Research on determining the safe mining depth in special geological conditions of Mong Duong coal mine

The displacement and deformation of strata due to underground mining is one of the factors that negatively affect the safety of production activities. The strata displacement and deformation depend on many factors such as mining geological conditions, safe mining depths, and mining technologies. The determination of the safe depths is important for calculating the size of safety pillars to minimize mineral loss. To date, there have been many studies to determine safe mining depths under normal geological conditions. However, not much research has been conducted to determine safe mining depths with special geological conditions such as many folds, breaks, faults, and under water-bearing objects. This research introduces a method to determine the safe mining depths for the reservoir set in special geological conditions with folds and excavating several seams under water bodies. The proposed method employs the principle of the similar geological zone theory to calculate the safe mining depths. The method is applied to the Mong Duong coal mine, with three coal seams numbered 5, 6, and 7 with the depth of 210, 180, and 136 m, respectively. The results of mining depths safe obtained H5= 240m, H6 =192m, H7= 136m, respectively.

Bisphosphonates prevents the bone mineral loss in lymphoma patients treated with glucocorticoids: a prospective, randomized controlled phase 3 trial in China

Background Glucocorticoids-containing regimens are the standard first line treatment for most lymphoma patients, however, as the improvement of overall survival in these cases, glucocorticoids related osteopenia or osteoporosis attracted attention in clinical administration. We aim to investigate the efficacy of bisphosphonates in prevention bone mineral loss in glucocorticoids-treated lymphoma patients. Methods This is a prospective, randomized controlled phase 3 trial. Eligible lymphoma adults from China with first line glucocorticoids involved treatment, were randomly assigned 1:1 to receive either Zoledronic acid (ZA) for twice infusion or not. All patients received daily oral calcium and vitamin D3 for one year. The primary endpoint, alternations of bone mineral loss from enrollment to the twelfth month at the lumbar spine (L1-L4), left hip and left femoral neck, measured by the dual-energy, x-ray absorptiometry scanners, recorded as T score; and new bone fractures during the first year, were analyzed by intent-to-treat. This trial was registered with www.Chictr.org, number ChiCTR-INR-17010771. Results Between May, 2016 to July, 2019, 84 patients were randomly assigned to both Zoledronic acid and control groups, 29 patients completed the study and were on follow-up. We found a marked improvement of T score in ZA group compared with the control in a year at lumbar spine, T score changes of L1-4 in ZA group and control group were as following: L1, 0.14±0.61 vs. -0.33±0.40, p=0.009; L2, 0.28±0.41 vs. -0.35±0.54, p=0.003; L3, 0.23±0.42 vs. -0.23±0.66, p=0.020; L4, 0.28±0.44 vs. -0.35±0.54, p=0.020. Meanwhile, no severe adverse event was observed on both groups. Conclusions Glucocorticoids-treatment lymphoma patients that prophylactic ZA infusion could relieve BMD loss to prevent osteoporosis without increasing severe adverse effects in Chinese population, providing reference for clinicians to consider ZA application in this situation.

Effect of Strontium-Doped Bioactive Glass on Preventing Formation of Demineralized Lesion

This study investigated the effect of strontium-doped bioactive glass (SBAG) on the formation of dental demineralized lesions. Materials and methods: The study materials were 48 sound human tooth specimens with both dentine and enamel, divided equally into four groups: Group 1 (SBAG), Group 2 (SBAG+Fluoride), Group 3 (Fluoride), and Group 4 (Water as control). After 14 days of pH cycling, the surface morphology of the specimens was observed by scanning electron microscopy. Crystal characteristics of the precipitates were assessed by X-ray diffraction (XRD). Micro-CT was used to measure the mineral loss and the depths of the demineralized lesions formed. Results: Exposure of collagen in inter-tubular areas in dentine was seen in the control group (Group 4) but not in Groups 1 to 3. In Group 2, there were obvious granular particles on the surface of the dentine. XRD revealed precipitation of apatites on the surface of the tooth specimens in Groups 1 to 3. The mean lesion depths in dentine were 81.80 μm, 30.68 μm, 39.04 μm, and 146.36 μm in Groups 1 to 4, respectively (p < 0.001). Lesions in enamel were only found in the control group. The mean mineral loss values in the dentine lesions were 1.25 g/cm3, 0.88 g/cm3, 0.87 g/cm3, and 1.65 g/cm3, in Groups 1 to 4, respectively (p < 0.001). Conclusion: Strontium-doped bioactive glass has a preventive effect on the formation of demineralized lesions in enamel and dentine.

In vitro effect of experimental nanocomposites solutions on the prevention of dental caries around orthodontic brackets

This study aimed to evaluate the in vitro effect of a single application of experimental nanocomposite solutions on the prevention of dental caries around orthodontic brackets. The specimens were exposed to mesoporous silica (MS) nanocomposites containing fluoride by association with titanium tetrafluoride (TiF4) or sodium fluoride (NaF). Nanocomposites also could contain calcium and groups were described as MSCaTiF4, MSTiF4, MSCaNaF, MSNaF, and controls (TiF4, and NaF). Specimens were subjected to the formation of a multispecies biofilm to generate a cariogenic challenge. After 24h, both pH and total soluble fluoride concentration of the culture medium were assessed. Mineral loss was evaluated by percentage of surface mineral loss (%SML), mineral volume variation (ΔZ) of inner enamel and polarized light microscopy (PL). Linear (Ra) and volumetric (Sa) surface roughness and scanning electronic microscopy (SEM) were used to assess enamel topography. Statistical analyses were conducted considering p<0.05. MSNaF had the highest value of culture medium pH after cariogenic challenge, similarly to MSTiF4. All nanocomposite solutions released less fluoride than their controls NaF and TiF4 (p<0.05). All nanocomposite solutions presented lower %SML compared to their respective control groups (p<0.05). Lower Ra, Sa and ΔZ were observed for experimental groups compared to TiF4 (p<0.05). The results were confirmed by PL and SEM analysis. The experimental nanocomposite solutions contributed for lower enamel demineralization around orthodontic brackets.

AB0133 LATE-ONSET AND BONE LOSS IN RHEUMATOID ARTHRITIS: WHAT FACTORS SHOULD WE CONSIDER?

Background:Rheumatoid arthritis (RA) is an inflammatory rheumatism that causes alterations in bone components through the increased production of pro-inflammatory cytokines. Besides traditional risk factors of osteoporosis (OP), elderly RA patients are at higher risk of progressive decline in bone mineral density resulting from the disease.Objectives:This study aimed to determine factors associated with bone loss in late-onset RA patients.Methods:A cross-sectional study including patients with RA (according to ACR/EULAR classification criteria) in whom disease onset was after age 65 years. Sociodemographic data, daily calcium intake, and menopausal state were recorded. The characteristics of the disease were transcribed, including inflammatory markers (erythrocyte sedimentation rate (ESR) and C- reactive protein (CRP)), the disease activity assessed by Disease Activity Score 28 (DAS28), seropositivity for anti-cyclic citrullinated peptide antibody (ACPA) and rheumatoid factor (RF), and treatment modalities (cumulative dose of corticosteroids and Methotrexate). Bone mineral density (BMD) was assessed by Dual-energy X-ray absorptiometry. The risk of hip fracture (HF) and major osteoporotic fracture (MOF) after ten years were assessed using the fracture risk assessment tool (FRAX). Patients were divided into two groups (G1 with bone mineral loss (BML) and G2 without BML). Statistical analysis was performed using Kruskal-Wallis Test and chi-square. The level of significance was fixed for p< 0.05.Results:The study included 58 late-onset RA patients with a female predominance (sex ratio M/F=0.3). The mean age was 71.6 ± 5.9 years [65-85], and the mean disease duration was 3.1 ±2.9 years [0-15]. The mean calcium intake was 416.4± 168.6 mg per day [168-1043]. The mean BMD was 1.5 g/cm2[0.1-28.3] at the vertebral site and 0.7±0.2 g/cm [-0.1,1.2] at the femoral site. Bone loss was found in 55.2% of cases and was significantly associated with age (p=0.022) and longer disease duration (p=0.015). Similarly, there was a positive correlation between CRP and BML (p=0.023). However, bone loss was not correlated to sex (p=0.865), RF and ACPA positivity (p=0.9, p=0.1 respectively), or to coxitis (p=1). Similarly, disease activity, body mass index, and calcium intake were comparable between the two groups (p=0.311, p=0.179, p=0.099, respectively). G1 had a higher incidence of fractures without reaching a statistically significant correlation (63.2% in G1 and 51.3% in G2, p=0.393). Also, G1 had a higher risk of MOF (p=0.003) but not with a higher risk of HP (p=0.127). Regarding treatment modalities, the BML was significantly correlated to non-steroidal anti-inflammatory drug (NSAIDs) intake (85.7% in G1 and 37.8% in G2, p=0.001), but was not correlated to the cumulative dose of corticosteroids (p=0.384) and Methotrexate (p=0.054).Conclusion:Our study showed that age, disease duration, NSAIDs, and inflammation were risk factors for a bone mineral loss in late-onset RA. Screening for these factors would be useful as part of an ideal form of fracture risk management.Disclosure of Interests:None declared

Secondary Caries Adjacent to Bulk or Incrementally Filled Composites Placed after Selective Excavation In Vitro

Objectives: selective caries excavation (SE) is recommended for deep carious lesions. Bulk fill composites (BF) may be considered to restore SE-cavities. We compared the susceptibility for secondary caries adjacent to BF versus incrementally filled composites (IF) in SE and non-selectively excavated teeth (NS) in vitro. Methods: in 72 extracted human premolars, artificial caries lesions were induced on pulpo-axial walls of standardized cavities. The lesions were left (SE) or removed (NS), and teeth were restored using two BF, GrandioSO x-tra/Voco (BF-Gra) and SDR/Dentsply (BF-SDR), and an IF, GrandioSO/Voco (IF-Gra) (n = 12/group for SE and NS). After thermo-mechanical cycling (5–55 °C, 8 days), teeth were submitted to a continuous-culture Lactobacillus rhamnosus biofilm model with cyclic loading for 10 days. Mineral loss (ΔZ) of enamel surface lesions (ESL), dentin surface lesions (DSL), and dentin wall lesions (DWL) was analyzed using transversal microradiography. Results: ΔZ was the highest in DSL, followed by ESL, and it was significantly lower in DWL. There were no significant differences in ΔZ between groups in DSL, ESL, and DWL (p > 0.05). Regardless of lesion location, ΔZ did not differ between SE and NS (p > 0.05). Conclusions: BF and IF both showed low risks for DWL (i.e., true secondary caries) after SE in vitro, and surface lesion risk was also not significantly different between materials. SE did not increase secondary caries risk as compared with NS. Clinical Significance: the risk of secondary caries was low after selective excavation in this study, regardless of whether bulk or incrementally filled composites were used

Association of Bone Mineral Density to Cerebral Small Vessel Disease Burden

ObjectiveTo test the hypothesis that bone mineral loss is mechanistically related to cerebral small vessel disease (SVD), we investigated the relationship between bone mineral density and the prevalence and intensity of SVD among patients with stroke.MethodsWe analyzed data of 1,190 consecutive patients with stroke who were >50 years of age and underwent both brain MRI and dual-energy x-ray absorptiometry from the stroke registry of Chung-Ang University Hospital in Seoul, Korea. The patients were categorized into 3 groups according to their bone mineral density (normal, osteopenia, and osteoporosis). White matter hyperintensities, silent lacunes, cerebral microbleeds, and extensive perivascular space were assessed from brain MRI. Multinomial logistic regression model was used to examine the association between osteoporosis and total SVD score. We also recruited 70 patients with stroke to study serum bone turnover markers and microRNAs related to both cerebral atherosclerosis and bone metabolism to understand bone and brain interaction.ResultsOsteoporosis was determined among 284 patients (23.9%), and 450 patients (37.8%) had osteopenia. As bone mineral density decreased, total SVD score and the incidence of every SVD phenotype increased except strictly lobar cerebral microbleeds. Multinomial logistic regression analysis showed that osteoporosis was independently associated with severe SVD burden. The levels of microRNA-378f were significantly increased among the patients with osteoporosis and maximal total SVD score and positively correlated with parathyroid hormone and osteocalcin.ConclusionsThese findings suggest a pathophysiologic link between bone mineral loss and hypertensive cerebral arteriolar degeneration, possibly mediated by circulating microRNA.

The Evaluation of Different Treatments of Incipient Caries Lesions: An in Situ Study of Progression Using Fluorescence-based Methods

Clinical Relevance Effective methods to control incipient caries lesions are needed. In this investigation, several methods provide encouraging results. SUMMARY This study aimed to evaluate in situ the inhibition of incipient caries lesion progression using different treatment protocols and to evaluate the effectiveness of fluorescence-based methods (DIAGNOdent, DIAGNOdent pen, and VistaProof fluorescence camera [FC]) in monitoring this process. The research was conducted in four phases: (1) at baseline, (2) after a first cariogenic challenge, (3) after treatment modalities, and (4) after a second cariogenic challenge. Sixteen volunteers used intraoral acrylic palatal appliances, each containing six enamel blocks (n=96). The cariogenic challenge was performed using a 20% sucrose solution over a 14-day period. The appliances were removed eight times a day and, upon removal, two drops of the solution were placed onto each enamel block. The enamel blocks were randomly assigned to three treatment groups: fluoride varnish ([FV] Duraphat; n=32), resin infiltrant ([RI] Icon; n=32), and adhesive system ([AS] Scotchbond; n=32). At the end of each phase, the surface microhardness (SMH) was measured, and two trained examiners evaluated the specimens using fluorescence-based methods. In addition, integrated mineral loss (ΔΔZ; vol%.min x μm) and lesion depth (ΔLD; μm) were evaluated using transverse microradiography. A two-way analysis of variance and a Tukey post hoc test were calculated (α=5%). Significant differences in SMH were observed according to the treatment, phases, and interaction of factors (p&lt;0.001). Treatment with FV resulted in significantly higher SMH values in phases 3 and 4 compared to RI and AS, with the last two treatments resulting in similar values (p&gt;0.05). The ΔΔZ value was similar for FV and AS but significantly higher for RI (p=0.016). ΔLD was not significantly different among the groups (p=0.126). Significant differences in the measurement of fluorescence for each fluorescence-based method were observed between each phase of the study (p&lt;0.05). It can be concluded that all treatments were effective in inhibiting the in situ progression of incipient lesions, although to different degrees, with minor mineral loss changes observed for the AS and FV. Besides, all fluorescence-based methods tested, except for that using the FC device, were effective in monitoring caries lesion progression.