Objectives: To determine polymerization shrinkage kinetics and hardness of photo-activated polymer matrix composites (PMC) after plasma arc vs. halogen standard or soft-start irradiation.
Methods: Polymerization shrinkage was measured using the 'deflecting disk technique', and Knoop hardness was measured at the bottom of 1.5 mm thick specimens stored for 24 h at 37 degrees C. The materials comprised one micro-filled (Silux Plus) and four fine hybrid PMC (Definite, Herculite XRV, Solitaire 2 and Z250). The irradiation protocols included halogen standard irradiation at three intensities (TriLight, ESPE), ramp curing (dito), step curing (HiLight, ESPE), pulse polymerization (VIP Light, BISCO) and plasma curing (Apollo 95E, DMDS; PAC Light, ADT).
Results: Standard halogen irradiation at reduced intensity delayed the start and slowed down the progression of shrinkage strain, but (except for Z250) as well produced lower hardness. Soft-start halogen curing produced similar kinetics but maintained hardness. Plasma arc irradiation resulted in an immediate start and a rapid progression of polymerization contraction, but produced low hardness values in Definite (cured by the ADT unit) and in Solitaire 2 (both units). Z250 featured the highest, Silux Plus the lowest maximum rate of contraction. Despite soft-start irradiation, contraction of Z250 progressed faster than that of Silux Plus with halogen standard irradiation at high intensity.
Conclusions: Soft-start halogen irradiation protocols provide better chances for compensation of shrinkage stress by flow within PMC without compromising hardness and may contribute to a better marginal integrity of the restorations. Irradiation protocols should be individually adjusted to compensate for the different curing characteristics of PMC.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1016/s0300-5712(03)00089-7 | DOI Listing |
Zhonghua Yu Fang Yi Xue Za Zhi
January 2025
Department of Environmental Health, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou310051, China.
To analyze the iodine nutrition status and its related factors among adults aged 18 years and above in Zhejiang Province in 2022. A multistage stratified sampling method was used to select 4 320 adults aged 18 years and above from 16 on-site survey sites in Zhejiang Province for the study. A questionnaire was used to investigate the general demographic information and personal dietary characteristics of the study participants.
View Article and Find Full Text PDFJ Health Popul Nutr
January 2025
Student Research Committee, School of Health Management and Information Sciences, Shiraz University of Medical Sciences, Shiraz, Iran.
Background: Socioeconomic inequality in nutritional status as one of the main social determinants of health can lead to inequality in health outcomes. In the present study, the socioeconomic inequality in the burden of nutritional deficiencies among the countries of the world using Global Burden of Disease (GBD) data was investigated.
Methods: Burden data of nutritional deficiencies and its subsets including protein-energy malnutrition, iodine deficiency, vitamin A deficiency, and dietary iron deficiency form GBD study and Human Development Index (HDI), a proxy for the socio-economic status of countries, from united nations database were collected.
Biomolecules
December 2024
Department of Anesthesiology, Virgen de la Victoria University Hospital, 29010 Malaga, Spain.
Background: The effects of anesthetic drugs on myocardial cells have been a subject of research for the last 50 years. The clinical benefits of halogenated agents, particularly sevoflurane, have been demonstrated in cardiac surgery patients. These benefits are due to the action of different enzymes and a variety of molecular pathways mediated by the action of small noncoding RNAs (sRNA) such as microRNAs (miRNAs).
View Article and Find Full Text PDFEur J Med Chem
February 2025
School of Pharmaceutical Sciences, Lovely Professional University, Phagwara, 144411, India. Electronic address:
This study presents a comprehensive exploration of the synthesis of novel compounds targeting Chagas Disease (CD) caused by Trypanosoma cruzi. It is a global health threat with over 6-7 million infections worldwide. Addressing challenges in current treatments, the investigation explores diverse compound classes, including thiazoles, thiazolidinone, imidazole, pyrazole, 1,6-diphenyl-1H-pyrazolo[3,4-b] pyridine, pyrrole, naphthoquinone, neolignan, benzeneacyl hydrazones, and chalcones-based compounds.
View Article and Find Full Text PDFChemosphere
February 2025
Medical University of Lodz, Department of Toxicology, 90-151, Lódź, Poland.
Following a decline in the production and use of polychlorinated naphthalenes (PCNs) and the restrictions introduced by the Stockholm Convention, dietary intake represents the most significant pathway of human exposure to these dioxin-like contaminants. PCNs occur ubiquitously in foods, originating from the legacy of historical production that is now globally redistributed, as well as from ongoing industrial and domestic combustion sources which have a stronger influence on occurrence patterns in countries where they were not produced. Recent studies have benefited from a wider set of available PCN reference standards, enabling more accurate reporting of a diverse range of congeners.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!