Introduction: Clinical performance of light cured resin composites is related to their degree of polymerization. The purpose of this study was to compare the degree of conversion of packable and hybrid composites by FTIR (Fourier Transform Infrared Spectroscopy).Materials & Methods: In this experimental study, 40 composite disks were prepared in two groups from Z250 and P60 composites. Each group was divided into four subgroups (2mm thickness cured with QTH unit, 2mm thickness cured with LED unit, 5mm thickness cured with QTH unit, and 5mm thickness cured with LED unit). Then samples were evaluated by FTIR to determine the degree of conversion (DC). Data were analyzed by Kolmogorov-Smirnov and three way ANOVA.Results: There was not a significant difference among the DC of the materials tested. LED significantly increased the degree of conversion of materials tested (P<0.001). DC values were significantly greater in 2mm diameter samples vs 5mm ones (P<0.001).Conclusion: The use of incremental technique in deep cavities restored with these composites is suggested. Also using LED is advised for curing composites because of a better result.

Nature has aesthetics of its own, what can provoke the human mind into better recognizing the concept of beauty via mental perception. As such, human mind can interact with the nonverbal expressions of nature only to better his/her primitive aesthetic knowledge and reach a more novel recognition of aestheticism via the practice of interpretative deduction. This article has been the result of a series of discussions and dialogues between the authors on the nature of aesthetic geotouring and exploring the natural phenomena based on the Dialectical Method of Socrates and modelled after the Platonic dialogues. The outcome of this dialectic study brings to light the fact that touring in nature through providing the due opportunity for mental perception of aesthetic phenomena can provide a clearer definition of ‘beauty’ in its rich variety. Aesthetic search as such will culminate in forming a more illuminated mental concept of beauty in mind, what can influence human rationale for aesthetic judgment and enrich even more the texture of human aesthetic creation. Such aesthetico-interpretative endeavor might lead to a higher potential for creating more original works of literature and art and culminate in a better judgment about such aesthetic creations.

Background: A fair amount of important objects in natural images have circular and elliptical shapes. For example, the nucleus of most of the biological cells is circular, and a number of parasites such as Oxyuris have elliptical shapes in microscopic images. Hence, atomic representations by two‑ dimensional (2D) basis functions based on circle and ellipse can be useful for processing these images. The first researches have been done in this domain by introducing circlet transform. Methods: The main goal of this article is expanding the circlet to a new one with elliptical basis functions. Results: In this article, we first introduce a new transform called ellipselet and then compare it with other X‑ let transforms including 2D‑ discrete wavelet transform, dual‑ tree complex wavelet, curvelet, contourlet, steerable pyramid, and circlet transform in the application of image denoising. Conclusion: Experimental results show that for noises under 30, the ellipselet is better than other geometrical X-lets in terms of Peak Signal to Noise Ratio, especially for Lena which contains more circular structures. However, for Barbara which has fine structures in its texture, it has worse results than dual‑ tree complex wavelet and steerable pyramid.

The purpose of this study was to compare the technique of taking cephalometric radiographs in Natural Head Position (NHP) with slightly changing of the head in the direction of flexion and extension (In the amount of 5 degrees.) 40 Cephalometric head films of 20 cases, all of whom were dental students, were utilized in this study.The cephalograms were divided into two groups. At first lateral cephalometric radiographs in NHP were taken from all of the cases, then another radiograph was taken in extended head position (the head changed 5 degrees upward from NHP position) from cases of group one, and in flexion head position (the head changed 5 degrees downward from NHP position) from cases of the second group. In this study 24 landmarks and 36 variable were evaluated.All radiographs were twice and data captured with a digitizer and computer. Evaluation of the results, which are shown in table I, revealed that 9 of the variable among 36 showed significant differences compared to NHP position, and two of the variable was common between the two groups. However, 27 of the measurments didn't show any significant differences. Considering the fact that one fourth of the landmark measurments which were evaluated in this study showed significant differences during slight extension or flexion of head, taking of lateral cephalometric headfilms in NHP is recommended specially when they are to be used in serial studies or ar taken for research purpose.However, because other 27 measurment (which comprise three fourth of all the measurments) showed no significant changes, we concluded that lateral cephlograms which are not taken in NHP may be used for diagnostic and treatment planning purpose.