FRP Pedestrian Bridges—Analysis of Different Infill Configurations

The main aim of this study is to analyze fiber-reinforced polymer (FRP) bridge decks according to their material, cross-section, and shape geometry. Infill cell configurations of the decks (rectangular, triangular, trapezoidal, and honeycomb) were tested based on the FRP cell units available in the market. A comparison was made for each cell configuration in flat and curved bridge shapes. Another comparison was made between the material properties. Each model was computed for a composite layup material and a quasi-isotropic material. The quasi-isotropic material represents chopped fibers within a matrix. FE (finite element) analysis was performed on a total of 24 models using Abaqus software. The results show that the bridge shape geometry and infill configuration play an important role in increasing the stiffness, more so than improving the material properties. The arch shape of the bridge deck with quasi-isotropic material and chopped fibers was compared to the cross-ply laminate material in a flat bridge deck. The results show that the arch shape of the bridge deck contributed to the overall stiffness by reducing the deformation by an average of 30–40%. The results of this preliminary study will provide a basis for future research into form finding and laboratory testing.

SPECIFIC FEATURES OF VARIANT ANATOMY AND MORPHOMETRIC CHARACTERISTICS OF THE PALATAL VAULT IN ADULTS WITH DIFFERENT GNATHIC AND DENTAL TYPES OF ARCHES

Cone-beam computed tomograms of 68 people (age — 21–35) with physiological occlusion and various gnathic dental arches were analyzed by a method developed for identifying the palatal arch index, taken as a height (depth)-to-width dimension ratio. The results of the study revealed that palatal parameters are determined by main variants (types) of the palatal vault. In case of the mesopalatal type of the arch (index value — 35–45%), the width parameters exceeded the depth values by an average of 2.4 times, while the divergence angle of alveolar processes was 116.7 ± 5.6°. The dolichopalatal type of the arch (index value – above 45%) featured domination of the width parameters over the depth-related ones, by an average of 1.8 times, while the alveolar processes divergence angle made up 127.6 ± 6.1°. As far as the brachypalatal type of the arch is concerned (index value — below 35%), the width parameters exceeded the depth parameters by 4.0 times on average, the divergence angle of the alveolar processes being 113.5 ± 5.3°. The obtained data can be used in clinical orthodontics when diagnosing pathologies of the palatal vault, as well as to interpret data from additional methods of examination and to choose the right treatment for issues related to the dental arch shape and size.

Optimum Shape Design of Geometrically Nonlinear Submerged Arches Using the Coral Reefs Optimization with Substrate Layers Algorithm

In this paper, a novel procedure for optimal design of geometrically nonlinear submerged arches is proposed. It is based on the Coral Reefs Optimization with Substrate Layers algorithm, a multi-method ensemble evolutionary approach for solving optimization problems. A novel arch shape parameterization is combined with the Coral Reefs Optimization with Substrate Layers algorithm. This new parameterization allows considering geometrical parameters in the design process, in addition to the reduction of the bending moment carried out by the classical design approach. The importance of considering the second-order behaviour of the arch structure is shown by different numerical experiments. Moreover, it is shown that the use of Coral Reefs Optimization with Substrate Layers algorithm leads to nearly-optimal solutions, ensuring the stability of the structure, reducing the maximum absolute bending moment value, and complying with the serviceability structural restrictions.

Relationship between Maxillary Arch Shape and Maxillary Labial Bone Dimensions: A Pilot Study

OBJECTIVE: To determine whether there is any relationship between the thickness of the labial alveolar bone wall in the anterior portion of the maxilla and arch shape.MATERIALS AND METHODS: Thirty patients (age, 12–53 years) were selected from archived cone beam computed tomography (CBCT) cases. All maxillary front teeth were present in all the cases. The distance between the cementoenamel junction (CEJ) and the facial bone crest and the thickness of the labial alveolar bone wall at distances of 1, 3, and 5 mm apical to the facial bone crest were measured.RESULTS: The distance between the CEJ and the facial bone crest ranged from 2.24 mm and 3.08 mm. No significant differences were found between the thickness of the bone wall at 1, 3, and 5 mm apical to the crest. A significant difference was found between the U-shaped arch on one side and the V-shaped and square-shaped arches on the other side. The U-shaped arch and labial bone wall thickness were correlated at the 1-mm distance (F = (8, 276) = 3.24, p = 0.002). U-shaped and V-shaped arches were common in women, whereas square-shaped arches were common in men (χ2 = 105.5, p = 0.000).CONCLUSION: Our study is the first to associate arch shape and labial alveolar bone wall thickness.CLINICAL RELEVANCE: The association between the U-shaped arch and bone wall thickness may constitute a new indicator for the tendency of the labial alveolar bone to resorb after extraction and placement of endo-osseous implants.

A METHOD FOR MODELING ARTIFICIAL DENTURES IN PATIENTS WITH ADENTIA BASED ON INDIVIDUALSIZES OF ALVEOLAR ARCHES AND CONSTITUTION TYPE

87 persons of older age groups with complete adentia underwent somatometric (anthropometric) as well as biometric measurements with cast models of the toothless jaws. The linear and index somatometric parameters, and linear and index parameters for the upper jaw alveolar arches, were calculated. Alveolar arches were classified in view of the total sum of the diagonal dimensions (macro-, micro- and normodiagonal type), the arch index (brachy-, dolicho- and mesoarch type). Modelling the projected shape of the dental arch was based on the parameters of length (the sum of the alveolar arches diagonals multiplied by the 1.06 coefficient), width (the product of the width of the alveolar arches by a coefficient of 1.16). The depth of the dental arch frontal segment was calculated as the product of the diagonal by the incisor-canine angle sine, which in case of mesotrusion arches is 0.42 (angle value — 25°), for protrusion arches — 0.5 (angle value — 30°), for retrusion arches — 0.34 (angle value — 20°). Given the regularities of the circle geometry, the frontal segment dimensions served to determine the radius of the circle where the front teeth sat. The graphical method developed to construct the forecasted upper dental arch shape, based on the balance of the alveolar and dental arches major parameters, allows forecasting the optimal shape and size of the artificial dental arch, achieving a balanced relationship between the shapes of the teeth and the alveolar arches, as well as constructing a balanced articulatory relationship while achieving optimal functional and aesthetic results.

Non-Syndrome Case of Multiple Erupted Supernumerary Teeth and Wisdom Tooth Anodontia

Supernumerary teeth can be detected during a routine clinical or radiographic examination. They are defined as any tooth or tooth substances that are excess of the usual configuration of twenty deciduous and thirty-two permanent teeth (1). Supernumerary teeth can cause several complications. It depends on the location or stage of their formation, such as: preventing or delaying the eruption of associated permanent teeth, crowding or malocclusion The main aim of orthodontic treatment of supernumerary teeth is to restore adequate dental aesthetics and functions. After the clinical, radiographic and tomographic diagnosis, the orthodontic treatment of supernumerary teeth will depend on several factors. Such as; the location, proximity to vital anatomical structures, space availability in the arch, shape and the amount of supporting periodontal tissue. Reports in Western Region in Saudi Arabia showed that the range of the prevalence of supernumerary teeth was 0.1–3.8% of the population. The current finding, however, was 0.3%, a finding that is not in concert with what was reported by Fardi et al. in which the prevalence of supernumerary teeth was 1.8%.This case reported a unilateral four premolars erupted to occlusion in the right mandibular arch for non-syndrome patient.

Alveolar arch shapes and its relation to complete denture retention

The alveolar ridge consists of denture bearing mucosa, sub-mucosa and periosteum, and residual alveolar bone. After tooth extraction, the remaining alveolar bone undergoes a remodeling process that leads to morphological reduction and alteration, which results in the change in alveolar ridge forms. However, it does not change alveolar arch shapes. This literature review aimed to analyze the relationship of alveolar arch shapes with complete denture retention. According to House (1958), alveolar arch shapes classified into three classes: Class I-square, Class II-tapering, Class III-ovoid. Those three alveolar arch shapes have a difference in the denture bearing area, with the largest denture bearing site on Class I-Square alveolar arch shape. Some factors that influence complete denture retention are adhesion, cohesion, interfacial force, oral and facial musculature, atmospheric pressure, undercut, rotational insertion path, parallel walls, and gravity. The alveolar arch shapes can affect retention regarding the size of the denture bearing area.The alveolar arch forms with a wider denture bearing area provide more considerable surface contact between the denture and mucous membranes. The forces resulting from those factors of retention might produce more excellent complete denture retention. The square arch shape is the alveolar arch shape with the largest denture bearing area. Hence, the square arch shape is believed to have the best complete denture retention.KEYWORDS: arch shape; retention; complete denture; denture bearing area

The extensibility of the plantar fascia influences the windlass mechanism during human running

The arch of the human foot is unique among hominins as it is compliant at ground contact but sufficiently stiff to enable push-off. These behaviours are partly facilitated by the ligamentous plantar fascia whose role is central to two mechanisms. The ideal windlass mechanism assumes that the plantar fascia has a nearly constant length to directly couple toe dorsiflexion with a change in arch shape. However, the plantar fascia also stretches and then shortens throughout gait as the arch-spring stores and releases elastic energy. We aimed to understand how the extensible plantar fascia could behave as an ideal windlass when it has been shown to strain throughout gait, potentially compromising the one-to-one coupling between toe arc length and arch length. We measured foot bone motion and plantar fascia elongation using high-speed X-ray during running. We discovered that toe plantarflexion delays plantar fascia stretching at foot strike, which probably modifies the distribution of the load through other arch tissues. Through a pure windlass effect in propulsion, a quasi-isometric plantar fascia's shortening is delayed to later in stance. The plantar fascia then shortens concurrently to the windlass mechanism, likely enhancing arch recoil at push-off.