The landscape of endodontic education research area: A bibliometric analysis.

OBJECTIVES: Educational research is essential for rationalizing curriculum design, improving evaluation systems, and updating teaching content. This bibliometric study aimed at analyzing the characteristics of publications relevant to endodontic education, thus forming a comprehensive scope of this research area. METHODS: The search was conducted in the Web of Science Core Collection database in May 2022. Knowledge units of the included publications, such as year of publication, journal, country/institution/author, keywords, and highly cited articles/references, were analyzed. RESULTS: The United States ranked first in the number of articles with a total of 17 articles. The majority of included articles were published in Journal of Dental Education (n = 25), International Endodontic Journal (n = 21), and European Journal of Dental Education (n = 14). The top 3 most frequent keywords were Endodontics, Education, and Root canal treatment. The main topic in endodontic education were curriculum, preclinical education, educational technology, and continuing education. CONCLUSION: Forming a full scope of the endodontic research area, this bibliomertic analysis can help mine the hot topic, predict the frontiers in the field and provide the data necessary to determine the direction of research, rationalize resource allocation, and formulate policy.

Natural products from traditional medicine as promising agents targeting at different stages of oral biofilm development.

Oral cavity is an ideal habitat for more than 1,000 species of microorganisms. The diverse oral microbes form biofilms over the hard and soft tissues in the oral cavity, affecting the oral ecological balance and the development of oral diseases, such as caries, apical periodontitis, and periodontitis. Currently, antibiotics are the primary agents against infectious diseases; however, the emergence of drug resistance and the disruption of oral microecology have challenged their applications. The discovery of new antibiotic-independent agents is a promising strategy against biofilm-induced infections. Natural products from traditional medicine have shown potential antibiofilm activities in the oral cavity with high safety, cost-effectiveness, and minimal adverse drug reactions. Aiming to highlight the importance and functions of natural products from traditional medicine against oral biofilms, here we summarized and discussed the antibiofilm effects of natural products targeting at different stages of the biofilm formation process, including adhesion, proliferation, maturation, and dispersion, and their effects on multi-species biofilms. The perspective of antibiofilm agents for oral infectious diseases to restore the balance of oral microecology is also discussed.

The Arginine Biosynthesis Pathway of Candida albicans Regulates Its Cross-Kingdom Interaction with Actinomyces viscosus to Promote Root Caries.

The cross-kingdom interactions between Candida albicans and Actinomyces viscosus play critical roles in root caries. However, the key pathway by which C. albicans regulates its interactions with A. viscosus is unclear. Here, we first employed 39 volunteers with root caries and 37 caries-free volunteers, and found that the abundances of C. albicans and A. viscosus were significantly increased in the individuals with root caries and showed a strong positive correlation. Their dual-species combination synergistically promoted biofilm formation and root caries in rats. The arginine biosynthesis pathway of C. albicans was significantly upregulated in dual-species biofilms and dental plaques from another 10 root caries volunteers compared with the 10 caries-free volunteers. The exogenous addition of arginine increased the cariogenicity of the dual-species biofilm. The C. albicans ARG4, a key gene from the arginine biosynthesis pathway, null mutant failed to promote dual-species biofilm formation and root caries in rats; however, the addition of arginine restored its synergistic actions with A. viscosus. Our results identified the critical roles of the C. albicans arginine biosynthesis pathway in its cross-kingdom interactions with A. viscosus for the first time and indicated that targeting this pathway was a practical way to treat root caries caused by multiple species. IMPORTANCE Root caries is a critical problem that threatens the oral health of the elderly population. Our results identified the essential roles of the C. albicans arginine biosynthesis pathway in its cross-kingdom interactions with A. viscosus in root caries for the first time and indicated that targeting this pathway was a practical way to treat root caries caused by multiple species.

Anticaries activity of GERM CLEAN in Streptococcus mutans and Candida albicans dual-species biofilm.

OBJECTIVE: To evaluate the antimicrobial effects of a peptide containing novel oral spray GERM CLEAN on dual-species biofilm formed by Streptococcus mutans and Candida albicans and to investigate whether GERM CLEAN inhibits the demineralization procedure of bovine enamel in vitro. METHODS: The antimicrobial effects of GERM CLEAN on dual-species biofilm were analyzed by initial adherence rate calculation, water-insoluble exopolysaccharides quantification, total biomass quantification, and colony-forming units (CFUs) counting. Scanning electron microscopy and confocal laser scanning microscopy were applied to evaluate the impacts of GERM CLEAN on the biofilm structure. Further, the effects of GERM CLEAN on acidogenicity of dual-species were appraised via glycolytic pH drop analysis and hydroxyapatite dissolution measurement. The percentage of Surface Microhardness Reduction (%SMHR) evaluation, Atomic Force Micrograph (AFM) examination, and Transverse Microradiography (TMR) analysis after pH cycling were used to determine whether GERM CLEAN inhibited the demineralization of bovine enamel. RESULTS: GERM CLEAN decreased the adherence rate, water-insoluble EPS production, biofilm formation, and acidogenicity of the dual-species. Moreover, GERM CLEAN significantly inhibited the demineralization status of bovine enamels. CONCLUSION: This peptide containing novel oral spray GERM CLEAN has antimicrobial potential toward the dual-species. GERM CLEAN can also impede the demineralization procedure of enamel.

CBCT evaluation of root canal morphology and anatomical relationship of root of maxillary second premolar to maxillary sinus in a western Chinese population.

BACKGROUND: To evaluate the root anatomy, root canal morphology and the anatomical relationship between the roots and maxillary sinus of maxillary second premolars by CBCT in a western Chinese population. METHODS: A total of 1118 CBCT scans of the maxillary second premolars were collected from West China Hospital of Stomatology, Sichuan University. Information below were measured on axial, coronal and sagittal sections, recorded and evaluated properly: the number of roots and canals, the morphology of canal system classified by Vertucci standard, the inter-orifice distance of canal orifices, the curvature of each canal and the distance from root tip to maxillary sinus floor. RESULTS: Among the 1118 teeth, 94.2% (1053) are single-rooted and 55.1% (616) have one canal. Type I (55.1%) is the commonest root canal morphology followed by Type II (31.9%). The mean inter-orifice distance (IOD) for multi-canal teeth ranging from 2.72 ± 0.32 to 3.41 ± 0.11 mm. Of 1622 canals, 38.8% (630) curvature are mesiodistal and 30.9% (501) are straight canals. The distance from root tip to maxillary sinus floor increased with age and the mean distance of single-rooted ones is 2.47 ± 3.45 mm. CONCLUSIONS: All kinds of canal morphology category can be detected in maxillary second premolars. The IOD might be a predictable factor for root canal morphology. Roots of maxillary second premolars are related to maxillary sinus which should be treated carefully.

Prevalence of middle mesial canal and radix entomolaris of mandibular first permanent molars in a western Chinese population: an in vivo cone-beam computed tomographic study.

BACKGROUND: The aim of this study was to investigate the prevalence of the middle mesial canal (MMC) and radix entomolaris (RE) in mandibular first permanent molars in a western Chinese population using cone-beam computed tomography (CBCT). METHODS: A total of 1174 CBCT images of the mandibular first molars were collected from West China Hospital of Stomatology, Sichuan University. The following information was recorded and evaluated: the detection rate and location of the MMC and RE, the curvature of the RE, the canal configuration and bilateral symmetry. RESULTS: The detection rates of the MMC and RE were 3.41 and 25.04%, respectively, as calculated by individuals, and 1.79 and 22.15%, respectively, as calculated by total teeth. The average curvature in the buccolingual (BL) orientation (40.63 ± 14.39°) was significantly larger than that in the mesiodistal (MD) orientation (17.64 ± 7.82°) (p < 0.05). Of 587 patients, 71.72% (421/587) had bilateral symmetry according to the root canal morphology. The prevalence of three-rooted mandibular first molars was higher in males than in females, while the prevalence of two-rooted mandibular first molars was higher in females than in males. CONCLUSIONS: Our results showed that the RE could be detected in almost 1/4 of the western Chinese population; thus, RE detection requires special attention and careful assessment in endodontic treatment.

Water-soluble fluorescent sensor for Zn2+ with high selectivity and sensitivity imaging in living cells.

A new water-soluble 4-amino-1, 8-naphthalimide based fluorescent sensor, with iminoacetic acid and iminoethoxyacetic acid as receptor contained two different arms, was developed. Under physiological pH conditions, it demonstrates good water solubility, high selectivity and sensitivity for sensing Zn2+ with about 20-fold enhancement in aqueous solution, with a characteristic emission band of 4-amino-1, 8-naphthalimide with a green color centered at 550 nm. It was applied successfully to detect Zn2+ in living cells.

A highly selective and sensitive 1,8-naphthalimide-based fluorescent sensor for Zn2+ imaging in living cells.

A new 4-amino-1,8-naphthalimide-based fluorescent sensor, with iminoacetic acid and iminoethoxyacetic acid as receptor, was developed. It was applied successfully to detect Zn2+ in aqueous solution and living cells. Under physiological pH conditions, it demonstrates high selectivity and sensitivity for sensing Zn2+ with about 7-fold enhancement in aqueous solution, with a characteristic emission band of 4-amino-1,8-naphthalimide with a green color centered at 550 nm.

Lactobacillus reuteri improves gut barrier function and affects diurnal variation of the gut microbiota in mice fed a high-fat diet.

Lactobacillus reuteri FN041 is a secretory IgA-targeted Lactobacillus strain from human breast milk that has probiotic potential. The aim of this study was to test whether FN041 can alleviate dyslipidaemia and mucosal-barrier damage caused by a high-fat diet (HFD) and whether it can affect diurnal variation of the intestinal microbiota. C57BL/6 mice were fed either a normal chow diet or high-fat diet (HFD) for 7 weeks and were treated with either PBS as a control or L. reuteri FN041 for 4 weeks. Our results showed that FN041 treatment significantly attenuated HFD-induced weight gain (P < 0.01), accumulation of testicular fat, an increase in locomotor activity during the active phase (P < 0.01), triglyceridaemia, hypercholesterolaemia (P < 0.05), liver Fas overexpression, and Srebp1c mRNA expression inhibition. Moreover, FN041 treatment improved intestinal epithelial barrier function and induced a daily oscillation-dependent change in short-chain fatty acid production by the gut microbiota. A deeper understanding of the molecular pathways participating in intestinal barrier and microbiota modifications, and changes to lipid metabolism under the influence of FN041, will have important implications by potentially opening new horizons for the development of relevant foods to prevent metabolic disorders and unrelated intestinal diseases.

IgA-Targeted Lactobacillus jensenii Modulated Gut Barrier and Microbiota in High-Fat Diet-Fed Mice.

IgA-coated Lactobacillus live in the mucous layer of the human or mammalian intestine in close proximity to epithelial cells. They act as potential probiotics for functional food development, but their physiological regulation has not yet been studied. We isolated IgA-targeted (Lactobacillus jensenii IgA21) and lumen lactic acid bacterial strains (Pediococcus acidilactici FS1) from the fecal microbiota of a healthy woman. C57BL/6 mice were fed a normal (CON) or high fat diet (HFD) for 6 weeks and then treated with IgA21 or FS1 for 4 weeks. HFD caused dyslipidemia, mucosal barrier damage, and intestinal microbiota abnormalities. Only IgA21 significantly inhibited dyslipidemia and gut barrier damage. This was related to significant up-regulation of mucin-2, PIgR mRNA expression, and colonic butyrate production (P < 0.05 vs. HFD). Unlike IgA21, FS1 caused a more pronounced gut dybiosis than did HFD, and, in particular, it induced a significant decrease in the Bacteroidales S24-7 group and an increase in Desulfovibrionaceae (P < 0.05 vs. CON). In conclusion, IgA-coated and non-coated lactic acid bacteria of gut have been demonstrated to differentially affect the intestinal barrier and serum lipids. This indicates that IgA-bound bacteria possess the potential to more easily interact with the host gut to regulate homeostasis.

Origin of Hofmeister Effects for Complex Systems.

Hofmeister effects have been recognized as important as Mendel's work was to genetics while remain largely controversial, especially for the mechanistic aspects. Here we demonstrated that complex colloids in electrolyte solutions show resembling aggregation kinetics as model colloid, and then quantitatively evaluated the resulting Hofmeister effects. Mechanism for the aggregation of complex colloids has been proposed that is closely associated with the charges of their constituents; despite that, electrostatic interactions play a minor role while polarization effect is evidenced to be the driving force for the aggregation processes. Polarization effect is further ascribed to arouse the resulting Hofmeister effects, which is supported by the fine correlation of activation energies vs. polarizability data of different alkali ions and the calculations of dipole moments for minerals with different charges and adsorbed alkali ions. Because of neglecting polarization effect, the prevailing DLVO theory is not sufficient to describe Hofmeister effects that are ubiquitous in nature. We speculate that polarization effect should also be responsible for Hofmeister effects of other charged systems such as proteins and membranes.

Unraveling the size distributions of surface properties for purple soil and yellow soil.

Soils contain diverse colloidal particles whose properties are pertinent to ecological and human health, whereas few investigations systematically analyze the surface properties of these particles. The objective of this study was to elucidate the surface properties of particles within targeted size ranges (i.e. >10, 1-10, 0.5-1, 0.2-0.5 and <0.2 µm) for a purple soil (Entisol) and a yellow soil (Ultisol) using the combined determination method. The mineralogy of corresponding particle-size fractions was determined by X-ray diffraction. We found that up to 80% of the specific surface area and 85% of the surface charge of the entire soil came from colloidal-sized particles (<1 µm), and almost half of the specific surface area and surface charge came from the smallest particles (<0.2 µm). Vermiculite, illite, montmorillonite and mica dominated in the colloidal-sized particles, of which the smallest particles had the highest proportion of vermiculite and montmorillonite. For a given size fraction, the purple soil had a larger specific surface area, stronger electrostatic field, and higher surface charge than the yellow soil due to differences in mineralogy. Likewise, the differences in surface properties among the various particle-size fractions can also be ascribed to mineralogy. Our results indicated that soil surface properties were essentially determined by the colloidal-sized particles, and the <0.2 µm nanoparticles made the largest contribution to soil properties. The composition of clay minerals within the diverse particle-size fractions could fully explain the size distributions of surface properties.

[Impact of SDBS/Na+ on red soil colloidal stability].

The interactions between soil colloidal-sized particles and organic contaminants or inorganic ions profoundly affect numerous soil physical, chemical and biological processes. The coupling effect of sodium dodecylbenzene sulfonate (SDBS) and Na+ on the aggregation process of red soil colloid was studied using the dynamic light scattering method, and the mechanism of interactions between soil colloidal-sized particles and SDBS/Na+ was analyzed according to the pH and Zeta potential of suspension during the aggregation process. Results show that, (1) under a given concentration of Na+, the soil colloidal suspension becomes more stable with increasing SDBS concentrations. For example, under 120 mmol x L(-1) Na+, as the concentrations of SDBS increase from 0 mmol x L(-1) to 10 mmol x L(-1), the effective diameters of aggregates decrease from 702 nm to 193 nm, and the total average aggregation rates of aggregates decrease from 28.6 nm x min(-1) to 3.36 nm x min(-1). (2) Under a given concentration of SDBS, as the concentrations of Na+ increase, the Zeta potential of suspension sharply decreases, while the effective diameters and the total average aggregation rates of aggregates gradually increase. (3) The absolute values of Zeta potential for suspensions without adding NaNO3 solution increase from 47.6 mV to 62.2 mV as the SDBS concentrations increase, and the pH of the suspensions increase from 6.17 to 6.76, although these pH values are lower than that of initial soil colloidal suspension (6.89). Therefore, the adsorption of SDBS onto soil colloidal-sized particles, which is attributed to the hydrophobic effect and electrostatic effect, results in the increment of surface charge number, as well as the decrease in effective concentration of Na+ around colloidal-sized particles' surface (resulting from the steric hindrance of long hydrophobic chain of adsorbed SDBS and adsorption of Na+ by SDBS micelle). As a result, soil colloidal suspension becomes more stable and needs to absorb more Na+ to aggregate.

Activation energies of colloidal particle aggregation: towards a quantitative characterization of specific ion effects.

A quantitative description of specific ion effects is an essential and focused topic in colloidal and biological science. In this work, the dynamic light scattering technique was employed to study the aggregation kinetics of colloidal particles in the various alkali ion solutions with a wide range of concentrations. It indicated that the activation energies could be used to quantitatively characterize specific ion effects, which was supported by the results of effective hydrodynamic diameters, aggregation rates and critical coagulation concentrations. At a given concentration of 25 mmol L(-1), the activation energies for Li(+) are 1.2, 5.7, 28, and 126 times as much for Na(+), K(+), Rb(+), and Cs(+), respectively. Most importantly, the activation energy differences between two alkali cation species increase sharply with decrease of electrolyte concentrations, implying the more pronounced specific ion effects at lower concentrations. The dominant role of electrolyte cations during the aggregation of negatively charged colloidal particles was confirmed by alternative anions. Among the various theories, only the polarization effect can give a rational interpretation of the above specific ion effects, and this is substantially supported by the presence of strong electric fields from montmorillonite surfaces and its association mainly with electrolyte cations and montmorillonite particles. The classical induction theory, although with inclusion of electric field, requires significant corrections because it predicts an opposite trend to the experimentally observed specific ion effects.

N'-[(5-Methyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)(thio-phen-2-yl)methyl-idene]benzohydrazide.

In the title compound, C(22)H(18)N(4)O(2)S, the seven-membered ring generated by an intra-molecular N-H⋯O hydrogen bond adopts an envelope conformation in both of the two independent mol-ecules in the asymmetric unit. In the crystal, mol-ecules are linked into C(9) chains along [100] by N-H⋯O hydrogen bonds. The mol-ecules are also weakly linked by C-H⋯O and C-H⋯N inter-actions, forming dimers with edge-connected R(2) (2)(9) rings. The dimers are inter-linked by further weak C-H⋯N hydrogen bonds into chains along [010].

Bis[4-(1-imino-eth-yl)-3-methyl-1-phenyl-1H-pyrazol-5-olato-κO,N]copper(II).

In the title complex, [Cu(C(12)H(12)N(3)O)(2)], the Cu(II) ion is tetra-coordinated by two N atoms and two O atoms from two bis-chelating 4-(1-imino-eth-yl)-3-methyl-1-phenyl-1H-pyrazol-5-olate ligands in a square-planar geometry. The two N atoms and two O atoms around the Cu(II) atom are trans to each other, as the Cu(II) atom lies on an inversion centre. The six-membered ring composed of the Cu, an O, an N and three C atoms of the ligand and the pyrazole ring is nearly planar, the largest deviation being 0.037 (4) Šfor an N atom. In the crystal, weak inter-molecular C-H⋯N hydrogen-bonding inter-actions link the mol-ecules into chains along the c axis.

Methyl 2-{[(3-methyl-5-oxo-1-phenyl-4,5-dihydro-1H-pyrazol-4-yl-idene)(thio-phen-2-yl)meth-yl]amino}-3-phenyl-propionate.

In the title compound, C(25)H(23)N(3)O(3)S, an intra-molecular N-H⋯O inter-action generates an S(6) ring, which stabilizes the enamine-keto form of the compound. This S(6) ring and the pyrazole ring are essentially coplanar, making a dihedral angle of 1.49 (6)°. The bond lengths within the S(6) ring of the mol-ecule lie between classical single- and double-bond lengths, indicating extensive conjugation. The structure exhibits a thienyl-ring flip disorder, with occupancy factors in the ratio 64.7 (3):35.3 (3).

1,5-Dimethyl-4-(1-methyl-3-oxo-3-phenylprop-1-enyl-amino)-2-phenyl-1H-pyrazol-3(2H)-one.

In the title compound, C(21)H(21)N(3)O(2), an intra-molecular N-H⋯O inter-action generates an S(6) ring, which stablizes the enamine-keto tautomer. The S(6) ring makes dihedral angles of 33.07 (7), 56.50 (8) and 38.59 (8)°, respectively, with the benzoyl-acetone benzene ring and the anti-pyrine pyrazole and benzene rings.

1,5-Dimethyl-4-{[(3-methyl-5-oxo-1-phenyl-4,5-dihydro-1H-pyrazol-4-yl-idene)(thio-phen-2-yl)meth-yl]amino}-2-phenyl-1H-pyrazol-3(2H)-one.

In the title compound, C(26)H(23)N(5)O(2)S, an intra-molecular N-H⋯O inter-action generates an S(6) ring. The essentially planar S(6) and pyrazole rings [maximum deviations = -0.0270 (14) and 0.0195 (15) Å, respectively] are nearly coplanar, making a dihedral angle of 3.94 (6)°. The S(6) ring makes dihedral angles of 23.79 (6), 78.53 (6) and 67.91 (6)° with the pyrazolone ring, the pyrazole ring and the benzene ring of anti-pyrine, respectively. The structure exhibits a thienyl-ring flip disorder with occupancy factors in the ratio 0.82:0.18.

Methyl 2-{1-[(Z)-3-methyl-5-oxo-1-phenyl-4,5-dihydro-1H-pyrazol-4-yl-idene]ethyl-amino}-3-phenyl-propanoate.

The mol-ecule of the title compound, C(22)H(23)N(3)O(3), exists in the enamine-keto form. A strong intra-molecular N-H⋯O hydrogen bond occurs, generating an S(6) ring. The dihedral angle between the heterocycle and the adjacent phenyl ring is 3.75 (15)°.