There is no consensus on the true meaning of clinical regenerative endodontics, and there is confusion over the concept and the term. Commonly used terms include revitalization and revascularization. ...The clinical methods for endodontic revitalization procedures and the tissue engineering concept differ depending on whether there is exogenous delivery of cells – called cell therapy, or not. Here, in this review, the difference is clarified by emphasizing the correct terminology: cell‐free versus cell‐based regenerative endodontic therapy (CF‐RET versus CB‐RET). The revitalization procedures practised clinically do not fit into the modern tissue engineering concepts of pulp regeneration but can be categorized as CF‐RET. The modern tissue engineering concept in pulp regeneration is a CB‐RET, which so far is at the clinical trial stage. However, histological examination of teeth following regenerative endodontic treatments reveals healing with repair derived from stem cells that originate from the periodontal, bone and other tissues. The aim of regenerative endodontics is regeneration of the pulp–dentine complex. This review discusses why CF‐RET is unlikely to regenerate a pulp–dentine complex with current protocols. The American Association of Endodontists and the European Society of Endodontology have not yet recommended autologous stem cell transplantation (CB‐RERT) which aspires for regeneration. Therefore, an understanding of the concept, term, difficulties and differences in current protocols is important for the clinician. However, rather than being discouraged that ideal regeneration has not been achieved to date, repair can be an acceptable outcome in clinical regenerative endodontics as it has also been accepted in medicine. Repair should also be considered in the context that resolution of the clinical signs/symptoms of pulp necrosis/apical periodontitis is generally reliably obtained in clinical regenerative endodontics.
Innovation activities create substantial firm value, but they are difficult to manage owing to agency risk, which is commonly thought to result in shirking, and hence underinvestment in innovation. ...However, agency risk can also create inefficient allocation of resources among innovation activities, on which the literature has provided limited understanding. We examine an important outcome created by agency risk-that agents pursue quantity of innovation at the expense of novelty-and investigate how it is influenced by corporate and public governance. We theorize that improved corporate governance tools, including better alignment of agents' private incentives and stronger monitoring, and high-quality public governance reduce such agency risk in state-owned enterprises (SOEs). Furthermore, higher-quality public governance enhances the functioning of corporate governance tools in further reducing such agency risk in innovation. We test our theory by examining SOEs in China that responded to the state's pro-innovation policies relying disproportionately on quantifiable outcomes (e.g., patent counts) for assessing innovation performance. Our difference-in-differences estimates provide overall support for our hypotheses. These findings provide new insights on how agency risk affects innovation by distinguishing the consequences for quantity and novelty of innovation and for how conventional corporate governance tools shaping innovation depend on public governance.
In this paper, we demonstrate the consequence of using different equivalent models to represent a lattice system consisting of mass-in-mass units and why negative mass is needed in the equivalent ...model. Dispersive wave propagation in the lattice system is studied and compared to various equivalent models. It is found that, if the classical elastic continuum is used to represent the original mass-in-mass lattice system, the effective mass density becomes frequency dependent and may become negative for frequencies near the resonance frequency of the internal mass. In contrast, if a multi-displacement microstructure continuum model is used to represent the mass-in-mass lattice system, the dispersive behavior of wave propagation and the band gap structure can be adequately described. However, while the acoustic mode is accurately described by the microstructure continuum model, the description of the optical mode is accurate only for a limited frequency range.
Semiconductor InSb nanowires are expected to provide an excellent material platform for the study of Majorana fermions in solid state systems. Here, we report on the realization of a Nb–InSb ...nanowire–Nb hybrid quantum device and the observation of a zero-bias conductance peak structure in the device. An InSb nanowire quantum dot is formed in the device between the two Nb contacts. Due to the proximity effect, the InSb nanowire segments covered by the superconductor Nb contacts turn to superconductors with a superconducting energy gap Δ InSb ∼ 0.25 meV. A tunable critical supercurrent is observed in the device in high back gate voltage regions in which the Fermi level in the InSb nanowire is located above the tunneling barriers of the quantum dot and the device is open to conduction. When a perpendicular magnetic field is applied to the devices, the critical supercurrent is seen to decrease as the magnetic field increases. However, at sufficiently low back gate voltages, the device shows the quasi-particle Coulomb blockade characteristics and the supercurrent is strongly suppressed even at zero magnetic field. This transport characteristic changes when a perpendicular magnetic field stronger than a critical value, at which the Zeeman energy in the InSb nanowire is E z ∼ Δ InSb , is applied to the device. In this case, the transport measurements show a conductance peak at the zero bias voltage and the entire InSb nanowire in the device behaves as in a topological superconductor phase. We also show that this zero-bias conductance peak structure can persist over a large range of applied magnetic fields and could be interpreted as a transport signature of Majorana fermions in the InSb nanowire.
To date, 5 different human dental stem/progenitor cells have been isolated and characterized: dental pulp stem cells (DPSCs), stem cells from exfoliated deciduous teeth (SHED), periodontal ligament ...stem cells (PDLSCs), stem cells from apical papilla (SCAP), and dental follicle progenitor cells (DFPCs). These postnatal populations have mesenchymal-stem-cell-like (MSC) qualities, including the capacity for self-renewal and multilineage differentiation potential. MSCs derived from bone marrow (BMMSCs) are capable of giving rise to various lineages of cells, such as osteogenic, chondrogenic, adipogenic, myogenic, and neurogenic cells. The dental-tissue-derived stem cells are isolated from specialized tissue with potent capacities to differentiate into odontogenic cells. However, they also have the ability to give rise to other cell lineages similar to, but different in potency from, that of BMMSCs. This article will review the isolation and characterization of the properties of different dental MSC-like populations in comparison with those of other MSCs, such as BMMSCs. Important issues in stem cell biology, such as stem cell niche, homing, and immunoregulation, will also be discussed.
Summary Objective Increased activity of histone deacetylase 2 (HDAC2) has been found in patients with osteoarthritis (OA) and cartilage matrix degradation and has been shown to mediate the repression ...of cartilage-specific gene expression in human chondrocytes. We aimed to determine whether microRNA-92a-3p (miR-92a-3p) regulates cartilage-specific gene expression via targeted HDAC2 in chondrogenesis and degradation. Methods miR-92a-3p expression was assessed in vitro in a human mesenchymal stem cells (hMSCs) model of chondrogenesis and in normal and OA primary human chondrocytes (PHCs), and in normal and OA human cartilage by in situ hybridization. hMSCs and PHCs were transfected with miR-92a-3p or its antisense inhibitor (anti-miR-92a-3p), respectively. PHCs were transfected with miR-92a-3p or anti-miR-92a-3p for 24 h before chromatin immunoprecipitation assay was performed with anti-ac-H3 antibody. Direct interaction between miR-92a-3p and its putative binding site in the 3’ untranslated region (3’-UTR) of HDAC2 mRNA was confirmed by luciferase reporter assay. Results miR-92a-3p expression was elevated in chondrogenic and hypertrophic hMSC, while reduced in OA cartilage compared with normal cartilage. The overexpression of miR-92a-3p suppressed the activity of a reporter construct containing the 3’-UTR and inhibited HDAC2 expression in both hMSCs and PHCs, while treatment with anti-miR-92a-3p enhanced HDAC2 expression. Chromatin immunoprecipitation assays showed that miR-92a-3p enhances H3 acetylation on ACAN, COMP and Col2a1 promoter, and also promotes relative cartilage matrix expression. Conclusion Our results suggest that miR-92a-3p regulates cartilage development and homeostasis, which directly targets HDAC2, indicating histone hyperacetylation plays an important role in increased expression of cartilage matrix.
Aim
To determine factors that may influence treatment outcome and healing time following root canal treatment.
Methodology
Root filled and restored teeth by pre‐doctoral students were included in ...this study. Teeth/roots were followed‐up regularly, and treatment outcome was evaluated at every follow‐up appointment (healed, healing, uncertain or unsatisfactory). Host (age, immune condition, pulp/periapical diagnosis, tooth/root type, location and anatomy) and treatment factors (master apical file size, apical extension, voids and density of root filling) were recorded from patient dental records. Univariate, bivariate and multivariate analyses were performed to determine the impact of the factors on treatment outcomes and healing times.
Results
A total of 422 roots from 291 teeth met the inclusion criteria with a mean follow‐up period of 2 years. The preoperative pulp condition, procedural errors during treatment, apical extension and density of root fillings significantly affected the treatment outcome. The average time required for a periapical lesion to heal was 11.78 months. The healing time increased in patients with compromised healing, patients older than 40 years, roots with Weine type II root canal systems, root canal systems prepared to a master apical file size <35, and roots with overextended fillings (P < 0.1).
Conclusion
Multiple host and treatment factors affected the healing time and outcome of root canal treatment. Follow‐up protocols should consider these factors before concluding the treatment outcome: patient's age, immune condition, as well as roots with overextended fillings, root canal systems with smaller apical preparations (size <35) or roots with complex canal systems. Intervention may be recommended if the treatment quality was inadequate or if patients became symptomatic.
We conduct a 3-y study involving 11,662 respondents to map cultural tightness—the degree to which a society is characterized by rules and norms and the extent to which people are punished or ...sanctioned when they deviate from these rules and norms—across 31 provinces in China. Consistent with prior research, we find that culturally tight provinces are associated with increased governmental control, constraints in daily life, religious practices, and exposure to threats. Departing from previous findings that tighter states are more rural, conservative, less creative, and less happy, cultural tightness in China is associated with urbanization, economic growth, better health, greater tolerance toward the LGBT (lesbian, gay, bisexual, and transgender) community, and gender equality. Further, analyzing about 3.85 million granted patents in China (1990–2013), we find that provinces with tighter cultures have lower rates of substantive/radical innovations yet higher rates of incremental innovations; individuals from culturally tighter provinces reported higher levels of experienced happiness.
Aim
To investigate the new tissues growing into the pulp space of immature dog teeth that were infected, disinfected and filled with blood clot (BC), dental pulp cells (DPCs), platelet‐rich plasma ...(PRP) or a combination of DPCs and PRP in immature dog teeth with apical periodontitis.
Methodology
Fifty‐six immature roots from mandibular premolars of four beagles were divided into four experimental groups (n = 40) and two control groups. After the induction of apical periodontitis, the root canals of experimental groups were disinfected with NaOCl irrigation and a tri‐antibiotic paste medication. The canals were then filled with different materials according to the experimental group: BC group, DPCs group, PRP group or DPCs + PRP group. Access cavities were sealed with MTA and composite. Radiographs were taken after 90 days, and the jaws including the teeth were processed for histologic analysis. The data were statistically analysed using chi‐square evaluation and Student's t‐test.
Results
Radiographic analyses demonstrated no significant difference between experimental groups in periradicular bone healing (P > 0.05), whilst those groups that used DPCs produced a significantly greater root thickening (P < 0.01). The histologic evaluation showed that the groups with PRP formed more tissues in the canals (P = 0.01). The groups with DPCs had substantially more mineralized tissue formation in the canal than those without DPCs, especially in the apical third. In DPCs + PRP group, bone‐like tissue grew into the canal space from the periapical tissue.
Conclusions
A combination of DPCs + PRP increased vital tissue regeneration within the root canals of immature teeth associated with apical periodontitis.
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