Significant anisotropic deformation and optical shifts in stretched cholesteric liquid crystal elastomers.

This study explores the opto-mechanical response of cholesteric liquid crystal elastomers (CLCEs) subjected to uniaxial stretching along the x-axis, perpendicular to their helical z-axis. A definitive crossover is observed in the strain (εx) dependencies of various optical and mechanical properties, such as the transmission spectra, degree of mesogen orientation, Poisson's ratios, and tensile stress. At low strains, CLCEs exhibit a blue shift in the selective reflection band due to a reduction in the helical pitch, accompanied by a decrease in reflection selectivity for circularly polarized light. Beyond a certain critical strain further pitch alterations halt. This strain regime is marked by substantial anisotropic lateral contractions without any z-axis contraction, as indicated by a Poisson's ratio (µxz) of zero. Within this intermediate strain regime, local directors predominantly reorient towards the x-direction within the xy-plane, resulting in a quasi-plateau of tensile stress. Approaching a higher critical strain a complete loss of reflective selectivity occurs. Past this threshold, while the mechanical responses resemble those of isotropic conventional rubber, they retain a periodic structure albeit without phase chirality. These observed features are accounted for by the Mao-Terentjev-Warner model, especially when the network anisotropy parameter is adjusted to match the critical strain magnitude associated with the cessation of selective reflection.

Unraveling Non-Uniform Strain-Induced Crystallization Near a Crack Tip in Natural Rubber.

Strain-induced crystallization (SIC) in natural rubber (NR) near crack tips significantly enhances crack growth resistance, but understanding the interplay between local strain field and crystallization remains challenging due to confined and heterogeneous characteristics. Using micro-scale digital image correlation (DIC) and scanning wide-angle X-ray diffraction (WAXD, with a narrow 10 µm square beam), this study maps local strain tensor properties and SIC in the vicinity of the crack tip and its peripheral zone (≈3 mm × 1 mm area). The analysis reveals a significant correlation between these properties. In the peripheral zone, there is a noticeable deviation of both the principal strain axis and the crystal orientation from the crack opening direction. These deviations are linearly correlated, which indicates that shear strain plays a significant role in determining the crystal orientation. Crucially, the maximum tensile component in the tensor of local principal strains predominantly dictates local crystallinity. This simplicity is attributed to the limited variation in types of deformation within the SIC region, with corresponding to deformations falling between planar and uniaxial stretching. These findings pave the way for predicting crystallinity distribution using solely strain field data, offering valuable insights into the role of SIC in enhancing the crack growth resistance of NR.

Significantly High Melting Temperature of Homopolymer Crystals Obtained in a Poly(l-Lactic Acid)/Poly(d-Lactic Acid) (50/50) Blend.

The isothermal crystallization of a poly(l-lactic acid) (PLLA)/poly(d-lactic acid) (PDLA) (50/50) blend, neat PLLA, and neat PDLA, was studied at different crystallization temperatures (110 °C, 150 °C, 170 and 180 °C) for different durations (1-300 min) by means of differential scanning calorimetry (DSC), polarized optical microscope (POM) observations, and time-resolved wide-angle X-ray diffraction (WAXD). The effects of both the isothermal crystallization temperature and the duration of the isothermal crystallization were investigated for the blend specimens fully crystallized at these crystallization temperatures. The formation of homopolymer crystallites (HC) was confirmed at the isothermal crystallization temperature of 170 °C, which was previously considered too high for its formation, after 70 min had elapsed from the temperature stabilization. Moreover, the melting temperature of the formed HC was found to be significantly high (Tm = 187.5 °C) compared to the one obtained during the nonisothermal DSC measurement of the same specimen of the PLLA/PDLA (50/50) blend, as well as the neat PLLA and PDLA specimens. To the best of our knowledge, this extremely high Tm (=187.5 °C) for HC has never been reported before.

Bioresorbable Poly (L-Lactic Acid) Flow Diverter Versus Cobalt-Chromium Flow Diverter: In Vitro and In Vivo Analysis.

BACKGROUND: Permanent metallic flow diverter (FD) implantation for treatment of intracranial aneurysms requires antiplatelet therapy for an unclear duration and restricts postprocedural endovascular access. Bioresorbable FDs are being developed as a solution to these issues, but the biological reactions and phenomena induced by bioresorbable FDs have not been compared with those of metallic FDs. METHODS: We have developed a bioresorbable poly (L-lactic acid) FD (PLLA-FD) and compared it with an FD composed of cobalt-chromium and platinum-tungsten (CoCr-FD). FD mechanical performance and in vitro degradation of the PLLA-FD were evaluated. For in vivo testing in a rabbit aneurysm model, FDs were implanted at the aneurysm site and the abdominal aorta in the PLLA-FD group (n=21) and CoCr-FD group (n=15). Aneurysm occlusion rate, branch patency, and thrombus formation within the FD were evaluated at 3, 6, and 12 months. Local inflammation and neointima structure were also evaluated. RESULTS: Mean strut, porosity, and pore density for the PLLA-FD were 41.7 µm, 60%, and 20 pores per mm2, respectively. The proportion of aneurysms exhibiting a neck remnant or complete occlusion did not significantly differ between the groups; however, the complete occlusion rate was significantly higher in the PLLA-FD group (48% versus 13%; P=0.0399). Branch occlusion and thrombus formation within the FD were not observed in either group. In the PLLA-FD group, CD68 immunoreactivity was significantly higher, but neointimal thickness decreased over time and did not significantly differ from that of the CoCr-FD at 12 months. Collagen fibers significantly predominated over elastic fibers in the neointima in the PLLA-FD group. The opposite was observed in the CoCr-FD group. CONCLUSIONS: The PLLA-FD was as effective as the CoCr-FD in this study and is feasible for aneurysm treatment. No morphological or pathological problems were observed with PLLA-FD over a 1-year period.

Bioengineered Silkworm for Producing Cocoons with High Fibroin Content for Regenerated Fibroin Biomaterial-Based Applications.

Silk fibroin exhibits high biocompatibility and biodegradability, making it a versatile biomaterial for medical applications. However, contaminated silkworm-derived substances in remnant sericin from the filature and degumming process can result in undesired immune reactions and silk allergy, limiting the widespread use of fibroin. Here, we established transgenic silkworms with modified middle silk glands, in which sericin expression was repressed by the ectopic expression of cabbage butterfly-derived cytotoxin pierisin-1A, to produce cocoons composed solely of fibroin. Intact, nondegraded fibroin can be prepared from the transgenic cocoons without the need for sericin removal by the filature and degumming steps that cause fibroin degradation. A wide-angle X-ray diffraction analysis revealed low crystallinity in the transgenic cocoons. However, nondegraded fibroin obtained from transgenic cocoons enabled the formation of fibroin sponges with varying densities by using 1-5% (v/v) alcohol. The effective chondrogenic differentiation of ATDC5 cells was induced following their cultivation on substrates coated with intact fibroin. Our results showed that intact, allergen-free fibroin can be obtained from transgenic cocoons without the need for sericin removal, providing a method to produce fibroin-based materials with high biocompatibility for biomedical uses.

Enhancing the bioactivity of melt electrowritten PLLA scaffold by convenient, green, and effective hydrophilic surface modification.

As an emerging additive manufacturing (AM) technique, melt electrospinning writing (MEW) is used to fabricate three-dimensional (3D) submicron filament-based scaffolds with adjustable pore size and customized structure for bone regeneration. Poly(L-lactic acid) (PLLA) scaffold with excellent biodegradability and biocompatibility is first successfully manufactured using our self-assembled MEW device. However, the ultralow cell affinity and poor bioactivity severely hamper their practical applications in bone tissue engineering. These issues are caused by the severe inherent biologically inert, hydrophobicity as well as the smooth surface of the MEW PLLA filaments. In this study, a green and robust alkaline method is applied to modify the scaffold surface and to improve the bioactivity of the MEW PLLA scaffold. Without deterioration in mechanical property but robust surface hydrophilicity, the optimal MEW PLLA scaffold shows promoted surface roughness, enhanced filament tensile modulus (~ 2 folds of the as-prepared sample), and boosted crystallizability (ultrahigh WAXD intensity). Moreover, after being cultured with KUSA-A1 cells, the 0.5 M NaOH, 2 h treated MEW PLLA scaffold exhibits higher osteoinductive ability and increased immature bone tissue amounts (3 times of controlled scaffold). Thus, the flexible surface functionalization by the specific alkaline treatment was found to be an effective method for the preparation of bioactivated MEW PLLA scaffolds with promoted bone regeneration.

Impact of Strain-Induced Crystallization on Fast Crack Growth in Stretched cis-1,4-Polyisoprene Rubber.

cis-1,4-Polyisoprene (IR) elastomers harden via strain-induced crystallization (SIC) when the imposed stretch (λ) exceeds the onset value of SIC (λ*). We investigate the Mode-I fast crack growth in the IR sheets as a function of λ in a pure shear geometry. The steady-state crack velocity (V) increases with increasing λ, and V exceeds the shear wave speed of sound at λ > λs. Further stretch beyond λ* (>λs) causes SIC-driven hardening, resulting in a pronounced increase in V. The characteristics of the crack-tip strain field are also significantly influenced by the SIC-driven hardening: The crack-tip opening displacement increases with increasing λ at λ < λ* but exhibits an abrupt reduction beyond λ*. The crack-tip singularity and the area of strain increment caused by the crack growth change discontinuously around λ*. The abrupt variations in these crack-tip characteristics result from the considerable differences in the mechanical properties prior to the crack growth between the entirely amorphous state at λ < λ* and the partially crystallized state at λ > λ*.

Utilization of microalgae residue and isolated cellulose nanocrystals: A study on crystallization kinetics of poly(ɛ-caprolactone) bio-composites.

Exploration of biodegradable materials for conventional application has taken a rising interest across the world. The presented work primarily focused on exploring the effectiveness of isolated CNCs from marine de-oiled green algae biomass residue (Dunaliella tertiolecta) in synthesized poly(ɛ-caprolactone) (PCL). The washed algae biomass residue (WABR) and algae derived CNCs were explored as two different bio-fillers incorporated into PCL for comparison and development of biodegradable and flexible bio-composites with varying bio-filler loading. FTIR, XRD, TGA, UTM, DSC, POM, and SAXS characterized the developed PCL/WABR and PCL/CNC bio-composites. Improved thermal stability was observed in PCL/CNC bio-composites by ~10 °C rise. Besides, increased modulus of 18.38 MPa and tensile strength was obtained in PCL/CNC/1 bio-composites. However, the isothermal kinetics study (at 45 °C) revealed the reduction in the degree of crystallinity of bio-composites, and the axialite formation was visualized via POM. Moreover, CNCs was found as an excellent nucleating agent and effective bio-filler as compared to WABR.

Stress-Strain and Stress-Relaxation Behaviors of Solution-Coated Layers Composed of Block Copolymers Mixed with Tackifiers.

The relationship between the mechanical properties and the structure of block copolymers mixed with tackifiers whose relative solubility to the respective components of block copolymers differs was examined. Coated layers were prepared by solution coating using a block copolymer composed of polystyrene (PS) and polyisoprene (PI), which forms spherical microdomains of PS in the PI matrix, mixed with three types of tackifiers: aliphatic (C5) resin, aliphatic-aromatic (C5-C9) resin, and rosin ester (RE) resin. Furthermore, the correlation between the changes in the nanostructure and mechanical properties including the stress-relaxation behaviors was clarified by two-dimensional small-angle X-ray scattering measurement. The amount of the PI-bridge conformation in the case of C5 resin is the lowest, resulting in the lowest stress. On the contrary, the largest amount of RE resin was solubilized in the PS phase so that it can be considered that pulling out of the PS chains took place easily. We were able to explain the stress-relaxation behavior by fitting with the three-component exponent functions. The triple exponential decay functions indicate the hierarchy of the structures that are the origins of the ″fast mode″ relating to the local relaxation due to the rotation of the repeating unit of polymer chains; the ″intermediate mode″ of the disentanglement of the mid-PI chains; and the ″slow mode″ relating to, in this particular case, pulling out of the PS chains from the PS sphere.

Regular ordering of spherical microdomains in dewetted monolayer islands induced by thermal annealing of spin-coated ultrathin films of a triblock copolymer.

We report here spontaneous dewetting of a spin-coated, ultra-thin film of a sphere-forming block copolymer (BCP) upon thermal annealing, and that the dewetting resulted in the formation of plateau-shaped islands with a constant thickness consistent with the thickness of a monolayer, in which the spherical microdomains are regularly ordered two-dimensionally in a deformed hexagonal lattice. Thus, the spontaneous dewetting was ascribed to a mismatch between the initial spin-coated film thickness with respect to the monolayer thickness. Such dewetting of sphere-forming BCPs is considered to be deterministic compared to the cases of lamella- and cylinder-forming BCPs, as incommensuration in thickness is avoided by attaining perpendicular orientation without dewetting. We further quantitatively examined the ordering regularity of spherical microdomains in the dewetted monolayer islands to clarify the effect of confinement on sphere ordering. The degree of deformation of the hexagonal lattice was found to have an increasing tendency as a function of the degree of the deformation of the dewetted islands (the island shape), irrespective of the size of the island. Namely, islands with almost round shapes exhibit a well-ordered arrangement of the spherical microdomains in a perfect hexagonal lattice. Another notable finding is that the regular ordering of the spherical microdomains was found to be spoiled in the vicinity of the edge of the island. In other words, the spherical microdomains were well-ordered in a hexagonal lattice far from the edge of the island, while they were not regularly ordered in the vicinity of the edge, which may be due to mismatch between the curvature of the island's perimeter and the polygonal shape of ordered sphere grains.

Effect of cellulose nanocrystals derived from Dunaliella tertiolecta marine green algae residue on crystallization behaviour of poly(lactic acid).

Marine green algae biomass residue (ABR), a waste by-product of Dunaliella tertiolecta, left behind after the extraction of oil from the algal biomass, was utilized for the fabrication of cellulose nanocrystals (CNCs). The fabricated sulphuric acid hydrolysed CNCs had needle-like morphology, with dominant cellulose type I polymorph and a high crystallinity index of 89 %. ICP-MS elemental analysis confirmed the presence of a variety of minerals in the ABR. Washed ABR (WABR)/PLA and CNC/PLA bio-composite films were developed via solvent casting technique with varying bio-filler loadings for comparing their effectiveness on the crystallization behaviour of PLA. FESEM, FTIR, XRD and TGA were used to characterize the bio-fillers. The nucleating and crystallization behaviour of the bio-composite films were confirmed using DSC, SAXS and POM analysis which indicated better effectiveness of CNCs with a significant reduction in cold crystallization temperature, and noteworthy increment in crystallinity and spherulite growth rate.

Fabrication and Properties of Electrospun Collagen Tubular Scaffold Crosslinked by Physical and Chemical Treatments.

Tissue engineered scaffold was regarded as a promising approach instead of the autograft. In this study, small diameter electrospun collagen tubular scaffold with random continuous smooth nanofibers was successfully fabricated. However, the dissolution of collagen in concentrated aqueous (conc. aq.) acetic acid caused to the serious denaturation of collagen. A novel method ammonia treatment here was adopted which recovered the collagen triple helix structure according to the analysis of IR spectra. Further dehydrothermal (DHT) and glutaraldehyde (GTA) treatments were applied to introduce the crosslinks to improve the properties of collagen tube. The nanofibrous structure of collagen tube in a wet state was preserved by the crosslinking treatments. Swelling ratio and weight loss decreased by at least two times compared to those of the untreated collagen tube. Moreover, tensile strength was significantly enhanced by DHT treatment (about 0.0076 cN/dTex) and by GTA treatment (about 0.075 cN/dTex). In addition, the surface of crosslinked collagen tube kept the hydrophilic property. These results suggest that DHT and GTA treatments can be utilized to improve the properties of electrospun collagen tube which could become a suitable candidate for tissue engineered scaffold.

Effect of stretching angle on the stress plateau behavior of main-chain liquid crystal elastomers.

The equilibrium nonlinear stress-stretch relationships for a monodomain main-chain nematic elastomer (MNE) are investigated by varying the angle between the stretching and initial director axes (θ0). Angle θ0 has pronounced effects on the ultimate elongation as well as on the width of the low stress plateau regime (Λp) during director rotation, whereas θ0 has no appreciable effect on the plateau stress (σp). In the stretching normal to the initial director (θ0 = 90°), the plateau end exceeds 200% strain. At oblique angles of 90° > θ0≥ 35°, Λp decreases with decreasing θ0, whereas the definite plateau regime vanishes at θ0 < 24°. Wide-angle X-ray scattering and polarized optical microscopy measurements reveal that the director rotates uniformly in the biased direction for the MNE of θ0°â‰ª 90°, whereas directors rotating clockwise and counterclockwise are coexistent for θ0 = 90°. Over the entire plateau regime, the MNEs exhibit pure shear deformation characterized by a Poisson's ratio of zero in the direction of the rotation axis. The Λp for the corresponding polydomain NE (PNE) undergoing a transition to the monodomain alignment is smaller than that of the MNE of θ0 = 90°, while the σp values for both NEs are almost similar. The semi-soft elasticity concept satisfactorily explains the effects of θ0 on Λp, and the Λp value of the PNE, using a single anisotropy parameter which is evaluated from the degree of thermally induced deformation of MNEs.

Ion transfer channel network formed by flower and rod shape crystals of hair hydrolysate in poly(vinyl alcohol) matrix and its application as anion exchange membrane in fuel cells.

Ion transfer phenomena occurring in nature are known to be most efficient. Many efforts have been made to mimic such phenomena, especially in the area of energy transfer. Proteins consisting of various amino acids are known to be the fundamental materials behind these phenomena. In the current study, an effort was made to extract proteinaceous material from human hair bio-waste by a green chemical-free thermal hydrolysis process. A simple heat treatment of the human hairs in presence of water led to the formation of a water soluble material, which was called hair hydrolysate (HH), contains 70 wt% proteinaceous material. It was utilized for the fabrication of poly(vinyl alcohol) (PVA) matrix-based anion exchange membrane (AEM). Presence of 27 wt% charged amino acids and 19 wt% polarizable amino acids in the HH provided effective charge transfer sites. 7 wt% arginine present in the HH, having continuous delocalized net positive charge helped the membrane to be stable in highly alkaline conditions, which was confirmed by an indirect analysis of alkaline stability. Formation of rod and flower shaped crystal morphology by the HH in glutaraldehyde crosslinked PVA matrix, created a continuous channel network at higher loadings, which provided a simple path for ion transfer, achieving OH- conductivity of 7.46 mS/cm at 70 °C. Swelling of the PVA matrix was minimized by annealing of the HH loaded sample, which resulted in reduction of ionic conductivity to 6.16 mS/cm (at 70 °C). At the same time, improvement in the properties like increase in thermal, mechanical and thermo-mechanical stability, reduction in water uptake, %swelling and methanol permeability was observed. The selectivity of the membrane was increased to almost a decimal place. Thus, the HH obtained from simple green thermal hydrolysis of human hair bio-waste is a cheap material, which is found to be suitable as ion conductive material for alkaline fuel cells.

Glassy Porphyrin/C60 Composites: Morphological Engineering of C60 Fullerene with Liquefied Porphyrins.

Morphological control of C60 fullerene using liquefied porphyrins (1 and 2) as the host matrices was explored. Slow evaporation of the solvent of the equimolar mixture of porphyrin and C60 in toluene afforded the porphyrin/C60 composite with a 3:1 molar ratio. The stoichiometric binding behaviors suggest that specific porphyrin-C60 interactions operate the formation of the porphyrin/C60 composites, as corroborated by spectroscopic and thermal properties, and glazing-incidence wide-angle X-ray diffraction. Under the bulk conditions, the conventional thermodynamic advantage of multiple binding cooperativity for molecular recognition is unlikely to explain the stoichiometric binding behaviors. Instead, we propose a size-matching effect on the porphyrin-C60 interaction in the bulk porphyrin matrices, i.e., "supramolecular solvation". The glassy nature of the porphyrin matrices was transmitted to C60 through the specific interaction, and the porphyrin/C60 composites adopted glassy states at room temperature.

Extraction and Characterization of Novel Natural Hydroxyapatite Bioceramic by Thermal Decomposition of Waste Ostrich Bone.

A novel natural hydroxyapatite (HAp) bioceramic was extracted from the ostrich cortical bone by the thermal decomposition method. HAp was characterized by different analytical tools such as thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM). Removal of organic impurities from the bone powder was confirmed by TGA analysis. FTIR spectra of HAp confirmed the presence of the major functional groups such as phosphate (PO4 3-), hydroxyl (OH-), and carbonate (CO3 2-) in the bioceramic. The XRD data revealed that the HAp was the crystalline phase obtained by calcination of the bone powder at 950°C, and the SEM analyses confirmed the typical plate-like texture of the nanosized HAp crystals.

Modification of decellularized vascular xenografts with 8-arm polyethylene glycol suppresses macrophage infiltration but maintains graft degradability.

Because acellular vascular xenografts induce an immunological reaction through macrophage infiltration, they are conventionally crosslinked with glutaraldehyde (GA). However, the GA crosslinking reaction inhibits not only the host immune reaction around the graft but also the graft's enzymatic degradability, which is one of the key characteristics of acellular grafts that allow them to be replaced by host tissue. In this study, we used an 8-arm polyethylene glycol (PEG) to successfully suppress macrophage infiltration, without eliminating graft degradation. Decellularized ostrich carotid arteries were modified with GA or N-hydroxysuccinimide-activated 8-arm PEG (8-arm PEG-NHS), which has a molecular weight of 17 kDa. To evaluate the enzymatic degradation in vitro, the graft was immersed in a collagenase solution for 12 hr. The 8-arm PEG-modified graft was degraded to the same extent as the unmodified graft, but the GA-modified graft was not degraded. The graft was transplanted into rat subcutaneous tissue for up to 8 weeks. Although CD68-positive cells accumulated in the unmodified graft, they did not infiltrate into either modified graft. However, the GA-modified grafts calcified, but the 8-arm PEG-modified graft did not calcify after transplantation. These data suggested that 8-arm PEG-NHS is a promising modification agent for biodegradable vascular xenografts, to suppress acute macrophage infiltration only.

Helical-Ribbon and Tape Formation of Lipid Packaged [Ru(bpy)3]2+ Complexes in Organic Media.

Anionic lipid amphiphiles with [RuII(bpy)3]2+ complex have been prepared. The metal complexes have been found to form ribbon and tape structures depending on chemical structures of lipid amphiphiles. Especially, the composites showed hypochromic effect and induced circular dichroism in organic media, and flexibly and weakly supramolecular control of morphological and optical properties have been demonstrated.

Structural Evolution in Isothermal Crystallization Process of Poly(L-lactic acid) Enhanced by Silk Fibroin Nano-Disc.

The nucleating effect of silk fibroin nano-disc (SFN) on the crystallization behavior of poly(L-lactic acid) (PLLA) was investigated by simultaneous synchrotron small- and wide-angle X-ray scattering measurements. For the isothermal crystallization at 110 °C from the melt, the induction period of the PLLA specimens containing 1% SFN was reduced compared to that of the neat specimens, indicating the acceleration of the nucleation of PLLA. The final degree of crystallinity was also increased, and the crystallization half-time was decreased, which indicates that the overall crystallization process was accelerated. Furthermore, the final value of the crystallite size (the lateral size of the crystalline lamella) was slightly lower for the specimens containing 1% SFN than that for the PLLA neat specimen, although the crystallites started growing much earlier. However, it was found that there was no effect of SFN on the growth rate of the crystallite size. The lamellar thickening process was also accelerated with a clear overshooting phenomenon with the inclusion of 1% SFN. As for the polymorphism, the α' phase is dominant with about 96%, but a small amount of the α phase (4%) is found to exist. It was found that the SFN can also accelerate the formation of the minor α phase as well as the major α' phase.

A longitudinal study on the relationship between dental health and metabolic syndrome in Japan.

BACKGROUND: A close relationship has been reported between metabolic syndrome (MetS) and periodontitis. However, as there are only a few longitudinal studies, the association between MetS and periodontitis has not been fully elucidated. The aim of the present study was to investigate the relationships between periodontal conditions and internal changes in MetS components using a longitudinal analysis. METHODS: A total of 985 out of 2716 individuals who underwent systemic medical checkups in 2014 and 754 out of 2454 in 2016 received dental checkups including Community Periodontal Index. Of these, 390 individuals underwent medical and dental checkups in 2014 and 2016 and were included and reviewed. RESULTS: Of the 390 individuals, the positive number of MetS components decreased in 62 individuals (15.9%) and increased in 104 (26.7%). A multivariate analysis identified sex (risk ratio (RR): 0.55, 95% confidence interval (CI): 0.37-0.82, P < 0.05), alcohol intake (RR:2.06, 95%CI:1.14-3.73, P < 0.05), and the mediation of glycemia (RR:6.45, 95%CI:1.45-27.9, P < 0.01) as significant influencing factors for MetS. The number of MetS components was higher in individuals with persistent or progressive periodontitis than in those with no/improved periodontitis (RR:1.75, 95%CI:1.14-2.70, P < 0.01)). Improvements in periodontitis had a significant positive impact on MetS components, including hypertension (RR:2.14, 95%CI:1.03-4.43, P < 0.05) and hyperglycemia (RR:2.52, 95%CI:1.27-4.98, P < 0.01), but a negative impact on hypertension. CONCLUSIONS: The results of the present study suggest that since the prevalence of individuals with more positive MetS components was higher in those with persistent/progressive periodontitis than in those with no/improved periodontitis, reducing periodontitis may be important for preventing pre-MetS and MetS.