Designing Calcium Silicate Cements with On-Demand Properties for Precision Endodontics

Calcium silicate (C3S) cements are available in kits that do not account for patients' specific needs or clinicians' preferences regarding setting time, radiopacity, mechanical, and handling properties. Moreover, slight variations in powder components and liquid content affect cement's properties and bioactivity. Unfortunately, it is virtually impossible to optimize several cement properties simultaneously via the traditional "one variable at a time" strategy, as inputs often induce trade-offs in properties (e.g., a higher water-to-powder ratio [W/P] increases flowability but decreases mechanical properties). Herein, we used Taguchi's methods and genetic algorithms (GAs) to simultaneously analyze the effect of multiple inputs (e.g., powder composition, radiopacifier concentration, and W/P) on setting time, pH, flowability, diametral tensile strength, and radiopacity, as well as prescribe recipes to produce cements with predicted properties. The properties of cements designed with GAs were experimentally tested, and the results matched the predictions. Finally, we show that the cements increased the genetic expression of odonto/osteogenic genes, alkaline phosphatase activity, and mineralization potential of dental pulp stem cells. Hence, GAs can produce cements with tailor-made properties and differentiation potential for personalized endodontic treatment.

Graphene Nanocoating: High Quality and Stability upon Several Stressors

Titanium implants present 2 major drawbacks-namely, the long time needed for osseointegration and the lack of inherent antimicrobial properties. Surface modifications and coatings to improve biomaterials can lose their integrity and biological potential when exposed to stressful microenvironments. Graphene nanocoating (GN) can be deposited onto actual-size dental and orthopedic implants. It has antiadhesive properties and can enhance bone formation in vivo. However, its ability to maintain structural integrity and quality when challenged by biologically relevant stresses remains largely unknown. GN was produced by chemical vapor deposition and transferred to titanium via a polymer-assisted transfer technique. GN has high inertness and did not increase expression of inflammatory markers by macrophages, even in the presence of lipopolysaccharides. It kept high coverage at the top tercile of tapered dental implant collars after installation and removal from bone substitute and pig maxilla. It also resisted microbiologically influenced corrosion, and it maintained very high coverage area and quality after prolonged exposure to biofilms and their removal by different techniques. Our findings show that GN is unresponsive to harsh and inflammatory environments and that it maintains a promising level of structural integrity on the top tercile of dental implant collars, which is the area highly affected by biofilms during the onset of implant diseases. Our findings open the avenues for the clinical studies required for the use of GN in the development of implants that have higher osteogenic potential and are less prone to implant diseases.

Pulsed electromagnetic fields synergize with graphene to enhance dental pulp stem cell-derived neurogenesis by selectively targeting TRPC1 channels

Conventional root canal treatment replaces the infected pulp with defined materials. Alternative cell-based tissue engineering strategies aim to regenerate a fully functional pulp within the root canal. Despite recent advances in this area, however, the regeneration of an innervated pulp remains a major challenge in the field. Both graphene (2DG) and pulsed electromagnetic fields (PEMFs) independently have been shown to promote diverse cellular developmental programs. The present study showed that 2DG promoted the neurogenic induction of human dental pulp stem cells (hDPSCs) by upregulating and accelerating the expression of mature neuronal markers. Notably, 2DG induced the highest expression of transient receptor potential canonical cation channel type 1 (TRPC1) during early neurogenesis. As brief PEMF exposure promotes in vitro differentiation by activating a TRPC1-mitochondrial axis, an opportunity to combine 2DG with developmentally targeted PEMF exposure for synergistic effects was realizable. Neurogenic gene expression, neurotransmitter release, and reactive oxygen species (ROS) production were greatly enhanced by a brief (10 min) and low amplitude (2 mT) PEMF exposure timed to coincide with the highest TRPC1 expression from hDPSCs on 2DG. In contrast, hDPSCs on glass were less responsive to PEMF exposure. The capacity of PEMFs to promote neurogenesis was precluded by the administration of penicillin/streptomycin, mirroring previous studies demonstrating that aminoglycoside antibiotics block TRPC1-mediated calcium entry and verifying the contribution of TRPC1 in this form of magnetoreception. Hence, graphene created a more conducive environment for subsequent PEMF-stimulated neurogenic induction of hDPSCs through their mutual capacity to activate TRPC1with subsequent ROS production.

Comparative clinical prognosis of massive and non-massive pulmonary embolism: A registry-based cohort study

AIMS

Little is known about the prognosis of patients with massive pulmonary embolism (PE) and its risk of recurrent venous thromboembolism (VTE) compared with non-massive PE, which may inform clinical decisions. Our aim was to compare the risk of recurrent VTE, bleeding, and mortality after massive and non-massive PE during anticoagulation and after its discontinuation.

METHODS AND RESULTS

We included all participants in the RIETE registry who suffered a symptomatic, objectively confirmed segmental or more central PE. Massive PE was defined by a systolic hypotension at clinical presentation (<90 mm Hg). We compared the risks of recurrent VTE, major bleeding, and mortality using time-to-event multivariable competing risk modeling. There were 3.5% of massive PE among 38 996 patients with PE. During the anticoagulation period, massive PE was associated with a greater risk of major bleeding (subhazard ratio [sHR] 1.72, 95% confidence interval [CI] 1.28-2.32), but not of recurrent VTE (sHR 1.15, 95% CI 0.75-1.74) than non-massive PE. An increased risk of mortality was only observed in the first month after PE. After discontinuation of anticoagulation, among 11 579 patients, massive PE and non-massive PE had similar risks of mortality, bleeding, and recurrent VTE (sHR 0.85, 95% CI 0.51-1.40), but with different case fatality of recurrent PE (11.1% versus 2.4%, P = .03) and possibly different risk of recurrent fatal PE (sHR 3.65, 95% CI 0.82-16.24).

CONCLUSION

In this large prospective registry, the baseline hemodynamic status of the incident PE did not influence the risk of recurrent VTE, during and after the anticoagulation periods, but was possibly associated with recurrent PE of greater severity.

Inhibiting Corrosion of Biomedical-Grade Ti-6Al-4V Alloys with Graphene Nanocoating

The identification of metal ions and particles in the vicinity of failed implants has raised the concern that biomedical titanium alloys undergo corrosion in healthy and infected tissues. Various surface modifications and coatings have been investigated to prevent the deterioration and biocorrosion of titanium alloys but so far with limited success. Graphene is a cytocompatible atom-thick film made of carbon atoms. It has a very high surface area and can be deposited onto metal objects with complex shapes. As the carbon lattice has a very small pore size, graphene has promising impermeability capacity. Here, we show that graphene coating can effectively protect Ti-6Al-4V from corrosion. Graphene nanocoatings were produced on Ti-6Al-4V grade 5 and 23 discs and subjected to corrosive challenge (0.5M NaCl supplemented with 2-ppm fluoride, pH of 2.0) up to 30 d. The linear polarization resistance curves and electrochemical impedance spectroscopy analysis showed that the graphene-coated samples presented higher corrosion resistance and electrochemical stability at all time points. Moreover, the corrosion rate of the graphene-coated samples was very low and stable (~0.001 mm/y), whereas that of the uncoated controls increased up to 16 and 5 times for grade 5 and 23 (~0.091 mm/y) at the end point, respectively. The surface oxidation, degradation (e.g., crevice defects), and leaching of Ti, Al, and V ions observed in the uncoated controls were prevented by the graphene nanocoating. The Raman mappings confirmed that the graphene nanocoating presented high structural stability and resistance to mechanical stresses and chemical degradation, keeping >99% of coverage after corrosion challenge. Our findings open the avenues for the use of graphene as anticorrosion coatings for metal biomedical alloys and implantable devices.

Resistência de União Entre Cerâmica Infiltrada por Polímero e Resina Composta Utilizando Diferentes Tratamentos de Superfície

Avaliar a resistência de união de um polímero infiltrado em uma rede de cerâmica (PICN) após diferentes tratamentos de superfície por meio do teste de microtração. Foram utilizados 6 blocos (17,5 x 14 x 12 mm) CAD-CAM de Vita Enamic que forma cortados em 18 blocos menores e posteriormente submetidos a 5 ciclos de autoclave. Os blocos foram divididos em dois grupos para tratamentos de superfície. Um grupo recebeu aplicação de ácido hidrofluorídrico 5% por 60 s (G1 1 a G3) e outro foi jateado com partículas de oxido de alumínio de 45 µm, com uma pressão de 2,5 bar (G4 a G6). Posteriormente foram separados aleatoriamente em 6 grupos experimentais. Em G1 e G4 aplicou-se agente de união silano (RelyX ceramic primer), em G2 e G5 adesivo universal (Single Bond Universal) e G3 e G6 agente de união silano seguido do adesivo universal. Cada superfície foi restaurada com resina composta de forma incremental. Os blocos foram cortados em microbarras com 1 mm2 ± 0,2 e submetidas ao teste de microtração. Os dados em MPa foram submetidos à análise de Anova e tukey (a 0,05) e foram G4 (34.4), G1 (32,2), G6 (31,2), G3 (30,4), G2 (22,3) e G5 (11,7) respectivamente. Os maiores valores de resistência de união foram encontrados com aplicação do agente de união silano, tanto para os grupos com ácido hidrofluorídrico quanto para os grupos com jateamento. A aplicação do agente de união silano continua sendo um passo fundamental na união de restaurações cerâmicas. O uso de adesivo universal como tratamento de superfície cerâmica demonstrou os resultados mais baixos de união no reparo de uma cerâmica híbrida.Palavras-chave: Adesão. Cerâmica. Resina.

Functional Odontoblastic-Like Cells Derived from Human iPSCs

The induced pluripotent stem cells (iPSCs) have an intrinsic capability for indefinite self-renewal and large-scale expansion and can differentiate into all types of cells. Here, we tested the potential of iPSCs from dental pulp stem cells (DPSCs) to differentiate into functional odontoblasts. DPSCs were reprogrammed into iPSCs via electroporation of reprogramming factors OCT-4, SOX2, KLF4, LIN28, and L-MYC. The iPSCs presented overexpression of the reprogramming genes and high protein expressions of alkaline phosphatase, OCT4, and TRA-1-60 in vitro and generated tissues from 3 germ layers in vivo. Dentin discs with poly-L-lactic acid scaffolds containing iPSCs were implanted subcutaneously into immunodeficient mice. After 28 d from implantation, the iPSCs generated a pulp-like tissue with the presence of tubular dentin in vivo. The differentiation potential after long-term expansion was assessed in vitro. iPSCs and DPSCs of passages 4 and 14 were treated with either odontogenic medium or extract of bioactive cement for 28 d. Regardless of the passage tested, iPSCs expressed putative markers of odontoblastic differentiation and kept the same mineralization potential, while DPSC P14 failed to do the same. Analysis of these data collectively demonstrates that human iPSCs can be a source to derive human odontoblasts for dental pulp research and test bioactivity of materials.

Outcome of Patients with Venous Thromboembolism and Factor V Leiden or Prothrombin 20210 Carrier Mutations During the Course of Anticoagulation

BACKGROUND

Individuals with factor V Leiden or prothrombin G20210A mutations are at a higher risk to develop venous thromboembolism. However, the influence of these polymorphisms on patient outcome during anticoagulant therapy has not been consistently explored.

METHODS

We used the Registro Informatizado de Enfermedad TromboEmbólica database to compare rates of venous thromboembolism recurrence and bleeding events occurring during the anticoagulation course in factor V Leiden carriers, prothrombin mutation carriers, and noncarriers.

RESULTS

Between March 2001 and December 2015, 10,139 patients underwent thrombophilia testing. Of these, 1384 were factor V Leiden carriers, 1115 were prothrombin mutation carriers, and 7640 were noncarriers. During the anticoagulation course, 160 patients developed recurrent deep vein thrombosis and 94 patients developed pulmonary embolism (16 died); 154 patients had major bleeding (10 died), and 291 patients had nonmajor bleeding. On multivariable analysis, factor V Leiden carriers had a similar rate of venous thromboembolism recurrence (adjusted hazard ratio [HR], 1.16; 95% confidence interval [CI], 0.82-1.64), half the rate of major bleeding (adjusted HR, 0.50; 95% CI, 0.25-0.99) and a nonsignificantly lower rate of nonmajor bleeding (adjusted HR, 0.66; 95% CI, 0.43-1.01) than noncarriers. Prothrombin mutation carriers and noncarriers had a comparable rate of venous thromboembolism recurrence (adjusted HR, 1.00; 95% CI, 0.68-1.48), major bleeding (adjusted HR, 0.75; 95% CI, 0.42-1.34), and nonmajor bleeding events (adjusted HR, 1.10; 95% CI, 0.77-1.57).

CONCLUSIONS

During the anticoagulation course, factor V Leiden carriers had a similar risk for venous thromboembolism recurrence and half the risk for major bleeding compared with noncarriers. This finding may contribute to decision-making regarding anticoagulation duration in selected factor V Leiden carriers with venous thromboembolism.

The Clinical Course of Venous Thromboembolism May Differ According to Cancer Site

BACKGROUND

We hypothesized that the clinical course of venous thromboembolism in patients with active cancer may differ according to the specificities of primary tumor site.

AIM AND METHODS

We used data from RIETE (international registry of patients with venous thromboembolism) to compare the clinical venous thromboembolism-related outcomes during the course of anticoagulation in patients with one of the 4 more frequent cancers (breast, prostate, colorectal, or lung cancer).

RESULTS

As of September 2014, 3947 cancer patients were recruited, of whom 938 had breast, 629 prostate, 1189 colorectal, and 1191 lung cancer. Overall, 55% had metastatic disease (42%, 36%, 53%, and 72%, respectively). During the course of anticoagulant therapy (mean duration, 139 days), the rate of thromboembolic recurrences was similar to the rate of major bleeding in patients with breast (5.6 [95% confidence interval (CI), 3.8-8.1] vs 4.1 [95% CI, 2.7-5.9] events per 100 patient-years) or colorectal cancer (10 [95% CI, 7.6-13] vs 12 [95% CI, 9.4-15] per 100 patient-years). In contrast, in patients with prostate cancer, the rate of venous thromboembolic recurrences was half the rate of major bleeding (6.9 [95% CI, 4.4-10] vs 13 [95% CI, 9.2-17] events per 100 patient-years), whereas in those with lung cancer, the rate of thromboembolic recurrences was twofold higher than the rate of major bleeding (27 [95% CI, 22-23] vs 11 [95% CI, 8.6-15] per 100 patient-years).

CONCLUSIONS

Significant differences in the clinical profile of venous thromboembolic-related outcomes were observed according to the site of cancer. These findings suggest the development of cancer-specific anticoagulant strategies as an area for further research.

Behaviour of human dental pulp cells cultured in a collagen hydrogel scaffold cross-linked with cinnamaldehyde

AIM

To investigate the effects of the cross-linking agent cinnamaldehyde (CA) on differentiation of human dental pulp cells (hDPCs) cultured in a collagen hydrogel, which may be useful as a scaffold for regenerative endodontic therapy.

METHODOLOGY

The odontogenic potential of hDPCs exposed to CA was examined using alkaline phosphatase (ALP) activity, Alizarin red S staining and real-time polymerase chain reaction for odontogenic gene expression. The morphological features of hDPCs cultured in CA-treated collagen were evaluated by scanning electron microscopy. Determination of cell numbers for evaluating proliferation was assessed by optical and fluorescence microscopy. To assess the mechanical properties of collagen treated with CA, setting time, compressive strength and surface roughness were measured. Statistical analysis was performed using Student's t-test compared with control (P = 0.05).

RESULTS

CA per se did not increase ALP activity, calcium nodule formation and expression of odontogenic-related markers (P > 0.05). On the contrary, the proliferation and odontogenic differentiation of hDPCs cultured in a collagen scaffold was promoted in the presence of CA (P < 0.05). The setting time was significantly shortened, and the compressive strength and surface roughness were increased by treatment with CA (P < 0.05).

CONCLUSIONS

Cross-linking of collagen scaffolds by CA had beneficial effects with respect to attachment, proliferation and differentiation of hDPCs. Consequently, the application of cross-linking agents such as CA may represent a new strategy for dentine-pulp complex regeneration.

A prognostic score to identify low-risk outpatients with acute deep vein thrombosis in the lower limbs

BACKGROUND

No prior studies have identified which patients with deep vein thrombosis in the lower limbs are at a low risk for adverse events within the first week of therapy.

METHODS

We used data from the Registro Informatizado de la Enfermedad TromboEmbólica (RIETE) to identify patients at low risk for the composite outcome of pulmonary embolism, major bleeding, or death within the first week. We built a prognostic score and compared it with the decision to treat patients at home.

RESULTS

As of December 2013, 15,280 outpatients with deep vein thrombosis had been enrolled. Overall, 5164 patients (34%) were treated at home. Of these, 12 (0.23%) had pulmonary embolism, 8 (0.15%) bled, and 4 (0.08%) died. On multivariable analysis, chronic heart failure, recent immobility, recent bleeding, cancer, renal insufficiency, and abnormal platelet count independently predicted the risk for the composite outcome. Among 11,430 patients (75%) considered to be at low risk, 15 (0.13%) suffered pulmonary embolism, 22 (0.19%) bled, and 8 (0.07%) died. The C-statistic was 0.61 (95% confidence interval [CI], 0.57-0.65) for the decision to treat patients at home and 0.76 (95% CI, 0.72-0.79) for the score (P = .003). Net reclassification improvement was 41% (P < .001). Integrated discrimination improvement was 0.034 for the score and 0.015 for the clinical decision (P < .001).

CONCLUSIONS

Using 6 easily available variables, we identified outpatients with deep vein thrombosis at low risk for adverse events within the first week. These data may help to safely treat more patients at home. This score, however, should be validated.

Dental pulp tissue engineering in full-length human root canals

The clinical translation of stem-cell-based dental pulp regeneration will require the use of injectable scaffolds. Here, we tested the hypothesis that stem cells from exfoliated deciduous teeth (SHED) can generate a functional dental pulp when injected into full-length root canals. SHED survived and began to express putative markers of odontoblastic differentiation after 7 days when mixed with Puramatrix™ (peptide hydrogel), or after 14 days when mixed with recombinant human Collagen (rhCollagen) type I, and injected into the root canals of human premolars in vitro. Roots of human premolars injected with scaffolds (Puramatrix™ or rhCollagen) containing SHED were implanted subcutaneously into immunodeficient mice (CB-17 SCID). We observed pulp-like tissues with odontoblasts capable of generating new tubular dentin throughout the root canals. Notably, the pulp tissue engineered with SHED injected with either Puramatrix™ or rhCollagen type I presented similar cellularity and vascularization when compared with control human dental pulps. Analysis of these data, collectively, demonstrates that SHED injected into full-length human root canals differentiate into functional odontoblasts, and suggests that such a strategy might facilitate the completion of root formation in necrotic immature permanent teeth.

Upper extremity DVT in oncological patients: analysis of risk factors. Data from the RIETE registry

AIM

The aim of the study is to up date informations on the clinical characteristics and outcome of patients with upper-extremity deep vein thrombosis (DVT) from the Informatised Registry on Venous Thromboembolism (RIETE).

METHODS

RIETE is an ongoing registry of consecutive patients with symptomatic, objectively confirmed, acute venous thromboembolism. In this analysis the clinical characteristics and 3-month outcome of all cancer patients with upper-extremity DVT were evaluated.

RESULTS

Up to February 2006, a total of 14,391 patients with symptomatic, objectively confirmed acute venous thromboembolism had been enrolled in RIETE. Of the 2,945 patients with active cancer 196 (6.7%) had arm DVT: 104 had catheter-associated DVT. Most cancer patients with arm DVT were males, younger than 65, and had a low incidence of additional risk factors or underlying diseases. Twenty of them (10%) had symptomatic pulmonary embolism (PE). Most patients were treated with low-molecular-weigh heparin, both initially (94%) and after discharge (75%). During the 3-month follow-up period 12 patients (6.1%) developed VTE recurrences (PE 6, DVT 6), 8 (4.1%) had major bleeding (fatal in 3), 43 (22%) died.

CONCLUSIONS

Our data from the RIETE registry show that upper limb DVT is a serious complication in patients with cancer, with a high incidence of recurrences and bleeding complications.

Critical analysis of the impedance method for the evaluation of permittivity and conductivity of the plasma membrane

We report a critical analysis of a typical method of dielectric spectroscopy consisting in impedance measurements as a function of frequency. Experimental data were obtained by measuring impedance on human erythrocyte suspensions. Since these cells do not have a nucleus they represent an ideal material for the application of the well established single shell model. This allows the evaluation of permittivity and conductivity of the plasma membrane. We discuss the influence on the reliability of results of parameters such as fractional volume, average dimensions and membrane thickness of cells.

Sex differences in the perception of tactile simultaneity

A tactile simultaneity task was used to investigate the effects of sex on simultaneity thresholds. Participants were required to judge whether pairs of tactile stimuli delivered unimanually or bimanually were simultaneous. Unimanual stimulation delivered stimuli to the same cerebral hemisphere, while bimanual stimulation resulted in the delivery of one stimulus to each hemisphere, therefore requiring interhemispheric transmission before judging simultaneity. The data of 114 right-handed participants were analysed. Females (N = 56) perceived simultaneity at longer intervals than males (N = 58) when bimanual stimulation was received. Furthermore, males had shorter interhemispheric transmission times (10.9 ms) than those of females (15.0 ms). The results also provided some support for the predictions of the Hemispheric Equivalence Model of temporal processing since bimanual simultaneity thresholds were longer than unimanual; and unimanual stimulation of the left vs right hand did not differ. An advantage for stimulation of right hand first (vs left first) in the bimanual condition was small (2.7 ms), and was the only prediction of the Left Hemisphere Specialisation Model to receive support. A modification of the Equivalence Model which allows for a slight left hemispheric advantage is proposed.

Effects of preferred hand and sex on the perception of tactile simultaneity

The effects of handedness, sex and the influence of hand placement in extrapersonal space on temporal information processing was investigated by measuring thresholds for perceiving the simultaneity of pairs of tactile stimuli. Simultaneity thresholds of preferred right handed and left handed university students with left hemisphere speech representation were compared using unimanual and bimanual stimulation at three hand placements (midline, lateral and crossed). In unimanual conditions two fingers of one hand were stimulated (single hemisphere), whereas in the bimanual conditions one finger of each hand was stimulated (cross hemispheres). Bimanual minus unimanual thresholds provided an estimate of interhemisphere transmission time (IHTT) regardless of hand placement. The effects of hemispace varied with the type of stimulation. With unimanual stimulation, overall thresholds were longer at the midline placement, however, with bimanual stimulation, thresholds were longer when the hands were spatially separated (crossed and/or uncrossed). Left handers' IHTTs were 8 ms faster than those of right handers. IHTTs in males were faster than females with hands placed in lateral (by 10.8 ms) or crossed (by 9.8 ms) but not midline positions. It was concluded that the cerebral hemispheres are equally capable of discriminating temporal intervals, but that the left hemisphere predominates when there is uncertainty about location of stimulation.

[Use of tranexamic acid for bleeding control in myocardial revascularization]

PURPOSE

To compare two groups of 80 patients undergoing to myocardial revascularization with the use of antifibrinolytic drug tranexamic acid and its efficacy in reduce bleeding and blood transfusion.

METHODS

Prospective analysis of two groups of 80 patients. Group A-no antifibrinolytic therapy (dec 91-may 92) and group B-fibrinolytic therapy-tranexamic acid-10g EV (jun-dec/92). Quantification of mediastinal drainage over 12h as well as the blood or derivatives received at the same time.

RESULTS

Hospital mortality: group A-3.8%, group B-2.5%. Drainage (12h): group A-602 +/- 547 ml and group B-260 +/- 260 ml (p < 0.001). Blood transfusion (12h): group A-1,782 +/- 1,163 ml and group B-1,105 +/- 839 ml (p < 0.001).

COMPLICATIONS

group A-two cases of intraoperative myocardial infarction, one episode of jaundice; group B-one case of intraoperative MI, one reoperation for bleeding control, one episode of jaundice, one of renal insufficiency, two mediastinitis and one seizure. The mean hospitalization time was ten days in both groups.

CONCLUSION

Tranexamic acid was an effective drug in bleeding control and in reducing blood transfusion in the postoperative of patients submitted to myocardial revascularization.