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To investigate the prospective role of intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) in evaluating terminal ileal Crohn's disease (CD) inflammation quantitatively, compared with quantitative dynamic contrastenhanced magnetic resonance imaging (DCE-MRI) and ileocolonoscopic segmental score.Fifty CD patients underwent magnetic resonance enterography (MRE) including IVIM-DWI and quantitative DCE-MRI from Jan. 2017 to Nov. 2019. ADC, D, D* and f value of IVIM-DWI and Ktrans, Kep, and Ve value of DCE-MRI in normal (n = 50) and inflamed bowel segments (n = 50), defined during the clinical MRI analysis, were calculated and compared using Wilcoxon signed-rank tests respectively. Receiver operating characteristic (ROC) analysis was performed. Correlations between IVIM-DWI and DCE-MRI parameters in comparison with ileocolonoscopic segmental score were assessed using Spearman's rank correlation analysis.For IVIM-DWI, ADC, D, D* and f value showed significant differences respectively between normal and inflamed bowel segments (p 0.05). ADC value presented the highest diagnostic accuracy (AUC = 0.813) and sensitivity (92%), and D value presented the highest specificity (84%) for the evaluation of inflamed bowel segments. For DCE-MRI, Ktrans value presented the highest diagnostic accuracy (AUC = 0.835), the highest sensitivity for Kep value (88%) and the highest specificity for Ve value (96%). ADC, f and Ktrans value had high correlations with ileocolonoscopic score respectively (r = -0.739-0.876, p 0.01). The logarithm of normalized signal intensity/b-values for IVIM-DWI could also indicate directly the evident difference between the normal and inflamed bowel segments of terminal ileal CD.IVIM-DWI will be another promising noninvasive tool to provide precise quantitative-indicators in evaluating inflamed bowel segments of terminal ileal CD with little contrast-agent damage worries.

SPU/Sr-TiO2/MDI nanocomposite adhesive showed satisfactory antibacterial activity and cell nontoxicity, it greatly promoted the formation of new bone tissue in tooth extraction socket when used for healing.

Objective Fluoride (F)-releasing restoratives typically are either weak mechanically or release only low levels of F ions. The objectives of this study were to: (1) develop a novel photo-cured nanocomposite with strong mechanical properties and high levels of sustained F ion release via a two-step “co-precipitation + spray-drying” technique to synthesize CaF2 nanoparticles (nCaF2); and (2) investigate the effect of spray-drying treatment after co-precipitation of nCaF2 on mechanical properties and F ion release of composite. Methods Two types of CaF2 particles were synthesized: A co-precipitation method yielded CaF2cp; “co-precipitation + spray-drying” yielded nCaF2cpsd. Composites were fabricated with fillers of: (1) 0% CaF2 + 70% glass; (2) 10% CaF2cp + 60% glass; (3) 15% CaF2cp + 55% glass; (4) 20% CaF2cp + 50% glass; (5) 10% nCaF2cpsd + 60% glass; (6) 15% nCaF2cpsd + 55% glass; and (7) 20% nCaF2cpsd + 50% glass. A commercial F-releasing nanocomposite served as control. Results The nCaF2cpsd had much smaller particle size (median = 32 nm) and narrower distribution (22–57 nm) than CaF2cp (median = 5.25 μm, 162 nm–67 μm). The composite containing nCaF2cpsd had greater flowability, flexural strength, elastic modulus and hardness than CaF2cp composite and commercial control composite. At 84-day immersion in water, the nanocomposites containing 20% nCaF2cpsd had 65 times higher cumulative F release, and 77 times greater long-term F-release rate, than commercial control. Conclusions A novel two-step “co-precipitation + spray-drying” technique of synthesizing nCaF2 was developed. The photo-cured nanocomposite containing 20% nCaF2cpsd possessed strong mechanical properties and excellent long-term F-release ability, and hence is promising for dental restoration applications to inhibit secondary caries.

Objectives. This study is aimed at investigating the root and root canal morphology by cone beam computed tomography (CBCT) and palatal furcation groove of the buccal root by microcomputed tomography (micro-CT) of maxillary first premolars in a Chinese subpopulation. Methods. This study assessed CBCT images of 440 patients aged 14-80 years. Based on Vertucci’s classification, the number of roots and the canal configuration were determined. Forty-eight maxillary first premolars with furcation grooves were analyzed by micro-CT in patients aged 18-25 years. Results. Based on the CBCT assay, 70.22% and 29.32% of maxillary first premolars were 1 root and 2 roots, respectively. The configuration indicated statistical difference ( P < 0.05 ) between male and female patients. The most common canal type was type IV and was found in 44.32% of cases, followed by type I in 27.84%, and then type II in 20.57%. Root bifurcations had 40.13% prevalence which was distributed more in the middle third than in the cervical and the apical third. For the micro-CT study, 95.83% of the furcation groove configuration was found in the bifurcated maxillary first premolars. The length varied from 1.02 to 7.63 mm. The mean depth of this groove was 0.57 mm in the root coronal, 0.47 mm in the root middle, and 0.22 mm in the root apical level. Palatal dentin width was smaller than 1 mm. Conclusion. The anatomy of the root and root canal system and the irregular wall width of maxillary first premolars with furcation grooves may help dentists to understand the anatomical morphology and improve the outcomes of endodontic treatment.

Objective Pit and fissure sealants with antibacterial and remineralization properties have broad application prospects in caries prevention. The objectives of this study were to: (1) develop a novel pit and fissure sealant containing CaF2 nanoparticles (nCaF2) and dimethylaminohexadecyl methacrylate (DMAHDM); and (2) investigate the effects of nCaF2 and DMAHDM on biofilm response and fluoride (F) ion release for the first time. Methods Helioseal F was used as a control. Bioactive sealants were formulated with DMAHDM and nCaF2. Flow properties, enamel shear bond strength, hardness and F ion releases were measured. Streptococcus mutans (S. mutans) biofilms were grown on sealants. Biofilm metabolic activity, lactic acid production, colony-forming units (CFU), and pH of biofilm culture medium were measured. Results Adding 5% DMAHDM and 20% nCaF2 did not reduce the paste flow and enamel bond strength, compared to control (p Significance The new bioactive pit and fissure sealant with nCaF2 and DMAHDM achieved high fluoride release and strong antibacterial performance. This novel fluoride-releasing and antibacterial sealant is promising to inhibit caries and promote the remineralizaton of enamel and dentin.

Objective Secondary caries and micro-cracks are the main limiting factors for dentin bond durability. The objectives of this study were to develop a self-healing adhesive containing dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP), and investigate the effects of water-aging for 12 months on self-healing, dentin bonding, and antibacterial properties for the first time. Methods Microcapsules were synthesized with poly (urea-formaldehyde) (PUF) shells containing triethylene glycol dimethacrylate (TEGDMA) and N,N -dihydroxyethyl- p -toluidine (DHEPT). The adhesive contained 7.5% microcapsules, 10% DMAHDM, and 20% NACP (all mass). Specimens were water-aged at 37 °C for 1 day to 12 months. Dentin bond strength was measured using extracted human teeth. A single-edge-V-notched-beam (SEVNB) method was used to measure fracture toughness K IC and self-healing efficiency. A dental plaque microcosm biofilm model was used with human saliva as inoculum. Results The microcapsules + DMAHDM + NACP group showed no decline in dentin bond strength after water-aging for 12 months, which was significantly higher than that of other groups without DMAHDM ( p IC was obtained even after 12 months of water immersion, indicating that the self-healing ability was not lost in water-aging ( p > 0.1). The bacteria-killing ability of this adhesive did not decline from 1 day to 12 months ( p > 0.1), with biofilm CFU reduction by 3–4 orders of magnitude after the resin was water-aged for 12 months, compared to control resin. Significance This novel adhesive with triple merits of self-healing, antibacterial and remineralization functions showed an excellent long-term durability in water-aging for 12 months. This multifunctional adhesive has the potential for dental applications to heal cracks, inhibit bacteria, provide ions for remineralization, and increase the restoration longevity.

Objective Calcium phosphate cements (CPCs) mimic nanostructured bone minerals and are promising for dental, craniofacial and orthopedic applications. Vascularization plays a critical role in bone regeneration. This article represents the first review on cutting-edge research on prevascularization of CPC scaffolds to enhance bone regeneration. Methods This article first presented the prevascularization of CPC scaffolds. Then the co-culture of two cell types in CPC scaffolds was discussed. Subsequently, to further enhance the prevascularization efficacy, tri-culture of three different cell types in CPC scaffolds was presented. Results (1) Arg–Gly–Asp (RGD) incorporation in CPC bone cement scaffold greatly enhanced cell affinity and bone prevascularization; (2) By introducing endothelial cells into the culture of osteogenic cells (co-culture of two different cell types, or bi-culture) in CPC scaffold, the bone defect area underwent much better angiogenic and osteogenic processes when compared to mono-culture; (3) Tri-culture with an additional cell type of perivascular cells (such as pericytes) resulted in a substantially enhanced prevascularization of CPC scaffolds in vitro and more new bone and blood vessels in vivo, compared to bi-culture. Furthermore, biological cell crosstalk and capillary-like structure formation made critical contributions to the bi-culture system. In addition, the pericytes in the tri-culture system substantially promoted stability and maturation of the primary vascular network. Significance The novel approach of CPC scaffolds with stem cell bi-culture and tri-culture is of great significance in the regeneration of dental, craniofacial and orthopedic defects in clinical practice.

The conceptual research aims to identify antecedents conducive to bilateral trade during the COVID-19 pandemic. Considering the relevance of bilateral trade for foreign policy and economy studies, there is a need for a renewed framework in times of extreme economic instability. As international commerce is essential for improving the country’s economy, we have examined how economic distance, population, trade percentage of GDP, exchange rate, and political changes interconnect and relate to COVID-19, influencing trade flows. This conceptual paper illustrates the likely impact of COVID-19 on international trade by exploring pandemics’ effects on standard trading parameters such as GDP, distance, policy stability, and population. We model the resulting shock as a multifaceted variable reflected in capital underutilization, manufacturing output decline, international trade costs inflation, production costs inflation, decrease in demand for certain services and shift from everyday needs towards activities that exclude the proximity between people, e.g., proclivity towards virtual market products. The sudden decrease in GDP and bilateral trade, as well as FDI, is amplified by further development of pandemics’ long-term consequences. We take COVID-19 to be a technological, financial, and policy shock significantly influencing international trade and economic development and argue that it will have a varying impact on diverse sectors and economies. The paper offers preliminary insight into the pandemic-related economics that are unfolding and deduce recommendations on positive changes in trading policy to fully leverage on arising trading opportunities and point to potential research directions.

Background Dental fluorosis is characterized by hypomineralization of tooth enamel caused by ingestion of excessive fluoride during enamel formation. Excess fluoride could have effects on the ERK signaling, which is essential for the ameloblasts differentiation and tooth development. MAP kinase phosphatase-1 (MKP-1) plays a critical role in regulating ERK related kinases. However, the role of MKP-1 in ameloblast and the mechanisms of MKP-1/ERK signaling in the pathogenesis of dental fluorosis are incompletely understood. Results Here, we adopted an in vitro fluorosis cell model using murine ameloblasts-like LS8 cells by employing sodium fluoride (NaF) as inducer. Using this system, we demonstrated that fluoride exposure led to an inhibition of p- MEK and p-ERK1/2 with a subsequent increase in MKP-1 expression in a dose-dependent manner. We further identified, under high dose fluoride, MKP-1 acted as a negative regulator of the fluoride-induced p-ERK1/2 signaling, leading to downregulation of CREB, c-myc, and Elk-1. Conclusion Our results identify a novel MKP-1/ERK signaling mechanism that regulates dental fluorosis and provide a framework for studying the molecular mechanisms of intervention and fluorosis remodeling under normal and pathological conditions. MKP-1 inhibitors may prove to be a benefit therapeutic strategy for dental fluorosis treatment.

Fluoride (F)-releasing restoratives typically are either weak mechanically or release only low levels of F ions. The objectives of this study were to: (1) develop a novel photo-cured nanocomposite with strong mechanical properties and high levels of sustained F ion release via a two-step "co-precipitation + spray-drying" technique to synthesize CaFTwo types of CaFThe nCaFA novel two-step "co-precipitation + spray-drying" technique of synthesizing nCaF

The dentin bonding often fails over time, leading to secondary caries and restoration failure. The objectives of this study were to develop an adhesive with dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP), and investigate the effects of storage in artificial saliva for six months on the bonding durability, antibacterial activity, ion release and biofilm pH properties for the first time.DMAHDM was added at 5% (by mass) to Scotchbond Primer and Adhesive (SBMP). NACP was added at 10%, 20%, and 30% to SBMP adhesive. Dentin bonding durability, antibacterial activity against Streptococcus mutans biofilms, and calcium (Ca) and phosphate (P) ion liberation properties were investigated after 1 day and 6months of storage in artificial saliva.Dentin bond strength (n = 50) had 25% loss after 6 months of aging for SBMP control. However, SBMP + DMAHDM+10NACP and SBMP + DMAHDM+20NACP showed no loss in bond strength after storage in artificial saliva for 6 months. The DMAHDM + NACP incorporation method dramatically reduced the biofilm metabolic activity and acid production, and decreased the biofilm CFU by four orders of magnitude, compared to SBMP control, even after 6 months of aging (p0.05). DMAHDM + NACP had long-lasting Ca and P ion releases, and raised the biofilm pH to 6.8, while the control group had a cariogenic biofilm pH of 4.5.Incorporating DMAHDM + NACP in bonding agent yielded potent and long-lasting antibacterial activity and ions liberation ability, and much higher long-term dentin bond strength after 6-month of aging. The new bonding agent is promising to inhibit caries at the restoration margins and increase the resin-dentin bonding longevity.The novel bioactive adhesive is promising to protect tooth structures from biofilm acids and secondary caries. NACP and DMAHDM have great potential for applications to a wide range of dental materials to reduce plaque and achieve therapeutic effects.

OBJECTIVES: A nanoparticle-doped adhesive that can be controlled with magnetic forces was recently developed to deliver drugs to the pulp and improve adhesive penetration into dentin. However, it did not have bactericidal and remineralization abilities. The objectives of this study were to: (1) develop a magnetic nanoparticle-containing adhesive with dimethylaminohexadecyl methacrylate (DMAHDM), amorphous calcium phosphate nanoparticles (NACP) and magnetic nanoparticles (MNP); and (2) investigate the effects on dentin bond strength, calcium (Ca) and phosphate (P) ion release and anti-biofilm properties. METHODS: MNP, DMAHDM and NACP were mixed into Scotchbond SBMP at 2%, 5% and 20% by mass, respectively. Two types of magnetic nanoparticles were used: acrylate-functionalized iron nanoparticles (AINPs); and iron oxide nanoparticles (IONPs). Each type was added into the resin at 1% by mass. Dentin bonding was performed with a magnetic force application for 3 minutes, provided by a commercial cube-shaped magnet. Dentin shear bond strengths were measured. Streptococcus mutans biofilms were grown on resins, and metabolic activity, lactic acid and colony-forming units (CFU) were determined. Ca and P ion concentrations in, and pH of biofilm culture medium were measured. RESULTS: Magnetic nanoparticle-containing adhesive using magnetic force increased the dentin shear bond strength by 59% over SBMP Control (p < 0.05). Adding DMAHDM and NACP did not adversely affect the dentin bond strength (p > 0.05). The adhesive with MNP+DMAHDM+NACP reduced the Streptococcus mutans biofilm CFU by 4 logs. For the adhesive with NACP, the biofilm medium became a Ca and P ion reservoir. The biofilm culture medium of the magnetic nanoparticle-containing adhesive with NACP had a safe pH of 6.9, while the biofilm medium of commercial adhesive had a cariogenic pH of 4.5. CONCLUSIONS: Magnetic nanoparticle-containing adhesive with DMAHDM and NACP under a magnetic force yielded much greater dentin bond strength than commercial control. The novel adhesive reduced biofilm CFU by 4 logs and increased the biofilm pH from a cariogenic pH 4.5 to 6.9, and therefore is promising to enhance the resin-tooth bond, strengthen tooth structures, and suppress secondary caries at the restoration margins.

Decreased expression and increased phosphorylation of Forkhead box o1 (Foxo1) in ameloblasts were observed both in vivo and in vitro when treated by fluoride. The present study aims to investigate the possible relationship between Foxo1 and enamel matrix proteinases, matrix metalloproteinase 20 (MMP20), and kallikrein 4 (KLK4), in NaF-treated ameloblasts. Ameloblast-like cells (LS8 cells) were exposed to NaF at selected concentration (0/2 mM) for 24 h. Gene overexpression and silencing experiments were used to up- and down-regulate Foxo1 expression. The expression levels of Foxo1, MMP20, and KLK4 were detected by quantitative real-time PCR and western blot. Dual luciferase reporter assay was performed to evaluate the regulation of Foxo1 on the transcriptional activity of KLK4 promoter. The results showed that KLK4 expression was decreased in LS8 cells treated by NaF, while MMP20 expression was not changed. Foxo1 activation led to significantly up-regulation of KLK4 in LS8 cells under NaF condition. Knockout of Foxo1 markedly decreased klk4 expression in mRNA level, and intensified inhibition occurred in LS8 cells when combined with NaF treatment. However, the variation trend of MMP20 was not clear. Dual luciferase reporter assay showed that Foxo1 activation enhanced the transcriptional activity of KLK4 promoter. These findings suggest that the decrease of Foxo1 expression induced by high fluoride was a cause for low KLK4 expression.

Objective This study aimed to investigate the effect of high fluoride on runt-related transcription factor 2 (Runx2) expression and to explore the possible relationship among Runx2, forkhead box o1 (Foxo1) and kallikrein 4 (KLK4) in high fluoride-treated ameloblasts. Design Ameloblast-like cells (LS8 cells) were exposed to various concentrations of sodium fluoride (NaF) for up to 48 h. Runx2 expression was downregulated by gene silencing, and Foxo1 expression was up- and downregulated by gene overexpression and silencing, respectively. The mRNA and protein levels of Runx2, Foxo1, KLK4 and matrix metalloproteinase 20 (MMP20) were detected by qRT-PCR and western blotting. Results Runx2 expression was decreased in a dose- and time-dependent manner in NaF-treated LS8 cells. The knockdown of Runx2 markedly decreased KLK4 expression in LS8 cells under NaF conditions. However, the variation trend of MMP20 was unclear. In addition, forced Foxo1 expression led to significant upregulation of Runx2 in LS8 cells under NaF conditions. In contrast, the knockdown of Foxo1 markedly decreased the Runx2 protein levels under NaF conditions. Moreover, Foxo1 downregulation markedly decreased runx2 mRNA levels, and this inhibition in LS8 cells was intensified when combined with NaF treatment. Conclusion The results indicated that NaF reduces Runx2 expression in LS8 cells and that decreased Foxo1/Runx2 expression induced by high fluoride is a cause of low KLK4 expression.

Objective The RNA-binding proteins Lin28 and Lin28b are expressed in many developing tissues and are involved in the biosynthesis of the microRNA let-7 family and embryogenesis processes. However, their roles in mammalian tooth development remain ill-defined. Design The spatiotemporal expressions of Lin28 and Lin28b during mouse molar odontogenesis from day E11.5 to P21 were examined through immunohistochemistry and western blot analysis. Results Both Lin28 and Lin28b were initially expressed in dental epithelium, but the expression patterns varied thereafter. Lin28 was expressed in tooth germ from early embryonic stages and was consistently expressed in the ameloblasts and odontoblasts throughout all stages of tooth development. However, positive staining of Lin28b gradually faded out with tooth germ development, before finally disappearing in tooth organ cells after birth. Conclusions These results indicate that Lin28 was spatiotemporally expressed in tooth germ throughout tooth development progression and may play an active role in ameloblast and odontoblast differentiation, as well as matrix secretion and the mineralization of enamel and dentin. Its paralogue Lin28b may have a distinct function in tooth germ formation.

To investigate the prevalence and intra-oral distribution of dentine hypersensitivity (DH) and to evaluate the related risk factors.A total of 1320 subjects, aged between 20 and 69 years old, were selected from six communities in the urban areas of Xi'an, China. The data were collected by conducting individual interviews using a standard questionnaire; then, the clinical examination was performed for patients who reported about the discomforts they felt in their teeth when subjected to chemical, mechanical and thermal stimuli. Dentine hypersensitivity (DH) was diagnosed by a subject short, sharp pain in response to a blast of cold air from a triple syringe.While replying to the questionnaire, 445 subjects reported about signs of discomfort in the teeth. DH was diagnosed in 336 persons by clinic examination. Thus, the overall prevalence of DH was 33.7% in the questionnaire and 25.5% in the intraoral test. The prevalence of DH was higher in females (33.8%) than in males (22.2%). Furthermore, we found that the prevalence of DH was highest in the age group of 50-59 years (39.3%). The most common initiation factors were acid (37.7%) followed by cold stimuli (35.8%). In general, most subjects with sensitive teeth had a higher educational background.The prevalence of DH was 25.5% in the population of Xi'an City in China. More emphasis should give to middle-aged and old females while planning oral health intervention campaigns. In addition, premolars and cervical surfaces should be examined for the prevention of DH.

Amoxicillin is a common pediatric drug. However, to the best of our knowledge, the role of amoxicillin in enamel hypomineralization has not yet been fully elucidated. The aim of the present study was to assess the effects of amoxicillin on enamel mineralization, the morphology of ameloblasts, as well as the expression of kallikrein‑related peptidase 4 (KLK4), and the tight junction proteins, claudin 1 (CLDN1), claudin 4 (CLDN4) and occludin (OCLN), in ameloblasts of juvenile mice. A total of 36 3‑day‑old Kunming mice were randomly divided into three groups. The mice were administered 0, 50 or 100 mg/kg amoxicillin by intragastric administration for 19 days. The surface morphology and calcium (Ca), phosphorous (P) and carbon contents of mandibular incisors and first molars were examined by scanning electron microscopy and energy dispersive X‑ray spectroscopy. Histological changes in the ameloblasts of mandibular incisors were analyzed by hematoxylin and eosin staining. The KLK4, CLDN1, CLDN4 and OCLN expression levels of ameloblasts were observed by immunohistochemical staining. The incidence of white patches in the incisor was 100% in the 100 mg/kg amoxicillin‑treated groups. A greater number of enamel defects were observed in the incisal/occlusal half of mandibular incisors/molars compared with in the cervical half in the amoxicillin‑treated groups. Following phosphoric‑acid treatment, the enamel rod and interrod were aligned in a disorderly manner in the amoxicillin‑treated groups. Amoxicillin decreased the Ca/P ratio in the enamel of mandibular incisors and molars. More intercellular spaces among maturation ameloblasts were observed in the amoxicillin‑treated groups. Amoxicillin decreased KLK4 and CLDN1, CLDN4 and OCLN expression in mature ameloblasts. The administration of amoxicillin in juvenile mice induced enamel hypomineralization, and the effects of amoxicillin on enamel hypomineralization may be mediated via multiple pathways.

Objective Human periodontal ligament stem cells (hPDLSCs) are promising for periodontal regeneration. However, to date, there has been no report of hPDLSC differentiation into the fibrogenic lineage. There has been no report demonstrating hPDLSC differentiation into all three (osteogenic, fibrogenic and cementogenic fibrogenic) lineages in the same report. The objectives of this study were to harvest hPDLSCs from the periodontal ligaments (PDL) of the extracted human teeth, and use the same vial of hPDLSCs to differentiate into all three (osteogenic, fibrogenic and cementogenic) lineages for the first time. Methods hPDLSCs were harvested from PDL tissues of the extracted premolars. The ability of hPDLSCs to form bone, cementum and collagen fibers was tested in culture mediums. Gene expressions were analyzed using quantitative real-time polymerase chain reaction (qRT-PCR). Immunofluorescence, alizarin red (ARS), Xylenol orange, picro sirius red staining (PSRS), alcian blue staining (ABS) and alkaline phosphatase (ALP) staining were evaluated. Results In osteogenic medium, hPDLSCs had high expressions of osteogenic genes (RUNX2, ALP, OPN and COL1) at 14 and 21 days (15–20 folds of that of control), and produced mineral nodules and ALP activity (5 and 10 folds those of the control). hPDLSCs in fibrogenic medium expressed high levels of PDL fibrogenic genes (COL1, COL3, FSP-1, PLAP-1 and Elastin) at 28 days (20–70 folds of control). They were stained strongly with F-actin and fibronection, and secreted PDL collagen fibers (5 folds of control). hPDLSCs in cementogenic medium showed high expressions of cementum genes (CAP, CEMP1 and BSP) at 21 days (10–15 folds of control) and synthesized mineralized cementum (50 folds via ABS, and 40 folds via ALP staining, compared to those of control). Conclusions hPDLSCs differentiated into bone-, fiber- and cementum-forming cells, with potential for regeneration of periodontium to form the bone-PDL-cementum complex.

Pit and fissure sealants with antibacterial and remineralization properties have broad application prospects in caries prevention. The objectives of this study were to: (1) develop a novel pit and fissure sealant containing CaFHelioseal F was used as a control. Bioactive sealants were formulated with DMAHDM and nCaFAdding 5% DMAHDM and 20% nCaFThe new bioactive pit and fissure sealant with nCaF

Objectives. To investigate the root morphology and root canal anatomy of maxillary first premolar using microscopic computed tomography (micro-CT). Methods. 324 maxillary first premolars were collected and scanned. The root and canal diameter, canal wall thickness, root taper, and cross-sectional shapes were determined in the single root with 1 canal (SR1C), single root with 2 canals (SR2C), and 2 roots with 2 canals (2R2C) by micro-CT. Results. The results showed that single-rooted maxillary premolars were more common than other types. The incidence of SR1C, SR2C, and 2R2C reached 25%, 26.39%, and 26.39%, respectively. Root and canal diameters and canal wall thickness were decreased from coronal third to apical foramen. The three parameters and canal taper showed increases from buccal and palatal (BP) to mesiodistal (MD) aspects. The root canal tapers were smallest of the middle third level. The findings showed the different variations in 2R2C teeth. The root canal cross-sectional morphology in maxillary first premolars is complicated, including round, oval, long oval, flat canal, and irregular canal shapes. The distribution varied in different aspects. Conclusion. Root canal morphology showed a wide variation and complicated structure. The single-rooted teeth were more common in the Chinese adolescent population, and the majority of maxillary first premolars have two canals.

Caries, pulpitis, and trauma are the main causes of dental pulp damage. The regeneration capacity of dental pulp declines with age. Lin28 is a conserved RNA-binding protein in higher eukaryotes that regulates several important cellular functions associated with development, glucose metabolism, differentiation, and pluripotency. Conditional reactivation of Lin28 gene in adult mice markedly accelerates the wound-healing process in injured digits. However, little is known about its functions and molecular mechanism in human dental pulp. The aim of this study was to investigate the effects and mechanism of overexpression of Lin28 gene on the proliferation of human dental pulp cells (HDPCs). For this purpose, a number of molecular and biochemical analytical techniques, including the ethynyl-2'-deoxyuridine (EdU) incorporation assay, RNA-protein immunoprecipitation (RIP) analysis, and luciferase assays, were used for detailed characterization. In addition, factors regulating HDPCs activation were explored through gain-of-function and loss-of-function analyses. The results demonstrate that Lin28 promotes cell proliferation and the S-G2/M transition of HDPCs and directly binds to a group of cell cycle regulatory mRNAs in HDPCs. Through bioinformatics analysis and luciferase assays, we confirmed that let-7a targets IGF2BP2. Silencing of IGF2BP2 showed similar cellular and molecular effects as let-7a. Similarly, restoration of IGF2BP2 counteracted the effects of let-7a expression. In conclusion, Lin28 promotes cell proliferation by regulation of both mRNA translation (let-7-independent) and miRNA biogenesis (let-7-dependent). Lin28 can promote the expression of pro-proliferative genes by directly enhancing their translation to maintain a tight control over HDPC proliferation.

Objectives The present study aimed to investigated the effect and mechanism of Ca2+ treatment on fluoride in ameloblast-lineage cells (ALCs). Materials and methods The effects of fluoride and different Ca2+ levels treatment on the proliferative activity, cell apoptosis, cell cycle, intracellular free Ca2+, were firstly determined. Kallikrein 4 (KLK4), glucose-responsive protein 78 (GRP78), Protein kinase R -like endoplasmic reticulum kinase (PERK), the α subunit of eukaryotic initiation factor 2 (eIF2α), activating transcription factor 4 (ATF4), CCAAT enhancer-binding protein homologous protein (CHOP), were investigated in ALCs. Results The proliferative activity was obviously inhibited under concentrations of single fluoride high than 1 mM, and indicated highest proliferation at single 2.5 mM Ca2+ concentration in ALC cells. In addition, we found that single fluoride markedly induced intracellular free Ca2+ increasing, G2/M phase arrest, apoptosis. GRP78 and endoplasmic reticulum stress pathway of PERK/eIF2α/ATF4/CHOP were significantly increased, while the proliferation and KLK4 were markedly reduced in ALCs. Ca2+ additional treatment can obviously reverse the effect of fluoride-induced apoptosis and inhibition of KLK4. The effect of GRP78 and endoplasmic reticulum stress pathway of PERK/eIF2α/ATF4/CHOP were also alleviated under Ca2+ additional treatment in ALCs. More important, the results of 2.5 mmol/L Ca2+ treatment on the proliferation, cell cycle and apoptosis suggest this concentration is relatively better to mediate the intracellular Ca2+ homeostasis in ALCs. Conclusions In sum, Ca2+-supplementation exerts antagonistic the toxic effects on fluoride and this inhibitory effect suggests the potential implications for Ca2+-supplementation on fluorosis.

Objective: To investigate the possible biological mechanism of dental fluorosis at a molecular level.Material and methods: Cultured LS8 were incubated with serum-free medium containing selected concentrations of NaF (0 ∼ 2 mM) for either 24 or 48 h. Subcellular microanatomy was characterized using TEM; meanwhile, selected biomolecules were analysed using various biochemistry techniques. Transient transfection was used to modulate a molecular pathway for apoptosis.Results: Apoptosis of LS8 was induced by NaF treatment that showed both time and concentration dependency. The activity of caspase-3, -8, -9 was found to be increased with NaF in a dose-dependent manner. Western blot revealed that the protein expression of p-ERK and p-JNK were decreased, while the expression of p-P38 was increased. Inhibition of the p-ERK and p-JNK pathways resulted in a similar decrease for caspase-3.Conclusion: During NaF-induced apoptosis of LS8, p-ERK and p-JNK were closely associated with induction of apoptosis, whic...

Objectives To investigate the effect and mechanism of calcium on LS8 cell differentiation, especially on phosphatidylinositol 3 kinase (PI3K) /protein kinase B(AKT) pathway. Materials and methods Ameloblast-like LS8 cell line was used and additional 0–3.5 mmol/L calcium chloride was treated for 24 h, 48 h. Cell viability and morphological changes, cell cycle and associated regulatory proteins were analyzed. Results No significant effects on morphological changes were observed. Decreased cell viability and increased S phase cells were accompanied by the significant decrease of cyclin A and cyclin B proteins, and significant increase of cyclin D protein in LS8 cells. Additionally, kallikrein-4 and amelotin expressions were significantly increased. Finally, the levels of PI3K, AKT, p-AKT and forkhead box O3 (FOXO3) significantly downregulated after calcium treatment in LS8 cells. Conclusions Calcium inhibit proliferation and promotes differentiation in LS8 cells, this is closely related to the downregulation of PI3K/AKT signal in LS8 cells.

Nan Jiang,1–3 Lu Chen,1–3 Qianli Ma,4,5 Jianping Ruan1–3 1Department of Preventive Dentistry, College of Stomatology, Xi’an JiaoTong University, Xi’an, People’s Republic of China; 2Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi’an JiaoTong University, Xi’an, People’s Republic of China; 3Clinical Research Center of Shaanxi Province for Dental and Maxillofacial Diseases, College of Stomatology, Xi’an JiaoTong University, Xi’an, People’s Republic of China; 4Department of Immunology, School of Basic Medicine, Fourth Military Medical University, Xi’an, People’s Republic of China; 5Department of Prosthodontics, College of Stomatology, Xi’an JiaoTong University, Xi’an, People’s Republic of China Purpose: To investigate the amelogenesis-inductive effects of surface structures at the nanoscale. For this purpose, variable nanostructured titanium dioxide (TiO2) surfaces were used as a framework to regulate the amelogenic behaviors of ameloblasts with the administration of retinoic acid (RA)/dexamethasone (DEX). Materials and methods: TiO2 nanotubular (NT) surfaces were fabricated via anodization. Mouse ameloblast-like LS-8 cells were seeded and cultured on NT surfaces in the presence or absence of RA/DEX for 48 h. The amelogenic behaviors and extracellular matrix (ECM) mineralization of LS-8 cells on nanostructured Ti surfaces were characterized using field emission scanning electron microscope, laser scanning confocal microscope, quantitative polymerase chain reaction, MTT assay, and flow cytometry. Results: TiO2 NT surfaces (tube size ~30 and ~80 nm) were constructed via anodization at 5 or 20 V and denoted as NT5 and NT20, respectively. LS-8 cells exhibited significantly increased spread and proliferation, and lower rates of apoptosis and necrosis on NT surfaces. The amelogenic gene expression and ECM mineralization differed significantly on the NT20 and the NT5 and polished Ti sample surfaces in standard medium. The amelogenic behaviors of LS-8 cells were further changed by RA/DEX pretreatment, which directly drove maturation of LS-8 cells. Conclusion: Controlling the amelogenic behaviors of ameloblast-like LS-8 cells by manipulating the nanostructure of biomaterials surfaces represents an effective tool for the establishment of a systemic framework for supporting enamel regeneration. The administration of RA/DEX is an effective approach for driving the amelogenesis and maturation of ameloblasts. Keywords: TiO2 nanotube, LS-8, surface nanostructure, amelogenesis, retinoic acid

Reactivation of Lin28 accelerates hair, cartilage, bone and mesenchyme regrowth after ear and digit injuries. However, the relationship of Lin28 to reparative dentin has been under investigation. The aim of the present study was to examine whether Lin28 participates in the reparative dentin process and lipopolysaccharide (LPS)-stimulated human dental pulp cells (HDPCs) and to identify the underlying signaling pathway mechanisms. The study established a wound-healing model of the dentin-dental pulp complex in vivo and LPS-induced dental pulp cell inflammation in vitro. In vivo, the results of hematoxylin and eosin staining demonstrated the obvious appearance of reparative dentin and odontoblast-like cells were arranged along the reparative dentin. Immunohistochemical examination demonstrated that Lin28 expression was increased by 72 h after cavity preparation but was decreased by 21 d after cavity preparation. In vitro, HDPCs were exposed to 100 ng/ml LPS for 24 h, and the expression of Lin28 was increased. Overexpression of Lin28 was associated with the downregulated expression of let-7b, let-7g and miR-98. These findings suggest that the wound-healing model was successfully established. Lin28 was involved in the reparative process of the dentin-dental pulp complex and HDPCs exposed to LPS, and Lin28/let-7 may be the underlying mechanism.

Enamel fluorosis is characterized by hypomineralization, and forkhead box O1 (Foxo1) is essential for mouse enamel biomineralization. This study investigated the effect of fluoride on Foxo1 expression and its implications for enamel fluorosis. Mandibular incisors were extracted from Sprague Dawley rats treated for 3 months with water containing 0, 50, or 100 p.p.m. F⁻. Immunohistochemistry was used to localize and quantify FOXO1 expression in dental epithelial layer cells of the incisors. The effect of fluoride on expression of Foxo1, kallikrein-4 (Klk4), and amelotin (Amtn) mRNAs was analyzed by real-time RT-PCR, and western blotting was used to measure total and nuclear FOXO1 protein levels in mature dental epithelial cells. The results revealed that nuclear FOXO1 was mainly localized in the transition and the mature ameloblasts and exhibited weaker expression in the rats exposed to fluoride. In addition to the reduced levels of Foxo1, Klk4, and AmtnmRNAs, the protein levels of total and nuclearFOXO1 were decreased in the mature dental epithelial cells exposed to fluoride. Thus, excessive fluoride may have an effect on the expression levels of Foxo1 in dental epithelial cells and thereby affect hypomineralization of the enamel during fluorosis.

Secondary caries is a primary reason for dental restoration failures. The objective of this study was to investigate the remineralization of human dentin lesions in vitro via restorations using nanocomposites containing nanoparticles of amorphous calcium phosphate (NACP) or NACP and tetracalcium phosphate (TTCP) for the first time.NACP was synthesized by a spray-drying technique and incorporated into a resin consisting of ethoxylated bisphenol A dimethacrylate (EBPADMA) and pyromellitic glycerol dimethacrylate (PMGDM). After restoring the dentin lesions with nanocomposites as well as a non-releasing commercial composite control, the specimens were treated with cyclic demineralization (pH 4, 1h per day) and remineralization (pH 7, 23h per day) for 4 or 8 weeks. Calcium (Ca) and phosphate (P) ion releases from composites were measured. Dentin lesion remineralization was measured at 4 and 8 weeks by transverse microradiography (TMR).Lowering the pH increased ion release of NACP and NACP-TTCP composites. At 56 days, the released Ca concentration in mmol/L (mean±SD; n=3) was (13.39±0.72) at pH 4, much higher than (1.19±0.06) at pH 7 (p0.05). At 56 days, P ion concentration was (5.59±0.28) at pH 4, much higher than (0.26±0.01) at pH 7 (p0.05). Quantitative microradiography showed typical subsurface dentin lesions prior to the cyclic demineralization/remineralization treatment, and dentin remineralization via NACP and NACP-TTCP composites after 4 and 8 weeks of treatment. At 8 weeks, NACP nanocomposite achieved dentin lesion remineralization (mean±SD; n=15) of (48.2±11.0)%, much higher than (5.0±7.2)% for dentin in commercial composite group after the same cyclic demineralization/remineralization regimen (p0.05).Novel NACP-based nanocomposites were demonstrated to achieve dentin lesion remineralization for the first time. These results, coupled with acid-neutralization and good mechanical properties shown previously, indicate that the NACP-based nanocomposites are promising for restorations to inhibit caries and protect tooth structures.

Objective The aim of the present study was to select the optimal concentration of TiF 4 solution to facilitate the remineralization of early dentine caries lesions. Design Sixty human dentine specimens were cut and randomly divided into 6 groups (1%, 2%, 3%, 4% TiF 4 groups, 2.712% NaF group and distilled deionized water (DDW) control group). Artificial dentine caries-like lesions were created. After being subjected to fluoride treatment and immersed in remineralizing solution for 2 weeks, the specimens were observed by microCT, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Data were analysed using linear regression analysis ( P Results The lesion depths of the specimens treated by 2% TiF 4 solution were statistically less than those of the other groups. Further, the greyscale values of these lesion areas were greater. The 3% and 4% TiF 4 solutions caused further lesion demineralization. The 2.712% NaF solution seemed to be detrimental to remineralization during the experimental time, as the subsurface area remained hypomineralized with a thick precipitation layer on the surface. Conclusions The 2% TiF 4 solution demonstrated better remineralizing potency than did the other treatments.

Fluoride-induced ameloblast apoptosis is a key event in dental fluorosis development. Forkhead box o1 (Foxo1) is a transcription factor involved in cell apoptosis. The present study aims to investigate the effect of Foxo1 on ameloblast apoptosis induced by fluoride in vitro and to explore its possible mechanism. Ameloblast-like cells (LS8 cells) were exposed to various concentrations of NaF for up to 48 h. Foxo1 activation was modulated using lentiviral vectors, and cell apoptosis was measured by flow cytometry. The expression levels of Foxo1, c-Jun N-terminal kinase (JNK), and some well-known regulators of the mitochondrial pathway of apoptosis (cytoplasmic cytochrome c, cleaved caspase-9, cleaved caspase-3, Bcl-2, and Bax) were detected by quantitative real-time PCR, western blot, and immunofluorescence assay. The results showed significantly decreased expression and increased phosphorylation of Foxo1 in NaF-treated LS8 cells. Further investigation revealed that forced Foxo1 activation with lentiviral vectors attenuated NaF-induced apoptosis of LS8 cells, markedly decreasing protein levels of cytoplasmic cytochrome c, cleaved caspase-9, and cleaved caspase-3 while increasing the Bcl-2/Bax ratio and JNK expression level. These findings suggest that Foxo1 attenuated NaF-induced apoptosis of LS8 cells via inhibiting the mitochondrial pathway and activating JNK.

Repair of craniofacial bony defects remains a challenge for surgeons due to the delicate and complex anatomy of the craniofacial skeleton. Stromal cell-derived factor-1α (SDF-1α) is an important chemokine which plays a critical role in the homing of mesenchymal stem cells (MSC), while, the shortcomings including short half-life and easy degradation by enzymes made it in relatively low efficacy. In this work, SDF-1α/chitosan/carboxymeymethy-chitosan nanoparticles (SDF-1α/CS/CMCS NPs) were prepared and characterized for various parameters including morphology, particle size, zeta potential, loading efficiency and the release characteristics from thermosensitive chitosan/β-glycerol phosphate disodium salt (CS/GP) hydrogels. The SDF-1α encapsulated in CS/CMCS NPs within CS/GP hydrogels showed significantly sustained release effect. The cumulative release of SDF-1α was only 40% during 28d. The data from rat calvarial defects model revealed that the SDF-1α/CS/CMCS NPs embedded hydrogels group could significantly promote the new bone formation (38.5±4.5%), compared to that of the SDF-1α embedded hydrogels group (26.3±7.25%, p

Que K, Ruan J, Fan X, Liang X, Hu D. A multi-centre and cross-sectional study of dentine hypersensitivity in China. J Clin Periodontol 2010; 37: 631–637. doi: 10.1111/j.1600-051X.2009.01513.x. Abstract Aim: The objective of this study was to establish the prevalence of dentine hypersensitivity (DH) in Chinese urban adults and the possible effects of smoking on DH. Materials and Methods: A total of 2640 subjects were distributed equally in 12 communities in Chengdu and Xian City, respectively, and of all age groups (10 years for an age group) including the same number of male and female subjects in each community. Each subject completed a structured interview and the subjects who reported hypersensitivity symptoms were examined with cold air from a dental triple syringe in order to confirm the diagnosis of DH. Attachment loss and gingival recession of sensitive teeth were measured by a Williams periodontal probe. Results: The diagnosis of DH established following a clinical assessment yielded an overall prevalence of 25.5%. The 50–59-year-old age group had the greatest number of subjects with DH (p 0.05). Conclusions: The prevalence of DH in a selected community population was 25.5%.

The objective of this study was to establish the prevalence of dentine hypersensitivity (DH) in Chinese urban adults and the possible effects of smoking on DH.A total of 2640 subjects were distributed equally in 12 communities in Chengdu and Xian City, respectively, and of all age groups (10 years for an age group) including the same number of male and female subjects in each community. Each subject completed a structured interview and the subjects who reported hypersensitivity symptoms were examined with cold air from a dental triple syringe in order to confirm the diagnosis of DH. Attachment loss and gingival recession of sensitive teeth were measured by a Williams periodontal probe.The diagnosis of DH established following a clinical assessment yielded an overall prevalence of 25.5%. The 50-59-year-old age group had the greatest number of subjects with DH (p0.05). 78.6% and 31.4% of sensitive teeth were associated with attachment loss and gingival loss, respectively. Subjects who smoked did not have more sensitive teeth on average than subjects who did not smoke (p0.05).The prevalence of DH in a selected community population was 25.5%.

Background The current oral health status and possible dental risk factors among children in rural Shaanxi Province, western China are unreported. This study aimed to describe the oral health status and to analyze the possible risk factors for the oral health status in this population. Methods A multi-stage cluster sampling method was used to survey 12- to 15-year-olds and 4- to 6-year-olds in villages in Shaanxi Province. The structured questionnaires were provided to the 12- to 15-year-olds and to the caregivers of the 4- to 6-year-olds to collect information on the subjects’ oral health knowledge, attitudes and behavior. A clinical examination was performed to assess dental caries and gingival bleeding (only 12- to 15-year-olds). SPSS 17.0 statistical software was used to analyze the data. Results The decayed, missing, filled teeth (DMFT) index scores of 12- to 15-year-olds and 4-to 6-year-olds averaged 0.45 and 3.05, respectively. The caries prevalence was 23.9% in 12- to 15-year-olds and 67% in 4-to 6-year-olds. Additionally, 45.2% of the 12- to 15-year-olds had gingival bleeding and 62.8% had calculus. The oral health knowledge of the subjects was generally poor, whereas they held very positive attitudes toward oral health. A low number of participants reported that they brushed their teeth at least twice daily. Moreover, a statistically significant relationship was found between oral health knowledge scores, tooth brushing frequency and DMFT scores as well as gingival bleeding in the 12- to 15-year-olds. Frequency of sweets consumption was strongly related to dmft scores in the 4- to 6-year-olds. Conclusion The oral health status, oral health knowledge and behaviors among village children in Shaanxi Province are poor. Oral health education to improve oral health knowledge and to increase the frequency of tooth brushing should be undertaken in the rural schools in western China.