Behavioral and cognitive effects of methylxanthines. A meta-analysis of theophylline and caffeine

BACKGROUND

Theophylline has been extensively studied as a treatment of asthma. However, some studies have suggested that theophylline may precipitate adverse behavioral and cognitive effects on children. Other reports have evaluated the effects of caffeine, another commonly used methylxanthine, as a treatment of attention-deficit hyperactivity disorder.

OBJECTIVE

To present a meta-analysis of research on the behavioral and cognitive effects of methylxanthines in children.

METHODS

The meta-analyses were conducted on 12 studies of theophylline and nine studies of caffeine that met inclusion criteria.

RESULTS

In contrast to popular beliefs and earlier scientific reports, meta-analyses of controlled studies did not indicate that either theophylline or caffeine resulted in significant deleterious effects on cognition or behavior. In fact, there was a small, positive effect on parental report of externalizing behavior for both methylxanthines.

CONCLUSIONS

There is little evidence to suggest that methylxanthines have adverse cognitive or behavioral effects on children. Questions remain with regard to the identification and determinants of either responsive or sensitive subgroups, dose-response relationships, and the effects of parent-teacher expectancies on behavioral ratings.

The Influence of Water Sorption of Dental Light-Cured Composites on Shrinkage Stress

The contraction stress generated during the photopolymerization of resin dental composites is the major disadvantage. The water sorption in the oral environment should counteract the contraction stress. The purpose was to evaluate the influence of the water sorption of composite materials on polymerization shrinkage stress generated at the restoration-tooth interface. The following materials were tested: Filtek Ultimate, Gradia Direct LoFlo, Heliomolar Flow, Tetric EvoCeram, Tetric EvoCeram Bulk Fill, Tetric EvoFlow, Tetric EvoFlow Bulk Fill, X-tra Base, Venus BulkFil, and Ceram.X One. The shrinkage stress was measured immediately after curing and after: 0.5 h, 24 h, 72 h, 96 h, 168 h, 240 h, 336 h, 504 h, 672 h, and 1344 h by means of photoelastic study. Moreover, water sorption and solubility were evaluated. Material samples were weighted on scale in time intervals to measure the water absorbency and the dynamic of this process. The tested materials during polymerization generated shrinkage stresses ranging from 6.3 MPa to 12.5 MPa. Upon water conditioning (56 days), the decrease in shrinkage strain (not less than 48%) was observed. The decrease in value stress in time is material-dependent.

Contraction and Hydroscopic Expansion Stress of Dental Ion-Releasing Polymeric Materials

Ion-releasing polymeric restorative materials seem to be promising solutions, due to their possible anticaries effect. However, acid functional groups (monomers) and glass filler increase hydrophilicity and, supposedly, water sorption. The purpose of the study was to evaluate the influence of water sorption of polymeric materials on the stress state at the restoration-tooth interface. Beautifil Bulk Fill Flow, Beautifil Flow Plus F00, Beautifil Flow F02, Dyract eXtra, Compoglass Flow, Ionosit, Glasiosite, TwinkiStar, Ionolux and Fuji II LC were used for the study. The stress state was measured using photoelastic analysis after: 0.5, 24, 72, 96, 168, 240, 336, 504, 672, 1344 and 2016 h. Moreover, water sorption, solubility and absorption dynamic were assessed. The water sorption, solubility and absorption dynamic of ion-releasing restorative materials are material dependent properties. The overall results indicated that the tested restorative materials showed significant stress decrease. The total reduction in contraction stress and water expansion stress was not observed for materials with low value of water sorption (Beautifil Bulk Fill, Dyract eXtra, Glasionosit and Twinky Star). The photoelastic method turned out to be inadequate to evaluate stress changes of resin modified glass-ionomer cement (RMGI, Fuji II LC and Ionolux).

The influence of filler amount on selected properties of new experimental resin dental composite

Aim of the study was to evaluate the influence of filler amounts on mechanical properties and contraction stress of light-curing experimental composite. Hardness, flexural strength, diametral tensile strength of material filled with 40, 50 or 60 wt. % of silanized silica were tested. The contraction stress was measured after 24 h by means of photoelastic study. The addition of 40-60 wt. % filler to composite caused significant increase in hardness, Young’s modulus and flexural strength. The DTS, after incorporating filler into polymer matrix, was valued at ~26 MPa. The composite containing 40 wt. % of filler demonstrated significantly lower contraction stress in comparison to neat resin and filled > 50 wt. % of silica.

Psychometric properties of the children's atypical development scale

The Children's Atypical Development Scale (CADS) is a 53-item rating scale designed to measure unusual behaviors in children. Principal-factor analysis on a clinic-referred and pediatric sample of 474 children resulted in a four-factor solution: Communication Deficits, Lability, Social Relatedness Deficits, and Preoccupation. The CADS is internally consistent and has adequate temporal stability. CADS factor scores were differentially associated with parent and teacher rating scales, IQ, and Continuous Performance Test errors. The scale shows promise as a clinical and research tool for assessing atypical behaviors associated with pervasive developmental disorder and other neurobehavioral disorders.

How Do the Etching Mode and Thermomechanical Loading Influence the Marginal Integrity of Universal Adhesives?

OBJECTIVE

This study evaluated the effect of etching mode and thermomechanical loading on universal adhesives.

METHODS AND MATERIALS

Two universal adhesives, Peak Universal and Adhese Universal, were used in two etching modes as the experimental groups: Peak Universal etch-and-rinse (PER), Peak Universal self-etch (PSE), Adhese Universal etch-and-rinse (AER), and Adhese Universal self-etch (ASE). Two adhesives considered gold standards were used as control groups: OptiBond FL (OER) was used as a control group for the etch-and-rinse (ER) mode, and Clearfil SE Bond (CSE) was used as a control group for the self-etch (SE) mode. Standardized class V cavities were created on the buccal and lingual surface in 30 extracted caries-free human third molars. Each adhesive and resin composite was applied according to the manufacturer's instructions. The specimens were subjected to thermomechanical loading (TML) immediately after the fillings were placed. Before and after TML, replicas and photographs of the fillings were performed and evaluated quantitatively and qualitatively. The Mann-Whitney U-test or Kruskal-Wallis test was used for quantitative analyses, and Fisher exact test was used for qualitative analysis.

RESULTS

Adhese Universal achieved a significantly higher percentage of continuous margin in the enamel than Peak Universal for the two types of etching both before and after TML (except for the SE group after TML). In dentin, the greatest percentage of continuous margin was achieved for Adhese Universal in the ER group (100%) before TML and for both universal adhesives in the SE groups (61%) after TML. For both etching modes and both time points, Adhese Universal had a greater percentage of continuous margin than Peak Universal for the whole margin. For the ER approach, significant differences were observed both before and after TML, and for the SE approach, significant differences were observed before TML. TML did not cause a significant decrease in the percentage of continuous margin in the enamel, but the results were the opposite in dentin. A qualitative assessment using World Dental Federation criteria did not show statistically significant differences between the groups.

CONCLUSIONS

Scanning electron microscope assessment of marginal integrity showed that the evaluated factors such as etching mode and TML significantly influenced the marginal integrity of the universal adhesives. The replica method shows that laboratory and clinical assessment methods complement each other and give a broader view of marginal integrity.

Mechanical properties of modern restorative "bioactive" dental materials - an in vitro study

This study aimed at assessing the mechanical properties and degradation of commercial bioactive materials. The bioactive materials (Activa Bioactive Restorative, Beautifil Flow Plus F00, F03, Predicta Bulk Bioactive) and composite resin Filtek Supreme Flow were submitted to flexural and diametral tensile strength tests (FS, DTS), modulus of elasticity (ME) evaluation, and analysis of aging in 70% ethanol and saliva on their hardness and sorption. The results for DTS ranged from 33.16 MPa (Beautifil Flow Plus F03) to 47.74 MPa (Filtek Supreme Flow). The highest FS was 120.40 MPa (Predicta Bulk Bioactive), while the lowest values were 86.55 MPa (Activa Bioactive Restorative). Activa Bioactive Restorative showed the lowest ME, as well as the highest water sorption both in alcohol and artificial saliva. Moreover, aging in saliva induced a significant decrease in hardness for Activa Restorative (p < .01). Alcohol storage caused a significant decrease in hardness for all materials (p < .0001). All tested materials met the basic requirements for light-curing materials in terms of DTS and FS. However, all materials showed higher sorption in alcohol than in saliva, while hardness decreased significantly after 30 days. Predicta Bulk Bioactive presented the highest mechanical parameters, initial hardness, and the lowest sorption of alcohol and saliva.

Evaluation of Hardness and Wear of Conventional and Transparent Zirconia Ceramics, Feldspathic Ceramic, Glaze, and Enamel

The aim of the study was to compare the hardness, coefficient of friction, and wear experienced by four different ceramic samples: 3Y-TZP zirconium oxide ceramics-Zi-Ceramill Zi (Amman Girrbach), 5Y-PSZ transparent zirconium oxide ceramics-Zol-Ceramill Zolid (Amman Girrbach), Sak-feldspathic ceramics-Sakura Interaction (Elephant), and Glaze (Amman Girrbach). The Vickers hardness of the samples was measured. Friction tests ball-on-disc were performed between the discs of four ceramics and a zirconia ceramic ball, then a premolar tooth as a counter-sample. The mass loss and the friction coefficients of the ceramic samples were determined. The tooth counter-samples were 3D scanned, and enamel attrition depths and mass were measured. The following hardness values (HV1) were obtained: 1454 ± 46 HV1 for Zi, 1439 ± 62 HV1 for Zol, 491 ± 16 HV1 for Sak, 593 ± 16 HV1 for Glaze, and 372 ± 41 HV1 for enamel. The mass losses of the teeth in contact with ceramics were 0.1 mg for Zi, 0.1 mg for Zol, 5.5 mg for Sak, and 4 mg for Glaze. Conventional and transparent zirconium oxide ceramics are four times harder than enamel and three times harder than veneering ceramics. Zirconia ceramics exhibit lower wear and a more homogenous, smoother surface than the other ceramics. Tooth tissues are subject to greater attrition in contact with veneering ceramics than with polished zirconium oxide ceramics.

A miniature microcontroller curve tracing circuit for space flight testing transistors

This paper describes a novel miniature microcontroller based curve tracing circuit, which was designed to monitor the environmental effects on Silicon Carbide Junction Field Effect Transistor (SiC JFET) device performance, while exposed to the low earth orbit environment onboard the International Space Station (ISS) as a resident experiment on the 7th Materials on the International Space Station Experiment (MISSE7). Specifically, the microcontroller circuit was designed to operate autonomously and was flown on the external structure of the ISS for over a year. This curve tracing circuit is capable of measuring current vs. voltage (I-V) characteristics of transistors and diodes. The circuit is current limited for low current devices and is specifically designed to test high temperature, high drain-to-source resistance SiC JFETs. The results of each I-V data set are transmitted serially to an external telemetered communication interface. This paper discusses the circuit architecture, its design, and presents example results.