The purpose of this study is to investigate the histopathological response of dentinopulpal
response of human teeth to the Er: YAG laser cavity preparation in comparison with the conventional
class I cavity preparation. Thirty five sound human upper and lower first premolar teeth which were
needed to be extracted for orthodontic purposes were used in the study. Regarding to the method of
cavity preparation, the teeth were grouped into three groups; Group1; Control group which consists of
seven sound teeth without cavity preparation, Group2; Conventional cavity preparation group and group
3; Er: YAG laser cavity preparation group. Each of Group2 and3 consists of fourteen teeth that is
subdivided into: A. 7teeth that extracted after two days after cavity preparation and B. 7 teeth that
extracted after twenty-one days after cavity preparation. Er: YAG Laser device emits radiation at
wavelength of 2940 nm in the infrared region. The laser irradiation was performed in a non-contact mode
with a focused beam of (energy density of 155985.96 mJ /cm2, energy of 600 mJ and a PRRs of 6 Hz for
enamel preparation) and (energy density=64994.151 mJ /cm2, energy = 250 mJ and a PRRs=4 Hz for
dentin preparation) with a spot diameter of 0.7mm at 12-15 mm distance and at right angle to the tooth
surface as possible. The histopathological results of the cavities prepared by Er: YAG Laser revealed the
early proliferation of the odontoblasts in the odontoblastic layer of the coronal part of the pulp which led
to the early formation of the reparative dentin in comparison to those prepared by conventional method.
It can be concluded that the use of the Er: YAG laser in class I cavity preparation has proved to be an
efficient technique in comparison to the conventional cavity preparation.
An experimental investigation has been made to study the influence of using v-corrugated aluminum fin on heat transfer coefficient and heat dissipation in a heat sink. The geometry of fin is changed to investigate their performance. 27 circular perforations with 1 cm diameter were made. The holes designed into two ways, inline arrangement and staggered in the corrugated edges arrangement. The experiments were done in enclosure space under natural convection. Three different voltages supplied to the heat sink to study their effects on the fins performance. All the studied cases are compared with v-corrugated smooth solid fin. Each experiment was repeated two times to reduce the error and the data recorded after reaching t
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The research in the linguistic structures of the historians Al-Yaqoubi is considered a model of the important topics in historical studies in general, given its importance in the lives of peoples due to its connotations and meanings that summarize interpretation, clarification, and prolonged speech, as it includes life meanings with many dimensions, these structures have been used in historical incidents Important, and throughout the different ages, as it can be used to support an opinion, solve problems, prove evidence, increase wisdom, and it needs rich life experiences, and a sound language, to use it, and needs a wide absorptive capacity for the recipient, the research included linguistic structures in the achievement of science , Lingu
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This paper describes the digital chaotic signal with ship map design. The robust digital implementation eliminates the variation tolerance and electronics noise problems common in analog chaotic circuits. Generation of good non-repeatable and nonpredictable random sequences is of increasing importance in security applications. The use of 1-D chaotic signal to mask useful information and to mask it unrecognizable by the receiver is a field of research in full expansion. The piece-wise 1-D map such as ship map is used for this paper. The main advantages of chaos are the increased security of the transmission and ease of generation of a great number of distinct sequences. As consequence, the number of users in the systems can be increased. Rec
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