Strain Effects in Twisted Spiral Antimonene.

Van der Waals (vdW) layered materials exhibit fruitful novel physical properties. The energy band of such materials depends strongly on their structures, and a tremendous variation in their physical properties can be deduced from a tiny change in inter-layer spacing, twist angle, or in-plane strain. In this work, a kind of vdW layered material of spiral antimonene is constructed, and the strain effects in the material are studied. The spiral antimonene is grown on a germanium (Ge) substrate and is induced by a helical dislocation penetrating through few atomic-layers of antimonene (ß-phase). The as-grown spiral is intrinsically strained, and the lattice distortion is found to be pinned around the dislocation. Both spontaneous inter-layer twist and in-plane anisotropic strain are observed in scanning tunneling microscope (STM) measurements. The strain in the spiral antimonene can be significantly modified by STM tip interaction, leading to a variation in the surface electronic density of states (DOS) and a large modification in the work function of up to a few hundreds of millielectron-volts (meV). Those strain effects are expected to have potential applications in building up novel piezoelectric devices.

Innate immune sensing of nucleic acid in endodontic infection.

Innate immunity is the first line of defence and fights against microorganisms. Nucleic acids are important pathogen-associated molecular patterns to be recognized in innate immunity. There are three types of nucleic acid sensors, including endosomal sensors (NA-sensing TLRs), cytosolic DNA sensors (cGAS and AIM2) and cytosolic RNA sensors (RLG-I, MDA5 and LGP2). Recent studies have shown that nucleic acid sensors are expressed differently in a variety of dental pulp cells and mediate inflammation through complex pathways. Nucleic acid sensing may play a vital role in the development of endodontic infection. This review aims to summarize and analyse the possible roles of various nucleic acid sensors in endodontic infection. It may help better understand the pathogenesis of these diseases and find new strategies for prevention and treatment.

Diverse microbiota in palatal radicular groove analyzed by Illumina sequencing: Four case reports.

BACKGROUND: A palatal radicular groove is an unusual developmental deformity of the tooth, which may serve as a channel linking the periodontal and periapical inflammation, and yet no literature could be obtained analyzing microbiota within the palatal radicular grooves. CASE SUMMARY: Four patients diagnosed with palatal radicular groove and concomitant periodontal-endodontic deformity in permanent maxillary lateral incisors were enrolled in this work. Twelve bacterial samples from 4 patients were collected from different parts of the palatal radicular groove during intentional replantation surgery. Illumina sequencing was performed to analyze the taxonomical composition and microbiome structure inside the palatal grooves, and 1162 operational taxonomic units were obtained. The phyla of Firmicutes and Proteobacteria predominated in most of the samples. An unknown genus from the Bacillaceae family, Lactococcus, and Porphyromonas were the most abundant genera identified. There was no difference in the microbiota richness and diversity in three sections of the groove. CONCLUSION: The unique ecological niches inside the palatal grooves harbored bacterial communities that shared some component features of both the endodontic and periodontal infections. The existence of palatal groove may play an interaction bridge between the root apex and tooth cervix and thus impair the outcome of traditional therapeutic methods such as root canal treatment and periodontal management.

[Vital pulp preservation treatment in mandibular right first molar with vertical root fractures: a case report].

This case presents vertical root fracture with vital pulp in mandibular right first molar. Examinations of the history, clinical tests, laser Doppler flowmetry, and radiographs revealed that the tooth showed positive response to electric pulp testing and was normal compared with the healthy control tooth. This study aimed to use a novel vital preserving surgical technique (microapical surgery and nanometer bioactive materials) to make an effective therapeutic decision for the vital tooth with vertical root fracture.

[Endodontic infection management in root canal preparation: question and solution].

The essence of pulp and periapical disease is bacterial infection. Thus, satisfactory infection control is the premise and foundation of healing, in which root canal preparation is a critical procedure. Root canal system anatomy, infection degree, physical cutting during root canal preparation, and certain cleaning measures affect the quality of infection control. Appropriate evaluation of the grades of infected root canals before treatment is necessary because different grades of root canal infection demand various disinfection schedules to facilitate tissue healing and guarantee the long-term success rate of endodontic treatment.

Effect of occlusal slope related to uneven attrition on root stress distribution and potential fracture.

BACKGROUND/PURPOSE: Severely uneven occlusal attrition is thought to play an important role in the occurrence of spontaneous vertical root fracture (VRF), a frequent problem among Chinese people. This study evaluated the influence of occlusal slope related to uneven attrition on the root stress condition. MATERIALS AND METHODS: A finite element model of the mandibular first molar was established. Two different occlusal slope patterns were simulated in 5 models: (A) sound tooth, (B) 0.5-1.5 mm and (C) 2-3 mm attrition increased buccally, and (D) 0.5-1.5 mm and (E) 2-3 mm attrition increased distally. A static load of 200 N was applied vertically or angled at 45° to the longitudinal axis. The von Mises stress was evaluated. RESULTS: Under vertical loading, more stress was transferred from the cervical to the middle root with attrition, especially the mesial root, while stress declined with attrition under oblique loading. Stress was mainly distributed in the buccal surface and mesial root with vertical loading, or in the lingual surface and distal root with oblique loading. The maximum von Mises with oblique loading was significantly higher than with vertical loading. CONCLUSION: Uneven occlusal attrition made the middle of the mesial root bear more stress, increasing fracture risk under vertical load. This finding suggests that timely restoration of the sloped occlusal morphology in teeth with severe attrition should be recommended to prevent VRFs. Lateral loading was not a risk factor of typical vertical root fractures, but the high stress could cause distal root cervical fracture.

Effect of neoadjuvant chemoradiotherapy on perioperative immune function of patients with locally advanced esophageal cancer.

This study aims to evaluate the effect of neoadjuvant chemoradiotherapy (NCRT) on perioperative immune function during surgery to treat resectable locally advanced esophageal cancer. Records were retrospectively analyzed for 220 patients with locally advanced esophageal cancer, of whom 112 received surgery alone and 98 received neoadjuvant NCRT plus surgery. The two groups were compared in terms of proportions of CD3+, CD4+, CD8+, and natural kill (NK) cells, as well as the ratio of CD4+ to CD8+ cells. These measurements were made using flow cytometry on preoperative day 1 and on postoperative days 1 and 7. Subgroup analysis were performed in terms of degrees of pathological response of NCRT. When the entire NCRT and no-NCRT (surgery alone) cohorts were compared, no significant differences in propocrtions of CD3+, CD4+, CD8+, or NK cells or in the CD4+/CD8+ ratio occurred at any of the three time points. Similar results were obtained using the subgroup of NCRT patients who were NCRT-sensitive, but the subgroup of NCRT-insensitive patients showed significantly lower CD4+ and NK proportions and lower CD4+/CD8+ ratio than the no-NCRT group. Our findings suggest that NCRT does not affect perioperative immune function in patients who are NCRT-sensitive, but it does significantly reduce such function in patients who are NCRT-insensitive.

Comparison of postoperative immune function in patients with thoracic esophageal cancer after video-assisted thoracoscopic surgery or conventional open esophagectomy.

AIM: The aim of the study was to compare postoperative immune function in patients with thoracic esophageal cancer (EC) after video-assisted thoracoscopic surgery (VATS) or conventional open esophagectomy. PATIENTS AND METHODS: Medical records were retrospectively analyzed for 228 patients with thoracic EC treated at a single hospital using VATS (n = 52) or conventional open esophagectomy (n = 176). Proportions of CD3(+), CD4(+), CD8(+), and natural kill (NK) cells, as well as the ratio of CD4(+) to CD8(+) cells, were measured in the two groups using flow cytometry on preoperative day (PrD) 1 and postoperative days (PoD) 1 and 7. RESULTS: Proportions of CD3(+), CD4(+), and NK cells as well as the CD4+/CD8+ ratio decreased significantly from PrD1 to PoD1 in both the VATS and open esophagectomy groups. In the VATS group, these parameters had returned to preoperative levels (PrD1) by PoD7. These parameters in open esophagectomy group increased from PoD1 to PoD7 but also lowered significantly to PrD1 by PoD7. The proportion of CD8(+) cells was similar between the two groups at all time points tested. CONCLUSION: Patients may experience less postoperative immune suppression after VATS than after conventional open esophagectomy, and they may recover preoperative immune function more quickly.

Occurrence of Dentinal Microcracks in Severely Curved Root Canals with ProTaper Universal, WaveOne, and ProTaper Next File Systems.

INTRODUCTION: This study aims to compare the incidence of dentinal microcracks produced by the ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland), WaveOne (Dentsply Maillefer), and ProTaper Next (Dentsply Maillefer) file systems during root canal procedures in severely curved canals using a dyeing technique. METHODS: Sixty extracted human molars with 25° to 40° root curvatures were divided into 3 groups of 20 canals each. ProTaper Universal, WaveOne, and ProTaper Next file systems were used for root canal procedures. Untreated root canals of 60 molars served as negative controls. After preparation, all roots were stained with 1% methylene blue for 24 hours. Roots were then sectioned at the most curved plane and 2 mm below and above the most curved plane with a low-speed saw under cold water. A stereomicroscope was used to inspect dentinal microcracks at 60× magnification, and differences between these 3 instrument groups were analyzed using the chi-square test. RESULTS: The ProTaper Next system induced less complete and incomplete dentinal microcracks compared with the ProTaper Universal and WaveOne systems (P < .05), and there were no significant differences between the ProTaper Universal and WaveOne systems (P > .05). The ProTaper Universal and WaveOne systems induced significantly more complete cracks in the plane 2 mm above the most curved plane compared with either of the other 2 planes (P = .004). CONCLUSIONS: The ProTaper Next system induces less dentinal microcracks during root canal procedures in severely curved root canals compared with the ProTaper Universal and WaveOne systems.

Bone morphogenetic protein 2-induced human dental pulp cell differentiation involves p38 mitogen-activated protein kinase-activated canonical WNT pathway.

Both bone morphogenetic protein 2 (BMP2) and the wingless-type MMTV integration site (WNT)/ß-catenin signalling pathway play important roles in odontoblast differentiation and dentinogenesis. Cross-talk between BMP2 and WNT/ß-catenin in osteoblast differentiation and bone formation has been identified. However, the roles and mechanisms of the canonical WNT pathway in the regulation of BMP2 in dental pulp injury and repair remain largely unknown. Here, we demonstrate that BMP2 promotes the differentiation of human dental pulp cells (HDPCs) by activating WNT/ß-catenin signalling, which is further mediated by p38 mitogen-activated protein kinase (MAPK) in vitro. BMP2 stimulation upregulated the expression of ß-catenin in HDPCs, which was abolished by SB203580 but not by Noggin or LDN193189. Furthermore, BMP2 enhanced cell differentiation, which was not fully inhibited by Noggin or LDN193189. Instead, SB203580 partially blocked BMP2-induced ß-catenin expression and cell differentiation. Taken together, these data suggest a possible mechanism by which the elevation of ß-catenin resulting from BMP2 stimulation is mediated by the p38 MAPK pathway, which sheds light on the molecular mechanisms of BMP2-mediated pulp reparative dentin formation.

Residual filling material in dentinal tubules after gutta-percha removal observed with scanning electron microscopy.

INTRODUCTION: In cases of failed root canal treatment, endodontic retreatment of the root canal system is necessary. The present study aimed to assess variation in the incidence and depth of residual filling material in dentinal tubules after gutta-percha removal with H-files, the ProTaper Universal System (Dentsply Maillefer, Ballaigues, Switzerland), and the SybronEndo K3 System (SybronEndo Corporation, Orange, CA). METHODS: Forty human mandibular premolars with single straight root canals were prepared with K-files (up to size 40) using the step-back technique and filled by cold lateral condensation with gutta-percha and AH Plus sealers (Dentsply DeTrey, Konstanz, Germany). After 1 year, the 40 teeth were divided into one control group and 3 retreatment groups (n = 10 each). Gutta-percha was removed using H-files, the ProTaper Universal System, or the SybronEndo K3 System. The teeth were sectioned, and the incidence and depth of residual filling material in the dentinal tubules were measured under scanning electron microscopy. RESULTS: The depth of filling material in the dentinal tubules did not differ significantly among groups (P > .05). Residual filling material was present in significantly more dentinal tubules in the ProTaper (P = .043) and K3 groups (P = .001) than in the H-file and control groups. CONCLUSIONS: The ProTaper Universal System and the SybronEndo K3 System left filling material in a greater proportion of dentinal tubules than did H-files.

TNF receptor-associated factor 6 suppression inhibits inflammatory response to Porphyromonas gingivialis in human periodontal ligament cells.

OBJECTIVE: Periodontitis is a group of inflammatory diseases caused by microorganisms. Porphyromonas gingivalis, a gram-negative bacteria, is strongly associated with the onset of periodontitis. Tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6) represents an important target in the regulation of many disease processes, including immunity, inflammation, and osteoporosis. The aim of this study was to investigate the role of TRAF6 for inflammatory response in P gingivalis-infected human periodontal ligament cells (HPDLCs). METHOD AND MATERIALS: HPDLCs were stimulated with 1 x 108 CFU/mL P gingivalis, or 10 ug/mL P gingivalis lipopolysaccharide (LPS), separately in the absence or presence of small interfering RNA (siRNA) for TRAF6. The expression of TRAF6 was examined by real-time polymerase chain reaction and Western blot analysis. Concentrations of IL-1B, IL-6, and IL-8 in the culture supernatants were determined by enzyme-linked immunosorbent assay (ELISA). RESULTS: In this study, we found that both P gingivalis and its LPS treatment increased the expression of TRAF6 and proinflammatory cytokine production in HPDLCs. In addition, we used siRNA for TRAF6, and the inhibition of TRAF6 expression reduced the production of proinflammatory cytokines in HPDLCs stimulated with P gingivalis and its LPS. CONCLUSION: The results suggested that TRAF6 may be a key molecule to control proinflammatory cytokine production induced by P gingivalis and its LPS. TRAF6 suppression may inhibit inflammatory responses in HPDLCs infected by P gingivalis and its LPS.

Detection of vertical root fracture using cone beam computed tomography: report of two cases.

Vertical root fractures (VRFs) often occur in endodontically treated teeth and in patients older than 40 years of age. However, VRFs in teeth without endodontic treatment are relatively uncommon. VRFs are difficult to diagnose as the symptoms are non-specific or often delayed. The most common radiographic findings are thickening of the periodontal ligament, deep, localized, vertical bone loss, and localized periradicular bone loss. The explicit feature for detecting VRFs is direct visualization of a radiolucent fracture line on radiographs. However, the fracture line can be difficult to directly visualize in conventional diagnostic methods such as periapical radiographs. If unrecognized, VRFs can lead to frustration and inappropriate endodontic treatment. The two cases reported here demonstrate that the use of cone beam computed tomography (CBCT) successfully diagnoses VRFs on teeth without representative clinical and periapical radiographic findings. The clear fracture line can be discerned from the images of CBCT. Thus, CBCT imaging is useful in rapid diagnosis of VRFs and designing of further treatment.

Evaluation of x-ray projection angulation for successful radix entomolaris diagnosis in mandibular first molars in vitro.

INTRODUCTION: The aim of this study was to evaluate the radiographic features of permanent three-rooted mandibular first molars with radix entomolaris (RE), investigate the correlation between anatomical classification and radiographic type of RE, and to determine the most effective horizontal beam angulation for the diagnosis of RE. METHODS: Twenty-five extracted mandibular first permanent molars with RE were selected for taking radiographs in 7 horizontal angulations. By using set criteria, 3 evaluators assessed morphologic and radiographic features of the RE and optimum beam angulation for RE diagnosis. Intraexaminer variability was analyzed with Cohen kappa test. RESULTS: Three types of curvature of RE presented with 3 distinct types of typical radiographic appearance on orthoradial radiographs. We classified the radiographic features of RE into 3 types, as follows: type i, type ii, and type iii. Seven teeth showed type i radiographic features. Zero-degree, 5-degree, 15-degree, and 25-degree radiographs were significantly better than the mesially angulated -15-degree and -25-degree images for detecting the type i RE images (P < .05). Fifteen-degree, 25-degree, and -25-degree horizontal beam angulations showed significantly more accurate diagnoses of RE in 8 type ii images (P < .05). Only 25-degree-angled radiographs were found to have a high diagnostic yield of type iii RE images (P < .05). A significant correlation was found between morphologic and radiographic types of RE (P < .05, contingency coefficient = 0.473). Intraexaminer variability was low, with kappa = 0.68 (P < .05). CONCLUSIONS: RE presents 3 types of typical radiographic features on orthoradial radiographs. Additional 25-degree mesial horizontal-angled radiographs are essential for preoperative identification and evaluation of RE, especially types ii and iii.

[Strategies of endodontic infection control].

Microbe infection is not only the key pathogenic factor of primary endodontic infectious diseases, but also the arch-crimina of endodontic treatment fail. Therefore, the endodontic treatment success is based on the debridement of infectious root canal, elimination of bacteria, and the prevention of endodontic reinfection. It is beset with difficulties to control the endodontic infection in clinic because of the bacterial variety, anatomic complexity of root canal, and limitation of the root canal therapeutic methods. In order to get the ideal prognosis of the root canal treatment, in the procedure of the therapy, it should be the tight isolation of tooth, reasonable choose of the root canal preparation technique, rational use of root canal preparation instrument, effective irrigation of root canal, proper root canal dressing, and the 3-dimensional obturation of root canal.

Tooth anatomy risk factors influencing root canal working length accessibility.

The aim of this study was to analyze the specific influence of root canal anatomy on the accessibility of working length during root canal therapy. Four hundred seventy-six root canal therapy cases (amounting to a total of 1 005 root canals) were examined. The anatomy risk factors assessed in each case included: tooth type (tooth location), root canal curvature, and root canal calcification, as well as endodontic retreatment. The investigation examined the correlation between each of these anatomic factors and the working length, with statistical analysis consisting of Chi-square tests and multiple logistic regression analysis. In an independent factor analysis, tooth type (tooth location), root canal curvature, canal calcification, and endodontic retreatment were determined to be the primary risk factors. In a multiple-factor regression model, root curvature and canal calcification were found to most significantly influence root canal working length accessibility (P<0.05). Root canal anatomy increases the difficulty of root canal preparation. Appropriate consideration of tooth anatomy will assist in accurate determination of preparation difficulty before instrumentation. This study alerts clinical therapists to anatomical factors influencing the working length accessibility, and allows for a direct estimate of success rate given in situ measurements of tooth factors during the root canal treatment procedure.

[The clinical analysis on the effects of different difficulty in root canal preparation].

OBJECTIVE: To investigate the effects of root canal preparation treated by endodontists of different levels in different difficulty associated with the root canal anatomy factors. METHODS: Totally 422 teeth with 901 root canals were randomly selected from the Conservative Dentistry Department, West China Stomatology Hospital, and these teeth were respectively treated by junior specialist postgraduates, senior specialist postgraduates and endodontic specialists. Grading criteria of root canal risk factor and root canal therapy difficulty assessment were found based on 6 items: Tooth type, working length, root curvature, calcification, number of canals, and the previous endodontic treatment. The effects of root canal preparation with different difficulty in different groups were analyzed with RxC Chi-square test. RESULTS: Success rates of root canal preparation in junior group and senior group during three difficulty groups were statistically different (P < 0.05), and the root canal therapy difficulty group I > group II > group III. The operator factors in root canal therapy difficulty group I and group II were not significantly different P > 0.05). But in root canal therapy difficulty group III, the endodontic specialist group have highest success rate in root canal preparation. CONCLUSION: The cases of root canal treatment should be treated by endodontist of corresponding level according to the difficulty. In difficult cases, endodontic specialist can provide better root canal preparation result.

[Isolation and identification of side population cells in human lung adenocarcinoma cell line A549].

OBJECTIVE: To isolate and characterize the side population cells (SP cells) in the lung adenocarcinomas cell line A549. METHODS: The protein expression of ABCG2 in human lung adenocarcinoma cell line A549 was detected by immunohistochemistry. SP and NSP cells in the cell line A549 were isolated by FACS, and their differentiation was analysed. ABCG2 expression in the two cell subsets was detected by RT-PCR. The cell growth curves, cell division indexes, cell cycles, plate clone formation tests, migration and invasion assays, chemotherapeutic susceptibility tests, tests of the intracellular drug levels, and the tumor cell implantation experiments on nude mice were applied to study the biological properties of the two cell subsets. The expression of ABCG2 in the transplanted tumor in nude mice was detected by immunohistochemistry and RT-PCR. RESULTS: The positive rate of ABCG2 expression in the A549 cells by immunohistochemistry was 2.13%. SP and NSP cells were isolated by FACS. The SP cells could produce both SP and NSP cells, while NSP cells only produced NSP cells. SP cells expressed ABCG2, but NSP cells did not. The proliferation and migration abilities of the two cell subsets were similar, but the invasion and tumorigenic ability of SP cells was significantly higher than that of NSP cells. The susceptibilities to DDP and its intracellular levels of the two cell subsets were similar, but the susceptibilities to 5-FU, VP16, NVB and GEM and their intracellular levels of NSP cells were significantly higher than those of the SP cells. CONCLUSIONS: SP cells in the human lung adenocarcinomas cell line A549 is enriched with tumor stem cells. An effective way to get lung adenocarcinomas stem cells is to isolate SP cells by FACS.

Expression of TRAF6 and pro-inflammatory cytokines through activation of TLR2, TLR4, NOD1, and NOD2 in human periodontal ligament fibroblasts.

OBJECTIVE: Human periodontal ligament fibroblasts (HPDLFs) play a crucial role in protecting against oral bacteria in periapical tissue. Toll-like receptors (TLRs) and nucleotide-binding oligomerization domain (NOD) are two major forms of innate immune sensors that recognize microbial pathogens and initiate pro-inflammatory signalling. Tumour necrosis factor receptor-associated factor 6 (TRAF6) is an adapter protein for TLR-mediated nuclear factor-κB (NF-κB) signalling pathway activation that induces the production of pro-inflammatory cytokines. The aim of this study was to investigate the expression of TLR2, TLR4, NOD1, and NOD2 in HPDLFs. We also investigated the expression of TRAF6 and pro-inflammatory cytokines induced by the activation of TLRs and NODs. METHODS: The expression of TLR2, TLR4, NOD1, and NOD2 was measured by reverse transcription-polymerase chain reaction (RT-PCR), flow cytometry, and immunostaining. HPDLFs were stimulated with TLR and NOD agonists. Then, the expression of TRAF6 was measured by real-time PCR and western blot. Concentrations of IL-1ß, IL-6, and IL-8 in the culture supernatants were determined by enzyme-linked immunosorbent assay (ELISA). Finally, by using small interfering RNA (siRNA) for TRAF6, we analysed the production of IL-1ß, IL-6, and IL-8 in HPDLFs upon stimulation with TLRs and NODs agonists. RESULTS: We found clear mRNA and protein expression of TLR2, TLR4, NOD1, and NOD2 in HPDLFs. The expression levels of TRAF6 and pro-inflammatory cytokines (IL-1ß, IL-6, and IL-8) were markedly up-regulated upon the activation of TLRs and NODs. Furthermore, the co-activation of TLRs and NODs had synergistic effect on the production of TRAF6 and pro-inflammatory cytokines. We also found TRAF6 suppression resulted in reduced IL-1ß, IL-6, and IL-8 expression upon TLR and NOD agonists challenge. CONCLUSION: These findings indicated that TLR2, TLR4, NOD1, and NOD2 are functional receptors in HPDLFs during innate immune responses to invading bacteria, and a combination of signalling through TLRs and NODs leads to the synergistic enhancement of inflammatory reactions in HPDLFs. In addition, TLR and NOD signalling involving TRAF6 contribute to inflammatory responses in HPDLFs.

[Maxillary second molar with curved single root and single canal: a case report].

Incidence rate of single root canal in maxillary second molar is very low. The emergence of curved single root canal in maxillary second molar with single root is especially rare. A case of curved single root canal in maxillary second molar with single root was successfully treated and reported in this article. This report also highlighted the role of cone beam computed tomography as an objective method to confirm the three-dimensional anatomy of teeth.