Mechanical behavior and reloading reinforcement characteristics of fractured coal under low confining pressure.

To study the basic mechanical behavior and the reloading reinforcement characteristics of fractured coal, conventional triaxial loading tests with different fissure angle were first carried out. On this basis, conventional triaxial loading and unloading tests were conducted to investigate the reloading reinforcement characteristics of fractured coal. The results reveal that when the fissure angle was small, the stress-strain curve exhibited the multi-peak phenomena. As the fissure angle increased, the stress drop phenomenon in the peak region was weakened. With the increase of the fissure angle, the peak stress of the specimens increased and then decreased, while the elastic modulus showed an overall increasing trend, demonstrating the controlling effect of the crack angle. Meanwhile, the cyclic loading exhibited a certain enhancement effect on the strength of the fractured coals when the specimens was unloaded near the crack closure stress. The findings can provide a better understanding of the failure mechanism and reloading reinforcement characteristics of fractured coal.

Derivation of a Risk Score for High Caries Risk in 3- to 5-year-old Children in Sichuan Province.

PURPOSE: To explore potential caries risk indicators in 3- to 5-year-old children, and develop a simple risk-score model to screen the children at high risk of caries with decayed, filled, and missing teeth (dmft) > 2. MATERIALS AND METHODS: A cross-sectional study involving 2746 children 3 to 5 years of age was conducted in Sichuan province. Children were examined for dmft index, and sociodemographic and behavioural factors were acquried through a questionnaire completed by their caregivers. A prediction model was developed by backward multivariate logistic regression, and its overfitting degree was examined with 5-fold cross-validation. A simple risk-score model was derived to screen the children with dmft > 2 at high risk of caries with the ß regression coefficient obtained from the multivariate regression model. RESULTS: A child's oral health status was identified as the highest risk indicator with a ß regression coefficient of 1.093. The mean area under curve (AUC) from the 5-fold cross-validation was 0.7408 (95% CI: 72.21%, 75.95%), with a bias of only ca 1%. This result allowed us to eliminate substantial overfitting of the prediction model. The AUC of the risk scoring system was 0.7455 (95% CI: 72.70%, 76.40%), which indicated good screenability. CONCLUSIONS: This risk score model has the advantages of simplicity, low cost and relatively high accuracy, and is suitable for use in developing countries, especially for primary screening for high risk of caries. It shows that certain child behaviours and parental attitude play an important role in dental caries among preschool children.

Evaluation of the effect of a toothpaste containing Pudilan extract on inhibiting plaques and reducing chronic gingivitis: A randomized, double-blinded, parallel controlled clinical trial.

ETHNOPHARMACOLOGICAL RELEVANCE: Pudilan is a famous traditional Chinese medicine compound which contains several Chinese herbal ingredients, and has been wildly used to treat a variety of inflammatory diseases in China. Recently, it was reported that Pudilan extract had been used in the oral field, especially in the treatment of minor oral ulcers for its anti-inflammatory, pain relieving, antibacterial, clearing heat, and detoxifying effects. AIM OF THE STUDY: To evaluate the effectiveness and safety of Pudilan extract-containing toothpaste in controlling plaques and reducing chronic gingivitis. MATERIALS AND METHODS: A total of 120 patients with chronic gingivitis were randomized into an experiment group and a control group (n = 60 patients per group) based on a double-blinded method. Patients in the experiment group used a Pudilan extract-containing toothpaste, whereas patients in the control group used a Pudilan toothpaste simulator, which were identical as the toothpaste used by the experiment group, except for not containing the Pudilan extract. The Plaque Index (PI), Gingival Index (GI), Bleeding Index (BI), and Bleeding On Probing proportion (BOP%) were recorded at baseline, 4 weeks, 8 weeks and 12 weeks after using the toothpaste. RESULTS: After using the toothpaste for 8 and 12 weeks, PI, BI, GI, and BOP% of the experiment group were significantly lower when compared to the control group (both p < 0.001). Moreover, after using the toothpaste for 4, 8, and 12 weeks, the decline of the PI and GI in the experiment group were significantly higher than the control group (p < 0.001, except 4weeks PI p = 0.011). After 12 weeks, the PI of the experiment group decreased 35.73% (p < 0.001) whereas the GI decreased 29.04% (p < 0.001). BI and BOP decline rates were statistically significant when compared to those of the control group at 8 and 12 weeks (both p < 0.001). Moreover, at 12 weeks, the BI of the experiment group decreased 34.33% (p < 0.001) and BOP% decreased 54.71% (p < 0.001). CONCLUSION: Toothpaste with Pudilan extract demonstrated good effect on relieving symptoms of chronic gingivitis by inhibiting plaque formation, reducing gingival inflammation and the degree of bleeding, and the bleeding rate. Toothpaste containing Pudilan extract has prospective application potentials in the prevention and treatment of chronic gingivitis.

Dental Caries in Chinese Elderly People: Findings from the 4th National Oral Health Survey.

OBJECTIVE: To investigate the dental caries status and related factors in Chinese elderly people, using data from the 4th National Oral Health Survey of China. METHODS: In this cross-sectional study, a multistage, cluster strategy was used to recruit 4,431participants (2,222 male and 2,209 female) aged 65 to 74 years from all 31 provinces, autonomous regions and municipalities of the mainland of China. The survey was performed according to the diagnostic standard proposed by the World Health Organization (WHO). Socio-demographic information was collected with a closed questionnaire. RESULTS: The caries prevalence in 65 to 74-year-olds was rather high; the report shows it was 98.0% (DMFT ≥ 1) among elderly people in China. The mean DMFT, DT, MT and FT was 13.33 ± 9.32, 3.33 ± 4.17, 9.50 ± 8.66 and 0.49 ± 1.41, respectively. The filling rate was very low, assessed as 12.8%. The number of DMFT related to gender, residential district type, educational level, level of annual household income, toothbrushing frequency, consumption frequency of desserts, attitudes to oral health and oral health-related knowledge. CONCLUSION: The prevalence of dental caries in Chinese elderly people is rather high and a lot of decayed teeth still need to be filled and suitable prevention and treatment for this group is urgently needed.

How Root Caries Differs between Middle-aged People and the Elderly: Findings from the 4th National Oral Health Survey of China.

OBJECTIVE: To investigate the differences in distribution of root caries and related factors between middle-aged and elderly people in China. METHODS: In this cross-sectional study, a multistage, cluster strategy was used to recruit 4,410 participants (2,197 males and 2,213 females) aged 35 to 44 years and 4,431 participants (2,222 males and 2,209 females) aged 65 to 74 years from all 31 provinces, autonomous regions and municipalities of the mainland of China. The survey was conducted according to the basic methods proposed by the World Health Organization (WHO). Sociodemographic information, oral health behaviour, attitude and knowledge, history of dental prophylaxis and general health condition were collected with a closed questionnaire. RESULTS: A great increase in the occurrence of root caries in Chinese adults from 35 to 44-year-old to 65 to 74-year-olds, with the prevalence (DFR ≥ 1) from 25.4% to 61.9% and with the mean DFR score from 0.54 ± 1.34 to 2.63 ± 3.75. Filling rates were also very low, only 1.8% and 3.0%, respectively. Females and residents of rural areas were more likely to suffer from root caries. In both the middle-aged group and the elderly group, root caries related to gender, education level, sweet food/drinks consumption, oral health knowledge and status of root surface explosion. In 35 to 44 year olds, toothbrushing is a significant protection factor (OR = 0.88, 95%CI 0.81 ~ 0.96), while using toothpicks is a risk factor (OR = 1.06, 95%CI 1.02 ~ 1.10). In 65 to 74 year olds, not having dental had scaling in the past 12 months is a risk factor (OR = 1.66, 95%CI 1.09 ~ 2.53). CONCLUSION: Root caries among middle-aged people and elderly people in China have different risk factors and need more attention in future research to develop proper prevention.

The Regulator Gene rnc Is Closely Involved in Biofilm Formation in Streptococcus mutans.

Streptococcus mutans is an important factor in the etiology and pathogenesis of dental caries, largely owing to its ability to form a stable biofilm. Previous animal studies have indicated that rnc could decrease the amount of sulcal caries, and that the downregulation of cariogenicity might be due to its capacity to disrupt biofilm formation. However, the biofunctions by which rnc is involved in biofilm formation remain to be elucidated. In this study, we further investigate the role of rnc based on the study of mature biofilm. Scanning electron microscopy and the crystal violet assay were used to detect the biofilm forming ability. The production and distribution of exopolysaccharides within biofilm was analyzed by exopolysaccharide staining. Gel permeation chromatography was used to perform molecular weight assessment. Its adhesion force was measured by atomic force microscopy. The expression of biofilm formation-associated genes was analyzed at the mRNA level by qPCR. Here, we found that rnc could occur and function in biofilm formation by assembling well-structured, exopolysaccharide-encased, stable biofilms in S. mutans. The weakened biofilm forming ability of rnc-deficient strains was associated with the reduction of exopolysaccharide production and bacterial adhesion. Over all, these data illustrate an interesting situation in which an unappreciated regulatory gene acquired for virulence, rnc, most likely has been coopted as a potential regulator of biofilm formation in S. mutans. Further characterization of rnc may lead to the identification of a possible pathogenic biofilm-specific treatment for dental caries.

Molecular characterization and expression analysis of a novel r-spondin member (rspo2l) in Chinese tongue sole (Cynoglossus semilaevis).

Numerous studies suggest R-spondins (Rspos) plays a role in mammalian sex development and differentiation by activating WNT signaling pathways. However, Rspos are frequently less reported in teleosts. In this study, a molecular characterization and expression analysis was conducted with a new rspondin member in the Chinese tongue sole, rspondin2-like (rspo2l). The length of rspo2l cDNA is 1251 bp with 732 bp of coding sequence. A qRT-PCR analysis revealed that the transcription of rspo2l was distributed in various tissues, with high transcription levels in the liver, skin, and gills which might indicate a possible role in immunity. We next examined a time-course of transcription levels in four immune tissues (gill, liver, spleen, and kidney) after Vibrio harveyi challenge. It was found that rspo2l was up-regulated in the gills, spleen, and kidney and down-regulated in the liver, and the greatest responses occurred at 24 and 48 h after bacterial challenge. An assessment of ß-catenin, the key regulator of the canonical WNT signaling pathway, at different time points in four immune organs revealed that its transcription profile was similar to that of rspo2l after bacterial challenge. The results suggest that tongue sole rspo2l might play a role in immune responses after bacterial challenge, while the potential link with the WNT signaling pathway still requires further investigation. This is the first report about the involvement of rspondins in fish immune responses.

An in vitro study on the efficacy of removing calcium hydroxide from curved root canal systems in root canal therapy.

To compare the efficacy of various irrigants (citric acid, ethylenediaminetetraacetic acid (EDTA) and NaOCl) and techniques in removing Ca(OH)2 in two types of curved root canal systems, simulated root canals with specific curvatures were used to investigate the effects of different irrigants and instruments on Ca(OH)2 removal. The optimal methods were verified on extracted human teeth. Simulated root canals were assigned to one of two groups based on the irrigation solution: 10% citric acid or 2.5% NaOCl. Each group was divided into four subgroups according to the technique used to remove Ca(OH)2. The percentage of Ca(OH)2 removal in different sections of root canals was calculated. On the basis of the results obtained for the simulated canals, 10% citric acid and 17% EDTA were applied to remove Ca(OH)2 from the extracted human teeth with curved root canal systems. The teeth were scanned by micro computed tomography to calculate the percentage of Ca(OH)2 removal in the canals. In simulated root canals, we found that 10% citric acid removed more Ca(OH)2 than 2.5% NaOCl in the 0-1 mm group from the apex level (P<0.05). Ultrasonic and EndoActivator activation significantly removed more Ca(OH)2 than a size 30 K file in the apical third (P<0.05). However, there were no significant differences in any sections of the canals for 10% citric acid or 17% EDTA in removing Ca(OH)2 in extracted human teeth. We concluded that it was effective to remove residual Ca(OH)2 using the decalcifying solution with EndoActivator or Passive Ultrasonic Irrigation in a curved root canal system. A protocol for Ca(OH)2 removal was provided based on the conclusions of this study and the methods recommended in previous studies.

Oral health status in Sichuan Province: findings from the oral health survey of Sichuan, 2015-2016.

To investigate oral health status in the residents of Sichuan Province, southwest China, a cross-sectional study was performed using the latest Oral Health Survey Basic Methods recommended by the World Health Organization. A multistage stratified random cluster-sampling method was used to enroll participants from the following three groups: children aged 3-5 years, adolescents aged 12 years, and people aged 65-74 years. In these three groups, the mean numbers of teeth that were affected by caries were 3.28, 0.86 and 5.13, respectively, resulting in a prevalence of 63.47%, 37.20% and 83.20%, respectively. Relative to the high rate of decayed teeth, the prevalence of fillings was very low in all age groups (0.97%, 7.24% and 5.43%, respectively). In the 12-year-old adolescent group, only 3.61% had good pit and fissure sealing. In addition, the rate of dental fluorosis was 24.80%, and the Community Fluorosis Index value was 0.39. In the elder group, the community periodontal index was 2.92. The prevalence in the elderly of having lost at least one tooth was 75.54%. Additionally, 4.44% of these participants were edentulous. The incidence of dental prosthesis was 51.75%, the proportion with a removable partial denture, a fixed denture, full dentures, dental implants and an informal fixed bridge was 21.59%, 11.45%, 4.64%, 0 and 16.67%, respectively. In this study, 8.2% of the elderly participants were affected by different types of oral mucosal lesions. Among such lesions, recurrent aphthous ulcers were most prevalent (2.69%) and oral lichen planuses were second (1.6%). The conclusion presented in this survey is that oral diseases, especially dental caries and periodontal disease, are frequent and common in Sichuan province, China. Moreover, the treatment rate is very low, and primary prevention and treatment options are therefore urgently needed in this population.

CBCT-Aided Microscopic and Ultrasonic Treatment for Upper or Middle Thirds Calcified Root Canals.

Root canal calcification is considered a great challenge during root canal treatment. Although the application of ultrasonic instruments and dental operating microscope (DOM) has advantages, dealing with calcified root canals still suffers a great risk of failure because of limited information about the location, length, and direction of obliteration on periapical radiographs. In this work, a cone-beam computed tomography- (CBCT-) aided method aimed at solving complicated calcified root canals in which conventional approaches could not work was proposed. Thirteen teeth with sixteen calcified canals (12 calcified in the upper third, 4 calcified in the middle third), which cannot be negotiated with conventional methods, were treated with the aid of CBCT. The location of calcification and depth of instrumentation and operating direction were calculated and assessed in three dimensions with ultrasonic instruments under DOM. In all thirteen teeth, canals with upper and middle thirds calcification were treated successfully. Finally, a guideline was proposed to help achieve consistent apical patency in calcified canals.

The rnc Gene Promotes Exopolysaccharide Synthesis and Represses the vicRKX Gene Expressions via MicroRNA-Size Small RNAs in Streptococcus mutans.

Dental caries is a biofilm-dependent disease that largely relies on the ability of Streptococcus mutans to synthesize exopolysaccharides. Although the rnc gene is suggested to be involved in virulence mechanisms in many other bacteria, the information regarding it in S. mutans is very limited. Here, using deletion or overexpression mutant assay, we demonstrated that rnc in S. mutans significantly positively regulated exopolysaccharide synthesis and further altered biofilm formation. Meanwhile, the cariogenecity of S. mutans was decreased by deletion of rnc in a specific pathogen-free (SPF) rat model. Interestingly, analyzing the expression at mRNA level, we found the downstream vic locus was repressed by rnc in S. mutans. Using deep sequencing and bioinformatics analysis, for the first time, three putative microRNA-size small RNAs (msRNAs) targeting vicRKX were predicted in S. mutans. The expression levels of these msRNAs were negatively correlated with vicRKX but positively correlated with rnc, indicating rnc probably repressed vicRKX expression through msRNAs at the post-transcriptional level. In all, the results present that rnc has a potential role in the regulation of exopolysaccharide synthesis and can affect vicRKX expressions via post-transcriptional repression in S. mutans. This study provides an alternative avenue for further research aimed at preventing caries.

Scissors stab wound to the cervical spinal cord at the craniocervical junction.

BACKGROUND CONTEXT: Stab wounds resulting in spinal cord injury of the craniocervical junction are rare. A scissors stab wound to the cervical spinal cord has been reported only once in the literature. PURPOSE: This paper aimed to report a case of Brown-Séquard-plus syndrome in an 8-year-old boy secondary to a scissors stab wound at the craniocervical junction. STUDY DESIGN: Case report and review of the literature. PATIENT SAMPLE: Case report of an 8-year-old boy accidentally stabbed in the neck by scissors, which were thrown as a dart. METHODS: The case study of an 8-year-old boy who was hospitalized because of a scissors stab wound at the craniocervical junction. The patient developed Brown-Séquard-plus syndrome on the left side of the body. Magnetic resonance imaging revealed a laceration of the spinal cord at the craniocervical junction with cerebrospinal fluid leakage. Careful cleansing and interrupted sutures of the wounds were performed to prevent cerebrospinal fluid leakage. Rehabilitation therapy was performed 2 days later. RESULTS: A follow-up examination revealed complete recovery of the neurologic deficit 8 months post-injury. CONCLUSION: Treatment of scissors stab wounds to the cervical spinal cord, whether conservative management or thorough surgical exploration, should be individualized based on history, examination, and imaging. As shown in this case report, despite conservative management, complete recovery, which was unexpected, was attributed to the initial mild laceration of the spinal cord and ipsilateral spinal cord functional compensation.

Co-operative effect of exogenous dextranase and sodium fluoride on multispecies biofilms.

BACKGROUND/PURPOSE: The co-operative effect of exogenous dextranase (Dex) and sodium fluoride (NaF) on Streptococcus mutans monospecies biofilms is impressive. Here we investigated the effects of the combination on a mature cariogenic multispecies biofilm and analyzed the potential mechanism. MATERIALS AND METHODS: A multispecies biofilm of S. mutans, Lactobacillus acidophilus, and Actinomyces viscosus was established in vitro. Dex and NaF were added separately or together. The effects of the agents on the biomass were measured. The exopolysaccharide production was determined with the scintillation counting method. The viability and morphology were evaluated using colony forming unit and confocal laser scanning microscopy, respectively. RESULTS: In general, biofilms treated with Dex and a little concentration of NaF exhibited a lower biomass, exopolysaccharide production, and viability compared with the control group (P < 0.05). Confocal laser scanning microscopy using a vital fluorescence technique showed the combination treated biofilms appeared to be loose relatively and single cells could be observed. Furthermore, the thickness and viability were also lower than either of the separate agent groups (P < 0.05). CONCLUSION: Overall, these findings reveal that a combination of 1 U/mL Dex and 80 µg/mL NaF is a promising candidate for disrupting complex cariogenic multispecies biofilms. This feature may be in that Dex loses the structure of biofilms, thereby facilitating NaF penetration and enhancing its antibacterial effects.

[Effects of interaction of genotypes with environments on major latently fragrant substances of flue-cured tobacco in Baoshan of Yunnan, Southwest China].

To study the stability of major latently fragrant substances of flue-cured tobacco of different varieties in Baoshan of Yunnan, three tobacco cultivars (K326, Y87 and Y99) in two soil types at three test sites with different altitudes were tested. The contents of major latently fragrant substances were measured and the effects of genotypes, environments and their interactions were analyzed by AMMI model. The results showed that genotypes, environments and their interactions had significant effects on the contents of lutein, ß-carotene, and chlorogenic acid. The rutin content was mainly influenced by genotypes while the major latently fragrant substances and their stability were affected significantly by the interactions of genotypes and environments. The contents of lutein, ß-carotene, and chlorogenic acid increased remarkably with altitude, and their stabilities were strengthened to different extents. K326 adapted well to middle-lower altitude, while Y87 and Y99 adapted well to middle-higher altitude.

Effects of combined exogenous dextranase and sodium fluoride on Streptococcus mutans 25175 monospecies biofilms.

PURPOSE: To investigate the effects of exogenous dextranase and sodium fluoride on a S. mutans monospecies biofilm. METHODS: S. mutans 25175 was grown in tryptone soya broth medium, and biofilm was formed on glass slides with 1.0% sucrose. Exogenous dextranase and sodium fluoride were added alone or together. The biofilm morphology was analyzed by confocal laser scanning microscopy. The effects of the drug on the adhesion and exopolysaccharide production by the biofilms were evaluated by scintillation counting and the anthrone method, respectively. RESULTS: In this study, we found that the structure of initial biofilm and mature biofilm were partly altered by dextranase and high concentrations of sodium fluoride separately. However, dextranase combined with a low concentration of sodium fluoride could clearly destroy the typical tree-like structure of the biofilm, and led to less bacterial adhesion than when the dextranase or fluoride were used alone (P < 0.05). The amounts of soluble and insoluble exopolysaccharide were significantly reduced by combining dextranase with a low concentration of sodium fluoride, much more than when they were used alone (P < 0.05). These data indicate that dextranase and a low concentration of sodium fluoride may have synergistic effects against S. mutans biofilm and suggest the application of a low concentration of sodium fluoride in anticaries treatment.

[Effects of glycyrrhizic acid on the growth and acid-producing of Streptococcus mutans in vitro].

OBJECTIVE: To investigate the antibacterial activity of glycyrrhizic acid against Streptococcus mutans (S. mutans, ATCC 25175) in vitro. METHODS: The minimal inhibitory concentration (MIC) and the minimal bactericidal concentration (MBC) of glycyrrhizic acid against S. mutans were detected using doubling dilution. The effects of glycyrrhizic acid on the growth and acidogenic profile of S. mutans and the inhibition ratio of glycyrrhizic acid on growth and acid-producing of S. mutans were investigated by detecting the Abs of bacteria suspension and the pH value of medium at definite time intervals (0 h, 3 h, 7 h, 12 h, 23 h, 40 h) during cultivation. RESULTS: The MIC determined for glycyrrhizic acid was 1.57 mg/mL and there was no bactericidal effect when concentration of glycyrrhizic acid up to 12.5 mg/mL. The glycyrrhizic acid inhibited the multiplication and acid-producing of S. mutans significantly and the effects became stronger with concentration increasing. When concentration up to 1.57 mg/mL, the inhibition ratio of glycyrrhizic acid on the growth and acid-producing of S. mutans were exceeded 80 and 70 percent, respectively. CONCLUSION: The glycyrrhizic acid can inhibit the growth and acid-producing of S. mutans in vitro.

Efficacy of subdural saline injection during surgery for acute epidural haematomas.

PRIMARY OBJECTIVE: The purpose of this study was to investigate the efficacy of subdural space saline injection surgery in the management of large acute epidural haematomas (EDHs). METHODS AND PROCEDURES: Over a period of 6 years, the authors employed the technique of subdural space saline injection to facilitate elevation of dura after evacuation of supratentorial epidural haematomas. MAIN OUTCOMES AND RESULTS. Eighty patients with supratentorial epidural haematomas underwent the procedure. Infusion of saline in the subdural space not only helps elevation of the dura, facilitate haemostasis and application of suspension stitches during operation, it also avoids ICP fluctuations during the operations. Post-operative CT scans showed rapid disappearance of saline and reposition of cerebral structure. No patient required re-operation for residual haematoma. CONCLUSIONS: Subdural saline injection is an effective operative technique in the management of large epidural haematoma.