Assessment of Tooth Preparations Submitted to Dental Laboratories for Fabrication of Monolithic Zirconia Crowns

Purpose: The objective of this study was to assess the quality of posterior teeth prepared for monolithic zirconia crowns. Materials and Methods: A total of 392 STL-files of posterior preparations for monolithic zirconia crowns were evaluated in this study. Three-dimensional (3D) images were evaluated using a software (3D Viewer; 3Shape A/S, Copenhagen, Denmark) for finish line design, finish line width, occluso-cervical dimension, total occlusal convergence (TOC), intercuspal angulation, finish line quality, line angle form, and presence or absence of undercut at the axial wall and unsupported lip of enamel. The assessment was performed by two calibrated evaluators. Then, data were descriptively analyzed. Data for occluso-cervical dimension and TOC were descriptively analyzed according to their location. Results: Thirty-nine percent of premolars, 77% of first molars, and 91% of second molars had an average occluso-cervical dimension of less than 3 mm (premolars) and 4 mm (molars), with most of the preparations having a TOC of more than 20 degrees. More than 50% of preparations had undercut, unsupported enamel and/or unacceptable finish line quality. Conclusions: The quality of tooth preparation including finish line quality, absence of unsupported enamel and undercut at the axial wall should be evaluated when preparing monolithic zirconia crowns.

Application of a three-dimensional virtual model to study the effect of fluoroscopic angle on infra-acetabular corridor parameters and screw insertion rates

Purpose To use three-dimensional (3D) virtual models to study how the parameters and insertion rates of the infra-acetabular corridor (IAC) change under different fluoroscopic angles. Methods The pelvis computed tomography data of 187 patients are imported into Mimics software in DICOM format to generate a 3D model. The anterior pelvis plane is used as the reference plane to measure the diameter of the optimum IAC when the pelvis model is tilted forward by 5°, 15°, 25°, 35° and 45°. The diameter of at least 3.5 mm is defined as the cutoff for placing a 3.5 mm screw, the rate of infra-acetabular screw (IAS) insertion is calculated, and the mean length of the IAC and the mean tilt of the corridor axis in relation to the sagittal midline plane (SMP) are measured. Results The similar diameters of the IAC can be found under fluoroscopy at 5°–35°, with the largest diameter of 4.08 ± 1.84 mm and the highest screw insertion rate of 60.42% at 15° and 25°, whereas the diameter and insertion rate are lowest at 45°. The corridor length increases with increasing fluoroscopic angle, and the angle of the corridor axis to the SMP decreases gradually. Conclusion The conventional fluoroscopic angle of the pelvic inlet is not suitable for the IAS insertion. The parameters of the IAC vary according to a certain rule under different fluoroscopic angles, so a surgeon can select the appropriate fluoroscopic angle in accordance with the type of fracture and the fracture line angle.

SEYITOMER MOUND MİDDLE BRONZE AGE LİNE DECORATİON SPİNDLE WHORLS

Since prehistoric times, human beings have decorated their daily items such as tools, utensils, pots and fugitives by applying ornaments with various techniques. These decorations are not only haphazardly but also systematically and as works of art. Seyitömer Mound is located 30 km northwest of Kütahya Province in the north of Afyon-Altıntaş-road in Seyitömer Town of Kütahya. Nine years of uninterrupted excavations were carried out by the Kütahya Dumlupınar University Archeology Department in Seyitömer Mound. During the excavations carried out in Seyitömer Mound , spindle whorls dating back to the Middle Bronze Age and used in rope spinning are quite common. Decorations in various compositions were applied on these finds using the scraping technique. These decorations are divided into groups as Mixed Composition, Bow, Line, Angle, Zigzag and Star, Point, Nail, Ring, Wave, Radial Decoration. In this study, in Seyitömer Mound spindle whorl finds BC. twenty one spindle whorls belonging to the 2nd millennium and decorated (marked) with "arc-shaped" decoration were studied. In this spindle whorls group, many compositions have been created from arc-shaped lines. These compositions were mostly made in groups of nested double-triple-quadruple arcs, four-five. In the study, drawings of Seyitömer Mound bow-shaped spindle whorls, their location, dimensions and descriptions were added as a catalog. In addition, its contemporaries and similar peripheral centers are specified with a compared bibliography. The aim of the study is to include this group of finds, which is important for archaeological research, into the literature.

A Parametric Study on the Aeroelasticity of Flared Hinge Folding Wingtips

This paper presents a parametric study on the aeroelasticity of cantilever wings equipped with Flared Hinge Folding Wingtips (FHFWTs). The finite element method is utilized to develop a computational, low-fidelity aeroelastic model. The wing structure is modelled using Euler–Bernoulli beam elements, and unsteady Theodorsen’s aerodynamic strip Theory is used for aerodynamic load predictions. The PK method is used to estimate the aeroelastic boundaries. The model is validated using three rectangular, cantilever wings whose properties are available in literature. Then, a rectangular, cantilever wing is used to study the effect of folding wingtips on the aeroelastic response and stability boundaries. Two scenarios are considered for the aeroelastic analysis. In the first scenario, the baseline, rectangular wing is split into inboard and outboard segments connected by a flared hinge that allows the outboard segment to fold. In the second scenario, a folding wingtip is added to the baseline wing. For both scenarios, the influence of fold angle, hinge-line angle (flare angle), hinge stiffness, tip mass and geometry are assessed. In addition, the load alleviation capability of FHFWT is evaluated when the wing encounters discrete (1-cosine) gusts. Finally, the hinge is assumed to exhibit cubic nonlinear behavior in torsion, and the effect of nonlinearity on the aeroelastic response is assessed and analyzed for three different cases.

Application of a three-dimensional virtual model to study the effect of fluoroscopic angle on infra-acetabular corridor parameters and screw insertion rates

Purpose To use three-dimensional (3D) virtual models to study how the parameters and insertion rates of the infra-acetabular corridor (IAC) change under different fluoroscopic angles. Methods The pelvis computed tomography data of 187 patients are imported into Mimics software in DICOM format to generate a 3D model. The anterior pelvis plane is used as the reference plane to measure the diameter of the optimum IAC when the pelvis model is tilted forward by 5°, 15°, 25°, 35° and 45°. The diameter of at least 3.5 mm is defined as the cutoff for placing a 3.5 mm screw, the rate of infra-acetabular screw (IAS) insertion is calculated, and the mean length of the IAC and the mean tilt of the corridor axis in relation to the sagittal midline plane (SMP) are measured. Results The similar diameters of the IAC can be found under fluoroscopy at 5°–35°, with the largest diameter of 4.08 ± 1.84 mm and the highest screw insertion rate of 60.42% at 15° and 25°, whereas the diameter and insertion rate are lowest at 45°. The corridor length increases with increasing fluoroscopic angle, and the angle of the corridor axis to the SMP decreases gradually. Conclusions The traditional 45° pelvic inlet radiograph is not suitable as the fluoroscopic angle for IAS insertion. The parameters of the IAC vary according to a certain rule under different fluoroscopic angles, so a surgeon can select the appropriate fluoroscopic angle in accordance with the type of fracture and the fracture line angle.

Predictive Accuracy of Blumensaat Line Angle and Its Apex along with Anterior Cruciate Ligament Inclination Angle for Diagnosis of Anterior Cruciate Ligament Tear with Abundant Remnant

Background: Anterior Cruciate Ligament Blumensaat line angle and Anterior Cruciate Ligament Inclination angle can be measured when Anterior Cruciate Ligament is visualized on Magnetic Resonance Imaging. Both these angles can be helpful to determine the intactness of Anterior Cruciate Ligament. The aim of this study was to evaluate the diagnostic accuracy of Anterior Cruciate Ligament - Blumensaat line angle, apex of Anterior Cruciate Ligament - Blumensaat line angle and Anterior Cruciate Ligament - Inclination angle to determine the status of Anterior Cruciate Ligament in terms of tear or no tear. Methods: We conducted a prospective observational study with Magnetic Resonance Imagings of knees of 71 patients, who were divided into Anterior Cruciate Ligament tear and Anterior Cruciate Ligament intact groups based on Anterior Cruciate Ligament - Blumensaat line angle (<150- intact; ? 150 – torn Anterior Cruciate Ligament), Anterior Cruciate Ligament - Inclination angle (>450 – intact ACL; ? 450 – Anterior Cruciate Ligament tear) and apex of Anterior Cruciate Ligament - Blumensaat line angle ( apex towards femur – Intact Anterior Cruciate Ligament; apex towards tibia or parallel lines– Anterior Cruciate Ligament Tear) measured on MRI study. Diagnostic accuracy was calculated in terms of sensitivity, specificity, positive predictive value and negative predictive value of Anterior Cruciate Ligament - Blumensaat line angle, Anterior Cruciate Ligament - Inclination angle and apex of Anterior Cruciate Ligament - Blumensaat line angle.Results: The sensitivity and specificity of Anterior Cruciate Ligament - Blumensaat line angle to detect Anterior Cruciate Ligament status was 95.83% and 95.35% respectively. Similarly, the sensitivity of Anterior Cruciate Ligament - Inclination angle was 95.83% and specificity was 95.35%. The sensitivity of Apex Anterior Cruciate Ligament - Blumensaat line angle to detect Anterior Cruciate Ligament tear on MRI was calculated to be 95.74% and a specificity of 87.5% Conclusions: Anterior Cruciate Ligament - Blumensaat line angle and Anterior Cruciate Ligament - Inclination angle is highly sensitive and specific for the diagnosis of Anterior Cruciate Ligament tear. Apex of Anterior Cruciate Ligament - Blumensaat line angle is also helpful in determination of Anterior Cruciate Ligament tear. Keywords: Anterior cruciate ligament; magnetic resonance imaging; ACL blumensaat line angle; ACL inclination angle

Development of new metal structure for osteosynthesis of femoral fractures

We presented the results of analysis of characteristics of osteosynthesis of femur model with improved metal structure. We carried out the analysis of the literature and a patent search on the subject of the study, created a layout of this design, a prototype and tested strength characteristics using a breaking machine. We carried out the work on a bovine femur preparation, performed taking into account the maximum correspondence of the studied human femur segment. We carried out load samples for fabricated steel structures, as well as for prototypes of this design in the form of samples for shear, angular displacement and rupture, while for each sample, performed 2 versions of the location of the steel structure relative to the fracture – perpendicular to the fracture line (angle 90º), as well as with a deviation in the range of 30º (75º–105º). We detected a statistically significant increase in the load values for the new advanced steel structure at a right angle of 41 % and a variation of 56 % during the analysis of the sample for rupture. Thus, when comparing the values of the load samples of the prototype and the manufactured metal structure, we revealed an increase in the indicators of the burst sample for the new metal structure which indicates the justification of its use in clinical practice.

Genetic and environmental components of vertical growth in mono- and dizygotic twins up to 15–18 years of age

ABSTRACT Objectives To determine the additive genetic and environmental contributions to the vertical growth of craniofacial structures. Materials and Methods The sample consisted of 64 untreated monozygotic (44 male, 20 female) and 61 untreated dizygotic twins (32 male, 29 female). Lateral cephalograms taken at 15 and 18 years of age were traced to analyze the sella-nasion–nasal line angle (SN-NL), nasal line–mandibular line angle (ML-NL), sella-nasion–mandibular line angle (SN-ML), sella-nasion–sella-gnathion angle (Y-axis), posterior face height/anterior face height (PFH/AFH), and lower anterior face height/anterior face height (LAFH/AFH). The genetic and environmental components of variance were analyzed with structural equation modeling for multilevel mixed effects. Results At 15 years of age, strong dominant genetic control was seen for NL-ML (81%), LAFH/AFH (73%), and Y-axis (57%), whereas strong additive genetic components were found for PFH/AFH (78%), SN-NL (58%), and SN-ML (57%). Unique environmental factors accounted for 18–42% of observed variance, with SN-NL being affected the most (42%). At 18 years of age, only LAFH/AFH (86%) was under strong dominant genetic control, whereas the remainder were under additive genetic influence. The sole exception was SN-NL, which changed from additive to unique environmental influence. Conclusions Either additive or dominant genetic components were found at 15 or 18 years of age for most vertical variables. Environmental factors accounted for about 10–40%, with SN-NL being mostly affected.