Features, Potential Invasion Pathways, and Reproductive Health Risks of Microplastics Detected in Human Uterus.

Microplastics (MPs) are ubiquitous in global ecosystems and may pose a potential risk to human health. However, critical information on MP exposure and risk to female reproductive health is still lacking. In this study, we characterized MPs in human endometrium and investigated their size-dependent entry mode as well as potential reproductive toxicity. Endometrial tissues of 22 female patients were examined, revealing that human endometrium was contaminated with MPs, mainly polyamide (PA), polyurethane (PU), polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), and polyethylene (PE), ranging from 2-200 µm in size. Experiments conducted in mice demonstrated that the invasion of the uterus by MPs was modulated either through diet-blood circulation (micrometer-sized particles) or via the vagina-uterine lacuna mode (larger particles reaching a size of 100 µm. Intravenous exposure to MPs resulted in reduced fertility and abnormal sex ratio in mouse offspring (P < 0.05). After 3.5 months of intragastric exposure, there was a significant inflammatory response in the endometrium (P < 0.05), confirmed by embryo transfer as a uterine factor leading to decreased fertility. Furthermore, human endometrial organoids cultured with MPs in vitro exhibited significantly apoptotic responses and disrupted growth patterns (P < 0.01). These findings raise significant concerns regarding MP contamination in the human uterus and its potential effects on reproductive health.

Antifouling strategies for electrochemical sensing in complex biological media.

Surface fouling poses a significant challenge that restricts the analytical performance of electrochemical sensors in both in vitro and in vivo applications. Biofouling resistance is paramount to guarantee the reliable operation of electrochemical sensors in complex biofluids (e.g., blood, serum, and urine). Seeking efficient strategies for surface fouling and establishing highly sensitive sensing platforms for applications in complex media have received increasing attention in the past. In this review, we provide a comprehensive overview of recent research efforts focused on antifouling electrochemical sensors. Initially, we present a detailed illustration of the concept about biofouling along with an exploration of four key antifouling mechanisms. Subsequently, we delve into the commonly employed antifouling strategies in the fabrication of electrochemical sensors. These encompass physical surface topography (micro/nanostructure coatings and filtration membranes) and chemical surface modifications (PEG and its derivatives, zwitterionic polymers, peptides, proteins, and various other antifouling materials). The progress in antifouling electrochemical sensors is proposed concerning the antifouling mechanisms as well as sensing capability assessments (e.g., sensitivity, stability, and practical application ability). Finally, we summarize the evolving trends in the field and highlight some key remaining limitations.

Research Progress on Dental Age Estimation Based on MRI Technology.

Dental age estimation is a crucial aspect and one of the ways to accomplish forensic age estimation, and imaging technology is an important technique for dental age estimation. In recent years, some studies have preliminarily confirmed the feasibility of magnetic resonance imaging (MRI) in evaluating dental development, providing a new perspective and possibility for the evaluation of dental development, suggesting that MRI is expected to be a safer and more accurate tool for dental age estimation. However, further research is essential to verify its accuracy and feasibility. This article reviews the current state, challenges and limitations of MRI in dental development and age estimation, offering reference for the research of dental age assessment based on MRI technology.

Knife-edged crown fabricated by 3-dimensional gel deposition and soft milling.

STATEMENT OF PROBLEM: Restorations with knife-edge margins are more prone to margin chipping during the manufacturing process. Three-dimensional gel deposition shows potential for fabricating zirconia restorations with good margin quality, but studies on its performance in fabricating knife-edged crowns are lacking. PURPOSE: The purpose of this in vitro study was to compare the 3-dimensional trueness, surface morphology, and margin quality of self-glazed zirconia and soft-milled zirconia crowns with knife-edge margins. MATERIAL AND METHODS: An abutment with a knife-edge finish line design was prepared and scanned with a laboratory scanner. Anatomic contour crowns were designed and fabricated by 3-dimensional gel deposition and soft milling (n=5). The crowns were digitalized, and the scan data were superimposed on the computer-aided design (CAD) data for 3-dimensional deviation analysis. Surface morphology and margin quality were characterized with microscopic examination. RESULTS: The self-glazed zirconia crowns showed a smooth and glossy appearance. The soft-milled crowns showed traces left by the removal of support bars and numerous micropits of various sizes. In internal areas, no significant difference was found in root mean square values between the 2 groups (P＞.05). For the external surface, self-glazed zirconia showed statistically lower root mean square values than the soft-milled crowns (P＜.05). When observed at ×5 magnification, all the self-glazed zirconia crowns showed smooth edges with no defects, whereas small or large margin defects were found in the soft-milled crowns. When characterized at ×200 magnification, minor margin flaws were observed in the self-glazed zirconia crowns. More and larger margin defects were found in the soft-milled crowns. CONCLUSIONS: Three-dimensional gel deposition forms a smoother and more homogeneous surface than soft milling. Knife-edged self-glazed zirconia crowns have good dimensional accuracy and margin quality.

Accuracy of zirconia crowns manufactured by stereolithography with an occlusal full-supporting structure: An in vitro study.

STATEMENT OF PROBLEM: Additive manufacturing is emerging as an alternative method of fabricating dental restorations, but the support design needs to be optimized. PURPOSE: The purpose of this in vitro study was to evaluate the 3-dimensional trueness and adaptations of zirconia crowns manufactured by stereolithography (SLA) with an occlusal full-supporting structure, compared with those SLA-printed with pillar supports, and those made by milling. MATERIAL AND METHODS: A zirconia abutment was prepared, and an anatomic contour crown was designed. The crowns were manufactured by SLA and milling (n=6). For SLA manufacturing, a full-supporting base and pillar supports were designed. The 3-dimensional (3D) trueness of the fabricated crowns was characterized by 3D deviation analysis. The adaptations of crowns in the SLA-base and milling groups were measured by using a triple-scan method. Color-difference maps and the root mean square (RMS) values were used to characterize the 3D trueness. One-way analysis of variance (ANOVA) and Tukey post hoc test were used to analyze the difference in RMS values among the 3 groups, and Student t test was used to analyze the difference in cement-gap width between the milling group and the SLA group with the full-supporting base (α=.05). RESULTS: The 3D deviation analysis showed that in the external area, the RMS value of the SLA-pillar group was significantly higher than that of the SLA-base and the milling groups (P<.05). In the intaglio area, the milling group showed a lower RMS value than the 2 SLA groups (P<.05). The color-difference maps showed the SLA-base group had smaller positive errors at the cusp inclines than the SLA-pillar group. No statistically significant difference was found in adaptations between the SLA-base and milling groups (P>.05). CONCLUSIONS: The occlusal full-supporting base provided improved support in fabricating the crowns, and no remnants were left after removal. The zirconia crowns manufactured by SLA with an occlusal full-supporting structure had good external 3D trueness and clinically acceptable adaptation.

Accuracy of two best-fit alignment strategies with different reference areas for wear measurement with an intraoral scanner: an in vitro study.

AIM: The aim of the present in vitro study was to assess and compare the accuracy of two best-fit alignment strategies with different reference areas for wear measurement with an intraoral scanner (IOS). MATERIALS AND METHODS: Eight anatomic contour zirconia crowns were fabricated and scanned twice with an IOS. One of the scan datasets (Data Trueness) was duplicated and wear facets were simulated (Data Wear). The other scan dataset (Data Baseline) was aligned to Data Wear by two best-fit alignment strategies with different reference areas (the occlusal surface with no signs of wear [Group Occlusal], and the axial surface [Group Axial]), and 3D deviation analysis was performed to detect wear loss. The 3D deviation between Data Trueness and Data Wear was calculated as the truth-value for accuracy evaluation (Group Trueness). RESULTS: The color-difference map showed Group Occlusal had a similar wear-facet distribution to Group Trueness while Group Axial showed an obvious tilting position, and the obtained height loss values were larger and with large standard deviations. Both Group Occlusal and Group Axial showed significant differences compared with Group Trueness in maximum height loss and mean height loss (P < 0.05) while showed no significant difference in mean distance (P > 0.05). The paired t test showed significant differences between Group Occlusal and Group Axial in maximum height loss and mean height loss (P < 0.05) while showed no significant difference in mean distance (P > 0.05). CONCLUSIONS: Best-fit alignment with the occlusal reference area produced a better alignment result than that with the axial reference area. Measuring wear with an IOS has potential, but the method is prone to overestimating the height loss.

Synergistic photothermal-photodynamic-chemotherapy toward breast cancer based on a liposome-coated core-shell AuNS@NMOFs nanocomposite encapsulated with gambogic acid.

A multifunctional nanoplatform with core-shell structure was constructed in one-pot for the synergistic photothermal, photodynamic, and chemotherapy against breast cancer. In the presence of gambogic acid (GA) as the heat-shock protein 90 (HSP90) inhibitor and the gold nanostars (AuNS) as the photothermal reagent, the assembly of Zr4+ with tetrakis (4-carboxyphenyl) porphyrin (TCPP) gave rise to the nanocomposite AuNS@ZrTCPP-GA (AZG), which in turn, further coated with PEGylated liposome (LP) to enhance the stability and biocompatibility, and consequently the antitumor effect of the particle. Upon cellular uptake, the nanoscale metal - organic framework (NMOF) of ZrTCPP in the resulted AuNS@ZrTCPP-GA@LP (AZGL) could be slowly degraded in the weak acidic tumor microenvironment to release AuNS, Zr4+, TCPP, and GA to exert the synergistic treatment of tumors via the combination of AuNS-mediated mild photothermal therapy (PTT) and TCPP-mediated photodynamic therapy (PDT). The introduction of GA serves to reduce the thermal resistance of the cell to re-sensitize PTT and the constructed nanoplatform demonstrated remarkable anti-tumor activity in vitro and in vivo. Our work highlights a facile strategy to prepare a pH-dissociable nanoplatform for the effective synergistic treatment of breast cancer.

Characterization and Interaction Analysis of the Secondary Cell Wall Synthesis-Related Transcription Factor PmMYB7 in Pinus massoniana Lamb.

In vascular plants, the importance of R2R3-myeloblastosis (R2R3-MYB) transcription factors (TFs) in the formation of secondary cell walls (SCWs) has long been a controversial topic due to the lack of empirical evidence of an association between TFs and downstream target genes. Here, we found that the transcription factor PmMYB7, which belongs to the R2R3-MYB subfamily, is involved in lignin biosynthesis in Pinus massoniana. PmMYB7 was highly expressed in lignified tissues and upon abiotic stress. As a bait carrier, the PmMYB7 protein had no toxicity or autoactivation in the nucleus. Forty-seven proteins were screened from the P. massoniana yeast library. These proteins were predicted to be mainly involved in resistance, abiotic stress, cell wall biosynthesis, and cell development. We found that the PmMYB7 protein interacted with caffeoyl CoA 3-O-methyltransferase-2 (PmCCoAOMT2)-which is involved in lignin biosynthesis-but not with beta-1, 2-xylosyltransferase (PmXYXT1) yeast two-hybrid (Y2H) studies. Our in vivo coimmunoprecipitation (Co-IP) assay further showed that the PmMYB7 and PmCCoAOMT2 proteins could interact. Therefore, we concluded that PmMYB7 is an upstream TF that can interact with PmCCoAOMT2 in plant cells. These findings lay a foundation for further research on the function of PmMYB7, lignin biosynthesis and molecular breeding in P. massoniana.

[Analysis of clinical phenotype and genetic variant in a Chinese pedigree affected with cleidocranial dysplasia].

OBJECTIVE: To analyze the clinical features and pathogenic variant in a Chinese pedigree affected with cleidocranial dysplasia (CCD). METHODS: Clinical data of 8 patients from the pedigree was collected, including physical examination and X-ray images of head, face, spine, limbs, and mouth. Peripheral blood samples were collected from 6 affected members for the extraction of genomic DNA. The proband and other 3 patients were subjected to trio-whole exome sequencing. Candidate variant was verified by Sanger sequencing of the other 2 affected members from the pedigree. RESULTS: This pedigree has included 22 members (8 affected) from four generations. Genetic testing revealed that the proband has harbored a novel pathogenic variant of the RUNX2 gene [NM_001024630: c.1268_1277del (p.P425Afs*56)], which was inherited from her mother and carried by all affected members in the pedigree. The same variant was not detected among the unaffected members, suggesting co-segregation with the phenotype. CONCLUSION: The c.1268_1277del (p.P425Afs*56) variant of the RUNX2 gene probably underlay the pathogenesis of CCD in this pedigree. Genetic testing has facilitated the definite diagnosis and enabled prenatal diagnosis.

Diagnosis and genetic analysis of a case with mandibuloacral dysplasia type B due to compound heterozygous mutations of the ZMPSTE24 gene.

Mandibuloacral dysplasia (MAD) is a rare autosomal recessive disorder, mainly caused by pathogenic variants of the LMNA and ZMPSTE24 genes. In this study, we reported the first case of a patient with type B cranial and mandibular dysplasia in China. The patient presented with distinctive facial features, feeding difficulties, significant physical retardation, and overall developmental delay with abnormal tooth and bone development. Trio-whole exome sequencing analysis showed that the patient carried compound heterozygous mutations of c.743C>T (p.Pro248Leu) (dbSNP: rs121908095) and the loss of exons 1-10 of the ZMPSTE24 gene. Sanger sequencing and real-time quantitative PCR (RT-qPCR) showed that these two mutations were inherited from the patient's phenotypically normal mother and father, respectively. By summarizing and analyzing the characteristics of this case and the pedigree of the family, we suggested that trio-whole-exome sequencing could be performed to assist in the diagnosis of diseases that are difficult to be diagnosed definitively based on clinical phenotypes. The publication of this case has improved clinicians' understanding of MAD disease and provide new clinical information for the subsequent genetic study of this disease.

Suitability of the triple-scan method with a dental laboratory scanner to assess the 3D adaptation of zirconia crowns.

STATEMENT OF PROBLEM: The triple-scan method for assessing the 3D adaptation of dental restorations has been introduced and reported to be reliable. However, the suitability of using a dental laboratory scanner in the triple-scan method has not been evaluated. PURPOSE: The purpose of this in vitro study was to evaluate the suitability of the triple-scan method using a dental laboratory scanner to assess the 3D adaptation zirconia crowns. MATERIAL AND METHODS: A zirconia abutment and a zirconia crown were fabricated, and the abutment was fixed in a custom-made base. The crown was seated onto the abutment with the interposition of light-body silicone impression material between them. The triple-scan method was performed by using a dental laboratory scanner, and the mean cement-gap thickness was calculated. The seating and digitalization process was repeated 10 times, and after each digitalization, the light-body silicone layer was stabilized by applying heavy-body silicone impression material over it. Cement-gap thickness was measured on cross-sections of the aligned scan data sets and of the physical silicone replica. The results were assessed by using the paired t test and the Bland-Altman method (α=.05). RESULTS: Mean 3D cement-gap thickness assessed by the triple-scan method reported small dispersion with a coefficient of variation of 5.6% for the occlusal area, 1.9% for the axial area, and 6.4% for the margin area. Cement gap thickness measured at corresponding locations in the aligned scan data sets and in the physical silicone replica reported no significant difference (P=.326) and good agreement. CONCLUSIONS: The cement gap was accurately duplicated in scan data sets. The triple-scan method by using a dental laboratory scanner is suitable for assessing the 3D adaptation of zirconia crowns.

High-Order Assembly toward Polysaccharide-Based Complex Coacervate Nanodroplets Capable of Targeting Cancer Cells.

High-order assembly plays a significant role in the formation of living organisms containing a large number of biomacromolecules and, thus, enlightens the construction of nanomaterials that can load macromolecular payloads at a high efficiency. Herein, by choosing anionic hyaluronic acid (HA) as a model payload, we demonstrated how the electrostatic-interaction-induced high-order assembly can be used to load efficiently biomacromolecules into complex coacervate nanodroplets. The resultant assemblies were primarily composed of HA and cationic chitosan oligosaccharide/dextran (COS/Dex) nanogels and had a controllable structure while also exhibiting biological functionality. HA in the assemblies is capable of targeting CD44-overexpressed tumor cells through CD44-mediated endocytic pathways, which are elucidated herein. Therefore, this study provides a reliable approach for the efficient loading of macromolecular payloads into complex coacervate nanodroplets via electrostatic-attraction-induced high-order assembly.

Periodontal disease and Helicobacter pylori infection in oral cavity: a meta-analysis of 2727 participants mainly based on Asian studies.

OBJECTIVES: To assess the association between periodontal disease and Helicobacter pylori (H. pylori) infection in oral cavity. MATERIALS AND METHODS: We searched PubMed, Embase, Web of Science, Cochrane library, Gray literature, and clinicaltrials.gov for eligible studies up to September 25, 2019. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. The random-effects model was used with the software STATA 13.0. The Newcastle-Ottawa-Scale was used for quality evaluation. RESULTS: Twelve observational studies (eight from Asia, one from Europe, and three from the South America) involving 2727 participants were included in the meta-analysis. The overall pooled results showed that H. pylori infection in oral cavity was associated with periodontal disease (OR 2.53, 95% CI 1.86-3.44, P < 0.05). No significant heterogeneity among the articles was observed (I2 = 44.3%, P < 0.05). The sensitivity analysis indicated that the result of our meta-analysis was generally stable. The Begg test and the Egger test both showed no publication bias was observed (P = 0.45 and P = 0.18 respectively). CONCLUSIONS: Based on current available evidence, it seemed there was a correlation between oral H. pylori infection and the occurrence of periodontal disease. However, since most of the data comes from Asia, more large-scale investigations with high quality from all over the world are needed to confirm the association. CLINICAL RELEVANCE: H. pylori infection in oral may have a positive association with the prevalence of periodontal disease mainly in Asian populations.

[Blepharoptosis and dysarthria in a boy aged 2 years].

A boy, aged 2 years and 4 months, had a sudden onset of blepharoptosis of the right eyelid, accompanied by the mouth deviated to the right side, drinking cough, nystagmus, and developmental regression. Cranial MRI showed softening lesions formed after infarction of the right dorsolateral medulla oblongata, while head CT angiography showed no imaging of the proximal part of the V4 segment of the right vertebral artery. The child was diagnosed with dorsolateral medulla oblongata syndrome and was treated with gamma globulin to regulate immune function, with mannitol to reduce neuronal edema, with low-molecular-weight heparin sodium to improve local hypercoagulation of occluded blood vessels, with hyperbaric oxygen to improve local ischemia and hypoxia and promote the recovery of brain function, and with neuromuscular electrical stimulation to promote the recovery of neuromuscular function. Before discharge, only mild right ataxia and Horner syndrome remained. This article reports the first case of infantile dorsolateral medulla oblongata syndrome and provides experience for the diagnosis and treatment of the disease.

A B-box zinc finger protein, MdBBX10, enhanced salt and drought stresses tolerance in Arabidopsis.

KEY MESSAGE: The expression of MdBBX10 was significantly induced by different stresses and ABA treatments. Overexpression of MdBBX10 in Arabidopsis significantly enhanced abiotic stresses tolerance by ABA signalling. The roles of B-box domain(s) containing proteins (BBXs) in regulation of flowering and light morphogenesis of plants were intensively studied. However, the roles of plant BBXs in abiotic stresses are poorly understood. A B-box protein encoding gene from apple (MdBBX10) was found to be up-regulated from gene expression profile under salt stress. qRT-PCR analysis indicated that the expression of MdBBX10 was significantly induced by different stresses and exogenous abscisic acid (ABA) in apple roots and leaves. The ß-glucuronidase activity driven by the promoter of MdBBX10 was also strongly induced by NaCl, H2O2, polyethylene glycol and exogenous ABA, which was consistent to the existence of rich cis-acting elements related to the abiotic stresses in the promoter sequence. Over-expression of MdBBX10 in Arabidopsis significantly enhanced tolerance to abiotic stresses, with higher germination ratio and longer length of roots than the wild type plants. Transgenic plants of over-expressing MdBBX10 lines were more sensitive to exogenous ABA than the wild type plants. Under abiotic stress treatments, the transcript levels of ABA- and stress-related genes were higher in MdBBX10-overexpressing plants than wild type plants. Over-expression of MdBBX10 could enhance plant's ability to scavenge reactive oxygen species (ROS) under stresses, which is correlated with the expression of ROS-scavenging genes. These results provided the evidences that MdBBX10 plays an important role in enhanced plant tolerance to abiotic stresses, which were involved in ABA-mediated response and ROS response.

Folate Ligand Orientation Optimized during Cell Membrane Mimetic Micelle Formation for Enhanced Tumor Cell Targeting.

Nanocarriers with strong tumor cell targeting ability have been expected to overcome limitations of cancer chemotherapy. Herein, cell membrane mimetic micelles were prepared from a random copolymer (PMNCF) containing cell membrane phosphorylcholine zwitterion, cholesterol, and tumor cell targeting folic acid (FA) at the side chain ends. Surface orientation of the FA ligand was optimized during PMNCF micelle preparation by controlling solvent solubility for FA. The out-oriented ligands on the micelles were immobilized by the strongly associated hydration layer around the closely packed phosphorylcholine zwitterions. The doxorubicin (DOX) loaded PMNCF micelles were demonstrated to reduce normal cell toxicity to less than 20%. More significantly, HeLa and MCF-7 tumor cell killing efficacy of the optimized formulation was enhanced to 160% compared with that of free DOX. The excellent performances of the drug loaded PMNCF micelles on both tumor cell killing and normal cell toxicity reducing efficacies reveal great potential for developing advanced drug delivery system.

Distinct gene expression characteristics in epithelial cell-Porphyromonas gingivalis interactions by integrating transcriptome analyses.

Porphyromonas gingivalis is a pivotal periodontal pathogen, and the epithelial cells serve as the first physical barrier to defend the host from bacterial attack. Within this host-bacteria interaction, P. gingivalis can modify the host immune reaction and adjust the gene expression, which is associated with periodontitis pathogenesis and developing strategies. Herein, a meta-analysis was made to get the differential gene expression profiles in epithelial cells with or without P. gingivalis infection. The network-based meta-analysis program for gene expression profiling was used. Both the gene ontology analysis and the pathway enrichment analysis of the differentially expressed genes were conducted. Our results determined that 290 genes were consistently up-regulated in P. gingivalis infected epithelial cells. 229 gene ontology biological process terms of up-regulated genes were discovered, including "negative regulation of apoptotic process" and "positive regulation of cell proliferation/migration/angiogenesis". In addition to the well-known inflammatory signaling pathways, the pathway associated with a transcriptional misregulation in cancer has also been increased. Our findings indicated that P. gingivalis benefited from the survival of epithelial cells, and got its success as a colonizer in oral epithelium. The results also suggested that infection of P. gingivalis might contribute to oral cancer through chronic inflammation. Negative regulation of the apoptotic process and transcriptional misregulation in cancer pathway are important contributors to the cellular physiology changes during infection development, which have particular relevance to the pathogenesis and progressions of periodontitis, even to the occurrence of oral cancer.

Phosphate-Based Ultrahigh Molecular Weight Polyethylene Fibers for Efficient Removal of Uranium from Carbonate Solution Containing Fluoride Ions.

This work provides a cost-effective approach for preparing functional polymeric fibers used for removing uranium (U(VI)) from carbonate solution containing NaF. Phosphate-based ultrahigh molecular weight polyethylene (UHMWPE-g-PO4) fibers were developed by grafting of glycidyl methacrylate, and ring-opening reaction using phosphoric acid. Uranium (U(VI)) adsorption capacity of UHMWPE-g-PO4 fibers was dependent on the density of phosphate groups (DPO, mmol∙g−1). UHMWPE-g-PO4 fibers with a DPO of 2.01 mmol∙g−1 removed 99.5% of U(VI) from a Na2CO3 solution without the presence of NaF. In addition, when NaF concentration was 3 g∙L−1, 150 times larger than that of U(VI), the U(VI) removal ratio was still able to reach 92%. The adsorption process was proved to follow pseudo-second-order kinetics and Langmuir isotherm model. The experimental maximum U(VI) adsorption capacity (Qmax) of UHMWPE-g-PO4 fibers reached 110.7 mg∙g−1, which is close to the calculated Qmax (117.1 mg∙g−1) by Langmuir equation. Compared to F−, Cl−, NO3−, and SO4²− did not influence U(VI) removal ratio, but, H2PO4− and CO3²− significantly reduced U(VI) removal ratio in the order of F− > H2PO4− > CO3²−. Cyclic U(VI) sorption-desorption tests suggested that UHMWPE-g-PO4 fibers were reusable. These results support that UHMWPE-g-PO4 fibers can efficiently remove U(VI) from carbonate solutions containing NaF.

[Remineralization of demineralized dentin induced by bioactive glass NovaMin].

OBJECTIVE: To explore the remineralization effect of bioactive glass NovaMin on demineralized dentin specimens, and to study the physical and chemical properties of formed structure at dentin surface.
 Methods: One mm-thickness coronal dentin slices were soaked in ethylene diamine tetraacetic acid (EDTA) for 48 h to prepare the completely demineralized dentin specimens and they were divided into 2 groups: an artificial saliva group (control group) and a NovaMin powder group. The specimens were treated with artificial saliva or NovaMin powder for 2 min (2 times every day), and the interval was 8 hours. Then, the specimens were soaked in the remineralization solution. After 7 days, the scanning electron microscope (SEM), energy dispersive X-ray (EDX), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray diffraction (XRD) were used to detect dentin morphology, the physical and chemical properties of the formed structure at dentin surface.
 Results: The results of SEM showed that a defined surface layer in the NovaMin powder group could be observed in the SEM imaging at the 7th day, which completely occluded dentinal tubules; the EDX, ATR-FTIR and XRD analysis found that the mineralized layer formed at dentin surface was mainly composed of calcium and phosphate elements, which was similar to the hydroxyapatite-like crystal. However, there were no materials formed at the dentin surface in the control group, and the dentinal tubules were still open.
 Conclusion: NovaMin can remineralize the demineralized dentin specimens and occlude the dentinal tubules in hydroxyapatite-like crystal structure.

The dentin tubule occlusion effects of desensitizing agents and the stability against acids and brushing challenges.

PURPOSE: To investigate the effects of desensitizing agents on dentin tubule occlusion, acid and tooth brushing challenge, and microhardness change of human dentin. METHODS: Partially demineralized dentin slabs were divided into four groups (n = 30): (1) Control, (2) Non-desensitizing toothpaste, (3) Pro-Argin toothpaste, (4) CPP-ACP paste. The specimens were treated with these dentifrices for 2 minutes/day and soaked in artificial saliva (AS) for 24-hour remineralization. Then the dentin discs were divided into three subgroups for removal resistance tests: acid challenge, mechanical brushing challenge and blank control. Changes in dentin morphology were observed using scanning electron microscopy (SEM). Vickers microhardness measurements were performed at baseline and after 24-hour remineralization for all groups. RESULTS: A surface layer and intra-tubular crystals were observed in SEM imaging of Pro-Argin toothpaste and CPP-ACP paste groups, which occluded most of the dentin tubules for those specimens. But the dentin tubules were opened after the acid challenge again. Moreover, the dentin microhardness showed a slight increase after 24-hour AS immersion. The percentage microhardness gain (PMG) values of these two groups were 5.4% and 5.1% respectively, which were significantly higher than the other groups (P < 0.05).