Statement of Problem: Evaluation of fracture properties is a basic principle for true assessment of brittle materials’ properties. Resin–based composite materials are being used extensively in today’s dentistry. Fracture toughness is considered an important parameter for providing useful information about material’s nature, properties and its resistance to fracture. Purpose: The purpose of this study was to evaluate the fracture toughness of a resin composite produced in the country and to compare it with that of other standard materials. Materials and Methods: Four types of resin composite materials were used as follow to prepare 60 specimens (n=15 for each group), A) Tetric Ceram (Ivoclar–Vivadent); B) Brilliant (Coltene-Whaledent); C) SpectrumTPH (Dentsply); and D) Ideal Macoo (Ideal Macoo, Iran). Specimens of 5 mm diameter (± 0.1 mm) and 2 mm depth (±0.1 mm) were prepared in a central notch (90° notch angle) PTFE mold. Then specimens were light cured with two applications of overlapping exposures for a total of 120 s and were stored in distilled water at 37ºC for 48 hours, A cylindrical roller of 3 mm diameter was seated inside the V sections and fracture was accomplished in a universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed by one–way ANOVA and post-hoc paired Tukey HSD test with P<0.05 as the limit of significance. Results: The mean KIC and torque to fracture (T) values for each material tested were; A) 3.08±0.42, 16.99±2.34, B) 2.88±0.63, 16.04±1.98; C) 3.40±0.53, 18.75±2.93 and D) 2.87±0.46, 15.78±2.57 MN/m3/2±SD and N/mm±SD, respectively. Group C showed significantly the highest mean KIC and T values among groups tested which was significantly higher than that of group B and D (P<0.05). The mean KIC and T values for groups A, B, and D were not significantly different (P>0.05). Conclusion: From evaluating the fracture properties of materials tested in this study it was concluded that the mean fracture toughness value for SpectrumTPH (Dentsply) was significantly higher than that of Ideal Macoo resin composite material (Ideal Macoo, Iran). The F.T value for Ideal Macoo was considered acceptable as it was not significantly different from that of other resin composite materials tested.  

Introduction: This study evaluated the degree of micro leakage of Ideal Makoo and Tetric Flow composites using two dentin adhesives of Scotch Bond Multipurpose (SBMP) and Excite.Materials &Methods: 60 premolar teeth were divided in to four groups of 15. and class V cavity preparations were done in CEJ. Group 1 was rest orated with SBMP and Ideal Makoo, Group II with SBMP and Tetric Flow, Group III with Excite and Ideal Makoo, and Group IV with Excite and Tetric Flow. Stereomicroscope (X40) was used to evaluate and dye penetration in occlusal and gingival margins. Chi Square test, Pearson’s correlation test and Fishers exact test were used for data analysis (α= 0.05).Results: 1- The degree of leakage was not in correspondence to the type of composite.2- The degree of leakage was not in correspondence to the type of dentin adhesive.3- In four groups, the degree of leakage in gingival wall was significantly more than occlusal wall.Conclusion: Type of composite and dentin adhesive have no effect on degree of leakage. The important factor is the type of wall. It means that in class V restorations, gingival wall is always observed to have more micro leakage than occlusal wall.

Future and ideal are something problematic now more than every day before. In this frustrating fog occupying everywhere, all attempts have been assigned to individual needs, personal successes and close future. Collective ideal and far future have become secondary goals. In such conditions “, self”,will cut its ties from social context, will alienated from the society, from history and from itself and will tend to reification. What role university and academic training will play here? The specific question of this article is how each of the two approaches of natural sciences and human sciences will relate in this alienation? Social faculty of Tehran university has been selected as representative of human sciences and engineering faculty of Tehran university as representative of natural sciences. 15 students of each faculty were interviewed about their ideals, wishes and futures. According to the results, linear determinative scientific causal law dominated on natural sciences in engineering faculty will permeate to the world of human relations. In the sphere of these disciplines society is not an independent totality but just sum of the singular individuals. Ideal and future have seen as not more than just personal success. In contrast in the fluid and multi-paradigm world of human sciences, relation between individual and society will be understood as complicated, multilateral and dialectical. Personal success and collective ideal will be seen as interwoven,and ideal will not know as just personal success inside the status quo, but the will of the change in the status quo itself.

Background and Aim: In removable dentures, artificial teeth are a significant part of the overall esthetical outcome .In the maintenance of esthetical effects, the color stability of artificial tooth materials is one major factor .The purpose of this in vitro study was to evaluate the color stability of one resin composite teeth (Glamour) and one resin acrylic teeth (Ideal dent) in tea & coffee.Materials and Methods: This in vitro-experimental study was done on a sample with size of 36 .all of the samples selected of the upper right santral; between them 18 teeth was the resin composite (Glamour) with size A13 and color A1 and 18 teeth was the re sin acrylic teeth (Ideal dent) with size I18and color A1. Sample were immersed in to two staining beverage as test groups (tea & coffee) and distilled water as control. Color measurements of teeth were performed by using spectrophotometer, before immersion, the initial color value of each tooth was recorded. Color change values were determined after 1 month. Color differences were characterized using the CIE lab color space.for evaluation color with clinical environment we use from NBS units. Statistically analyzes done with ANOVA test.Results: In the Glamour mark, for all samples, there were statistically significant differences between the mean  D E values after 1 month but in Ideal dent mark there were not.Conclusion: Color differences with corresponding DE values than 3.3are acceptable and NBS values than 3 are acceptable in clinical dentistry in the current study the DE values of all groups did not exceed 3.3. In the Glamour mark, coffee was found the more chromomeric agent between solutions .but in Ideal dent mark we did not found any color changes.

In this paper, by introducing two virtual decision-making units (DMUs) called ideal DMU (IDMU) and antiideal DMU (ADMU) with fuzzy inputs-outputs, the efficiency evaluation of DMUs are done by fuzzy data envelopment analysis (FDEA). Therefore, we evaluate DMUs from the perspective of the best and worst possible relative efficiency. For each DMU two efficiencies are calculated while inputs and outputs are fuzzy. These two distinctive efficiencies are combined with the closeness coefficient (CC) index. The CC index is then used for an overall ranking of all DMUs. Finally, we compare the result of proposed fuzzy DEA model with Leon et al.’s (2003) results by representing a numerical example.

Let R be a commutative ring with identity and A(R) be the set of ideals of R with non-zero annihilators. In this paper, we  rst introduce and investigate the principal ideal subgraph of the annihilating-ideal graph of R, denoted by AGP (R). It is a (undirected) graph with vertices AP (R) = A(R) \ P(R) n f(0)g, where P(R) is the set of proper principal ideals of R and two distinct vertices I and J are adjacent if and only if IJ = (0). Then, we study some basic properties of AGP (R). For instance, we characterize rings for which AGP (R) is  nite graph, complete graph, bipartite graph or star graph. Also, we study diameter and girth of AGP (R). Finally, we compare the principal ideal subgraph AGP (R) and spectrum subgraph AGs(R).