Background and Aim: ZOE has been used in different fields of dentistry for many years. A locally produced component (Zoliran) has been recently introduced to the marketwith similar characteristic to the original Zonalin. Because of a lower cost involved to use Zoliran cement and its availability, confirm reliability of its physical properties. This investigation was designed to assess the Compressive Strength of Zoliran cement in comparison to Zonalin cement as the standard material. Materials and Methods: Five samples with dimension of 4mmx6mm of each cement were provided and stored in distilled water in 370C±10C for a period of 24 hours. The lowest load of force was registered as the reference to which the sample could be broken by(according to the criteria No: 30 of ANSIIADA). The value of compressive Strength was then calculated using the following formula (K =4F/πD2 ). Results: The mean compressive Strength of five samples was measuredas: 14.33 Mpa for Zoliran cement and 31.83 Mpa for Zonalin cement. The mean compressive Strength of Zonalincement was significantly higher than the mean suggested in ANSl/ADA Specification No.30. The mean compressiveStrength of Zoliran cement was also lower than the mean value registered in ANSI/ADA SpecificationNo.30. Conclusion: Compressive Strength of Zoliran cement was significantlylower than that of Zonalin cement. Further tests are required to compare the other physical properties of this material before it can be clinically recommended.

Several full porcelain systems are available in the market, among which In - Ceram (Vita Zahnfabrik, Bad Sackingen, Germany), has been introduced to show unique properties including: fine esthetic and high quality Strength. In this investigation Flexural Strength of In - Ceram core material has been evaluated by four - point bending test with Instron (Model 1195) machine. Samples were provided in form of ten bars of core material with the dimension of 30 × 6 × 2.5 mm.Results obtained show that the mean value of 538 ± 42 (MPa), of force is required to hit its resistance limit which is higher than similar values in other dental ceramics, within acceptable clinical range.

Strength measurement of rock requires testing that must be carried out on test specimens with particular sizes in order to fulfill testing standards or suggested methods. Often, the coring process breaks up the weaker core pieces, and they are too small to be used in either index tests or conventional Strength tests such as point load index (Is) and Brazilian tensile Strength (BTS). One of the index tests to indirectly determine the rock Strength is the block punch index (BPI) test, which requires flat disc specimens without special treatment. This study aimed to evaluate the applicability of the BPI test for predicting the uniaxial compressive Strength (UCS), BTS and IS of the sandstones by empirical equations. Also, we have compared the performance of the BPI and IS for predicting the UCS and BTS. It was experimentally shown that BPI is a reliable method for predicting the UCS, BTS and Is of the sandstones under study. Moreover, the results indicate that BPI could be utilized with same importance as Is for predicting the UCS, while predicting the BTS by Is appears to be more reliable than BPI.

Statement of Problem: Evaluation of new adhesives efficacy in bonding orthodontic brackets to enamel has led to different results. The new measuring method, micro-shear bond Strength, is preferred as an accurate method due to its ability to reduce confounding factors.Purpose: The purpose of this study was to evaluate and compare the micro-shear bond Strength of three different adhesive systems for enamel surface preparation before bracket bonding.Materials and Method: In this experimental study, 90 extracted premolars were randomly divided into three groups of 30. Transbond XT was bonded to enamel after enamel surface preparation with acid etch in the first (control) group, Transbond plus self-etch primer in second group, and Adper prompt L-pop self-etch adhesive in third group. Then each group was randomly divided into two subgroups of 15. Micro-shear bond test was performed after 24 hours (T1) and 3-months (T2). Bond failure mode was also evaluated according to Adhesive Remnant Index (ARI). Two way ANOVA and Tukey tests were used for bond Strength evaluation in groups, and mode of bond failure was analyzed with Kruskall Wallis and Mann Whitney tests.Results: The highest bond Strength was found in acid etch group (29.17 MPa). Difference of bond Strength at two intervals was statistically significant in all groups ( p <0.001). Bond Strength difference between T1 and T2 was also significant in three groups ( p <0.001). However changes over time in three groups did not reveal any significant differences ( p = 0.091). Bond failure analysis demonstrated significant differences in ARI between groups.Conclusion: Bond Strength of acid etch group was the highest and self etch primer showed higher bond Strength than self etch adhesive group. Less adhesive remnant was found in self etch group.

Background & Aim: More than 30 years has passed since introduction of glass-ionomer cement as a dental restorative material, luting cement and liner. Although they are sensitive to moisture and desiccation during the initial setting stages, relative poor physical properties because of chemical bonding to tooth substrate, and long-term esthetic quality, they are recommended for restoring anterior and posterior primary teeth, cervical lesions and root caries of permanent teeth. In this study, shear bond Strength of Fuji II was compared with of ariadent glass-ionomer cements. Materials & Methods: Thirty intact extracted primary molars were prepared for this study. Selected teeth were divided in two groups of 5. Sample were free of caries, fracture, crack, discoloration or any structural abnormality. The dentin of buccal surface of teeth were exposed by microtome apparatus. The surface was conditioned by polyacrylic acid (10%) for 20 seconds. Glass ionomer cements (Fuji II, and Ariadent) were prepared in a plastic cylinders (15 of each) and attached to the dentin of teeth horizontally. Shear bond stength of materials was measured by instron (Model 1159).Results: Mean shear bond Strength of Ariadent cement was 4.2±1.9 Mpa while 7.4±1.5 Mpa was of Fuji II cement (P=0.000).Failure mode was similar between two cements (P=ns). The most prevalent type of failure mode was cohesive failure leaving a firmly attached thin and homogenous layer of cement to dentin, in both groups.Conclusion: It appears that shear bond strenght of Ariadent cement to primary tooth is much lower than of Fuji II.

Background and Aim: Nonmetallic tooth- colored posts adhere to canal walls by dentin bonding agents and resin cements. Better retention and proper distribution of stress result from enough and proper bonding. The purpose of this study was to evaluate bond Strength of D.T. Light - post with two different resin cements (selfcure & dual-cure) and to investigate the effect of irrigating solutions applied in root canal on bond Strength of the resin cements and D.T.Light- post to root canal wall.Materials and Methods: In this experimental study 40 single root teeth (maxillary canine & central) were selected and stored in 0.1% thymol solution for one week and transferred to distilled water. The teeth were decoronated 2mm above CEJ. The canal space was mechanically enlarged using k-files (up to # 70). The teeth were randomly divided into two groups. The first group was irrigated with 2.6% NaOCl, and the second was irrigated with normal saline. After drying, the teeth were filled with gutta percha cones using lateral condensing method. After two weeks the post space was prepared and D.T.Light- post was inserted in each subgroup using self or dual-cure cements according to manufacturer's instructions. After thermocycling, the apical part was cut 1cm below CEJ. The remained length was divided into 9 equal sequential sections. Each section was submitted to shear push-out test in universal testing machine. Statistical analysis of the bond Strength data was performed using ANOVA and post hoc tests with p<0.05 as the level of significance. All failed specimens were examined under stereomicroscope. Degrees of conversion (DC) of the cements were determined by FTIR.Results: Significant difference in bond Strength values were found among sites (P=0.001) and cements (P=0.03). With increasing in depth, bond Strength decreased. The mean bond Strength value in dual-cure resin cement was higher than self-cure cement. The irrigating solutions caused no significant difference in bond Strength (P=0.46). DC% had significant difference in various depths.Conclusion: According to the results of this investigation, bond Strength of dual-cure cement is higher than self-cure one in D.T Light- post because of post's translucency. 2.6% sodium hypochlorite does not affect the bond Strength.

Introduction: The aim of this in vitro study was to evaluate the effect of calcium hydroxide mixed with different vehicles on the push-out bond Strength of mineral trioxide aggregate.Materials and Methods: The study was conducted on 80 extracted single-rooted human maxillary incisor teeth who secrowns had been removed. The root canals were instrumented and divided into 4 groups according to the vehicle of the calcium hydroxide paste: Group I – distilled water; Group II – propylene glycol; Group III – 0.2% chlorhexidine; Group IV – control. After placement ofthe root canal dressings, the teeth were washed with EDTA and sodium hypochlorite and sealed with MTA. After 7 days, the push-out test was carried out using a universal testing machine. Data were analyzed with one-way ANOVA and gomes-howell tests.Results: The maximum and minimum bond Strength values were recorded in the propylene glycol and distilled water groups, respectively. There was significant differences in push out bond Strength between chlorhexidine and propylene glycol groups (P=0.015). There were significant differences in resistance to dislodgement between group control - propylene glycol (P=0.032) and group control-chlorhexidine (P=0.012).Conclusion: Placement of propylene glycol before placement of MTA in root canal improves the push-out bond Strength of this material.