Distilled Water For 24h Research Articles

Bi-axial flexural strength of dual-polymerizing agents cemented to human dentin after photo-activation with different light-curing systems.

This study aimed to assess the bi-axial flexural strength of two dual-polymerizing resin luting agents cemented to human dentin when photo-activated with different light-curing units. Two dual-cured resin cements: choice (CH) and Variolink II (VL) were tested. Hybrid composite resin (Z-250) discs (12×1.5mm) were fabricated. Three types of light-curing units were used halogen-curing unit (QTH), light-emitting diode (LED) and plasma arc (PAC). Sixty dentin discs of 0.5mm thickness were prepared from extracted human teeth. A circular mold (2.5mm in height and 12mm diameter) was utilized to create supporting structure for dentin, resin cement complex. The resin luting cement (0.5mm) was placed on the previously prepared dentin discs and covered with the prefabricated composite discs. Photo-activation of cements was performed for 40s with QTH and LED units and for 3s with PAC. The specimens were divided into 12 groups (20 specimens for each light source). Six groups were kept in distilled water for 24h and the rest were stored for 6weeks. Bi-axial flexural strength was determined using Instron machine. The data was analyzed using two-way ANOVA and Tukey test for comparison. The findings indicated that the bi-axial flexural strength values for both cements CH and VL were higher for 24h over 6weeks but not statistically significant when cured with QTH. Meanwhile, when LED light was used for photo-activation the cements, the flexural strength values reported were statistically higher of 24h over 6weeks storage at P=0.4(E-6) However, PAC light did not record any statistically significant difference between two duration for the CH cement although when used for polymerization of VL the reported value for 6weeks were statistically significantly higher value than 24h duration at P=0.002. When high immediate flexural strength is preferred in clinical situation photo-activation the cements with LED reported the greatest value.

Microtensile bond strength of self-etching and self-adhesive resin cements to dentin and indirect composite resin

The purpose of this study was to evaluate the microtensile bond strength (μTBS), failure modes andbonding interfaces of self-etching and three self-adhesive resin cements to dentin and indirect compositeresin. Cylindrical composite blocks (Tescera, Bisco Inc.) were luted with resin cements (PA: Panavia F 2.0,Kuraray Medical Inc., RE: RelyX Unicem Clicker, 3M ESPE., MA: Maxem, Kerr Co., BI: BisCem, BiscoInc.) on the prepared occlusal dentin surfaces of 20 extracted molars. After storage in distilled water for 24h, 1.0 mm ×1.0 mm composite-dentin beams were prepared. μTBS was tested at a cross-head speed of0.5 mm/min. Data were analyzed with one-way ANOVA and Tukey’s HSD test. Dentin sides of all frac-tured specimens and interfaces of resin cements-dentin or resin cements-composite were examined at FE-SEM (Field Emission-Scanning Electron Microscope). In conclusion, PA and RE showed higher bond strength and closer adaptation than MA and BI whenindirect composite blocks were luted to dentin using a self-etching and three self-adhesive resin cements.

Role of phenolic compounds release by Peganum harmala L. on germination and growth suppression of Convolvulus arvensis L.

Peganum harmala L. (Zygophyllaceae) is a medicinal herb with a wide range of pharmacological properties [1]. In traditional medicine, various parts of the plant are used to treat several diseases [2]. In order to search for new integrated strategies to improve weed management, we investigated potential herbicidal activity of P. harmala against Convolvulus arvensis. Sixteen g of fresh P. harmala leaves were soaked in 100ml distilled water for 24h. After filtering and centrifuging, the extract was diluted with sterile distilled water to concentrations of 4, 8, 12 and 16% (w/v). Fifteen seeds of C. arvensis were placed in Petri dishes containing 5ml of each P. harmala extract (or distilled water for control). Results indicate that in 8, 12 and 16% extract concentrations, a significant reduction in germination, seedling length, seedling dry weight and total chlorophyll content of C. arvensis was obtained when compared to control. In general, the effect was concentration-dependent whereas there was a significant correlation between each parameter and extract concentration. The adverse effect on C. arvensis indicates the presence of some water-soluble inhibitory substances in P. harmala aqueous extract. Upon HPLC analysis, seven phenolic compounds were identified in the extract. Between these phenolics, 4- hydroxybenzoic was present in maximum amount followed by caffeic acid and ferulic acid. The study concluded that P. harmala aqueous extract exerted phytotoxicity effect on germination and growth of C. arvensis, possibly by releasing water-soluble phenolic acids.

Herbicidal properties of Peganum harmala under laboratory condition

Medicinal plants often contain natural substances having herbicidal effects on specific weed species [2,4]. Peganum harmala belongs to family Zygophyllaceae and several parts of this plant are used in folk medicine to treat several illnesses [1,3]. The aim of the present investigation was to evaluate potential herbicidal activity of P.harmala on growth of Amarantus retroflexus under laboratory condition. Fresh above-ground material (16g) of P. harmala was soaked in 100ml distilled water for 24h. After filtering and centrifuging, the extract was diluted with sterile distilled water to give final concentrations of 4, 8, 12 and 16% (w/v). Twenty five seeds of A. retroflexus were placed in Petri dishes containing 5ml of each P. harmala aqueous extract (or distilled water for control). Treatments were arranged in a completely randomized design with 3 replicates. After 8 days, final germination percentage and root and shoot length and seedling dry weight were measured. Results indicate that aqueous extract fresh biomass of P. harmala show strong inhibitory effect on seed germination of A. retroflexus. At highest extract concentration, 30% reduction in germination was observed when compared to control. Both root and shoot lengths were severely affected and the effect was higher on root than on shoot length. Dry seedling weight was significantly reduced. This reduction was approximately 79% for the highest extract concentration based on control. In conclusion, this research demonstrated that P.harmala is not only useful for its pharmacological properties but might be also used for biological control of weeds.