a new and general approach for developing molecular weight-controlled and light-colored lignins, which can find more applications in cosmetics, packing, and other fields.
Assuntos
Lignina , Alquilação , Cromatografia em Gel , Lignina/química , Estrutura Molecular , Peso Molecular , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
Hydrogel dressings with similar structural characteristics to the extracellular matrix and tunable physicochemical properties have become promising candidates for wound healing. However, the fabrication of an ideal hydrogel dressing with low-cost, good biocompatibility, excellent hemostatic capacity, potent and broad-spectrum antibacterial activity remains a huge challenge. Herein, a lignocellulose-based nanocomposite hydrogel (ATC/SA/PVA) is fabricated by simply mixing Ag nanoparticles loaded, tannic acid-decorated lignocellulose nanofibrils with sodium alginate and polyvinyl alcohol. Based on the dynamic borate ester bonds and multiple weak hydrogen bonds, the fabricated hydrogel exhibits excellent flexibility and self-healing performance. Its highly porous structure endows the gel excellent blood and tissue exudates absorption ability. Interestingly, the release behavior of Ag nanoparticles from hydrogel displays pH dependence, which can facilitate the accumulation of Ag nanoparticles at the wound site, thereby accelerating the process of wound healing. In vitro antibacterial assay demonstrates the potent antibacterial ability of hydrogel against both Gram-positive (S. aureus) and negative bacteria (E. coli). More importantly, in vivo investigations reveal that such hydrogel can effectively accelerate tissue regeneration and wound healing with no obvious adverse effects. All these results suggest that this nanocomposite hydrogel would be a promising candidate to accelerate wound healing.
Assuntos
Antibacterianos/química , Lignina/química , Nanocompostos/química , Nanogéis/química , Cicatrização/efeitos dos fármacos , Alginatos/química , Animais , Antibacterianos/farmacologia , Escherichia coli/efeitos dos fármacos , Feminino , Hidrogéis/química , Concentração de Íons de Hidrogênio , Lignina/farmacologia , Nanopartículas Metálicas/química , Camundongos , Álcool de Polivinil/química , Reologia , Prata/química , Prata/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Taninos/farmacologiaRESUMO
Lignin-based flame retardants represent great promising next-generation flame retardants due to their sustainability, unique aromatic structure, and high charring capability. However, their applications are still limited by the compatibility, processability, and efficiency of flame retardancy. Here, a green functional lignin-based nanofiller (lignin-diethylenetriamine/red phosphorus nanoparticles, Lignin-N-P NPs) was prepared by the chemical modification and co-precipitation. After blending with the commercial acrylonitrile butadiene styrene copolymers (ABS), the physical, chemical, and flame retardant properties of the blends reveal that Lignin-N-P NPs/ABS blend has acceptable processability, mechanical properties, and significantly improved thermal stability and fire performance. Its values of peak heat release rate and total heat released per unit area were significantly dropped 67.8% and 77.5%, respectively. This study will initiate a new design for not only flame retardants but also lignin-based materials.
Assuntos
Retardadores de Chama/análise , Lignina/química , Nanopartículas/química , Resinas Acrílicas/química , Butadienos/química , Calorimetria , Temperatura Alta , Lignina/ultraestrutura , Nanopartículas/ultraestrutura , Imagem Óptica , Poliestirenos/química , Prata/química , TermogravimetriaRESUMO
OBJECTIVES: This study aimed to investigate the common types and directions of root fractures of the maxillary first molar and the influence of root canal treatment on the prevalent sites of root fractures. METHODS: A total of 274 maxillary first molars with root fractures diagnosed via cone beam computed tomography were included. The root fractures of nonendodontically and endodontically treated teeth were identified to be spontaneous and secondary root fractures, respectively. The sites, types, and directions of spontaneous and secondary root fractures were determined. RESULTS: Among the spontaneous root fractures, the proportion of palatal root fractures (56.1%) was higher than those of mesial buccal root fractures (36.1%) and distal buccal root fractures (7.8%). Among the secondary root fractures, the proportion of mesial buccal root fractures (52.7%) was higher than those of palatal root fractures (36.5%) and distal buccal root fractures (10.8%). The distribution of predominant fracture sites was statistically significant (P<0.05), and vertical root fracture was the most common type. Palatal and buccal roots were commonly fractured at the mesiodistal and buccal-palatal directions, respectively. CONCLUSIONS: This study provided an epidemiological basis for the clinical features of root fractures of the maxillary first molar. During the dia-gnosis and treatment of the maxillary first molar, the possibility of palatal root fractures should be considered. The occurrence of mesial buccal root fractures may be related to root canal treatment. Therefore, the risk of mesial buccal root fractures caused by iatrogenic factors should be minimized.
Assuntos
Dente Molar , Dente não Vital , Tomografia Computadorizada de Feixe Cônico , Humanos , Tratamento do Canal Radicular , Raiz DentáriaRESUMO
OBJECTIVE: To investigate the remineralizing effect of a strontium-doped bioactive glass (HX-BGC) and fluoride on demineralized enamel and dentine. MATERIALS: Sixty demineralized human tooth specimens were allocated to four groups. Group 1 received 5% HX-BGC, Group 2 received 5% HX-BGC and 1450 ppm fluoride, Group 3 received 1450 ppm fluoride, and Group 4 received deionized water as negative control. The specimens were subjected to pH cycling for 14 days. The surface morphology, lesion depths, crystal characteristics and collagen matrix degradation of the specimens were assessed by scanning electron microscopy (SEM), micro-computed tomography (mico-CT), X-ray diffraction (XRD), and spectrophotometry with a hydroxyproline (HYP) assay, respectively. RESULTS: SEM images showed the enamel surface was smooth with regularly arranged enamel rods in Groups 1-3. Granular grains were observed in both inter-tubular and intra-tubular dentine in Groups 1-3. The mean lesion depths in enamel were 80.8 µm, 50.6 µm, 72.7 µm and 130.7 µm in Groups 1-4, respectively (p < 0.001), and those in dentine were 152.6 µm, 140.9 µm, 165.4 µm and 214.1 µm, respectively (p < 0.001). The differences in mean mineral loss in enamel and in dentine between the four study groups follow the same pattern as that of the differences in lesion depth. XRD illustrated apatite formation in each group. There were no significant differences in the HYP concentrations among the four groups (p = 0.261). CONCLUSION: Combined use of HX-BGC and fluoride can reduce mineral loss and promote remineralization of demineralized enamel and dentine through the precipitation of newly formed apatite. CLINICAL SIGNIFICANCE: Adjunctive use of HX-BGC may enhance the remineralization effect of fluoride in the management of early dental caries lesions.
Assuntos
Cárie Dentária , Fluoretos , Cariostáticos/farmacologia , Cárie Dentária/tratamento farmacológico , Esmalte Dentário , Dentina , Fluoretos/farmacologia , Humanos , Estrôncio/farmacologia , Remineralização Dentária , Microtomografia por Raio-XRESUMO
Hydrogel-based piezoresistive sensors have high practical value in many revolutionary applications, such as intelligent and electronic devices. However, with existing hydrogels, it is very difficult to achieve a combination of good mechanical properties, stable conductivity, and simple/green fabrication method. In this study, hybrid organic-inorganic nanoparticles (lignin-silver hybrid nanoparticles, Lig-Ag NPs) were synthesized by using alkaline lignin as the organic component and silver nanoparticle (Ag NPs) as the inorganic component. Interaction between the lignin and Ag NPs leads to the composite of hybrid nanoparticles that not only decreased the release of Ag NPs but also generated dynamically stable semi-quinone radicals in lignin. After compositing with polyvinyl alcohol (PVA) matrix, Lig-Ag NPs provided strong sacrificial hydrogen bonds and facilitated the delivery of electronic. Benefiting from these structural features and the pore-forming effect of ammonia (from Lig-Ag NPs solution), the PVA/Lig-Ag NPs hydrogel exhibits outstanding compressibility, pressure sensitivity, and stability of signal response. This study provides a green and simple design strategy for piezoresistive pressure sensors based on nanocomposite hydrogel.