Silica coating followed by heat-treatment of MDP-primer for resin bond stability to yttria-stabilized zirconia polycrystals.

This study evaluated the influence of silica coating, primer type and its heat treatment on bond strength durability between resin cement and an yttrium-stabilized polycrystalline tetragonal zirconia (Y-TZP). Eighty (80) Y-TZP blocks were allocated into 16 groups considering four factors: silica coating (without and with); type of primer (RelyX Ceramic Primer, a silane-based primer; Single Bond Universal, a universal MDP-based primer); heat treatment of the primer (without and with); aging (without and with). After zirconia treatments, resin cement cylinders (RelyX ARC) (n = 20; N = 320) were built. Half of the samples were tested after 24 h, and another half were subjected to aging (thermocycling 5-55°C/5.000, and storage in water for 6 months). Shear bond strength test and failure analysis were performed. Bond strength data were submitted to four-way ANOVA and Tukey test (p = 0.05). All factors were statistically significant (p < 0.001) for bond strength (MPa): silica coating (7.3 ± 5.9) > no-treatment (3.6 ± 4.3); universal primer (6.7 ± 4.8) > silane (4.2 ± 5.8); heat-treatment (6.5 ± 6.3) > no-heating (4.4 ± 4.3); no-aging (8.2 ± 5) > aging (2.7 ± 4.4). Tukey test revealed that the association of silica coating + universal primer + heat-treatment promoted higher and stable resin bond strength. Silica coating, universal adhesive application and heat treatment improve/increase durability and bond strength of zirconia. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 107B: 104-111, 2019.

Cloud forest trees with higher foliar water uptake capacity and anisohydric behavior are more vulnerable to drought and climate change.

Many tropical montane cloud forest (TMCF) trees are capable of foliar water uptake (FWU) during leaf-wetting events. In this study, we tested the hypothesis that maintenance of leaf turgor during periods of fog exposure and soil drought is related to species' FWU capacity. We conducted several experiments using apoplastic tracers, deuterium labeling and leaf immersion in water to evaluate differences in FWU among three common TMCF tree species. We also measured the effect of regular fog exposure on the leaf water potential of plants subjected to soil drought and used these data to model species' response to long-term drought. All species were able to absorb water through their leaf cuticles and/or trichomes, although the capacity to do so differed between species. During the drought experiment, the species with higher FWU capacity maintained leaf turgor for a longer period when exposed to fog, whereas the species with lower FWU exerted tighter stomatal regulation to maintain leaf turgor. Model results suggest that without fog, species with high FWU are more likely to lose turgor during seasonal droughts. We show that leaf-wetting events are essential for trees with high FWU, which tend to be more anisohydric, maintaining leaf turgor during seasonal droughts.

Foliar uptake of fog water and transport belowground alleviates drought effects in the cloud forest tree species, Drimys brasiliensis (Winteraceae).

Foliar water uptake (FWU) is a common water acquisition mechanism for plants inhabiting temperate fog-affected ecosystems, but the prevalence and consequences of this process for the water and carbon balance of tropical cloud forest species are unknown. We performed a series of experiments under field and glasshouse conditions using a combination of methods (sap flow, fluorescent apoplastic tracers and stable isotopes) to trace fog water movement from foliage to belowground components of Drimys brasiliensis. In addition, we measured leaf water potential, leaf gas exchange, leaf water repellency and growth of plants under contrasting soil water availabilities and fog exposure in glasshouse experiments to evaluate FWU effects on the water and carbon balance of D. brasiliensis saplings. Fog water diffused directly through leaf cuticles and contributed up to 42% of total foliar water content. FWU caused reversals in sap flow in stems and roots of up to 26% of daily maximum transpiration. Fog water transported through the xylem reached belowground pools and enhanced leaf water potential, photosynthesis, stomatal conductance and growth relative to plants sheltered from fog. Foliar uptake of fog water is an important water acquisition mechanism that can mitigate the deleterious effects of soil water deficits for D. brasiliensis.

In vitro antimicrobial activity of mouth washes and herbal products against dental biofilm-forming bacteria.

AIM: To evaluate in vitro, the antimicrobial effect of Cymbopogon citrates (lemon grass), Plectranthusamboinicus (Mexican mint) and Conyzabonariensis (hairy fleabane) tinctures as well as pure and diluted commercial mouth washes (Malvatricin(®), Periogard(®) and Listerine(®)) on wild isolates of Streptococcusmutans and reference strains of S. mutans, Streptococcus salivarius, Streptococcus oralis and Lactobacillus casei by determination of minimum inhibitory dilution (MID). MATERIALS AND METHODS: 0.12% chlorhexidine and 70% corn alcohol were used as positive and negative controls, respectively. Saliva samples were collected from 3 volunteers and seeded in MSB broth to obtain Streptococcus isolates after 72-hour incubation. Using the agar diffusion method, susceptibility tests were performed with overnight incubation in microaerophilia at 37°C. All tests were performed in duplicate. RESULTS: The bacterial species were resistant to the tinctures and Listerine(®), but were susceptible to 0.12% chlorhexidine, Malvatricin(®) and Periogard(®), with MIDs ranging from 12.5% to 1.56%. CONCLUSIONS: Plectrantusamboinicus, Conyzabonariensis and Cymbopongoncitratus tinctures and Listerine(®) did not show inhibitory action against the tested biofilm-forming bacteria.