The Effect of Salinized Nano ZrO2 Particles on the Microstructure, Hardness, and Wear Behavior of Acrylic Denture Tooth Nanocomposite

The wear of acrylic denture teeth is a serious problem that can change the vertical dimensions of dentures. This study evaluates the effect of adding salinized nano ZrO2 particles on the microstructure, hardness, and wear resistance of acrylic denture teeth. Heat polymerizing polymethyl methacrylate resin was mixed with salinized ZrO2 at concentrations of 5 wt% and 10 wt%. Acrylic resin specimens without filler addition were used as a control group. SEM/EDS analyses were performed and the Vickers’ hardness was evaluated. Two-body wear testing was performed using a chewing simulator with a human enamel antagonist. After subjecting the samples to 37,500 cycles, both height loss and weight loss were used to evaluate the wear behavior. The microstructural investigation of the reinforced-denture teeth indicates sound nanocomposite preparation using the applied regime without porosity or macro defects. The addition of zirconium oxide nanofillers to PMMA at both 5% and 10% increased the microhardness, with values of up to 49.7 HV. The wear mechanism in the acrylic base material without nanoparticle addition was found to be fatigue wear; a high density of microcracks were found. The addition of 5 wt% ZrO2 improved the wear resistance. Increasing the nanoparticles to 10 wt% ZrO2 further improved the wear resistance, with no microcracks found.

Association of Body Compartment Shrinkage with Subsequent Health Care Utilization in Older Men

Both height loss and weight loss among the very old are associated with adverse health outcomes including fractures and mortality. However, it is not clear whether the associations between weight loss and health outcomes are attributable to specific compartmental (fat vs. fat-free) loss or whether they are attributable to overall shrinkage. Our objective was to estimate the associations of compartmental loss and height loss with subsequent total health care costs, acute hospitalizations, and skilled nursing facility (SNF) stays over a three-year follow-up period, adjusted for each other and important covariates (age, race, multimorbidity, IADL impairment, depressive symptoms, walk speed). Our analytic cohort was 1505 older men (mean [SD] age 79.3 [5.2] years) who attended the 3rd Osteoporotic Fractures in Men (MrOS) study visit (V3) and who were enrolled in Medicare Fee for Service (FFS). Annualized changes in fat-free and fat mass (measured with dual-energy x-ray absorptiometry) and height were assessed over a mean (SD) 6.8 (0.3) years prior to V3. Total health care costs, acute hospital stays, and SNF stays were ascertained during 3 years after V3 using linked Medicare FFS claims files. Fat-free mass loss (per SD) was associated with total health care costs (cost ratio 1.10, 95% CI 1.01, 1.19), but not with acute hospital or SNF stays. Fat mass loss and height loss were not associated with health care utilization outcomes after multivariable adjustment. Loss of fat-free mass is modestly associated with higher total health care costs after accounting for age, race, multimorbidity, and IADL impairment.

Risk Factors of New Vertebral Compression Fracture After Percutaneous Kyphoplasty or Vertebroplasty: A Retrospective Study of 752 Patients

Summary Irregularly postoperative anti-osteoporosis treatment (AOT), number of treated vertebrae (NTV) ≥ 2, bone mineral density (BMD) ≤－3.0 SDs, body mass index (BMI) <18.5kg/m2 or BMI ≥ 24kg/m2, vertebral height loss ratio (VHLR)＞20% were strong risk factors associated with new vertebral compression fractures (NVCF) after percutaneous vertebroplasty or kyphoplasty (PVP/PKP) in patients with osteoporotic vertebral compression fractures (OVCF). There was no difference between NVCF occurred adjacent or remote after PKP/PVP intervention.Introduction NVCF have been connected to PVP/PKP surgery for patients with VCF. There are some debates about whether new vertebral body fractures are simply a result of the natural progression of osteoporosis or whether they should be regarded as a consequence of augmentation. We tried to investigate and identify the risk factors which may be relevant to NVCF after PVP/PKP surgery in OVCF patients.Methods The authors retrospectively analyzed the occurrence of NVCF in 752 patients treated with PVP or PKP for OVCF. Possible risk factors, such as age, gender, refracture time (RT), AOT, NTV, BMD, BMI, and VHLR, were assessed.All methods are carried out in accordance with relevant guidelines and regulations.Results Significant differences (P<0.05) were found between the NVCF and control groups with regard to AOT, number of treated vertebrae, BMD, BMI, and VHLR by univariate analysis. And irregularly AOT, NTV ≥ 2, BMD ≤－3.0 SDs, BMI < 18.5 kg/m2 or BMI ≥ 24kg/m2, VHLR＞20% were found to be the significant factors in multivariate analysis. To evaluate a direct and more precise effect of the procedures on untreated vertebrae, the NVCF group was subdivided into adjacent and remote fracture groups. All of factors have no significant difference between two subgroups.Conclusion In the current study, the incidence of NVCF after PVP/PKP is 9.58%. Irregularly AOT, NTV ≥ 2, BMD ≤－3.0 SDs, BMI <18.5kg/m2 or BMI ≥ 24kg/m2, VHLR＞20% were strong risk factors associated with NVCF after PVP/PKP in patients with OVCF. There was no difference between NVCF occurred adjacent or remote after PKP/PVP intervention and that might be the result of the osteoporosis itself. All of those should be addressed during preoperative communication and postoperative management.

A new method for roadheader pick arrangement based on meshing pick spatial position and rock cutting verification

This paper proposes a cutting head optimization method based on meshing the spatial position of the picks. According to the expanded shape of the spatial mesh composed of four adjacent picks on the plane, a standard mesh shape analysis method can be established with mesh skewness, mesh symmetry, and mesh area ratio as the indicators. The traversal algorithm is used to calculate the theoretical meshing rate, pick rotation coefficient, and the variation of cutting load for the longitudinal cutting head with 2, 3, and 4 helices. The results show that the 3-helix longitudinal cutting head has better performance. By using the traversal result with maximum theoretical meshing rate as the design parameter, the longitudinal cutting head CH51 with 51 picks was designed and analyzed. The prediction model of pick consumption is established based on cutting speed, direct rock cutting volume of each pick, pick rotation coefficient, uniaxial compressive strength, and CERCHAR abrasivity index. And the rock with normal distribution characteristics of Uniaxial Compressive Strength is used for the specific energy calculating. The artificial rock wall cutting test results show that the reduction in height loss suppresses the increase in pick equivalent loss caused by the increase in mass loss, and the pick consumption in this test is only 0.037–0.054 picks/m3. In addition, the correlation between the actual pick consumption and the prediction model, and the correlation between the actual cutting specific energy and the theoretical calculation value are also analyzed. The research results show that the pick arrangement design method based on meshing pick tip spatial position can effectively reduce pick consumption and improve the rock cutting performance.

Treatment of Kümmell’s disease following the occurrence of osteoporotic vertebral compression fracture

Background: The incidence of osteoporotic vertebral compression fracture (OVCF) is increasing with the increase in the elderly population. Kümmell’s disease following OVCF occurrence is not a rare complication and is frequently associated with severe pain or neurologic deficit with progressive kyphotic deformity. Kümmell’s disease initially meant post-traumatic delayed vertebral collapse, but now it is also termed nonunion, osteonecrosis, or intravertebral vacuum cleft, all of which suggest the disruption of the healing process.Current Concepts: The major pathogenesis of Kümmell’s disease is a vascular compromise caused by mechanical stress or intravascular pathology. The key radiologic sign to diagnose Kümmell’s disease is the presence of intravertebral vacuum cleft, observed using simple X-ray, computed tomography, or magnetic resonance imaging. Magnetic resonance imaging is the most useful diagnostic tool showing gas or fluid signals. The risk factors for the progression of Kümmell’s disease after OVCF include middle-column injury, confined low signal intensity on T2-weighted image, posterior wall combined fracture, kyphotic angle >10°, and a height loss >15%. Its treatment can be broadly classified as conservative treatment, bone cement injection, and surgical treatment. The appropriate treatment method is selected based on the pain intensity, neurological symptoms, and the severity of the kyphotic deformity.Discussion and Conclusion: Kümmell’s disease usually develops along with osteoporosis. Therefore, the treatment should be focused on relief from symptoms associated with Kümmell’s disease and osteoporosis. It is recommended that an anabolic agent should be administered after the diagnosis of Kümmell’s disease, regardless of the treatment modality.

Vertical Jumping as a Monitoring Tool in Endurance Runners: A Brief Review

Jumping performance (e.g., countermovement jump [CMJ]), as a measure of neuromuscular performance, has been suggested as an easy-to-use tool which simultaneously provides neuromuscular and metabolic information and, thereby, allows coaches to confidently monitor the status of their athletes during a workout. This hypothesis has been satisfactorily tested with sprint athletes. However, the rationale for the use of CMJ height loss as an index to monitor the workload during an endurance running session is not sufficiently evidence-based. First, it is assumed that a CMJ height loss occurs during typical interval training for endurance runners. Second, it is also assumed that a significant relationship between metabolic stress and the neuromuscular strain induced during these endurance workouts exists. These two assumptions will be questioned in this review by critically analyzing the kinetics of CMJ performance during and after running workouts, and the relationship between neuromuscular and physiological stress induced during different protocols in endurance runners. The current evidence shows that fatigue induced by common running workouts for endurance runners does not counterbalance the potentiation effect in the CMJ height. Additionally, the findings reported among different studies are consistent regarding the lack of association between CMJ height loss and physiological stress during interval sessions in endurance runners. In practical terms, the authors suggest that this marker of neuromuscular fatigue may not be used to regulate the external training load during running workouts in endurance runners. Nevertheless, the analysis of CMJ height during running workouts may serve to monitor chronic adaptations to training in endurance runners.

Resistance fracture of minimally prepared endocrowns made by three types of restorative materials: a 3D finite element analysis

A thin endocrown restoration was often applied in endodontically treated teeth with vertical bite height loss or inadequate clinical crown length. A model of mandibular molars made by endocrown restoration with 1 mm thickness and 2 mm depth of pulp chamber was constructed and imported into FEA ANSYS v18.0 software. The three CAD/CAM materials, feldspathic (Mark2), lithium disilicate (EMAX), and lava ultimate (LU), were assigned, and the five load indenters were loaded on the full occlusal (FO), occlusal center (OC), central fossa (CF), buccal groove (BG), and mesiobuccal cusp (MC) of restoration in the model. The MinPS and MaxPS of the thin endocrown were significantly higher than those of tooth tissue in five types of loads except for the LU endocrown loaded in the FO group. The smaller the contact surface of the load was, the higher MaxPS and MinPS were. MaxPS and MinPS of the MC were the highest, followed by the BG and CF in the restoration. In the stress distribution of tooth tissue, MaxPS in the LU endocrown accumulated at the external edge of enamel and was significantly higher than MaxPS in Mark2 and EMAX endocrown concentrated on the chamber wall of dentin under OC, CF and BG loads. Within the limitations of this FEA study, the LU endocrown transferred more stress to tooth tissue than Mark2 and EMAX, and the maximum principal stress on endocrown restoration and tooth tissue at the mesiobuccal cusp load was higher than that at the central fossa and buccal groove load.

Spirometry Examination of Adolescents with Thoracic Idiopathic Scoliosis: Is Correction for Height Loss Useful?

Loss of body height is observed in patients with idiopathic scoliosis (IS) due to spine curvatures. The study compared pulmonary parameters obtained from spirometry examination considering the measured versus the corrected body height. One hundred and twenty adolescents with Lenke type 1 or 3 IS who underwent preoperative spirometry examination and radiographic evaluation were enrolled. The mean thoracic Cobb angle was 68° ± 12.6, range 48–102°. The difference between the measured and the corrected body height increased with the greater Cobb angle. Using the corrected body height instead of the measured body height significantly changed the predicted values of pulmonary parameters and influenced the interpretation of the pulmonary testing results.

A Lateral Opening Injection Tool Used In Percutaneous Vertebroplasty To Treat Asymptomatic Osteoporotic Vertebral Burst Fractures: A Retrospective Study In 66 Cases

Background: This study aimed to assess the results of percutaneous vertebroplasty (PVP) with a lateral opening injection tool for treating asymptomatic osteoporotic vertebral burst fractures (OVBFs) patients.Methods: 66 patients diagnosed with acute asymptomatic OVBFs with a spinal canal occupational ratio under 20% were treated with bilateral PVP using a lateral opening injection tool in our study. The related clinical outcomes and images were assessed, including Visual Analogue Scale (VAS), vertebral height (VH) ratio (=fractured VH/ adjacent nonfractured VH), the bone union of the fractured vertebral posterior wall, bone cement distribution, and complications.Results: The VAS scores were 3.80±0.40 at postoperative one day and 0.59±0.41 at last follow-up, significantly lower than 8.37±0.49 at pre-operation (P<0.05). The vertical distribution of bone cement in 60 cases contacted the upper and lower endplates of fractured vertebras. There was no leakage of bone cement in the spinal canal or displacement of posterior wall fracture to the spinal canal in all cases. There was asymptomatic cement leakage in 7 cases. The mean anterior, middle and posterior vertebral height ratios were significantly increased after PVP compared with preoperative values in all patients (P<0.05). At 6 months follow-up, there was no significant height loss of the vertebral body. Three months postoperatively, the posterior wall of fractured vertebral bodies was healed in all cases according to CT images. Conclusions: PVP using a lateral opening injection tool was effective and safe for treating asymptomatic OVBF patients.