This study was designed to determine the effect of different restorative materials on fracture resistance of lower anterior teeth with class V cavities. One hundred and ninety non - carious with restored permanent mandibular incisors were selected and divided into nineteen groups with 10 samples, from each cavities. Only half of the samples were load cycled by three brands at 3HZ frequency for 250000 cyclesin artificial mouth unit. The samples tested by applying shear force with cross head speed of 5mm/min in instron . Loading did not have any significant bond strength . In all samples, 4mm width of cavity had less bond strength than 2, 3 mm widths. Also, in the compoglass and glassionomer L.C. groups, cavities with 2 had more strength than cavities with 4mm width. In the case of tetric flow restorative material, there wasn't significant difference among different widths of cavity. In 4 cavity widths, tetric flow had the highest shear bond strength. Although the results showed that all the restorations need an average load more than masticatory forces in the mouth to fail, but tetric flow composite with combination of chemical adhesion properties and optimum elastic characteristics widths. The intention point shows that long term success can be achieved by using tetric flow restorative material.      

Introduction. Glass ionomer materials have been, used for years as liners, bases and temporary restoration for children. Their bonding properties allow temporization, which would be difficult with conventional cements of restorative materials. The desirable properties include easy and rapid application, fluoride release, biocompatibility and adhesion to dentin and enamel tend to be used in children specially for precooperative or handicapped children and preclude the need for treatment using general anesthesia of sedation in this research, shear bond strength of glass ionomer in two groups, including normal group and hypoplastic enamel group is tested. Methods. For this purpose, 2 groups each including 12 samples of normal anterior deciduous teeth and hypoplastic anterior deciduous teeth (with attention to hypoplastic indices) were chosen. The labial surface of teeth were prepared with medium and fine size discs, chem fil glass ionomer cement was bonded to prepared surfaces of teeth, and then samples were fixed in special site of self curing acrylic. The specimens were tested with a model 4031 instron machine. A shear load was applied to the base of the bonded glass ionomer cylinder with a knife edge rod (width, 0.5 mm) at a cross head speed of 0.5 mm/mm.Results. The mean of obtained sbs for 2 groups was 16.35 and 11.63 KGF/mm2.Conclusions. Statistical analysis of the results showed significant defferences between studied groups. But with attention to desirable properties, application of glass ionomer cement in hypoplastic defects of enamel in children is recommended.

In this investigation the amount of fluoride release has been measured from three light activated glass ionomers, a conventional glass ionomer, a compomer and a composite restoration over a period of 12 months. Five discs (7 x 2 mm) of each material were made which were then immersed sequentially in 4 ml of deionised water at 37°C. Samples were rinsed with 1ml of deionised water before each measurement. An orion Model 901 microprocessor digital Ionalyzer was used for the measurements and the obtained data were then converted into µg/cm2. The amount of fluoride release was measured 86 times during this 12 - month test period.Results showed that the pattern of fluoride release from the light activated glass ionomer being similar to that of the conventional glass ionomer restoration. The light activated glass ionomer, however, released significantly more fluoride than the conventional material, while composite and compomer restorations showed the release of significantly lesser amount of fluoride. The difference between flouride release level in composite and compomer restorations was not significant.In conclusion: light cured glass ionomer restorative materials show a higher level of fluoride compared to the conventional glass ionomer, compomer and composite restorations.

In this research the one dimensional two-phase flow equqtion for the simultaneous flow of air and water from a vertical soil column presented here based on the aljebraic sum of the water and air velocities (the total velocity) which have been derived elsewhere .In evaluating some of hydraulic parameters, the Brooks - Corey functions (Brooks and Corey 1964) are used. For the relative permeability and effective saturated to wetting and no wetting phases are used to calculated the parameters in this equation.To obtain hydraulic parameters in the Brooks and Corey equation, experimental investigation presented and hydraulic conductivity is measured and the same column homogeneous soil is dryed.The experimental data is companied with the predicted values by this equation, which was showed a good agreement.On the other hand the values of D* and a are culculated by the Brooks - Corey functions and the results of the changes of these parameters over the conclusions were evaluated and it shoued that the D* changes had a significant or meaningful effect on the computations but the changes of a had not a considerable effect on the computations so, we can consider its quantity as (1) because its practical objects. Concerning to the complicated connection of quantities the volume of computations is reduced considerably.

The purpose of this study was to evaluate the effect of scotchbond multipurpose plus (SBMPP) in comparrison to that of vitrebond on transverse and diametral tensile strength of set amalgam.A total of 60 specimens were selected and divided into two groups (with 30 cases for transverse test and 30 for diametral tensile test). Each groups were then divided into 3 subgroups as: control - vitrebond and SBMPP. Prepared specimens were then filled with amalgam (Luxalloy) in two fgrms using Teflon molds. All samples were tested by Zuick testing machine 1494 at 0.5 mm/min speed. Results indicated that specimens lined with SBMPP and Vitrebond had significantly lower transverse and diametral tensile strength than unlined specimens (p<0.05). Transverse strength of lined specimens with Vitrebond was significantly lower than specimens lined with SBMPP (p<0.01).In conclusion: Incorporation of adhesive resin liners within the body of amalgam can affect the mechanical properties of amalgam.