Fumigant activity of essential oils from Cinnamomum and Citrus spp. and pure compounds against Dermanyssus gallinae (De Geer) (Acari: Dermanyssidae) and toxicity toward the nontarget organism Beauveria bassiana (Vuill.).

Dermanyssus gallinae(De Geer) (Acari: Dermanyssidae) is the main ectoparasite associated with laying poultry. This mite is commonly controlled by the application of synthetic chemical insecticides, wich lead to the selection of resistant populations and formation of residues in eggs. Thus, new molecules must be developed to control D. gallinae. This work evaluated the toxicity of essential oils (EOs) from Cinnamomum cassia, Cinnamomum camphora, Cinnamomum camphora var. linalooliferum, Citrus aurantium, Citrus aurantium var. bergamia, Citrus aurantifolia and Citrus reticulata var. tangerine against D. gallinae. Additionally, the chemical profiles of the most bioactive EOs were analyzed by gas chromatography coupled with mass spectrometry (GC-MS) and the major compounds were subjected to new tests using D. gallinae. The most toxic EOs against D. gallinae were evaluated for the nontarget entomopathogenic fungus Beauveria bassiana (Unioeste 88). The EOs from C. cassia (LC50 = 25.43 ± 1.0423 µg/cm3) and C. camphora var. linalooliferum (LC50 = 39.84 ± 1.9635 µg/cm3) were the most active in the fumigant bioassay and caused mortality rates of 96 and 61%, respectively. The GC-MS analysis revealed that the major constituents of EOs from C. cassia and C. camphora var. linalooliferum were trans-cinnamaldehyde and linalool, respectively. The pure compounds, trans-cinnamaldehyde (LC50 = 68.89 ± 3.1391 µg/cm3) and linalool (LC50 = 51.45 ± 1.1967 µg/cm3), were tested on D. gallinae and showed lower toxicity than the EOs. Thus, the compounds were not the only active substances produced by C. cassia and C. camphora var. linalooliferum; moreover synergism may have occurred between the substances. The EOs from C. cassia and C. camphora var. linalooliferum were also toxic to B. bassiana (Unioeste 88). Thus, EOs from C. cassia and C. camphora var. linalooliferum are promising candidates for use in D. gallinae control, but cannot be used in conjunction with the fungus B. bassiana.

Influence of curcumin photosensitizer in photodynamic therapy on the mechanical properties and push-out bond strength of glass-fiber posts to intraradicular dentin.

BACKGROUND: The effects of using curcumin as photosensitizer on the mechanical properties of intraradicular dentin and on the bond strength of glass-fiber posts are unknown. Thus, this in vitro study evaluated the influence of using curcumin as photosensitizer during photodynamic therapy on the Martens hardness, elastic modulus, and bond strength of glass-fiber posts luted to intraradicular dentin, in different tooth root thirds. METHODS: Eighty bovine teeth were divided into 5 groups according to the concentration of curcumin applied, with or without blue LED light activation: Control-deionized water; Curcumin 500 mg/L; Curcumin 500 mg/L + blue LED; Curcumin 1000 mg/L; and Curcumin 1000 mg/L + blue LED. Mechanical properties were measured in different thirds of the radicular dentin using an ultramicrohardness tester (n = 8). A universal testing machine was used to evaluate the push-out bond strength (n = 8). Mechanical properties were compared across groups with the Kruskal-Wallis test, and across regions with the Friedman test. Bond strength data were subjected to ANOVA, followed by Tukey's test (α = 0.05). Scanning electron microscopy was used to analyze the failure mode of the specimens. RESULTS: The use of curcumin photosensitizer, with or without blue LED light, improved mechanical properties compared to those of the control group (P < 0.05), and promote no statistically significant difference in bond strength values (P > 0.05). Overall, there was no difference among the intraradicular thirds for Martens hardness and push-out bond strength values (P > 0.05). CONCLUSIONS: Curcumin photosensitizer, with or without photodynamic therapy, changed the mechanical properties of intraradicular dentin; however, the Martens hardness and bond strength values did not differ with the depth of the dentin.