Purpose: Despite the high clinical accuracy of dynamic navigation, inherent sources of error exist. The purpose of this study was to improve the accuracy of dynamic navigated surgical procedures in the edentulous maxilla by identifying the optimal configuration of intra-oral points that results in the lowest possible registration error for direct clinical implementation. Materials and methods: Six different 4-area configurations were tested by 3 operators against positive and negative controls (8-areas and 3-areas, respectively) using a skull model. The two dynamic navigation systems (X-Guide® and NaviDent®) and the two registration methods (bone surface tracing and fiducial markers) produced four registration groups. The accuracy of the registration was checked at the frontal process of the zygoma. Intra- and inter- operator reliability for each registration group were reported. Multiple comparisons were conducted to find the best configuration with the minimum registration error. Results: Ranking revealed one configuration in the tracing groups (Conf.3) and two configurations in the fiducial groups (Conf.3 and Conf.5) that had the best accuracy. When the inferior surfaces of the zygomatic buttress were excluded, fiducial registration produced better accuracy with both systems (p 0.006 and <0.0001). However, tracing 1 cm areas at these surfaces bilaterally resulted in similar registration accuracy as placing fiducial markers there (p 0.430 and 0.237). NaviDent® performed generally better (p 0.049, 0.001 and 0.002) albeit having a wider margin of uncertainty in the obtained values. Changing the distribution of the 4 tracing areas or fiducial markers had a less pronounced effect with X-Guide® than with the NaviDent® system. Conclusion: For edentulous maxillary surgeries, 4 fiducial markers placed according to configuration 3 or 5 result in the lowest registration error. Where implants are being placed bilaterally, an additional 2 sites may reduce the error further. For bilateral zygomatic implant placement, it is optimal to place 2 fiducials on the inferior surfaces of the maxillary tuberosities, other 2 on their buccal surfaces, and 2 on the anterior labial surface of the alveolar bone. Utilising the inferior zygomatic buttress is recommended over the inferior maxillary tuberosities in other types of maxillary surgeries.
Infertility can be detected when the couples have not completed pregnancy after a year or more of normal coitus. So, in order to treat infertility, there are many supported reproductive techniques are in practice. The success rate of these techniques depends upon the way by which preparation of the paternal semen sample. Over the past 30 years, the manual has been standard as providing global standards and has been used extensively by research and clinical laboratories throughout the world. The spermatozoa of all placental (eutherian) mammals, including humans, are in a protective, no labile formal at ejaculation and are incapable of fertilization even if they are placed in direct contact with an oocyte. Accordingly, they must undergo a sub
... Show MoreWe present mid-infrared imaging observations of the debris disk around one of the main sequence star Epsilon Eridani in the Q-band at (20.5 µm) and (17.6 µm). The dust that produces emission in debris disk is spatially resolved in the inner region of the debris disk of Epsilon Eridani at distance approximately between 1.4 - 4 AU.
A study of the emission spectra of isotopic for electronic states has been carried out. The energies of the vibration levels ( =0,1,..25) and the values of spectral lines R(J) and P(J) versus rotational quantum number (J=0,1..25). It was found that were an increase of the value of R(J) with the increase of the values of J was found while the value of P(J) decreases with decreasing of the values of J . It was found that corresponding to R(J) and P(J) the spectral line R(J) increases when the values of m increased.
Assume that G is a finite group and X = tG where t is non-identity element with t3 = 1. The simple graph with node set being X such that a, b ∈ X, are adjacent if ab-1 is an involution element, is called the A4-graph, and designated by A4(G, X). In this article, the construction of A4(G, X) is analyzed for G is the twisted group of Lie type 3D4(3).
A Spectroscopic study has been focused in this article to study one of the main types of active galaxies which are quasars, and to be more precise this research focuses on studying the correlation between the main engine of Quasi-Stellar Objects (QSO), the central black hole mass (SMBH) and other physical properties (e.g. the star formation rate (SFR)). Twelve objects have been randomly selected for “The Half Million Quasars (HMQ) Catalogue” published in 2015 and the data collected from Salon Digital Sky survey (SDSS) Dr. 16. The redshift range of these galaxies were between (0.05 – 0.17). The results show a clear linear proportionality between the SMBH and the SFR, as well as direct proportional between the luminosit
... Show MoreThis study deals with The Millstone (1965) which is a dramatic depiction of a single
mother heroine in a classic predicament. This novel is considered as representative of the age
in which it was written. The primary theme is her intense preoccupation with questions of
fatalism and will. The work also involves, both explicitly and implicitly, feminist concerns.
Because the central protagonist is a woman and the society in which she lives is depicted,
accurately, as deeply patriarchal and class-bound, the problem of the individual's capacity for
self-determination is inevitably tied to the feminist perspective.
المقال منشور على موقع مجلة الفورين بوليسي الأميركية (Foreign Policy) على الانترنت في 27 أيلول/سبتمبر 2019. يُشير مصطلح العزل (Impeachment) في الثقافة السياسية الأميركية إلى مجموعة الإجراءات التي يتم بموجبها عزل الرئيس من منصبه، وهذه الإجراءات هي بمثابة عملية طويلة تجري داخل الكونجرس، وتتم وفقاً لخطوات يؤدي فيها كل من مجلسيّ النواب والشيوخ دوراَ. ولا يعني القيام بهذه الإجراءات أن يتم عزل الرئيس، فقد تتم إ
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