[Analysis on results of occupational health examination in 677 workers exposed to inorganic fluorine].

Objective: To analyze the health hazards of fluorine and its inorganic compounds to workers exposed to fluorine, and to provide technical support for the protection of workers exposed to fluorine and the revision of occupational disease diagnostic standards. Methods: In January 2019, 677 workers exposed to fluorine in a fluorine chemical company in Hunan Province were selected by cluster sampling, and occupational health examination was conducted. The suspected occupational poisoning workers were diagnosed as occupational diseases, which were divided into poisoning group and non-poisoning group. T test and Pearson χ(2) test were used for statistical analysis. Results: A total of 73 occupational chronic fluorosis patients were diagnosed. 93.15% (68/73) of the skeletal lesions were multiple, and the most frequent sites were the upper tibia and fibula. 35.00% (21/60) , 50.00% (18/36) and 58.82% (10/17) of the tibia, fibula, ulna and radius had periosteal changes only on one side. Other abnormal results were mainly dental calculus (60.71%, 411/677) , fatty liver (48.89%, 331/677) , abnormal electrocardiogram (44.17%, 299/677) , decreased bone mass (33.53%, 227/677) and increased ALT (13.15%, 89/677) . Compared with non-poisoning group, the age, length of service exposed to fluoride and fatty liver detection rate of poisoning group were higher, and the differences were statistically significant (P<0.01) . Conclusion: The changes of long bone caused by inorganic fluoride only occur in one side, so the basic location of occupational health examination should include bilateral long bone to avoid missed diagnosis. It is difficult to diagnose occupational poisoning with single slight periosteal ossification, it is suggested that the standard should be revised to specify the degree.

Proteomic profile of root canal contents in teeth with post-treatment endodontic disease.

AIM: To characterize the proteome of 20 root canals in teeth with post-treatment endodontic disease using mass spectrometry and to correlate the identified proteins with clinical features. METHODOLOGY: Twenty patients with radiographic evidence of apical periodontitis and need for root canal re-treatment were selected. Samples from the root canal contents were collected and processed using two-dimensional capillary nano-flow liquid chromatography and electrospray ionization tandem mass spectrometry. The acquired spectra were separately searched against specific protein database. The results obtained were analysed using descriptive statistics. Additionally, Pearson's chi-square test or one-sided Fisher's exact test, as appropriate, was chosen to examine the null hypothesis that there is no relationship between each clinical feature and the presence of specific microbial or human proteins. Significance levels were set at 5% (P < 0.05). RESULTS: A total of 1153 human and 720 microbial UniProt accession numbers corresponding to proteins were recovered. The greater prevalence of proteins was related to biological functions, such as cellular and metabolic processes. A considerable number of microbial proteins with clinical relevance functions, such as pathogenesis/virulence, proteolysis, cell adhesion and drug resistance, were detected. Common endodontic pathogens related to post-treatment endodontic disease such as Enterococcus spp., Propionibacterium spp. and Streptococcus spp. were associated with 23, 40 and 94 distinct proteins, respectively. As for human proteins, many factors related to the immune system process were detected. No significant correlations were found between microbial and human proteins and the clinical features investigated (P > 0.05). CONCLUSIONS: A considerable number of microbial and human proteins were identified using proteomic analyses, being mainly related to processes indicating cell viability. No significant correlation was found between proteins and clinical features. These findings suggest a network of important microbial pathogenic functions that may be responsible for the host immune system response.

The effects of 2-hydroxyethyl methacrylate on matrix metalloproteinases 2 and 9 in human pulp cells and odontoblast-like cells in vitro.

AIM: To assess the effects of 2-hydroxyethyl methacrylate (HEMA) on proliferation and migration of human pulp cells, as well as on matrix metalloproteinase (MMP-2 and MMP-9) expression in human odontoblast-like cells, contributing to the goal of determining the relationship between resin materials and MMP activity in pulp-dentine complexes. METHODOLOGY: Dental pulp cell cultures were established from pulp tissue of human teeth extracted for orthodontic purposes. Pulp cell differentiation was characterized in the presence of dentine sialophosphoprotein, bone sialoprotein and alkaline phosphatase by reverse transcription polymerase chain reaction. MMP activity was assessed by gelatine zymography with media containing HEMA. Cell viability was evaluated using methyl thiazolyl tetrazolium assay for 24-72 h. Cell migration was tested using Transwell migration assay. Western blotting was used to visualize MMP expression with the nontoxic HEMA concentrations (0-400 µg mL-1 ) for 48 h. RESULTS: Pulp cell proliferation decreased with HEMA exposure in a time- and concentration-dependent manner. HEMA concentrations ≤400 µg mL-1 did not induce changes in cell viability at 48 h (P < 0.05). Pulp cells were induced to differentiate into odontoblast-like cells in media containing 5 mg mL-1 ascorbic acid and 10 mmol L-1 ß-sodium glycerophosphate for 3-4 weeks. After incubation with HEMA, dose-dependent inhibition was observed; HEMA had a strong inhibitory effect on MMP activity. Compared with the control group, cell migration and MMP expression were inhibited significantly with increasing HEMA concentration at noncytotoxic doses (P < 0.05). CONCLUSIONS: Cell viability was not affected at HEMA concentrations ≤400 µg mL-1 . Within this range, HEMA inhibited MMP-2 and MMP-9 expression and activity, which may protect against type I collagen degradation effectively during dentine adhesive procedures.

Identification of the CAD gene from Eucalyptus urophylla GLU4 and its functional analysis in transgenic tobacco.

Cinnamyl alcohol dehydrogenase (CAD) catalyzes the final step in lignin biosynthesis. The genus Eucalyptus belongs to the family Myrtaceae, which is the main cultivated species in China. Eucalyptus urophylla GLU4 (GLU4) is widely grown in Guangxi. It is preferred for pulping because of its excellent cellulose content and fiber length. Based on GLU4 and CAD gene expression, a Eucalyptus variety low in lignin content should be obtained using transgenic technology, which could reduce the cost of pulp and improve the pulping rate, and have favorable prospects for application. However, the role and function of CAD in GLU4 is still unclear. In the present study, EuCAD was cloned from GLU4 and identified using bioinformatic tools. Subsequently, in order to evaluate its impact on lignin synthesis, a full-length EuCAD RNAi vector was constructed, and transgenic tobacco was obtained via Agrobacterium-mediated transformation. A significant decrease in CAD expression and lignin content in transgenic tobacco demonstrated a key role for EuCAD in lignin biosynthesis and established a regulatory role for RNAi. In our study, the direct molecular basis of EuCAD expression was determined, and the potential regulatory effects of this RNAi vector on lignin biosynthesis in E. urophylla GLU4 were demonstrated. Our results provide a theoretical basis for the study of lignin biosynthesis in Eucalyptus.

[Children's intelligence quotient following general anesthesia for dental care: a clinical observation by Chinese Wechsler young children scale of intelligence].

OBJECTIVE: It has been demonstrated that anesthetics exposure may lead to neurocognitive impairment in developing brain of animal models. However, for the limitation that the animal models cannot fully mimic the dose and duration in clinical settings especially for dental general anesthesia, the clinical significance of anesthetics exposure on developing central nervous system remains undetermined. Therefore, we conducted the current study in order to observe the fluctuation of intelligence quotient (IQ) after the administration of dental general anesthesia comparing to that before surgery. We conducted the current study in order to observe the fluctuation of intelligence quotient (IQ) after the administration of dental general anesthesia compared with that before surgery. METHODS: Thirty two patients, ASA I, who were exposed to dental general anesthesia in Department of Pediatric Dentistry Peking University School and Hospital of Stomatology, aged 4 to 6.5 years, were enrolled in this prospective study. Patients with severe learning difficulties or communication disorders were excluded. Written and informed consent was obtained from each patients' family which was fully explained of the purpose and method of study. Their intelligence quotients were evaluated with the Chinese Wechsler young children scale of intelligence (Urban version) before and 2 weeks after dental anesthesia. They were treated by experienced pediatric dentists and the sevoflurane, propofol and nitrous oxide were used for general anesthesia by anesthetist. Articaine hydrochloride and epinephrine tartrate injections were used for their pulp treatment or extraction. The examiners and scorers for IQ had technical training in the test administration. All the patients were tested by the same examiner and with standardized guide language. Each subtest was scored according to the tool review. Verbal IQ and performance IQ consisted of relevant 5 subtests and full scale IQ. Statistical analyses were performed by SPSS 18.0. All the scores of subtests and 3 types of IQ were expressed as mean±standard deviation. Paired two-tailed t test was applied and P<0.05 was accepted as statistically significant. RESULTS: The results of intelligent assessment from 28 subjects were collected. The anesthetic time was (163.4±32.6) min and the number of treated teeth was 12.1±2.3, mean age (4.60±0.41) years; age range=4.04 to 5.44 years. Among the patients, there were 13 girls and 15 boys. There was no significant difference in gender distribution. The postoperative full IQ (128.46±10.85) was higher than that before surgery (124.64±11.46, P= 0.017). We found that the elevation of performance IQ, to a large extent, contributed to this change in full IQ (P= 0.007). Correspondingly, there was no statistical difference in the verbal IQ, which was 119.68±11.74 to 120.21±15.61 (P=0.854). CONCLUSION: Dental general anesthesia has no negative effect on the intelligence of preschool children, who were treated under general anesthesia by sevoflurane, propofol and nitrous oxide for 2 to 4 hours. The full IQ and performance IQ were slightly enhanced after treatment which can be explained by the memory effect.

Multiple tooth loss is associated with vascular cognitive impairment in subjects with acute ischemic stroke.

BACKGROUND AND OBJECTIVE: Emerging evidence shows that tooth loss is associated with cognitive impairment and dementia. Vascular cognitive impairment (VCI) is a common consequence of ischemic stroke. This study investigated the association of tooth loss with VCI in patients with acute stroke. MATERIAL AND METHODS: A total of 161 subjects with acute ischemic stroke were recruited. Within 1 wk after admission, fasting blood tests were undertaken and the number of teeth present was recorded. VCI was evaluated with the Montreal Cognitive Assessment (MoCA). RESULTS: The patients with loss of ≥ 8 teeth exhibited significantly lower MoCA values as compared to those with loss of ≤ 7 teeth (13.2 ± 6.6 vs. 17.3 ± 6.0, p < 0.001). Multivariate logistic regression analysis showed that loss of ≥ 8 teeth (OR = 3.1, 95% CI: 1.2-7.9, p = 0.02) and stroke history (OR = 3.8, 95% CI: 1.1-14.1, p = 0.04) were significantly associated with VCI (MoCA score ≤ 20.0). CONCLUSION: Within the limitations of this study, the current findings provide the first evidence that multiple tooth loss is independently associated with VCI in patients with acute ischemic stroke.

Effect of dialyzed saliva on human enamel demineralization.

BACKGROUND: Saliva is supersaturated with respect to calcium and phosphate ions. Salivary ions may well play a role in the subsequent adsorption of proteins and consequently in the formation of the acquired enamel pellicle. Among several biological functions, the enamel pellicle forms a selectively permeable barrier that regulates demineralization processes. AIM: The aim of this study was to evaluate the importance of salivary proteins when adsorbed on enamel surface and the resultant protective effect against demineralization without the presence of salivary ions. METHODS: Enamel surfaces were coated with whole saliva, parotid saliva, dialyzed whole saliva or dialyzed parotid saliva (molecular weight cutoff 1 kDa). Adsorption was allowed to proceed for a period of 2 h. Enamel specimens were then washed with deionized water and immersed into a demineralization solution of pH 4.5 for 12 days. This solution was used to measure the amount of calcium and phosphate released from enamel specimens after the demineralization period. RESULTS: All coated specimen groups showed a significantly higher protection than those not coated with any type of saliva. In addition, undialyzed saliva (whole saliva and parotid saliva) was more effective in protecting the enamel against demineralization than dialyzed saliva. CONCLUSION: The present investigation indicates that the ionic composition of saliva can amplify the demineralization protection effect by reducing acid-induced enamel demineralization. Moreover, a protective effect of salivary proteins without presence of ions was demonstrated in this study.

Dual delivery for stem cell differentiation using dexamethasone and bFGF in/on polymeric microspheres as a cell carrier for nucleus pulposus regeneration.

This study aimed to investigate the feasibility of the nanostructured 3D poly(lactide-co-glycolide) (PLGA) constructs, which are loaded with dexamethasone (DEX) and growth factor embedded heparin/poly(L-lysine) nanoparticles via a layer-by-layer system, to serve as an effective scaffold for nucleus pulposus (NP) tissue engineering. Our results demonstrated that the microsphere constructs were capable of simultaneously releasing basic fibroblast growth factor and DEX with approximately zero order kinetics. The dual bead microspheres showed no cytotoxicity, and promoted the proliferation of the rat mesenchymal stem cells (rMSCs) by lactate dehydrogenase assay and CCK-8 assay. After 4 weeks of cultivation in vitro, the rMSCs-scaffold hybrids contained significantly higher levels of sulfated GAG/DNA and collagen type II than the control samples. Moreover, quantitative real time PCR analysis revealed that the expression of disc-matrix proteins including collagen type II, aggrecan, and versican in the rMSCs-scaffold hybrids was significantly higher than that in the control group, whereas the expression of osteogenic differentiation marker (collagen type I) was decreased. Taken together, these data indicate that Dex/bFGF PLGA microspheres could be used as a scaffold to improve the rMSCs growth and differentiating into NP like cells, and reduce the inflammatory response for IVD tissue engineering.

The long-term effect of dental treatment under general anaesthesia or physical restraints on children's dental anxiety and behaviour.

AIM: Dental anxiety (DA) is a common problem worldwide because it renders dental treatment in children challenging. This study aimed to evaluate the long-term effect of dental treatment under general anaesthesia (GA) or physical restraints (PR) on children's DA and behaviour. METHODS: A total of 103 children were recruited and divided into four groups: the GA group, PR group, cooperative (CO) group, and no experience (NE) group. The face version of the Modified Child Dental Anxiety Scale and modified Venham's Clinical Anxiety and Cooperative Behaviour Rating Scale were used to evaluate the level of DA and behaviour. CONCLUSION: Dental treatment under GA is associated with a higher risk for DA when compared with that under PR in the long term. Increased DA may lead to uncooperative dental behaviour, although the agreement is only moderate.

[Quality of life of patients with locally advanced rectal cancer after neoadjuvant therapy and sphincter-preserving surgery].

Objective: To investigate quality of life (QoL) of patients with locally advanced rectal cancer (LARC) who underwent low anterior resection with protective stoma under neoadjuvant therapy mode, and to explore the changes of QoL of patients from before neoadjuvant therapy to 12 months after stoma reversal. Methods: A descriptive case series study was carried out. A retrospective study was performed on patients with mid and low LARC who received complete neoadjuvant long course radiotherapy and chemotherapy, followed by radical low anterior resection (LAR) combined with protective stoma at Peking Union Medical College Hospital from December 2017 to January 2020. Inclusion criteria: (1) patients with rectal MRI assessment of mT3-4b or mN1-2 without distant metastasis (M0) before neoadjuvant therapy; (2) distance from tumor lower margin to the anal verge <12 cm; (3) rectal adenocarcinoma confirmed by biopsy before neoadjuvant therapy; (4) complete cycle of neoadjuvant therapy; (5) patients undergoing radical LAR with sphincter preservation and protective ostomy; (6) patients receiving follow-up for more than 12 months after stoma reversal. Exclusion criteria: (1) patients as grade Ⅳ to Ⅴclassified by the American Society of Anesthesiologists (ASA); (2) patients with multiple primary colorectal cancer; (3) patients with history of other malignant tumors in the past 5 years; (4) patients of emergency surgery; (5) pregnant or lactating women; (6) patients with history of severe mental illness; (7) patients with contraindication of MRI, radiotherapy, chemotherapy, or surgical treatment. A total of 83 patients were enrolled, including 51 males and 28 females with median age of 59 years and mean BMI of (24.4±3.1) kg/m(2). EORTC QLQ-CR29, international erectile function index (IIEF), Wexner constipation score and low anterior resection syndrome (LARS) score were applied to investigate the QoL of the patients before neoadjuvant therapy, 3 and 12 months after ostomy reversal, including rectal anal function and sexual function. M (P25, P75) was used for the scores of the scale. Results: (1) EORTC QLQ-CR29 score showed that before neoadjuvant therapy, before surgery, 3 months and 12 months after ostomy reversal, anxiety [64.4 (52, 0, 82.5), 75.3 (66.0, 89.5), 82.6 (78.5, 90.0), 83.6 (78.0, 91.0)] and concern about body image [76.8 (66.0, 92.0), 81.1 (76.5, 91.5), 85.5 (82.5, 94.0), 86.1 (82.0, 92.0)] were improved (all P<0.01); pelvic pain [5.4 (2.0, 8.0), 5, 0 (2.0, 7.8), 3.9 (1.0, 5.0), 3.0 (1.0, 5.0)], urinary incontinence [15.7 (7.0, 22.0), 11.1 (0, 17.5), 10.0 (0, 17.0), 9.9 (0, 16.0)], impotence [14.3 (4.2, 19.0), 12.2 (0, 16.8), 5.6 (0, 10.0), 5.2 (0.2, 8.0)], urinate [26.4 (13.0, 38.5), 13.9 (0, 20.0), 13.4 (2.5, 21.5), 13.2 (2.0, 20.0)] and mucous bloody stool [4.7 (3.0, 6.0), 2.6 (0, 5.0), 2.2 (0, 5.0), 1.9 (0, 4.0)] were improved as well (all P<0.01). The scores fluctuated in the improvement of male sexual function, abdominal pain, dry mouth, worry about body mass change, skin pain and dyspareunia, but the symptoms were significantly improved after ostomy reversal compared with before neoadjuvant therapy (all P<0.05). There were no significant changes in female sexual function, dysuria, dysgeusia and fecal incontinence after ostomy reversal compared with before neoadjuvant therapy (all P>0.05). (2) IIEF scale showed that all scores were similar before and after neoadjuvant therapy (all P>0.05). (3) Rectal and anal function scale revealed that before neoadjuvant therapy, before operation, 3 months and 12 months after stoma reversal, gas incontinence [3.1 (0, 4.0), 2.3 (0, 4.0), 1.8 (0, 4.0), 1.2 (0, 3.0)] and urgent defecation [7.2 (0, 11.0), 5.2 (0, 11.0), 2.9 (0, 9.0), 1.7 (0, 0)] were improved (all P<0.001). In terms of improving incomplete emptying sensation, the symptoms fluctuated, but the symptoms improved significantly after ostomy reversal compared with before neoadjuvant therapy (all P<0.05). While the symptoms of assistance with defecation [0 (0, 0), 0.7 (0, 1.0), 0.6 (0, 1.0), 0.7 (0, 1.0)] and defecation failure [0.2 (0, 0), 1.0 (0, 2.0), 0.8 (0, 1.5), 0.8 (0, 1.0)] showed a worsening trend (all P<0.001). Stratified analysis was performed on patients with different efficacy of neoadjuvant therapy to compare the changes in QoL before and after neoadjuvant therapy. Patients with less sensitive and more sensitive neoadjuvant therapy showed similar changes in function and symptoms. Patients with less sensitive therapy showed significant improvement in dysuria, urinary incontinence, skin pain and dyspareunia (all P<0.05), and the symptom of defecation frequency in more sensitive patients was significantly improved (P<0.05). Conclusions: For patients with LARC, neoadjuvant radiochemotherapy combined with radical LAR and protective stoma can improve QoL in many aspects. It is noted that patients show a worsening trend in the need for assistance with defecation and in defecation failure.

Porphyromonas gingivalis lipopolysaccharide alters atherosclerotic-related gene expression in oxidized low-density-lipoprotein-induced macrophages and foam cells.

BACKGROUND AND OBJECTIVE: The molecular mechanism linking atherosclerosis formation and periodontal pathogens is not clear, although a positive correlation between periodontal infections and cardiovascular diseases has been reported. The aim of this study was to determine whether stimulation with Porphyromonas gingivalis lipopolysaccharide (LPS) affected the expression of atherosclerosis-related genes, during and after the formation of foam cells. MATERIAL AND METHODS: Macrophages from human THP-1 monocytes were treated with oxidized low-density lipoprotein (oxLDL) to induce the formation of foam cells. P. gingivalis LPS was added to cultures of either oxLDL-induced macrophages or foam cells. The expression of atherosclerosis-related genes was assayed by quantitative real-time PCR, and the production of granulocyte-macrophage colony-stimulating factor, monocyte chemotactic protein-1, interleukin (IL)-1ß, IL-10 and IL-12 proteins was determined using ELISA. Nuclear translocation of nuclear factor-kappaB (NF-κB) P(65) was detected by immunocytochemistry, and western blotting was used to evaluate inhibitory kappa B-α (IκΒ-α) degradation to confirm activation of the NF-κB pathway. RESULTS: P. gingivalis LPS stimulated atherosclerosis-related gene expression in foam cells and increased the oxLDL-induced expression of chemokines, adhesion molecules, growth factors, apoptotic genes and nuclear receptors in macrophages. Transcription of the proinflammatory cytokines IL1ß and IL12 was elevated in response to LPS in both macrophages and foam cells, whereas transcription of the anti-inflammatory cytokine, IL10, was not affected. Increased activation of the NF-κB pathway was also observed in macrophages costimulated with LPS + oxLDL. CONCLUSION: P. gingivalis LPS appears to be an important factor in the development of atherosclerosis by stimulation of atherosclerosis-related gene expression in both macrophages and foam cells via activation of the NF-κB pathway.

The effect of loading icariin on biocompatibility and bioactivity of porous ß-TCP ceramic.

In order to enhance the ability of calcium phosphate-based biomaterials for bone defect repair, icariin (Ica), one natural product with ability of promoting osteoblasts differentiation in vitro and enhancing bone formation in vivo, was loaded into porous ß-tricalcium phosphate ceramic (ß-TCP) disks. The obtained Ica-loaded porous ß-TCP ceramic (Ica/ß-TCP) disks were characterized by SEM. The SEM photos indicated that the disks had porous structure and the surface morphology of the porous ß-TCP ceramic (ß-PTCP) disks had no obvious difference from the Ica/ß-TCP disks. The Ica release curve of Ica/ß-TCP disks showed a burst release during the first 1 day and the concentration of released Ica during the first 3 days had low cytotoxicity. The loading Ica in Ica/ß-TCP disks hardly affected the attachment and morphology of Ros17/28 cells, however, the Ica/ß-TCP disks were favorable to supporting the proliferation and differentiation of Ros17/28 cells better compared with the ß-PTCP disks. There was plenty of bone-like apatite formed on the surface of Ica/ß-TCP disks soaked in SBF solution for three days. After back intramuscular implantation of rats for three months, no obvious osteogenic evidence was detected in ß-PTCP disks, but new bone formation was observed in Ica/ß-TCP disks. Fibrous tissues and slight inflammatory reaction was also found in the Ica/ß-TCP disks and ß-TCP disks. Therefore, the loading Ica did not change the biocompatibility of ß-TCP ceramic, but enhanced the bioactivity of ß-TCP ceramic in vivo. The Ica/ß-TCP ceramic had potential to be used for bone defect repair.

The bonding property and cytotoxicity of a dental adhesive incorporating a new antibacterial monomer.

The incorporation of polymerisable cationic monomers has been attempted to generate dental resinous materials with antibacterial activity. This study tested whether the incorporation of a cationic monomer, methacryloxylethyl cetyl dimethyl ammonium chloride (DMAE-CB), into a commercial dental adhesive would influence the bonding property and biocompatibility of the parental adhesive, and whether DMAE-CB could leach out from the cured modified adhesive. Microtensile bond strengths of DMAE-CB-incorporated adhesive and its parental adhesive to dentin were compared. Dentin discs bonded with modified adhesive were incubated in artificial saliva at three different temperatures for 90 days to obtain eluents. The cytotoxicity of DMAE-CB monomer and adhesive eluents were tested with 3-(4, 5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cleavage assay (MTT assay). High-performance liquid chromatography (HPLC) was performed with the eluents of the modified adhesive. The results indicated that the incorporation of DMAE-CB into the dental adhesive did not adversely influence its bonding strength to dentin (P > 0·05). Although DMAE-CB monomer exhibited toxicity against L929 cells at the concentration of 2 µg mL(-1) or higher (P < 0·05), the eluents of DMAE-CB-incorporated adhesive did not show significant influence on cell growth (P > 0·05). Moreover, HPLC analysis detected four substances' peak baseline separation for the eluents of modified adhesives, which was identical to the eluent of the parental adhesive, indicating no detectable DMAE-CB monomer leaching even after soaking for 90 days. Those results suggest that DMAE-CB could be incorporated into the dental adhesive stably without compromising the bonding efficiency and biocompatibility of its parental adhesive.

Zeb1 Promotes Odontoblast Differentiation in a Stage-Dependent Manner.

A comprehensive study of odontoblastic differentiation is essential to understand the process of tooth development and to achieve the ability of tooth regeneration in the future. Zinc finger E-box-binding homeobox 1 (Zeb1) is a transcription factor expressed in various neural crest-derived tissues, including the mesenchyme of the tooth germ. However, its role in odontoblastic differentiation remains unknown. In this study, we found the expression of Zeb1 gradually increased during odontoblast differentiation in vivo, as well as during induced differentiation of cultured primary murine dental papilla cells (mDPCs) in vitro. In addition, the differentiation of mDPCs was repressed in Zeb1-silenced cells. We used RNA sequencing (RNA-seq) to identify the transcriptome-wide targets of Zeb1 and used assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) to explore the direct targets of Zeb1 in both the early stage (embryonic day 16.5; E16.5) and the late stage (postnatal day 0; PN0) of tooth development. We identified the motifs of transcription factors enriched in Zeb1-dependent accessible chromatin regions and observed that only in the early stage of mDPCs could Zeb1 significantly change the accessibility of chromatin regions. In vivo and in vitro experiments confirmed that silencing of Zeb1 at E16.5 inhibited dentinogenesis. Analysis of RNA-seq and ATAC-seq resulted in the identification of Runx2, a gene directly regulated by Zeb1 during early odontoblast differentiation. Zeb1 enhances the expression of Runx2 by binding to its cis-elements, and ZEB1 interacts with RUNX2. In the late stage of tooth development, we found that ZEB1 could directly bind to and increase the enhancer activity of an element upstream of Dspp and promote dentinogenesis. In this study, for the first time, we revealed that ZEB1 promoted odontoblast differentiation in the early stage by altering chromatin accessibility of cis-elements near genes such as Runx2, while in the late stage, it directly enhanced Dspp transcription, thereby performing a dual role.

The antibacterial effect and physical performance of pit and fissure sealants based on an antibacterial core-shell nanocomposite.

The application of pit and fissure sealants is a well-established method to prevent and treat early childhood caries. Resin-based sealants with antibacterial properties provide additional benefits for caries prevention in a cariogenic oral environment. The objective of this study was to evaluate the effect of an antibacterial core-shell AgBr/cationic polymer nanocomposite (AgBr/BHPVP) on the properties of a resin-based pit and fissure sealant. A commercialized pit and fissure sealant without fluoride, Concise (3M, ESPE, USA), was used as the parent material and negative control. Experimental antibacterial sealants were formulated by the addition of AgBr/BHPVP nanoparticles at mass fractions of 0.5, 1.0, and 1.5 wt% to the parent material. A fluoride-releasing sealant, Clinpro (3M, ESPE), was used as the positive control. Bacterial colony-forming unit (CFU) counts, metabolic activity tests, field emission-scanning electron microscopy (FE-SEM), and confocal laser scanning microscopy (CLSM) observations were used to evaluate the antibacterial properties of AgBr/BHPVP-modified sealants against Streptococcus mutans before and after five months of aging. The Vickers microhardness, degree of conversion, and microleakage level of the sealants were also investigated. According to the results of CFU counts and metabolic tests, sealants containing AgBr/BHPVP showed better contact-killing bactericidal activity against S. mutans than the two commercial sealants, irrespective of aging conditions (both P < 0.05). The AgBr/BHPVP-modified sealants also showed a significant inhibitory effect on the planktonic S. mutans around the cured sealant surfaces. In addition, the Vickers microhardness, degree of conversion, and microleakage level of the parent material were not damaged by modification with AgBr/BHPVP (P > 0.05). AgBr/BHPVP-modified pit and fissure sealant with a dual bactericidal mechanism is a promising option for the prevention of pit and fissure caries.

A novel dentin bonding scheme based on extrafibrillar demineralization combined with covalent adhesion using a dry-bonding technique.

Dentin bonding is a dynamic process that involves the penetration of adhesive resin monomers into the extrafibrillar and intrafibrillar demineralized collagen matrix using a wet-bonding technique. However, adhesive resin monomers lack the capacity to infiltrate the intrafibrillar space, and the excess water that is introduced by the wet-bonding technique remains at the bonding interface. This imperfectly bonded interface is inclined to hydrolytic degradation, severely jeopardizing the longevity of bonded clinical restorations. The present study introduces a dentin bonding scheme based on a dry-bonding technique, combined with the use of extrafibrillar demineralization and a collagen-reactive monomer (CRM)-based adhesive (CBA). Selective extrafibrillar demineralization was achieved using 1-wt% high-molecular weight (MW) carboxymethyl chitosan (CMCS) within a clinically acceptable timeframe to create a less aggressive bonding substance for dentin bonding due to its selectively extrafibrillar demineralization capacity. CMCS demineralization decreased the activation of in situ collagenase, improved the shrinking resistance of demineralized collagen, and thus provided stronger and more durable bonding than traditional phosphoric acid etching. The new dentin bonding scheme that contained CMCS and CBA and used a dry-bonding technique achieved an encouraging dentin bonding strength and durability with low technical sensitivity. This bonding scheme can be used to improve the stability of the resin-dentin interface and foster the longevity of bonded clinical restorations.

[Establishment of animal model of bacterial microleakage at implant-abutment interface].

Objective: To study the bacterial microleakage at the interface between dental implant and abutment in rats. Methods: Under aseptic conditions, suspension of 0.25 µl of Porphyromonas gingivalis (Pg) (10(9) CFU/ml) was added into the customized implant. After the abutment was connected, the suspension was cultured in an Ep (eppendorf) tube containing 1 ml brain heart infusion (BHI) culture medium. After 7 days and 14 days, the liquid in the Ep tube was taken and inoculated, and the growth of bacteria was observed. Six male SD rats with 12 implants were divided into experimental group (4 implants), negative control group (4 implants) and blank control group (4 implants). All 6 rats had two implants implanted in their bilateral upper jaws. During the second operation, suspension of 0.25 µl Pg (10(9) CFU/ml) was added to the inner part of the implant of the experimental group, culture solution of 0.25 µl was added to the control group and nothing was added to the blank control group. The amount of Pg and total bacteria in each group were evaluated by quantitative real-time PCR (qPCR). The inflammatory cell infiltrate in the peri-implant mucosa was evaluated histomorphometrically. Results: The in vitro model directly verified the presence of bacterial microleakage at implant-abutment interface (IAI), and the animal model confirmed the existence of microleakage through the infiltrate of inflammatory cells near the micro-gap in the experimental group indirectly. In vitro experiments found that Pg had penetrated from the implant within a week by observation and culture. In animal study, the presence of 10(2)-10(4) Pg was detected in the experimental group and it was not detected in the negative control group and the blank control group. At the same time, under the light microscope, in the experimental group, there were inflammatory cells aggregation in the connective tissue around the micro-gap and the density of inflammatory cells gradually decreased from the micro-gap to coronal and the apical of the connective tissue, while there were only scattered inflammatory cells in the connective tissue around the blank control group and the negative control group. In the experimental group, inflammatory cells density in area of 0.25-0.50 mm, 0-0.25 mm coronal to the micro-gap and 0-0.25 mm, 0.25-0.50 mm apical to the mico-gap was respectively, 976 (655), 1 673 (1 245), 2 267 (819) and 895 (162) cells/mm(2),which was significantly more than the blank control group in the corresponding position [respectively 201 (180), 321 (351), 309 (236) and 218 (272) cells/mm(2)] (P<0.05). Conclusions: Pg in the dental implants of rats can be found in the microleakage through implant-abutment interface, and cause the soft tissue inflammation around the implant, and the inflammation has certain distribution characteristics.

[Advances in the research of application of dental stem cells in neural tissue engineering].

Dental stem cell is a kind of stem cell isolated from dental hard tissue or periodontal tissue, including dental pulp stem cell, stem cell from human exfoliated deciduous teeth, stem cell from root apical papilla, periodontal ligament stem cell, dental follicle progenitor cell, and so on. As seed cell, dental stem cell provides safe and efficient cell source for nerve tissue engineering research. The review aims to introduce the characteristics of these dental stem cells in promoting the regeneration and preparation of nerve and the clinical application.

A novel trans-lymphatic drug delivery system: implantable gelatin sponge impregnated with PLGA-paclitaxel microspheres.

A translymphatic drug delivery system which incorporates poly-lactide-co-glycolide-paclitaxel (PLGA-PTX) or PLGA-rhodamine microspheres into gelatin sponge matrix is described. The system combines the sustained release properties of PLGA-PTX with the structural advantages of gelatin matrix that can be implanted directly to the lymphatic site for both therapeutic and prophylactic purposes. The PLGA microspheres were prepared using spray drying technique. The particles were in the size range of 1-8 microm, suitable for intraperitoneal and intrapleural lymphatic targeting delivery. Scanning electron microscopy revealed the homogeneous distribution of PLGA microspheres in the porous sponge network. The release of PTX was mainly controlled by the degradation of the PLGA. Crosslinking gelatin using carbodiimide reduced the biodegradation of the sponge and thereby delayed the release of the PLGA in vitro. In vivo lymphatic delivery was assessed in both healthy rats and rats bearing orthotopic lung cancer. Intraperitoneal and intrapleural implantation of the sponge impregnated with PLGA microspheres resulted in spontaneous absorption of the particles in the lymphatic system. It is concluded that the system provides great potential for targeted delivery of therapeutic agent to the lymphatic system especially for the control of lymphatic metastasis in cancer.

Gene expression profiling of cells involved in periodontal regeneration.

Understanding the molecular mechanisms involved in periodontal regeneration is important for the development of more predictable clinical techniques. This study aimed to identify these mechanisms by comparing the gene expression profiles of cells derived from regenerating defects with patient-matched periodontal ligament cells. Gene profiling was carried out via Affymetrix U133A arrays containing probes for 22,000 genes. Robust differences in gene expression were obtained by identifying genes that consistently changed by a minimum of 2-fold. Analysis of molecular function as designated by gene ontology (GO) identified differentially regulated mechanisms including protein metabolism, tyrosine kinase activity, and skeletal development. The differentially expressed genes could be broadly divided into the categories of protein biosynthesis and turnover, structural constituents of the cytoskeleton and extracellular matrix, and signal transduction. The differential expression of 4 genes (EGR-1, elastin, osteoprotegerin, and IGFBP3) was confirmed via real-time polymerase chain reaction (PCR). Further, the expression of another 2 differentially expressed transcripts, decorin and biglycan, was immunohistochemically confirmed in a periodontal wound healing model and the protein expression was consistent with the pattern of gene expression. This study gives insight into the molecular processes involved in periodontal regeneration and identifies cell markers that are characteristic of regenerating periodontal tissues.