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Beilchmiedia miersii (Gay) Kosterm (Belloto of the North), an endemic species of central Chile, belongs to the hydrophilous forest subtype within the sclerophyllous forest ecosystem; it is azonal in character and fragmented in distribution. Preferably, its populations are found near stream areas, given its high water needs, a situation that is aggravated by the intense and prolonged drought that affects the area where it grows. B. miersii faces strong environmental stress during the summer, and it is unknown if the reduction in precipitation also causes water stress during the winter. Therefore, we hypothesized that B. miersii would present a low level of stress under the water deficit during the winter season, a period in which climatic factors such as radiation, relative humidity and precipitation are less restrictive to vegetation. The field trial was established in a nursery in the Metropolitan Region of Chile and included two treatments: control (TRC) and restriction (TRR). In both treatments, growth (root collar diameter and length), biomass variation, leaf water potential and substrate water content were evaluated on days 1, 126 and 161. Contrary to our hypothesis, the results revealed that the winter water deficit generated stress in the TRR plants, leading to physiological and metabolic changes that negatively impacted their growth, development and biomass accumulation. In the short term, this resulted in a reduced capacity to face the adverse climatic conditions that occur during the summer period. [ABSTRACT FROM AUTHOR]

The use of pit and fissure sealants in the area of pediatric dentistry has been very helpful as a preventive measure to avoid carious lesions generally given in the occlusal area of the first permanent molars erupted. These sealants have had constant variations over time, however, the most used are resinous sealants. These types of sealants are mainly classified in polymerization, viscosity and translucency. As dentistry has advanced, they have been divided into two groups (hydrophobic and hydrophilic), both with different characteristics, but with the same purpose, to provide a protective barrier between extrinsic factors and the tooth. However, when in contact with different elements such as humidity, carbohydrates and saliva, as well as having a bad application on the pits and fissures, these tend to fail and begin to present diverse problems such as microfiltration, retention failures and their microhardness. The objective of this literature review was to recognize whether these sealants are adequate to protect the teeth from external factors and whether they can resist various mechanical changes. For this purpose, a literature review was carried out in various databases and dental journals, and articles were selected according to their evidence, established criteria and the year of publication, which was between 2015 and 2020. [ABSTRACT FROM AUTHOR]