Interfacial fracture toughness of different resin cements bonded to a lithium disilicate glass ceramic

Objectives

To evaluate the effect of HF acid etching and silane treatment on the interfacial fracture toughness of a self-adhesive and two conventional resin-based cements bonded to a lithium disilicate glass ceramic.

Methods

Lithium disilicate glass ceramic discs were prepared with two different surface preparations consisting of gritblasted with aluminium oxide, and gritblasted and etched with hydrofluoric acid. Ceramic surfaces with a chevron shaped circular hole were treated by an optimized silane treatment followed by an unfilled resin and then three different resin cements (Variolink II, Panavia F2, and Multilink Sprint). Specimens were kept in distilled water at 37 °C for 24 h and then subjected to thermocycling. The interfacial fracture toughness was measured and mode of failures was also examined. Data were analysed using analysis of variance followed by T-test analysis.

Results

No statistically significant difference in the mean fracture toughness values between the gritblasted and gritblasted and etched surfaces for Variolink II resin cement was found (P > 0.05). For the gritblasted ceramic surfaces, no significant difference in the mean fracture toughness values between Panavia F2 and Variolink II was observed (P > 0.05). For the gritblasted and etched ceramic surfaces, a significantly higher fracture toughness for Panavia F2 than the other cements was found (P < 0.05).

Conclusions

The interfacial fracture toughness for the lithium disilicate glass ceramic system was affected by the surface treatment and the type of luting agent. Dual-cured resin cements demonstrated a better bonding efficacy to the lithium disilicate glass ceramic compared to the self-adhesive resin cement.

Clinical significance

The lithium disilicate glass ceramic surfaces should be gritblasted and etched to get the best bond when used with Panavia F2 and Multilink Sprint resin cements, whereas for the Variolink II only gritblasting is required. The best bond overall is achieved with Panavia F2.     

Health-related quality of life in refugee minors from Syria,Iraq and Afghanistan resettled in Sweden: a nation-wide,cross-sectional study

Purpose

To examine health-related quality of life (HRQoL) in refugee minors resettled in Sweden and compare results to a European reference population, while exploring associations between sociodemographic factors and HRQoL dimensions.

Methods

A cross-sectional, nation-wide study was conducted with a stratified sample of refugee minors ages 12–15 and 16–18 from Afghanistan, Iraq and Syria, resettled in Sweden between 2014 and 2018. HRQoL was measured using KIDSCREEN-27. HRQoL dimension scores of the sample were compared to mean scores of European age and gender-matched reference population. Associations between sociodemographic factors and HRQoL dimensions were investigated with independent t tests and ANOVA. A multivariable regression analysis was performed to identify the sociodemographic factors associated with HRQoL.

Results

The questionnaire was sent to 10,000 potential respondents. The response rate was 26%, yielding n = 2559 refugee minors (boys 55%, girls 45%) in the study sample. Compared to European references, minors in the present study had significantly lower scores of HRQoL within psychological wellbeing and peers and social support, whereas levels for autonomy and parent/guardian relations and school environment were higher. Several sociodemographic factors were significantly associated with all HRQoL dimensions, with those 16–18 years old, having average or poor family economy, and living with an unrelated adult or family reporting lower levels of HRQoL. Minors from Afghanistan had significantly lower scores of HRQoL for all dimensions compared to those from Iraq and Syria.

Conclusion

Refugee minors had significantly lower levels of HRQoL for psychological wellbeing and peers and social support compared to European references. Future research should further investigate this potential HRQoL gap further.

     

The impact of primary care organization on avoidable hospital admissions for diabetes in 23 countries

Objective: Diabetes is a so-called ambulatory care sensitive condition. It is assumed that by appropriate and timely primary care, hospital admissions for complications of such conditions can be avoided. This study examines whether differences between countries in diabetes-related hospitalization rates can be attributed to differences in the organization of primary care in these countries. Design: Data on characteristics of primary care systems were obtained from the QUALICOPC study that includes surveys held among general practitioners and their patients in 34 countries. Data on avoidable hospitalizations were obtained from the OECD Health Care Quality Indicator project. Negative binomial regressions were carried out to investigate the association between characteristics of primary care and diabetes-related hospitalizations. Setting: A total of 23 countries. Subjects: General practitioners and patients. Main outcome measures: Diabetes-related avoidable hospitalizations. Results: Continuity of care was associated with lower rates of diabetes-related hospitalization. Broader task profiles for general practitioners and more medical equipment in general practice were associated with higher rates of admissions for uncontrolled diabetes. Countries where patients perceive better access to care had higher rates of hospital admissions for long-term diabetes complications. There was no association between disease management programmes and rates of diabetes-related hospitalization. Hospital bed supply was strongly associated with admission rates for uncontrolled diabetes and long-term complications. Conclusions: Countries with elements of strong primary care do not necessarily have lower rates of diabetes-related hospitalizations. Hospital bed supply appeared to be a very important factor in this relationship. Apparently, it takes more than strong primary care to avoid hospitalizations.

• Key points

• Countries with elements of strong primary care do not necessarily have lower rates of diabetes-related avoidable hospitalization.

• Hospital bed supply is strongly associated with admission rates for uncontrolled diabetes and long-term complications.

• Continuity of care was associated with lower rates of diabetes-related hospitalization.

• Better access to care, broader task profiles for general practitioners, and more medical equipment in general practice was associated with higher rates of admissions for diabetes.

     

Optimal topology design and distributed formation control of multiagent systems with complex-weights directed networks

In this article, we consider the optimal topology design and distributed formation control problem of multiagent systems (MAS) with complex-weighted directed topology. First, a framework is proposed to associate optimal topology of MAS to a constrained optimization problem with a complex Laplacian matrix, which is independent of the agent dynamics. The main contribution of the proposed approach compared with existing results is that the proposed approach does not require the calculation of the stabilizing matrix such that the closed-loop system is asymptotically stable, and a unique set of complex weights that satisfy associated cooperative conditions can be chosen. Then, a distributed formation control protocol is proposed to enable all agents to achieve the control goal. Finally, some numerical example results are provided to demonstrate the effectiveness of the proposed scheme.     

Synthesis of thioether derivatives of quinazoline-4-one-2-thione and evaluation of their antiplatelet aggregation activity

A series of 2-(arylmethylthio)-3-phenylquinazolin-4-one derivatives have been synthesized and their antiplatelet aggregation activities were assessed against ADP and arachidonic acid-induced platelet aggregation in human plasma. Among the tested thioethers, derivative 2, 3, 5 and 16 were the most potent compounds with satisfactory IC₅₀ for inhibition of platelet aggregation induced by ADP. Analysis of global physicochemical parameters shows some correlations between activities and molecular volume and also surface area of the studied derivatives.