Study of three types of desensitizers in dentin bonding strength

One hundred and twenty human molars without decay (premolars and complete third molars) freshly extracted for orthodontic purposes were used in the study to explore the impact of application of three kinds of desensitizers on self-etching/all-etching bond strength of dentin. The roots were ground along the cementoenamel junction (CEJ), the residual crowns were divided into two parts along mesial and distal direction, and the enamel layer was removed. The dentin was ground into standard pieces of 3x3x3 mm and then polished using alumina waterproof abrasive paper. Two hundred and forty specimens were divided into two groups according to self-etching bond (OptiBond, iBond, XenoIV) and all-etching bond (OptiBond, iBond, Probond). Each of the two groups were subdivided into three groups with different brands, and then further subdivided into three experimental groups and a control group (10 samples in each final group). The surface of dentin coated with desensitizer was examined using scanning electron microscope. Results showed that only the shear strength of iBond + Ddes + Z100 resin group was lower compared to the control group (P < 0.05). The comparison of the resin shear strength in other experimental groups with the control groups demonstrated no statistically significant difference (P > 0.05). The shear strength of Optibond + Gluma, Optibond + Ddes, iBond + Ddes + Z100 resin group in all-etching bond group and the experimental groups in Probond group was lower than in the control group (P < 0.05). The resin shear strength in other groups did not differ from the controls (P > 0.05).

The effects of water on degradation of the zirconia-resin bond

OBJECTIVES

10-methacryloyloxydecyldihydrogenphosphate (MDP) containing primers improve bonding of yttria-stabilised tetragonal zirconia (Y-TZP) to methacrylate resins. The present study investigated the role played by water in the deterioration of MDP-mediated zirconia-resin bonds.

METHODS

Grit-blasted Y-TZP plates were conditioned with two MDP primers and bonded with resin for shear bond strength (SBS) testing. Additional bonded plates were aged hydrothermally and compared with unaged Y-TZP after 24h of water-storage or 6 months of water/acid/alkali-storage. The monoclinic phase (m-ZrO₂) in different groups was determined by X-ray diffraction. Hydrolytic stability of the coordinate bond between MDP and zirconia in neutral/acid/alkaline environment was analysed using thermodynamic calculations. Microleakage and release of the element phosphorus from MDP-mediated Y-TZP/resin-bonded interfaces were evaluated via methylene blue dye infiltration and inductively coupled plasma-mass spectrometry (ICP-MS).

RESULTS

Hydrothermal ageing did not significantly alter SBS. Ageing in acidic or neutral medium led to significant decline in SBS. The m-ZrO₂ phase increased after hydrothermal ageing but no m-ZrO₂ was detected in the water/acid/alkali-aged specimens. A higher equilibrium constant was identified in the MDP-t-ZrO₂ complex when compared with the MDP-m-ZrO₂ complex. MDP-conditioning failed to prevent infiltration of the methylene blue dye. Phosphorus was detected by ICP-MS from the solutions used for soaking the resin-bonded specimens.

CONCLUSIONS

Hydrolysis of the coordinate bond between MDP and ZrO₂, rather than t→m phase transformation, weakens the bond integrity between MDP-conditioned Y-TZP and methacrylate resin.

CLINICAL SIGNIFICANCE

Hydrolysis of the coordinate bond between MDP and zirconia is responsible for deterioration of the integrity of the bond between MDP-conditioned Y-TZP and methacrylate resin.

Osteogenesis-promoting activity of composites SBA-15 mesoporous particles carrying oxytocin in vitro and in vivo

This study analyzes the performance of SBA-15 mesoporous particles carrying oxytocin (OT) in promoting osteogenesis in vitro and in vivo. The SBA-15 particles synthesized in the previous studies (about 30 μm in diameter and containing 10 nm deep pores) were loaded with the drug oxytocin and cultured with human osteosarcoma MG-63 cell line in vitro. The influence of particles on cell proliferation was studied. The level of the osteogenic marker (alkaline phosphatase and type I collagen) was measured. For in vivo studies, the connectivity defects of rabbit skull were prepared, and SBA-15 suspensions were regularly injected at the defect sites. The changes in the defect site calcium salt deposition were measured, and morphological changes were observed by microscopy. The material had to promote effect on osteogenesis-related indicators such as alkaline phosphatase and collagen I in bone sarcoma cell line MG-63. In vivo, the calcium salt deposition in OT/SBA-15 group was significantly higher than in the blank group. SBA-15 carriers appeared to persist in the region of the defect after the injection and release the drugs slowly, thus playing a more distinct role in promoting bone repair of local bone defects. The results showed that SBA-15 particles with OT could slow the release drugs and could help in promoting osteogenesis.

Bronchial lavage P 16INK4A gene promoter methylation and lung cancer diagnosis: A meta-analysis

OBJECTIVE

To evaluate the diagnostic value of bronchial lavage P16INK4A promoter methylation and lung cancer.

MATERIALS AND METHODS

The databases of PubMed, Medline, China National Knowledge Infrastructure, and Wanfang were electronically searched by two reviewers to find the suitable studies related to the association between P16INK4A promoter methylation and lung cancer. The P16INK4A promoter methylation rate was extracted from each included individual study. The diagnostic sensitivity, specificity, and area under the receiver operating characteristic ROC curve of bronchial lavage P16INK4Aas a biomarker for diagnosis of lung cancer were pooled by stata 11.0 software (Stata Corporation, College Station, TX, USA).

RESULTS

At last, 10 publications were included in this meta-analysis. Of the included 10 studies, five are published in English with relatively high quality and other five papers published in Chinese have relatively low quality. The pooled sensitivity and specificity of bronchial lavage P16INK4A promoter methylation for lung cancer diagnosis were 0.61 (95% confidence interval [CI]: 0.57-0.65) and 0.81 (95% CI: 0.78-0.85), respectively, with random effect model. The ROC curve were calculated and drawn according to Bayes' theorem by stata 11.0 software. The systematic area under the ROC was 0.72 (95% CI: 0.68-0.76), which indicated that the diagnostic value of bronchial lavage P16INK4A promoter methylation for lung cancer was relatively high. Moreover, no significant publication bias was existed in this meta-analysis (t = 0.69, P > 0.05).

CONCLUSION

Bronchial lavage P16INK4A promoter methylation can be a potential biomarker for diagnosis of lung cancer.

Pediatric tuberculosis drug market: an insider perspective on challenges and solutions

Representative stakeholders were consulted on how they felt access to pediatric tuberculosis (TB) drugs could be improved. A key recommendation is the development of new child-friendly, adequately dosed formulations with a good shelf life in all climate zones. There is also an urgent need to improve the diagnosis and reporting of children with TB. Manufacturers of pediatric TB medications are to be incentivized through improved coordination among all stakeholders, with streamlined regulatory approvals and increased consumer education on drug and regimen guidelines. Finally, pooled procurement is advised to ensure sustained market supply against affordable prices.

Topological design and additive manufacturing of porous metals for bone scaffolds and orthopaedic implants: A review

One of the critical issues in orthopaedic regenerative medicine is the design of bone scaffolds and implants that replicate the biomechanical properties of the host bones. Porous metals have found themselves to be suitable candidates for repairing or replacing the damaged bones since their stiffness and porosity can be adjusted on demands. Another advantage of porous metals lies in their open space for the in-growth of bone tissue, hence accelerating the osseointegration process. The fabrication of porous metals has been extensively explored over decades, however only limited controls over the internal architecture can be achieved by the conventional processes. Recent advances in additive manufacturing have provided unprecedented opportunities for producing complex structures to meet the increasing demands for implants with customized mechanical performance. At the same time, topology optimization techniques have been developed to enable the internal architecture of porous metals to be designed to achieve specified mechanical properties at will. Thus implants designed via the topology optimization approach and produced by additive manufacturing are of great interest. This paper reviews the state-of-the-art of topological design and manufacturing processes of various types of porous metals, in particular for titanium alloys, biodegradable metals and shape memory alloys. This review also identifies the limitations of current techniques and addresses the directions for future investigations.

Development of a new benazepril hydrochloride chewable tablet and evaluation of its bioequivalence for treatment of heart failure in dogs

The aim of the study was to develop a new chewable benazepril hydrochloride(BH) tablet, investigate its physical properties, and evaluate its bioequivalence with the branded formulation (Fortekor). A corrective agent was included in the formula to improve its palatability and convenience for administration to dogs. The tablet remained stable in light, heat, and humidity tests, and its physical properties such as hardness, uniformity of content, and dissolution rate were highly consistent with the technical standards. After single and repeated administrations to eight beagles and single dose to 14 mongrel dogs (0.5 mg/kg p.o.), plasma BH and its active metabolite, benazeprilat (BZ), were detected. There was no significant difference in the major pharmacokinetic parameters (Cmax , Tmax, and AUC₀₋₂₄) between the two formulations. The 90% confidence intervals calculated for the ratios of area under the time-concentration curve (AUC₀₋₂₄) were 92.4-116.3% for BH and 89.9-102.3% for BZ, within the accepted range for bioequivalence of 80-125%. The results showed our new chewable tablet is bioequivalent to the commercial product and suitable for addition to the benazepril product family for the treatment of heart failure in dogs.

Postural change from lateral to supine is an important mechanism enhancing cephalic spread after injection of intrathecal 0.5% plain bupivacaine for cesarean section

BACKGROUND

Spinal anesthesia is widely used for cesarean section, but the factors that affect the spread of the block in pregnant patients are still not fully explained. This study was designed to investigate the effect of postural changes on sensory block level.

METHODS

Thirty patients scheduled for elective cesarean section under combined spinal-epidural anesthesia were randomly allocated into three groups. After intrathecal injection of 0.5% plain bupivacaine 7.5mg, patients in group S were immediately placed in the supine position with left tilt, patients in group L5 were kept lateral for 5 min and then turned to the supine position with left tilt, and patients in group L10 were kept lateral for 10 min and then turned to the supine position with left tilt.

RESULTS

At 5 min, median cephalad level of sensory block was lower in groups L5 and L10 compared with group S (corrected P<0.001); at 10 min, median cephalad sensory block level was lower in group L10 compared with group S (corrected P<0.001) and group L5 (corrected P<0.001), and lower in group L5 compared with group S (corrected P=0.033); at 15 min, median cephalad level of sensory block was lower in group L10 compared with group S (corrected P=0.003) and group L5 (corrected P=0.015).

CONCLUSIONS

In our population, using 0.5% plain bupivacaine 7.5mg, postural change from the lateral position to the supine position is an important mechanism enhancing cephalic spread of spinal anesthesia during late pregnancy.

Concurrence of de-alloying and re-alloying in a ternary Al67Cu18Sn15 alloy and the fabrication of 3D nanoporous Cu–Sn composite structures

The creation of nanoporous Cu₃Sn–Cu–Cu₆Sn₅ composite structures in the form of self-supporting foils through the concurrence of de-alloying and re-alloying.

Impacts of trace carbon on the microstructure of as-sintered biomedical Ti-15Mo alloy and reassessment of the maximum carbon limit

The formation of grain boundary (GB) brittle carbides with a complex three-dimensional (3-D) morphology can be detrimental to both the fatigue properties and corrosion resistance of a biomedical titanium alloy. A detailed microscopic study has been performed on an as-sintered biomedical Ti-15Mo (in wt.%) alloy containing 0.032 wt.% C. A noticeable presence of a carbon-enriched phase has been observed along the GB, although the carbon content is well below the maximum carbon limit of 0.1 wt.% specified by ASTM Standard F2066. Transmission electron microscopy (TEM) identified that the carbon-enriched phase is face-centred cubic Ti2C. 3-D tomography reconstruction revealed that the Ti2C structure has morphology similar to primary α-Ti. Nanoindentation confirmed the high hardness and high Young's modulus of the GB Ti2C phase. To avoid GB carbide formation in Ti-15Mo, the carbon content should be limited to 0.006 wt.% by Thermo-Calc predictions. Similar analyses and characterization of the carbide formation in biomedical unalloyed Ti, Ti-6Al-4V and Ti-16Nb have also been performed.

Calibration of temperature measurement by infrared pyrometry in microwave heating of powder materials: an exothermic reaction based approach

Accurate temperature measurement remains a challenge for microwave heating of powder materials. We propose a temperature calibration method based on exothermic reactions and the resultant thermal runaway that occurs during microwave heating. The approach was demonstrated on microwave heating of four titanium alloys. Differential scanning calorimetry was used to determine the threshold reaction temperature for each selected titanium alloy. This served as a standard for the microwave heating of these titanium alloys. Infrared pyrometric temperature measurements were then calibrated by comparing the starting temperature of each thermal runaway event with the threshold reaction temperature.

Fast growth of branched nickel monosilicide nanowires by laser-assisted chemical vapor deposition

Branched nickel monosilicide (NiSi) nanowires (NWs), for the first time, have been synthesized on Ni foams by laser-assisted chemical vapor deposition using disilane precursor molecules. Studies indicate that 600 °C is the threshold temperature for the growth of a large number of branched NiSi NWs with 100-500 nm long branches extending from the main stems. Below the threshold temperature, unbranched NiSi NWs were obtained. The density of the branched NiSi NWs is relatively higher in comparison to that of the unbranched ones. The growth rate of the branched NiSi NWs at 700 °C is estimated up to 10 µm min(-1). High-resolution transmission electron microscopy and energy-dispersive x-ray spectroscopy of the branched NiSi NWs suggest that the formation of these branched nanostructures is ascribed to the Ni-dominant diffusion process. These NiSi NWs with branched nanostructures could bring them new opportunities in nanodevices.

Gadolinium Solubility Limits in Sodium-Aluminoborosilicate Glasses

Gadolinium and lanthanum solubility limits in a sodium-alumino-borosilicate glass system were studied. As melting temperature increased from 1400°C to 1450°C, 1500°C and 1550°C, the solubility of gadolinium in the baseline glass 15B2O3-5A12O3-20Na2O-60SiO2 (in molar composition) increased from 10.1 to 11.3, 12.2 and 13.1 (in mole percent of Gd2O3). The enthalpy change of Gd2O3 dissolution in this baseline glass is about 43.6 kJ/mol. Boron effect on lanthanum solubility was studied using the following baseline glasses: xB2O3-20Na2O- 5Al2O3-60SiO2, where x equals to 5, 10, 15, and 20, respectively. It was found that lanthanum solubility limit increased from 8.4 to 10.3, 12.5 and 14.9 (in mole percent of La2O3) as B2O3 increased from 5.1 to 9.5, 13.1 and 16.2 mol%. Gd2O. and La2O3 have similar solubility limits. Solubility limits of mixtures containing different ratios of Gd2O3 to La2O3 in the baseline glass 15B2O3-20Na2O-5A12O3-60SiO2 were found insensitive to the ratio of La/Gd. As far as gadolinium is concerned, its solubility limit will decrease when other lanthanides are introduced.

Short communication: Evaluation of supercritical fluid extraction aids for optimum extraction of nonpolar lipids from buttermilk powder

The milk fat globule membrane, present in buttermilk, contains complex lipids such as phospholipids. Microfiltration coupled with supercritical fluid extraction (SFE) may provide a method of enriching these nutritionally valuable lipids into a novel ingredient. Therefore, SFE as a method for phospholipid enrichment needs to be optimized for lipid removal effectiveness. The role of matrix additions to the buttermilk powder for extraction efficiency was evaluated. Diatomaceous earth (biosilicates), Teflon beads, and physical vibration were tested and shown to reduce total lipid by 86, 78, and 70%, respectively. Four consecutive treatments were shown to exhaust the system; however, similar extraction efficiencies were noted for 1 treatment with biosilicate addition, 2 treatments with physical vibration, or 3 treatments with added Teflon beads. The extracted lipid material consisted of the nonpolar fraction, and protein concentration was observed to increase slightly compared with the control. Although higher lipid extraction was achieved from the powder with addition of diatomaceous earth, a removable aid is ideal for an edible product.