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1
Easa, Said M., Yasser Hassan, and A. O. Abd El Halim. "Sight distance evaluation on complex highway vertical alignments." Canadian Journal of Civil Engineering 23, no. 3 (June 1, 1996): 577–86. http://dx.doi.org/10.1139/l96-866.
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Sight distance (stopping, passing, and decision) is a key element in highway geometric design. Existing models for evaluating sight distance on vertical alignments are applicable only to simple, isolated elements such as a crest vertical curve, a sag vertical curve, and a reverse vertical curve (a sag curve following a crest curve, or vice versa). This paper presents an analytical methodology for evaluating sight distance on complex vertical alignments that involve any combination of vertical alignment elements. The methodology can be used for evaluating passing sight distance on two-lane highways, and stopping sight distance and decision sight distance on all highways. Sight distance controlled by the headlight beam can also be evaluated. The locations of sight-hidden dips, which may develop when a sag vertical curve follows a crest vertical curve with or without a common tangent, can be determined. Also, sight distances obstructed by overpasses are evaluated. A profile of the available sight distance can be established and used to evaluate sight distance deficiency and the effect of alignment improvements. A software was developed and can be used for determining the available sight distance accurately. The software may replace the current field and graphical practice for establishing the no-passing zones and evaluating stopping and decision sight distances on complex vertical alignments. Key words: sight distance, vertical alignment, highway, passing zones.
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Mehdizadeh, Mojdeh, Negar Maarefat, and Shervin Bagherieh. "Comparison of Accuracy of determining the Distance between Alveolar Crest and Cementoenamel Junction in Digital Radiography with Scanora and DentalEye Software Programs." Journal of Contemporary Dental Practice 17, no. 10 (2016): 815–19. http://dx.doi.org/10.5005/jp-journals-10024-1936.
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ABSTRACT Aim To compare the accuracy of determining the distance between alveolar crest and cementoenamel junction (CEJ) in digital radiography with two image processing software programs. Materials and methods In this in vitro study, 63 sites in a dried human mandible underwent digital periapical radiography. The distance from the alveolar crest to the CEJ was calculated using DentalEye and Scanora software programs and compared with the standard mode (measured on the skull). Statistical analysis was performed with analysis of variance (ANOVA) and paired t-test using Statistical Package for the Social Sciences (SPSS) 23 at α = 0.05. Results There were significant differences in the distances between CEJ and the alveolar crest at the mesial surfaces as measured by the three techniques in standard mode, using DentalEye and Scanora (p-value ≤0.03) softwares; however, there were no significant differences between the results on distal surfaces (p-value = 0.248). Conclusion Under the limitations of the present study, the measurements made to determine the distance from the CEJ to the alveolar crest with DentalEye and Scanora, relative to each other, and relative to the standard mode, were accurate only on distal surfaces of teeth. Clinical significance Digital dental software programs are useful assets that can enhance the diagnosing ability and reduce the need of taking extra images. How to cite this article Mehdizadeh M, Maarefat N, Bagherieh S. Comparison of Accuracy of determining the Distance between Alveolar Crest and Cementoenamel Junction in Digital Radiography with Scanora and DentalEye Software Programs. J Contemp Dent Pract 2016;17(10):815-819.
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Sarkar, Sankar, Sk Zeeshan Ali, and Subhasish Dey. "Turbulence in Wall-Wake Flow Downstream of an Isolated Dunal Bedform." Water 11, no. 10 (September 22, 2019): 1975. http://dx.doi.org/10.3390/w11101975.
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This study examines the turbulence in wall-wake flow downstream of an isolated dunal bedform. The streamwise flow velocity and Reynolds shear stress profiles at the upstream and various streamwise distances downstream of the dune were obtained. The results reveal that in the wall-wake flow, the third-order moments change their signs below the dune crest, whereas their signs remain unaltered above the crest. The near-wake flow is featured by sweep events, whereas the far-wake flow is controlled by the ejection events. Downstream of the dune, the turbulent kinetic energy production and dissipation rates, in the near-bed flow zone, are positive. However, they reduce as the vertical distance increases up to the lower-half of the dune height and beyond that, they increase with an increase in vertical distance, attaining their peaks at the crest. The turbulent kinetic energy diffusion and pressure energy diffusion rates, in the near-bed flow zone, are negative, whereas they attain their positive peaks at the crest. The anisotropy invariant maps indicate that the data plots in the wall-wake flow form a looping trend. Below the crest, the turbulence has an affinity to a two-dimensional isotropy, whereas above the crest, the anisotropy tends to reduce to a quasi-three-dimensional isotropy.
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Dey, Subhasish, Prianka Paul, Sk Zeeshan Ali, and Ellora Padhi. "Reynolds stress anisotropy in flow over two-dimensional rigid dunes." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 476, no. 2242 (October 2020): 20200638. http://dx.doi.org/10.1098/rspa.2020.0638.
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Characteristics of turbulence anisotropy in flow over two-dimensional rigid dunes are analysed. The Reynolds stress anisotropy is envisaged from the perspective of the stress ellipsoid shape. The spatial evolutions of the anisotropic invariant map (AIM), anisotropic invariant function, eigenvalues of the scaled Reynolds stress tensor and eccentricities of the stress ellipsoid are investigated at various streamwise distances along the vertical. The data plots reveal that the oblate spheroid axisymmetric turbulence appears near the top of the crest, whereas the prolate spheroid axisymmetric turbulence dominates near the free surface. At the dune trough, the axisymmetric contraction to the oblate spheroid diminishes, as the vertical distance below the crest increases. At the reattachment point and one-third of the stoss-side, the oblate spheroid axisymmetric turbulence formed below the crest appears to be more contracted, as the vertical distance increases. The AIMs suggest that the turbulence anisotropy up to edge of the boundary layer follows a looping pattern. As the streamwise distance increases, the turbulence anisotropy at the edge of the boundary layer approaches the plane-strain limit up to two-thirds of the stoss-side, intersecting the plane-strain limit at the top of the crest and thereafter moving towards the oblate spheroid axisymmetric turbulence.
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Castro, Luma O., Iury O. Castro, Ana Helena G. de Alencar, José Valladares-Neto, and Carlos Estrela. "Cone beam computed tomography evaluation of distance from cementoenamel junction to alveolar crest before and after nonextraction orthodontic treatment." Angle Orthodontist 86, no. 4 (September 17, 2015): 543–49. http://dx.doi.org/10.2319/040815-235.1.
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ABSTRACT Objective: To evaluate the distance between the cementoenamel junction and the alveolar bone crest before and after orthodontic treatment using cone beam computed tomography (CBCT). Materials and Methods: The sample comprised 30 patients with Angle Class I malocclusion and mild to moderate crowding. The study database comprised dental CBCT scans obtained before and after orthodontic treatment. The distance between the cementoenamel junction to the bone crest of the buccal (n = 720) and lingual (n = 720) surfaces was measured in 24 teeth for each patient using a specific software tool (Xoran version 3.1.62). The Wilcoxon test was used for statistical analysis, and the level of significance was set at P < .05. Results: The distance between the cementoenamel junction and the bone crest increased in 822 (57%) of the 1440 surfaces after orthodontic treatment. The buccal surface of the lower central incisors had the greatest frequency of increased distance (75%), and the lingual surface of lateral incisors had the lowest (40%). The distance between the cementoenamel junction and the alveolar bone crest was greater than 2 mm (alveolar bone dehiscence) in 162 (11%) of the 1440 surfaces before orthodontic treatment and in 279 (19%) after treatment. Conclusions: The distance from the cementoenamel junction to the bone crest changed after orthodontic treatment; the distance was greater than 2 mm in 11% of the surfaces before treatment and in 19% after treatment.
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Taignidis, Ioannis, and George Kanellaidis. "Required Stopping Sight Distance on Crest Vertical Curves." Journal of Transportation Engineering 127, no. 4 (August 2001): 275–82. http://dx.doi.org/10.1061/(asce)0733-947x(2001)127:4(275).
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Srebrzyńska-Witek, Agnieszka, Rafał Koszowski, Ingrid Różyło-Kalinowska, and Magdalena Piskórz. "CBCT for estimation of the cemento-enamel junction and crestal bone of anterior teeth." Open Medicine 15, no. 1 (August 3, 2020): 774–81. http://dx.doi.org/10.1515/med-2020-0211.
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AbstractThe aim of the study is to evaluate the usefulness of cone-beam computed tomography (CBCT) in the assessment of the relationship between the cemento-enamel junction (CEJ) and bone crest of the anterior mandibular cortex. The study population comprised 39 males and 61 females, aged 18–71. A GENDEX GXCB-500 machine, i-CAT Vision and CorelDraw 9 software were used. The distances between the CEJ and bone crest at buccal and lingual sides of six anterior mandibular teeth were measured. Descriptive statistical methods, Student’s t-test and ANOVA were used. The mean distance between the bone crest and CEJ was 2.32 mm ± 0.78 mm at the buccal and 2.52 mm ± 0.85 mm at the lingual side. It was found that in males aged over 50 years, the mean distance at the buccal side was 2.84 mm ± 0.79 mm and was significantly higher than in males aged 49 and less – 2.08 mm ± 0.41 mm. The mean distance at the lingual side was 3.28 mm ± 1.08 mm and was significantly lower in the age group of 49 years and less – 2.10 mm ± 0.41 mm. CBCT allows determining the distance between the CEJ and crestal bone margin at buccal and lingual sides. The data provide crucial information for planning orthodontic treatment, implant placement and periodontal therapy.
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Fambro, Daniel B., Kay Fitzpatrick, and Charles W. Russell. "Operating Speed on Crest Vertical Curves with Limited Stopping Sight Distance." Transportation Research Record: Journal of the Transportation Research Board 1701, no. 1 (January 2000): 25–31. http://dx.doi.org/10.3141/1701-04.
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Horizontal and vertical elements of a highway are designed based on an assumed design speed. This concept was developed in the 1930s as a mechanism for designing rural alignments to permit most drivers to operate uniformly at their desired speed. In 1938, AASHO recognized that drivers select a speed influenced by the roadway environment instead of an assumed design speed. Recent research suggests that design speed is no longer the speed adopted by the faster group of drivers but that it has become a value used to establish the sharpness of horizontal and vertical design elements. The objective of this study was to establish the relationship between design and operating speeds for crest vertical curves with limited sight distance. Geometric data and 3,500 paired speeds (speeds at control and crest sections) were collected at 36 sites in 3 states. The results indicated that both the 85th percentile and the mean operating speeds were well above the inferred design speeds of the crest vertical curves for the range of conditions studied and that the lower the design speed the larger the difference between the 85th percentile speed and the design speed. The mean reductions in speed between the control and crest sections tend to increase as available sight distance is decreased; however, the reduction in speed is less than that suggested by current AASHTO criteria.
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Taiganidis, Ioannis. "Aspects of Stopping-Sight Distance on Crest Vertical Curves." Journal of Transportation Engineering 124, no. 4 (July 1998): 335–42. http://dx.doi.org/10.1061/(asce)0733-947x(1998)124:4(335).
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Dr. Nitin Bhalerao. "To Study the Correlation Between the Height & the Quadruple Semitendinosus Graft Diameters." VIMS Health Science Journal 7, no. 1 (March 6, 2020): 1–4. http://dx.doi.org/10.46858/vimshsj.7101.
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Background: Diameter of hamstring graft is variable. Premature tendon amputation occurs because of inability to identify and release all accessory bands. Preoperative prediction of hamstring graft size, number and distance of accessory bands is useful for surgeon. Methodology: This is cross-sectional study included 60 patients. Correlation coefficient (Pearson’s r) was used. T-test was used to compare the variables in both genders. Result: There were correlations between the mean semitendinosus tendon diameters- femoral side (FD) and tibial side (TB) with height of patient (Pearson correlation for FD =0.442 and P< 0.001) (Pearson correlation for TD =0.663 and P< 0.001). For the semitendinosus tendons, the mean number of accessory bands was 1.48. The average distance of the most distal band (D1) to the tibial crest insertion was 6.7 ± 2.04 cm (range 3- 11 cm). In our study, distance of most proximal band to the tibial crest insertion was 11.5 cm (mean 8.5 cm). Conclusion: In our study, positive correlation between the height and the quadruple semitendinosus graft diameters was present. Semitendinosus graft diameters were more in males as compare to females. Third accessory band was present only in males (n=4) in our study. As height of patient increases, distance of distal band (D1) increases from tibial crest. There was inverse correlation between number of accessory bands and distance of the most distal band (D1) insertion. As number of bands less, the more is distance of proximal band from tibial crest.
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Spicher, Sebastian, Dinar Abdullin, Stefan Grimme, and Olav Schiemann. "Modeling of spin–spin distance distributions for nitroxide labeled biomacromolecules." Physical Chemistry Chemical Physics 22, no. 42 (2020): 24282–90. http://dx.doi.org/10.1039/d0cp04920d.
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De Bellard, Maria Elena, Yi Rao, and Marianne Bronner-Fraser. "Dual function of Slit2 in repulsion and enhanced migration of trunk, but not vagal, neural crest cells." Journal of Cell Biology 162, no. 2 (July 21, 2003): 269–79. http://dx.doi.org/10.1083/jcb.200301041.
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Neural crest precursors to the autonomic nervous system form different derivatives depending upon their axial level of origin; for example, vagal, but not trunk, neural crest cells form the enteric ganglia of the gut. Here, we show that Slit2 is expressed at the entrance of the gut, which is selectively invaded by vagal, but not trunk, neural crest. Accordingly, only trunk neural crest cells express Robo receptors. In vivo and in vitro experiments demonstrate that trunk, not vagal, crest cells avoid cells or cell membranes expressing Slit2, thereby contributing to the differential ability of neural crest populations to invade and innervate the gut. Conversely, exposure to soluble Slit2 significantly increases the distance traversed by trunk neural crest cells. These results suggest that Slit2 can act bifunctionally, both repulsing and stimulating the motility of trunk neural crest cells.
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Mavromatis, Stergios, Nikiforos Stamatiadis, Basil Psarianos, and George Yannis. "Controlling Crest Vertical Curvature Rates Based on Variable Grade Stopping Sight Distance Calculation." Transportation Research Record: Journal of the Transportation Research Board 2521, no. 1 (January 2015): 31–44. http://dx.doi.org/10.3141/2521-04.
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Stopping sight distance (SSD) is a key control element that directly affects the suggested values of crucial road design parameters. Although there is a significant difference in SSD values between upgrades and downgrades, many design policies ignore the grade effect during vehicle braking on variable grades. Such a case occurs during the determination of crest vertical curvature rates in which the relevant SSD values are extracted assuming leveled road geometry. This paper investigates a possible deficiency of such an approach with regard to cases in which the length of the vertical curve exceeds the control SSD values. SSD calculation on variable grades during the braking process was addressed through a recently developed process that related the point mass model and the laws of mechanics. For a wide range of design speed values, charts illustrating the required SSDs were drawn as a function of negative ending grade values related to the control crest vertical curve rates adopted by AASHTO. The process revealed numerous SSD shortage areas for which revised crest vertical curvature rates were provided to grant SSD adequacy throughout the vehicles' braking process. This paper also aimed to provide designers with ready-to-use vertical design tools associated with amended vertical curvature rates to AASHTO's road functional classification as a function of the crest vertical curve's exit grade value.
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Fitzpatrick, Kay, Daniel B. Fambro, and Angela M. Stoddard. "Safety Effects of Limited Stopping Sight Distance on Crest Vertical Curves." Transportation Research Record: Journal of the Transportation Research Board 1701, no. 1 (January 2000): 17–24. http://dx.doi.org/10.3141/1701-03.
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Previous studies that examined the relationship between stopping sight distance and safety have been inconclusive and inconsistent; however, the fact that a relationship has not been established does not necessarily imply that stopping sight distance is not a contributing factor in some crashes. Instead, it means that existing databases have failed to quantify any relationship that might exist. A promising approach to identifying such a relationship is a detailed examination or case study of crashes from a relatively large sample of limited sight distance roadways. If limited sight distance is a factor that contributes to crashes, it should show up in such a study. The objective of this study was to determine whether stopping sight distance was a contributing factor in crashes on roadway segments with limited sight distance crest vertical curves. This objective was accomplished by reviewing 439 narratives from crashes that occurred on 33 multilane and two-lane roadways with limited sight distance crest vertical curves. The findings suggest that the crash rates on rural two-lane highways with limited stopping sight distance are similar to the crash rates on all two-lane rural highways. They also suggest that the percentage of accidents involving large trucks and older drivers is similar on limited sight distance highways and all two-lane rural highways. Thus, for the range of conditions studied, limited stopping sight distance does not appear to be a safety problem.
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dos Santos Oliveira, Rudyard, Maria Rodrigues Coutinho, and Francine Kühl Panzarella. "Morphometric Analysis of the Mental Foramen Using Cone-Beam Computed Tomography." International Journal of Dentistry 2018 (2018): 1–7. http://dx.doi.org/10.1155/2018/4571895.
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This study evaluated the effects of age and sex on the location and size of the mental foramen (MF). A total of 104 cone-beam computed tomography (CBCT) scans from patients’ aged 18–80 years were selected. Images were evaluated using the following parameters: position and size of the MF, and Distances A (distance from the upper limit of the MF to the apex of the first lower premolar), B (distance from the upper cortical border of the MF to the alveolar crest), and C (distance from the border of the MF to the base of the mandible). Results revealed that the location of the MF was predominantly apical (44.4%), between the long axes of the premolars, at an average distance of 4.92 mm from the root of the first lower premolar. The height of the MF was significantly different between both sexes (3.41 and 2.99 mm, resp.; mean height: 3.11 mm; P=0.003). The MF was located on average at 11.21 mm from the alveolar crest and 12.31 mm from the base of the mandible; the former measurement was significantly different between both sexes (13.13 and 11.98 mm, resp.; P≤0.001). In conclusion, the location of the MF was predominantly apical between the long axes of the premolars, and the mean size and distance of the MF were greater in men.
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Hassan, Y., and S. M. Easa. "Design Considerations of Sight Distance Red Zones on Crest Curves." Journal of Transportation Engineering 124, no. 4 (July 1998): 343–52. http://dx.doi.org/10.1061/(asce)0733-947x(1998)124:4(343).
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Hassan, Yasser, Said M. Easa, and A. O. Abd El Halim. "Modeling Headlight Sight Distance on Three-Dimensional Highway Alignments." Transportation Research Record: Journal of the Transportation Research Board 1579, no. 1 (January 1997): 79–88. http://dx.doi.org/10.3141/1579-10.
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Sight distance is one of the major elements that must be considered in the geometric design to achieve safe and comfortable highways. Daytime sight distance has been extensively studied, and analytical models for two-dimensional (2-D) and three-dimensional (3-D) alignments have been developed. However, nighttime (headlight) sight distance has received less attention. Despite the higher accident rate during nighttime than during daytime, existing analytical models evaluating headlight sight distance are very primitive. Moreover, the interaction between the horizontal and vertical alignments has not been modeled. A four-phase analytical model for headlight sight distance on 3-D combined alignments is presented. The model is an application of the finite-element technique in highway geometric design. The model can determine the maximum distance that can be covered by the vehicle’s headlights and that is not obstructed by any sight obstructions including the road surface. On the basis of this analytical model, computer software was developed and used in a preliminary application for 3-D headlight sight distances on a sag or crest vertical curve combined with a horizontal curve. The application showed that the 3-D sight distance on sag vertical curves was generally lower than the corresponding 2-D value when the sag curve was overlapping with a horizontal curve. On the other hand, the overlapping of horizontal curves with crest vertical curves enhanced the 3-D sight distance. The difference between 2-D and 3-D sight distance values in both cases increased with a decrease in the horizontal curve radius and an increase in the pavement cross slope. The model was proved to be extremely valuable in establishing 3-D highway geometric design standards.
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Longuet-Higgins, Michael S., and R. P. Cleaver. "Crest instabilities of gravity waves. Part 1. The almost-highest wave." Journal of Fluid Mechanics 258 (January 10, 1994): 115–29. http://dx.doi.org/10.1017/s0022112094003265.
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It is shown theoretically that the crest of a steep, irrotational gravity wave, considered in isolation, is unstable. There exists just one basic mode of instability, whose exponential rate of growth β equals 0.123(g / R)½, where g denotes gravity and R is the radius of curvature at the undisturbed crest. A volume of water near the crest is shifted towards the forward face of the wave; the ‘toe’ of the instability is at a horizontal distance 0.45R ahead of the crest. The instability may represent the initial stage of a spilling breaker. On small scales, the ‘toe’ may be a source of parasitic capillary waves.
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Godil, Aamir Zahid, Trupti Jagannath Devadiga, Shraddha Chandrashekhar Supnekar, Arshi Ilyas Kazi, Sanaa Akhlaq Wadwan, and Ramandeep Dugal. "Position of posterior superior alveolar artery in relation to the maxillary sinus using cone beam computed tomography in Indian sub-population." Journal of Oral Medicine and Oral Surgery 27, no. 3 (2021): 34. http://dx.doi.org/10.1051/mbcb/2021007.
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Purpose: To assess the location of posterior superior alveolar artery (PSAA) using CBCT in relevance to sinus lift procedure for implant placement. Patients and Methods: A retrospective study was conducted using the CBCT data of 500 patients (n = 500). Linear measurements were carried out to localize the medio-lateral and vertical position of posterior superior alveolar artery in postero-lateral wall of maxillary sinus and its proximity to the floor of maxillary sinus using CS 3D imaging 3.7.0 software program. The relative position of PSAA was determined as; (a) intra-osseous, (b) below the membrane and (c) outer-cortex of lateral sinus wall. The location of PSAA was assessed in molar region bilaterally by using following radiographic measurement; (1) distance between the lower border of posterior superior alveolar artery and alveolar crest, (2) height from the floor of maxillary sinus to alveolar crest and (3) distance from the posterior superior alveolar artery to medial wall of maxillary sinus. Results: The prevalence of the artery was observed in 99.4% of the sinuses and was mostly intraosseous (84.2%).The mean distance between the lower border of the artery and alveolar crest is significantly higher in males compared to females (P < 0.01). The distribution of artery location did not differ significantly across various age groups (P > 0.05). Discussion/Conclusion: The most common variant of PSAA was identified in the intra-osseous region and the mean distance of the vessel to crest of the residual ridge differs significantly with gender and not with age.
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Mehdizadeh, Mojdeh, Aram Mohammadi, and Arezoo Mahdian. "Study of Distance Measurement of the Alveolar Crest to Maxillary Sinus Floor on Different Views of CBCT." Scholars Journal of Dental Sciences 3, no. 6 (June 2016): 175–79. http://dx.doi.org/10.21276/sjds.2016.3.6.5.
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Kheur, Mohit, Nikhil V. Jain, Ramandeep Dugal, and Smita Musani. "Factors Influencing the Presence of Interproximal Dental Papillae between Maxillary Anterior Teeth: A Clinical and Radiographic Study of the Indian Population." World Journal of Dentistry 4, no. 3 (2013): 158–63. http://dx.doi.org/10.5005/jp-journals-10015-1224.
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ABSTRACT Introduction The presence of a normal and harmonically shaped papilla is crucial to avoid the presence of the ‘black triangle’ which is of major esthetic concern. The distance from the alveolar bone crest (BC) to the base of the contact area (CP) is a significant factor in determining whether a papilla will fill the interdental space. Aim To correlate the BC-CP distance with a different anatomic variable using a noninvasive method and to describe a simple, repeatable, observational measuring protocol to contribute to the prosthetic and surgical treatment planning. Materials and methods A total of 63 patients were enrolled in the study. A digital radiographs of the interdental embrasure between teeth 12 and 11, 11 and 21 and teeth 21 and 22 were taken with a paralleling cone technique using a RINN film holder. The radiographic data was used to measure the distance between the contact point and the bone crest (BC-CP) and the interdental distance (IDD) at the level of the bone crest. Results The number of papillae that filled the interproximal space decreased with the increasing BC-CP and IDD distance. Conclusion The vertical and horizontal dimensions of the interdental space influence the existence of interdental papilla. How to cite this article Jain N, Dugal R, Kheur M, Musani S. Factors Influencing the Presence of Interproximal Dental Papillae between Maxillary Anterior Teeth: A Clinical and Radiographic Study of the Indian Population. World J Dent 2013;4(3):158-163.
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Tosney, Kathryn W. "Long-distance cue from emerging dermis stimulates neural crest melanoblast migration." Developmental Dynamics 229, no. 1 (2003): 99–108. http://dx.doi.org/10.1002/dvdy.10492.
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Lum, C. S., Samuel J. Keith, and David Scott. "The long-distance hiking social world along the Pacific Crest Trail." Journal of Leisure Research 51, no. 2 (August 23, 2019): 165–82. http://dx.doi.org/10.1080/00222216.2019.1640095.
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Tubbs, R. Shane, Matthew R. Levin, Marios Loukas, Eric A. Potts, and Aaron A. Cohen-Gadol. "Anatomy and landmarks for the superior and middle cluneal nerves: application to posterior iliac crest harvest and entrapment syndromes." Journal of Neurosurgery: Spine 13, no. 3 (September 2010): 356–59. http://dx.doi.org/10.3171/2010.3.spine09747.
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Object To date, only scant descriptions of the cluneal nerves are available. As these nerves, and especially the superior group, may be encountered and injured during posterior iliac crest harvest for spinal arthrodesis procedures, the present study was performed to better elucidate their anatomy and to provide anatomical landmarks for their localization. Methods The superior and middle cluneal nerves were dissected from their origin to termination in 20 cadaveric sides. The distance between the posterior superior iliac spine (PSIS) and superior cluneal nerves at the iliac crest and the distance between this bony prominence and the origin of the middle cluneals were measured. The specific course of each nerve was documented, and the diameter and length of all cluneal nerves were measured. Results Superior and middle cluneal nerves were found on all sides. An intermediate superior cluneal nerve and lateral superior cluneal nerve were not identified on 4 and 5 sides, respectively. The superior cluneal nerves always passed through the psoas major and paraspinal muscles and traveled posterior to the quadratus lumborum. The mean diameters of the superior and middle cluneal nerves were 1.1 and 0.8 mm, respectively. From the PSIS, the superior cluneal branches passed at means of 5, 6.5, and 7.3 cm laterally on the iliac crest. At their origin, the middle cluneal nerves had mean distances of 2 cm superior to the PSIS, 0 cm from the PSIS, and 1.5 cm inferior to the PSIS. In their course, the middle cluneal nerves traversed the paraspinal muscles attaching onto the dorsal sacrum. Conclusions Knowledge of the cutaneous nerves that cross the posterior aspect of the iliac crest may assist in avoiding their injury during bone harvest. Additionally, an understanding of the anatomical pathway that these nerves take may be useful in decompressive procedures for entrapment syndromes involving the cluneal nerves.
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Silva Pierro, Viviane Santos da, Ivete Pomarico Ribeiro de Souza, and Ronir Raggio Luiz. "Influence of Local Factors on Cementoenamel Junction–Alveolar Bone Crest Distance in Primary Dentition." Journal of Clinical Pediatric Dentistry 33, no. 3 (April 1, 2009): 199–206. http://dx.doi.org/10.17796/jcpd.33.3.c707urm416867792.
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Objective: This study illustrated the influence of local factors (dental biofilm, gingival bleeding, probing depth, proximal contact and proximal caries/inadequate restorations) on the cementoenamel junction(CEJ)-alveolar bone crest (ABC) distance in primary canines and molars of healthy children with complete primary dentition. Study Design: Two hundred and four patients have been examined clinically with regard to biofilm's presence, gingival status, probing depth, proximal contact and dental condition (carious lesions/restorations). Two bitewings of each patient were also taken. Eight dental surfaces (second molars mesial, first molars mesial and distal, and canines distal) could be analyzed per bitewing and the CEJ-ABC distance was measured using a digimatic caliper. Statistical analyses were controlled by dental arch, tooth type and surface. Mann-Whitney test was used to verify the association between CEJ-ABC distance and local factors. Results: After stratifying the data according to those influencing factors, the only local factor associated with increased CEJ-ABC distances in most of the different analyzed dental surfaces was the increased probing depth (>2mm), although only two dental surfaces showed statistical significance(p<0.01). Conclusion: Among the analyzed local factors, increased probing depth was the only factor that proved to be relevant in children's alveolar bone loss screening.
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Mavromatis, Stergios, Vassilios Matragos, and Panagiotis Papantoniou. "Crest Vertical Curvature Safety Assessment through Variable Grade Stopping Sight Distance Control." Transportation Research Procedia 45 (2020): 426–33. http://dx.doi.org/10.1016/j.trpro.2020.03.035.
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Sun, Jian Cheng, and Chen Feng Chen. "Length Requirements for New Single-Arc Unsymmetrical Crest Vertical Curve for Highways." Advanced Materials Research 1065-1069 (December 2014): 755–59. http://dx.doi.org/10.4028/www.scientific.net/amr.1065-1069.755.
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Existing highway vertical curves may be grouped into two categories: symmetrical vertical curves and unsymmetrical vertical curves. In the past vertical curves design, parabolic arc was used as the vertical curve. This paper presents the new single-arc unsymmetrical vertical curve which is include only one cubic parabola. This curve has the gradual change of the rates of change in grade so that it can provide more comfort to the driver. This paper mainly presents the method by which to find the minimum length for a new single-arc unsymmetrical crest vertical curve based on the minimum sight distance . The discussion will be divided into two situations: the sight distance is longer than the curve length and the sight distance is not longer than the curve length.
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Sun, Wentao, Anhao Liu, Yin Gong, Rong Shu, and Yufeng Xie. "Evaluation of the Anastomosis Canal in Lateral Maxillary Sinus Wall With Cone Beam Computerized Tomography: A Clinical Study." Journal of Oral Implantology 44, no. 1 (February 1, 2018): 5–13. http://dx.doi.org/10.1563/aaid-joi-d-17-00129.
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This clinical study used cone beam computerized tomography (CBCT) to locate the position of the anastomosis canal in lateral wall of maxillary sinuses, and to evaluate the thickness of lateral sinus wall and the distance from the lower border of the canal to the sinus floor, which could provide surgeon with information about this anastomosis. Two hundred and forty-two (242) volumes of CBCT scans were included in this study. The distances from the lower border of the anastomosis canal to the sinus floor and from the maxillary alveolar crest to the sinus floor were evaluated in transversal plane, and the thickness of the lateral sinus wall was measured at the distance of 3, 6, 9 mm from the sinus floor and at the level of the lower border of the canal at the same plane. The canal was identified in 87.6% (424/484) of the sinus. Most canals were intraosseous, or beneath the sinus membrane. The mean distance was 9.2 ± 3.5 mm from the lower border of the canal to the sinus floor, and 10.8 ± 4.0 mm from the alveolar crest to the sinus floor. The thickness of the lateral sinus wall was 2.4 ± 0.9 mm, 1.8 ± 0.8 mm, 1.7 ± 0.7 mm, 1.8 ± 0.8 mm at the distance of 3, 6, 9 mm from the sinus floor and at the level of the lower border of the canal. The location of the anastomosis canals varied from each patient, but the distance from the sinus floor was similar in different teeth sites. The sinus floor could be an anatomic landmark of sinus floor augmentation. In order not to interrupt this canal, great care must be taken by the implant surgeon to identify this canal.
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Yousefzadeh, Saeed, Maryam Johari, Sedigheh Sheikhzadeh, Sina Haghanifar, Hemmat Gholinia, and Nazanin Arbabzadegan Hashemi. "A Cross-Sectional Study of Labial Bone and Covering Soft Tissue in Maxillary Anterior Segment: A Dilemma in Orthodontics." International Journal of Dentistry 2021 (July 12, 2021): 1–7. http://dx.doi.org/10.1155/2021/5553301.
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Purposes. The thickness of the buccal bone and its covering gingiva is pivotal in determining the prognosis of implant therapy as well as fixed orthodontic appliances, especially nonextraction treatments. The purpose of this study was to evaluate the buccal bone thickness and covering soft tissue in the maxillary anterior segment. Methods. This study measured the hard tissue thickness at 2 and 5 mm more apical from the crest and at the root apical apex, as well as the distance from the CEJ to the alveolar crest, using 80 CBCT images divided into three age groups. In addition, the distance from free gingiva to alveolar crest and from free gingiva to CEJ was measured. The acquired data then was analyzed using an ANOVA, t-test, and Pearson correlation to investigate any associations or statistically significant differences between parameters. Results. The highest mean soft tissue thickness at the 5 mm level was for central incisors and the least for canine. The highest mean thickness of soft tissue at the crest level and its 2 mm apical level was related to central incisors and the lowest mean thickness at these levels was related to canine. Analysis of hard tissue variables showed the lower thickness of hard tissue at higher ages compared to the young patients group, but the thickness of the soft tissue increases with age. Conclusion. The highest mean thickness of the buccal hard tissue in the maxillary anterior segment was in lateral and central incisors. Also, the most prominent thickness of the labial soft tissue was in the central and lateral incisors at levels close to the crest.
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Hassan, Yasser. "Improved Design of Vertical Curves with Sight Distance Profiles." Transportation Research Record: Journal of the Transportation Research Board 1851, no. 1 (January 2003): 13–24. http://dx.doi.org/10.3141/1851-02.
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Design of vertical alignment is one of the main tasks in highway geometric design. This task requires, among other things, that the designer ensure drivers always have a clear view of the road so they can stop before hitting an unexpected object in the road. Therefore, the ability to determine the required and available stopping sight distance (SSD) at any point of the vertical alignment is essential for the design process. Current design guides in the United States and Canada provide simple analytical models for determining the minimum length of a vertical curve that would satisfy the sight distance requirement. However, these models ignore the effect of grade on the required SSD. Alternative approaches and models have also been suggested but cover only special cases of vertical curves. Two specific models were expanded to determine the required SSD on crest and sag vertical curves. By comparing profiles of available SSD and required SSD on examples of vertical curves, it was shown that current North American design practices might yield segments of the vertical curve where the driver’s view is constrained to a distance shorter than the required SSD. An alternative design procedure based on the models was developed and used to determine the minimum lengths of crest and sag vertical curves. Depending on the approach grade, these new values of minimum curve length might be greater than or less than values obtained through conventional design procedures. Design aids were therefore provided in tabular form for designers’ easy and quick use.
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Easa, Said M. "Improved speed-profile model for two-lane rural highways." Canadian Journal of Civil Engineering 30, no. 6 (December 1, 2003): 1055–65. http://dx.doi.org/10.1139/l03-021.
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The speed-profile model has been suggested as a valuable tool for evaluating geometric design consistency for two-lane rural highways with isolated and combined horizontal and vertical alignments. The model determines the operating speeds on the speed-change (SC) segment, which is the distance between speed-limiting curves. The speed-limiting curves are the horizontal curves and the limited sight-distance crest vertical curves on horizontal tangents, where the sight distance required by the design guides is not satisfied. The model assumes that deceleration begins where required, which implies that the next curve is visible when deceleration starts. This paper presents an extension to the speed-profile model to incorporate the effect of sight obstruction on operating speeds and deceleration rates. The SC segment may include nonlimited sight–distance crest vertical and sag vertical curves. These curves may present sight obstruction. A procedure to determine whether the sight line is obstructed is developed. If it does, simple formulas are applied for revising the operating-speed profile. The extended model is suitable for inclusion in the design consistency module of the interactive highway safety design model.Key words: speed profile, model, two-lane highways, alignments, design consistency.
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Jiang, Chong, Jia-Li He, Lin Liu, and Bo-Wen Sun. "Effect of Loading Direction and Slope on Laterally Loaded Pile in Sloping Ground." Advances in Civil Engineering 2018 (November 15, 2018): 1–12. http://dx.doi.org/10.1155/2018/7569578.
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A series of three-dimensional finite element analyses were performed to study the behavior of piles in sloping ground under undrained lateral loading conditions. The analyses have been conducted for slopes with different angles and two loading directions. The obtained results show that as the slope increases, it can cause greater lateral displacement and internal force of the pile. In addition, the increase of the slope ratio will cause the position of the maximum bending moment and soil resistance zero point of the pile to move downward, further increasing the pile deflection. Furthermore, when the pile distance from slope crest B < 7D, the displacement and internal force development of the pile under toward loading is more obvious. When the pile distance from the slope crest exceeds 7D, the effect of loading direction on the pile can be neglected.
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Nordstrom, Taylor, and Chris Levitz. "A NEW APPROACH TO NEARSHORE BREAKWATERS: A CASE STUDY FOR UNDULATING CRESTS." Coastal Engineering Proceedings, no. 36 (December 30, 2018): 7. http://dx.doi.org/10.9753/icce.v36.structures.7.
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Traditionally, stone nearshore breakwaters are designed and constructed using standard parameters based on a series of existing equations and calculations (frequently those specified in the Coastal Engineering Manual for the U.S.). These include a calculated crest elevation based on design wave heights, along with computationally derived side slopes and crest widths chosen to either eliminate or reduce wave energy transmission by a desired amount. Another design decision is how frequent and how large to make gaps between the breakwaters, which is more standard for sandy scenarios, but less so when dealing with marsh and bluff shorelines. Additionally, the breakwaters are designed to be constructed within a range of design distances from the shoreline, with parameters chosen to define desired post-construction scenarios such as tombolo or spit formation. There are significant data and existing research allowing for these calculations in sandy environments. For marsh or bluff based shorelines, the offshore distance is often developed based on constructability or a desired marsh restoration template.
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Shalkamy, Amr, Karim El-Basyouny, and Hai Yang Xu. "Voxel-Based Methodology for Automated 3D Sight Distance Assessment on Highways using Mobile Light Detection and Ranging Data." Transportation Research Record: Journal of the Transportation Research Board 2674, no. 5 (May 2020): 587–99. http://dx.doi.org/10.1177/0361198120917376.
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Ensuring that the available sight distance (ASD) on highways meets the minimum requirements of geometric design standards is crucial for safe and efficient operation of highways. Current practices of ASD assessment using design software or through site visits are labor intensive, time consuming, and traffic disruptive. Thus, this paper introduces a fully automated algorithm that allows large-scale assessment of ASD in three-dimensional (3D) space on highways utilizing mobile light detection and ranging (LiDAR) data. The algorithm was tested on LiDAR data of highway segments in Alberta, Canada. The results showed that the algorithm was highly accurate in detecting sight distance limitations at the defined regions and, in all cases, the driver’s vision was restricted by the pavement surface on vertical crest curves. In the case of combined vertical and horizontal curves, the vertical crest curve was found to be the controlling element in sight distance deficiencies. In addition, the assessment of historical collision data revealed clusters along the regions defined with ASD limitations, indicating that restrictions in drivers’ vision could have contributed to the collision occurrence.
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Nitek, Stanisław, Leopold Bakoń, Mansoor Sharifi, Maciej Rysz, Lechosław P. Chmielik, and Iwona Sadowska-Krawczenko. "Morphometry of the Orbit in East-European Population Based on Three-Dimensional CT Reconstruction." Advances in Anatomy 2015 (October 29, 2015): 1–10. http://dx.doi.org/10.1155/2015/101438.
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Objectives. To determine safe distances within the orbit outlining reliable operative area on the basis of multislice computed tomography (MSCT) scans. Patients and Methods. MSCT of orbits of 50 Caucasian patients (26 males and 24 females, mean age 56) were analysed. Native scans resolutions were in all cases 0.625 mm. Measurements were done in postprocessing workstation with 2D and 3D reconstructions. The safe distances values were calculated by subtracting three standard deviations from the arithmetical average (X=AVG-3 STD). This method was chosen because this range covers 99.86% of every population. Results. The results of the measurements in men and women, respectively, are as follows (1) distance from optic canal to supraorbital foramen, mean 46,49 mm and 43,29 mm, (2) distance from the optic canal to maxillozygomatic suture at the inferior margin of the orbit mean 45,24 mm and 42,8 mm, (3) distance from the optic canal to frontozygomatic suture 46,15 mm and 43,58 mm, (4) distance from the optic canal to anterior lacrimal crest 40,40 mm and 38,39 mm, (5) distance from superior orbital fissure to the frontozygomatic suture 34,06 mm and 32,62 mm, and (6) distance from supraorbital foramen to the superior orbital fissure 42,32 mm and 39,39 mm. Conclusion. The most probable safe distances calculated by adopted formula were for the superior orbital fissure 23,39–30,58 mm and for the orbital opening of the optic canal 31,9–38,0 mm from the bony structures of the orbital entrance depending on the orbital quadrant.
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Fambro, Daniel B., Kay Fitzpatrick, and Rodger J. Koppa. "New Stopping Sight Distance Model for Use in Highway Geometric Design." Transportation Research Record: Journal of the Transportation Research Board 1701, no. 1 (January 2000): 1–8. http://dx.doi.org/10.3141/1701-01.
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Stopping sight distance is an important design parameter in that it defines the minimum sight distance that must be provided at all points along the highway. Thus, it influences geometric design values, construction costs, and highway safety. Stopping sight distance is defined as the sum of two components—brake reaction distance and braking distance. The basic model for calculating stopping sight distances was formalized in 1940, and the model’s parameters have been altered to compensate for changes in eye height, object height, and driver behavior over the past 50 years. Recent studies, however, question whether the model’s parameters and assumptions represent real-world conditions. A new model for determining stopping sight distance requirements for geometric design of highways is presented. This model is based on parameters describing driver and vehicle capabilities that can be validated with field data and defended as safe driving behavior. More than 50 drivers, 3,000 braking maneuvers, 1,000 driver eye heights, and 1,000 accident narratives were used to develop the recommended parameter values for the new model. The recommended values are attainable by most drivers, vehicles, and roadways. This model results in stopping sight distances, sag vertical curve lengths, and lateral clearances that are between the current minimum and desirable requirements and crest vertical curve lengths that are shorter than current minimum requirements.
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Balachandar, Ram, and V. C. Patel. "Flow over a fixed rough dune." Canadian Journal of Civil Engineering 35, no. 5 (May 2008): 511–20. http://dx.doi.org/10.1139/l08-004.
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Using a laser Doppler velocimeter (LDV) system, experiments were carried out to obtain detailed information on the flow over a long train of fixed two-dimensional rough-wall dunes. The experiments provide quantitative data on conventionally averaged velocity and turbulence parameters, as well as insights on the flow structures that play a crucial role in sediment transport. The results indicate that the shape of the dunes has a major influence on the flow features, whereas the effect of near-bed roughness is limited to the wall region extending to a distance of about 80% of the dune height about the crest. However, the length of the separation eddy seems to be influenced by the near-bed roughness. As in flow over a smooth dune, the turbulence data reveal large peaks along a line roughly coinciding with the shear layer emanating from the separation at the crest. However, the location of the peak turbulence is farther extended into the flow away from the bed with increasing bed roughness. Moreover, with increasing roughness the magnitude of the peak is also reduced. A secondary peak in the streamwise turbulence profiles is noticed at some distance from the bed. This feature is not influenced by the near-bed roughness and indicates sustenance of turbulence generated by the previous dune and relates to the convection of the upstream flow history. Based on the results obtained at several stations between two successive dune crests, one can conclude that the quantitative effect of roughness itself is limited to the near-bed region in the measurements at all levels.
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Fidyawati, Desy. "BIOLOGIC WIDTH CONCEPT IN GINGIVECTOMY." Jurnal Ilmiah dan Teknologi Kedokteran Gigi 16, no. 2 (February 23, 2021): 67–72. http://dx.doi.org/10.32509/jitekgi.v16i2.1086.
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Background: Relationship between periodontal tissue and aesthetic considerations is an important thing to determine the form, function and aesthetics of periodontal tissue itself. For orthodontic cases with gingival enlargement, using the biological width concept in gingivectomy to facilitate an optimal oral hygiene maintenance, function and aesthetic. Bone sounding before gingival recontouring is dictated by the distance from the gingiva crest to alveolar crest. Recommended distance between margins restoration and alveolar bone crest is 3 mm to avoid breaching the biologic width.Case and Case Management: Case 1: A 21 years old female patient whom referred from orthodontist with gingival enlargement in upper front teeth after treated with fixed orthodontic for 1.5 years. PBI: 1,6. After clinical examination, bone sounding was performed = 7mm and gingivectomy without ostectomy was determined. Case 2: A male patient, 24 years old, with gingival enlargement in upper front teeth while treated with fixed orthodontic. After determined the problem, bone sounding (6 mm) was performed along with gingivectomy without ostectomy also for anterior upper right site.Conclusion: The purpose of this report is to provide a diagnostic rationale for gingival recontouring. When gingivectomy is determined, the concept of biological width must be applied achieve a harmonious gingival contour with an optimal oral hygiene maintenance.
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Aoun, Georges, Ibrahim Nasseh, Sayde Sokhn, and Mohamad Rifai. "Lingual Foramina and Canals of the Mandible: Anatomic Variations in a Lebanese Population." Journal of Clinical Imaging Science 7 (April 25, 2017): 16. http://dx.doi.org/10.4103/jcis.jcis_15_17.
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Objective: The aim of this study was to evaluate the mandibular lingual foramina (LF) and canals and their anatomic variations using cone-beam computed tomography (CBCT) technology in a Lebanese population. Materials and Methods: In this study, we analyzed CBCT images of 90 adult Lebanese patients (41 males and 49 females). We assessed the number and location of the LF. In additional, we measured: (a) The distance from both the alveolar crest and the inferior border of the mandible to the LF and (b) the length of the lingual canals (LCs). The data obtained was analyzed statistically using Shapiro–Wilk normality test, t-test, Chi-square, and Fisher's exact tests. Statistical significance was set at 0.05. Results: In our sample, the LF and canals were present in 93.33% of the CBCT analyzed, and the majority (76.64%) was located above the genial tubercles. The distance from the foramen of the superior and the inferior LCs to the alveolar crest was 16.24 ± 2.82 mm and 25.49 ± 2.43 mm, respectively. The distance from the foramen of the superior canal to the inferior border of the mandible was 14 ± 2.32 mm. The mean length of the superior canal was 5.81 ± 1.6 mm and 4.25 ± 1.2 mm for the inferior one. There were no gender-related differences in the anatomic characteristics of the LF and canals except for the distance measured from the superior canal foramina to the alveolar crest where the measurement was significantly greater in males compared to females. Neither the number of canals nor the positions of the foramina were different between males and females. Conclusion: Within the limits of this study, we concluded that in our sample of Lebanese adults, there was substantial variability in the LF and canals anatomy and location.
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Kue, J., J. Gemma, and S. Roe. "Isometry of potential suture attachment sites for the cranial cruciate ligament deficient canine stifle." Veterinary and Comparative Orthopaedics and Traumatology 21, no. 03 (2008): 215–20. http://dx.doi.org/10.1055/s-0037-1617364.
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SummaryFor a suture that spans a joint to provide support without limiting range of motion, its attachment points on either side of the joint must remain the same distance from each other from full extension to full flexion. The effect of location of the tibial crest attachment for a fabello- tibial crest suture was studied in seven canine cadaveric stifles. The distance from a fabella marker to each of 11 tibial markers was determined from radiographs of each limb, as it progressed from 150° to 130°, 105°, 90°, 65° and 45° of flexion. The marker locations that were more proximal and cranial on the tibial crest had the least percent change in distance. The effect of anchoring the suture to the femur at a site other than the fabella was investigated using the same radiographs. Five marks were placed in a grid on the caudal portion of the femoral condyle and supracondylar region. The mean percent change in length from each femoral point to the five more proximal and cranial tibial markers was determined. The least change in length occurred for those femoral points located close to the origin of the cranial cruciate ligament. Locations more proximal or cranial resulted in large changes in length, particularly when matched with less ideal tibial locations. Although this study does not directly examine length changes in sutures, it demonstrates that there are some locations for the origin and insertion of an extracapsular suture that are associated with less length change than others, and also forms the basis for future investigations.
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Al Amri, Maha S., Hanadi M. Sabban, Doaa H. Alsaggaf, Fahad F. Alsulaimani, Ghassan A. Al-Turki, Mohammad S. Al-Zahrani, and Khalid H. Zawawi. "Anatomical consideration for optimal position of orthodontic miniscrews in the maxilla: a CBCT appraisal." Annals of Saudi Medicine 40, no. 4 (July 2020): 330–37. http://dx.doi.org/10.5144/0256-4947.2020.330.
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ABSTRACT BACKGROUND: Orthodontic miniscrews are commonly used as temporary anchorage devices. Bone thickness and bone depth are important factors when placing miniscrews. There are no studies to assess the maxillary bone thickness for optimum miniscrew placement in a Saudi population. OBJECTIVE: Assess the proximity of the maxillary sinus and nasal cavity in areas where miniscrews are usually inserted using cone beam computed tomography (CBCT). DESIGN: Retrospective, cross-sectional. SETTING: Department of maxillofacial radiology in a Saudi dental school. PATIENTS AND METHODS: Using CBCT images, we measured the distance between the maxillary sinus and nasal cavity to the palatal bone, buccal intra-radicular and infrazygomatic crest areas. Mean values (SD) were compared at various locations, including by gender, and correlation with age was calculated. MAIN OUTCOME MEASURE: Mean bone thickness at commonly used sites for orthodontic miniscrew placements in the maxilla. Secondary outcome was the insertion angle in the infrazygomatic crest area. SAMPLE SIZE: CBCT images of 100 patients (50 males and 50 females). RESULTS: The mean (standard deviation) age for the sample was 25.4 (6.5) years with no significant difference between males and females. In the palate, the distance to the nasal cavity and maxillary sinus was greater anteriorly and decreased significantly posteriorly ( P <.001). Buccally, the interdental bone depth was significantly greater between the second premolar and first molar (11.96 mm) compared to between the central and lateral incisors (7.53 mm, P <.001). The mean bone thickness of the infrazygomatic crest area at a 45° insertion angle was 4.94 mm compared to 3.90 at a 70° insertion angle ( P <.001). No correlation was found between age and bone thickness. CONCLUSION: The distance to the nasal cavity and maxillary sinus was greater in the anterior than posterior areas. There is minimal risk of injuring the maxillary sinus or nasal cavity using the buccal approach. Caution is needed when placing miniscrews in the infrazygomatic crest area. LIMITATIONS: Cross-sectional study from one center; hence, findings cannot be generalized to other populations. CONFLICT OF INTEREST: None.
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Shrestha, Bidhan, GM Kurtzman, BB Basnet, G. Adhikari, and D. Rokaya. "Assessment of buccal bone thickness of aesthetic maxillary region in Nepalese adults: A Cone Beam Computed Tomography (CBCT) Study." Journal of Nepalese Prosthodontic Society 2, no. 2 (December 31, 2019): 63–72. http://dx.doi.org/10.3126/jnprossoc.v2i2.31192.
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Introduction: The dental implant has now become a routine treatment for oral rehabilitation. The treatment planning and positioning of implants is greatly dependent upon the clinicians’ understanding of the alveolar architecture of the maxilla and mandible. In the esthetic zone, the implants therapy can be successful only if it is in harmony with the surrounding tissues.
Objectives: To study the labial osseous wall thickness of the anterior maxillary bone at various sites apical to the cemento-enamel junction using the cone beam computed tomography (CBCT).
Materials and Methods: Cone beam tomographic scans of 150 Nepalese adults (70 females and 80 males) were obtained from the Oral Radiology Unit, Kantipur Dental College Teaching Hospital & Research Center. CBCT scans were carried out by trained technicians using CS 9300 (Carestream Dental, Atlanta, GA, USA). In the CBCT images, distances between the CEJ and alveolar crest (AC) as well as the labial bone thickness at different levels (at the crest, 1mm, 3mm and 5 mm) were measured for central incisor (CI), lateral incisor (LI), and canine (C).
Results: It showed that the average distance between CEJ and crest of CI, LI, and C were 1.98±0.84 mm, 2.09±0.83 mm, and 2.12±1.20 mm, respectively. Only 3.3% of the CI, 10.7% of the LI, and 13.3% of the C showed a thick labial bone (1–2 mm) at the crestal level. At the 1 mm level, 75.3% of the CI, 64.5% of LI, and 70% C showed a very thin bony wall. Similarly, none showed very thick bony wall (>2mm). The thickness level was significant at the crest and at 5 mm level. The highest bone thickness of LI was found at the 1 mm level. In addition, there was also significant difference in different levels of LIs. The mean distance between the CEJ and the AC for the CI and the C was significantly higher in males than females.
Conclusion: The labial bone in the anterior maxilla is inherently thin, with more than 80% of the sites showing less than 1 mm. The results of this study may be useful for the implant planning in the esthetic zone and it is recommended tissue augmentation (soft and hard) to achieve esthetic emergence profile.
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Garib, Daniela Gamba, Marília Sayako Yatabe, Terumi Okada Ozawa, and Omar Gabriel da Silva Filho. "Alveolar Bone Morphology in Patients with Bilateral Complete Cleft Lip and Palate in the Mixed Dentition: Cone Beam Computed Tomography Evaluation." Cleft Palate-Craniofacial Journal 49, no. 2 (March 2012): 208–14. http://dx.doi.org/10.1597/10-198.
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Objectives To verify the thickness and level of alveolar bone around the teeth adjacent to the cleft by means of cone beam computed tomography (CBCT) in patients with complete bilateral cleft lip and palate prior to bone graft surgery and orthodontic intervention. Method The sample comprised 10 patients with complete bilateral cleft lip and palate (five boys and five girls) in the mixed dentition. The mean age was 9.5 years, and all subjects showed a G3 interarch relationship according to the Bauru index. The thickness of alveolar bone surrounding the maxillary incisors and the maxillary canines was measured in CBCT axial section using the software iCAT Xoran System. The distance between the alveolar bone crest and the cement-enamel junction (CEJ) was measured in cross sections. Results The tomography images showed a thin alveolar bone plate around teeth adjacent to clefts. No bone dehiscence was observed in teeth adjacent to clefts during the mixed dentition. A slight increase in the distance between the alveolar bone crest and the CEJ was observed in the mesial and lingual aspects of canines adjacent to cleft. Conclusion In patients with BCLP in the mixed dentition, teeth adjacent to the alveolar cleft are covered by a thin alveolar bone plate. However, the level of alveolar bone crest around these teeth seems to be normal, and no bone dehiscence was identified at this age.
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Nie, Shuyi, Yun Kee, and Marianne Bronner-Fraser. "Caldesmon regulates actin dynamics to influence cranial neural crest migration in Xenopus." Molecular Biology of the Cell 22, no. 18 (September 15, 2011): 3355–65. http://dx.doi.org/10.1091/mbc.e11-02-0165.
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Caldesmon (CaD) is an important actin modulator that associates with actin filaments to regulate cell morphology and motility. Although extensively studied in cultured cells, there is little functional information regarding the role of CaD in migrating cells in vivo. Here we show that nonmuscle CaD is highly expressed in both premigratory and migrating cranial neural crest cells of Xenopus embryos. Depletion of CaD with antisense morpholino oligonucleotides causes cranial neural crest cells to migrate a significantly shorter distance, prevents their segregation into distinct migratory streams, and later results in severe defects in cartilage formation. Demonstrating specificity, these effects are rescued by adding back exogenous CaD. Interestingly, CaD proteins with mutations in the Ca2+-calmodulin–binding sites or ErK/Cdk1 phosphorylation sites fail to rescue the knockdown phenotypes, whereas mutation of the PAK phosphorylation site is able to rescue them. Analysis of neural crest explants reveals that CaD is required for the dynamic arrangements of actin and, thus, for cell shape changes and process formation. Taken together, these results suggest that the actin-modulating activity of CaD may underlie its critical function and is regulated by distinct signaling pathways during normal neural crest migration.
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Gemmrich, Johannes. "Strong Turbulence in the Wave Crest Region." Journal of Physical Oceanography 40, no. 3 (March 1, 2010): 583–95. http://dx.doi.org/10.1175/2009jpo4179.1.
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Abstract High-resolution vertical velocity profiles in the surface layer of a lake reveal the turbulence structure beneath strongly forced waves. Dissipation rates of turbulence kinetic energy are estimated based on centered second-order structure functions at 4-Hz sampling. Dissipation rates within nonbreaking wave crests are on average 3 times larger than values found at the same distance to the free surface but within the wave trough region. This ratio increases to 18 times for periods with frequent wave breaking. The depth-integrated mean dissipation rate is a function of the wave field and correlates well with the mean wave saturation in the wave band ωp ≤ ω ≤ 4ωp. It shows a clear threshold behavior in accordance with the onset of wave breaking. The initial bubble size distribution is estimated from the observed distribution of energy dissipation rates, assuming the Hinze scale being the limiting size. This model yields the slope of the size distribution, , consistent with laboratory results reported in the literature, and implies that bubble fragmentation associated with intermittent high dissipation rates is a valid mechanism for the setup of bubble size spectra.
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Tarnow, D. P., S. C. Cho, and S. S. Wallace. "The Effect of Inter-Implant Distance on the Height of Inter-Implant Bone Crest." Journal of Periodontology 71, no. 4 (April 2000): 546–49. http://dx.doi.org/10.1902/jop.2000.71.4.546.
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Poommai, Satreethai, Kasem Chunkao, and Surat Bualerd. "Variation of Oxygen Transfer along the Rectangular Weir Crest Distance of Wastewater Treatment Pond." Procedia Environmental Sciences 13 (2012): 498–512. http://dx.doi.org/10.1016/j.proenv.2012.01.041.
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Sheldon, Kennon M. "Going the distance on the Pacific Crest Trail: The vital role of identified motivation." Motivation Science 6, no. 2 (June 2020): 177–81. http://dx.doi.org/10.1037/mot0000147.
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Ercan, Esra, Mevlut Celikoglu, Suleyman Kutalmis Buyuk, and Ahmet Ercan Sekerci. "Assessment of the alveolar bone support of patients with unilateral cleft lip and palate: A cone-beam computed tomography study." Angle Orthodontist 85, no. 6 (February 4, 2015): 1003–8. http://dx.doi.org/10.2319/092614-691.1.
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ABSTRACT Objective: To assess the bone support of the teeth adjacent to a cleft using cone-beam computed tomography (CBCT). Materials and Methods: The CBCT scans of 31 patients with unilateral cleft lip and palate (UCLP) were assessed. The data for teeth neighboring the cleft were compared with those of contralateral noncleft teeth. For each tooth analyzed, the distance between the cementoenamel junction (CEJ) and the bone crest (AC) at the buccal side was measured as was the thickness of the buccal bone level at 0, 1, 2, and 4 mm. Results: The bone thicknesses of the central teeth at the cleft region at the crest and 2 mm apically were statistically significantly thinner than that of the central incisor at a noncleft region. The CEJ-AC distance for central teeth at the cleft region was higher than that for central teeth in a noncleft region. Conclusions: Subjects with UCLP showed reduced bone support at teeth neighboring the cleft compared with controls. This may cause some problems during orthodontic treatment.
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Donato, Giuseppe, Ivan Presta, Biagio Arcidiacono, Marco F. M. Vismara, Annalidia Donato, Nastassia C. Garo, and Natalia Malara. "Innate and Adaptive Immunity Linked to Recognition of Antigens Shared by Neural Crest-Derived Tumors." Cancers 12, no. 4 (March 31, 2020): 840. http://dx.doi.org/10.3390/cancers12040840.
Full textAbstract:
In the adult, many embryologic processes can be co-opted by during cancer progression. The mechanisms of divisions, migration, and the ability to escape immunity recognition linked to specific embryo antigens are also expressed by malignant cells. In particular, cells derived from neural crests (NC) contribute to the development of multiple cell types including melanocytes, craniofacial cartilage, glia, neurons, peripheral and enteric nervous systems, and the adrenal medulla. This plastic performance is due to an accurate program of gene expression orchestrated with cellular/extracellular signals finalized to regulate long-distance migration, proliferation, differentiation, apoptosis, and survival. During neurulation, prior to initiating their migration, NC cells must undergo an epithelial–mesenchymal transition (EMT) in which they alter their actin cytoskeleton, lose their cell–cell junctions, apicobasal polarity, and acquire a motile phenotype. Similarly, during the development of the tumors derived from neural crests, comprising a heterogeneous group of neoplasms (Neural crest-derived tumors (NCDTs)), a group of genes responsible for the EMT pathway is activated. Here, retracing the molecular pathways performed by pluripotent cells at the boundary between neural and non-neural ectoderm in relation to the natural history of NCDT, points of contact or interposition are highlighted to better explain the intricate interplay between cancer cells and the innate and adaptive immune response.