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Journal articles on the topic 'Structural restorations'
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Tetschke, Florian, Jonas Golde, Julia Walther, Lars Kirsten, Edmund Koch, Christian Hannig, Claudia Rüger, Hartmut Schneider, and Rainer Haak. "Visualization of interfacial adhesive defects at dental restorations with spectral domain and polarization sensitive optical coherence tomography." Current Directions in Biomedical Engineering 4, no. 1 (September 1, 2018): 559–62. http://dx.doi.org/10.1515/cdbme-2018-0134.
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AbstractRestoration loss based on interfacial adhesive defects and associated caries at the restoration margin are the main causes for invasive replacement of dental restorations. Assessment of the interfacial quality based on clinical inspection and radiographic examination is often difficult and not reliable. In this work, we present spectral domain optical coherence tomography (SDOCT) and polarization sensitive optical coherence tomography (PSOCT) for the evaluation of tooth-composite bond failure. Imaging of two composite restorations at the occlusal surface are presented using intensity-based images obtained by SDOCT and PSOCT based degree of polarization uniformity (DOPU). Both modalities revealed several defects beneath the surface such as inhomogeneous adhesive layers, marginal gaps and bubbles. In addition, DOPU representation showed an inhomogeneous structure within the composite material. OCT based imaging of dental restorations could add a valuable diagnostic tool for the evaluation of structural defects in clinical practice. The representation of polarization characteristics with the DOPU algorithm provides further information on the homogeneity of the restoration.
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Bittar, Daniela Gonçalves, Christiana Murakami, Daniela Hesse, José Carlos Pettorossi Imparato, and Fausto Medeiros Mendes. "Efficacy of Two Methods for Restorative Materials’ Removal in Primary Teeth." Journal of Contemporary Dental Practice 12, no. 5 (2011): 372–78. http://dx.doi.org/10.5005/jp-journals-10024-1062.
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ABSTRACT Aim This in vitro study aimed to compare the time required for removal, the presence of residues of restorative material, tooth structure loss and dental surface morphology after removal of composite resin and amalgam restorations from occlusal cavities in primary molars using conventional high-speed bur and CVDentus® ultrasonic diamond tips. Materials and methods A total of 37 primary molars were allocated into four groups: Group 1 (n=9)—amalgam restorations removed using high-speed bur; Group 2 (n=10)—amalgam restorations removed using ultrasonic tip; Group 3 (n=8)— composite resin restorations removed using high-speed bur; Group 4 (n=10)—composite resin restorations removed using ultrasonic tip. After being restored, teeth were sectioned and analyzed through stereoscopic microscope images before and after restoration removal. The structural loss was analyzed by software of image analysis, and an examiner assessed for the presence of residues. Scanning electron microscopy was used to evaluate the morphology. Time and structural loss values were compared using ANOVA, and the percentages of samples with residues using Fisher test. Results There was no statistically significant difference in the tooth structure loss among different methods and restorative materials, as well as in the presence of residues of restorative material. However, diamond burs were faster than the ultrasonic method for both materials. Differences in dental morphology were observed between the methods of restoration removal, but not related to the restorative material. Conclusion Both conventional high-speed bur and ultrasonic diamond tip methods remove similar amounts of tooth structure, but the removal performed with diamond tips in ultrasonic devices is slower. Clinical significance This study shows that both ultrasonic and conventional high-speed bur methods for removing restorations generate similar loss of sound dental tissue, but the former is slower. How to cite this article Bittar DG, Murakami C, Hesse D, Imparato JCP, Mendes FM. Efficacy of Two Methods for Restorative Materials’ Removal in Primary Teeth. J Contemp Dent Pract 2011;12(5):372-378.
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da Silva Bertolini, Marília, Laurenn Borges de Macedo, Diego Henrique de Almeida, Felipe Hideyoshi Icimoto, and Francisco Antonio Rocco Lahr. "Restoration of Structural Timber Elements Using Epoxy Resin: Analysis of Mechanical Properties." Advanced Materials Research 778 (September 2013): 582–87. http://dx.doi.org/10.4028/www.scientific.net/amr.778.582.
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Brazil cultural heritage is composed by numerous constructions that describe the various historical periods lived by country. Constructions arent in good conservation status, showing systematically some deterioration level of their structural elements, among them those of wood. Restoration process aims to preserve the identity of original cultural heritage. It is essential maintain structural characteristics related to mechanical loads response which are closely dependent on wood properties avoiding possible structural shocks. Wood deterioration can be characterized by fungi decay or termite attack. Depending on level and position of the deteriorated area in structural set, local interventions are enough to maintain structural integrity. Polymeric resins are material options that can be used when removed these deteriorated regions, requiring compatibility with wood to maintain structural elements properties. This paper aims use of a technical for restoring structural timber from historic buildings, based on removal of decayed regions and filling them with epoxy resin. To analyze restoration effectiveness, properties in static bending, according to Brazilian standard, were determined. Samples were produced containing one and three restorations along the specimens (105 cm in length and nominal square cross section of 4.5 cm side), on the same side. Samples of Pinus taeda with gaps generated in the specimens with dimensions of 1.10 cm in depth and 8 cm in length were tested, with restorations placed in central region. For grafting of these gaps bicomponent epoxy resin was employed, prepared by mixing components in 1:1.5 proportions. Resin was injected into splices and its cure occurred in a seven days period, using methodology restoration to simulate a situation in which these structural elements have been used. Samples were requested in static bending to obtaining the product of inertia, analyzing the amendment under the aspect of tractioned and as well under compressed edge. It is observed the viability of restoration using filling epoxy resin in timber samples, considering the mechanical performance and practicality of the methodology for local keeping.
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Lingrey, Steven, and Oskar Vidal-Royo. "Evaluating the quality of bed length and area balance in 2D structural restorations." Interpretation 3, no. 4 (November 1, 2015): SAA133—SAA160. http://dx.doi.org/10.1190/int-2015-0126.1.
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The use of structural restorations as a tool to investigate structural evolution, fault and horizon relationships, and validity of interpretation has been widespread for more than four decades. The first efforts relied on hand-drafted bed-length measurements of commonly constant thickness stratigraphic units and were typically applied to fold-and-thrust belt settings. The advent of computer-assisted section construction and restoration software allowed for the assessment of more complicated structural interpretations by applying several new methods for forward and inverse strain transformation. Although quicker and more accurate than hand-drafted, the results of computer-aided structural modeling still need to be interrogated. We have reviewed the different strain transformation (restoration) methods available and their implications for bed length and area conservation: (1) fundamental simple shear and its two basic modes (flexural slip and inclined shear inversions), (2) fault-related folding techniques, and (3) the effects of mechanical stratigraphy and compaction. The assessment of the restoration methods was illustrated by examining two examples: the Mount Crandell Duplex Structure in southern Alberta and the Virgin River Extensional Basin in the southeast of Nevada. For both examples, we developed tables listing and confirming the deformed/restored state line lengths and areas. We believe that such tables should be provided for any strain transformation exercise, along with the restoration results as parameters for quality control, to prevent over- and underestimations that deviate more than 5% from the initial interpretation.
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Shah, Deepa N. "The Biomimetic Restorative Approach." Dental Update 48, no. 1 (January 1, 2021): 13–20. http://dx.doi.org/10.12968/denu.2021.48.1.13.
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Significant changes in prosthodontic considerations, with a movement away from traditional restorations and an emphasis on preservation of tooth structure, have led to the development of the concept of biomimetics in restorative dentistry. The idea of being able to design restorations, which are able to restore accurately the biomechanical, structural and aesthetic integrity of the biomechanically weakened tooth, has been embraced and adopted by clinicians globally. By combining key prosthodontic principles relating to occlusal design and the control of forces on teeth and restorations, together with minimally invasive adhesive dentistry, we are able to predictably restore the function and aesthetics of damaged dentitions without the need for aggressive tooth structure removal. Advances in dental materials science allowing minimal preparations and restorations that are strong and durable in thin section, as well as advances in adhesive dentistry have meant that the biomimetic restoration of teeth is no longer a novel concept, but something that we should all be applying as conservative and restorative dentists. CPD/Clinical Relevance: This paper describes the rationale and clinical protocols involved in the application of biomimetic restorative dentistry.
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Zolkafli, Umi Kalsum, Zahiriah Yahya, Norhanim Zakaria, Farid Wajdi Akashah, and Azlan Shah Ali. "Restoration of historical timber building: a Malaysian case study." Structural Survey 33, no. 4/5 (November 9, 2015): 309–21. http://dx.doi.org/10.1108/ss-01-2015-0004.
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Purpose – The purpose of this paper is to identify the most influential buildings elements in term of the cost for timber restoration works. Design/methodology/approach – The research employed the case studies methods with questionnaires surveys. Two case studies were chosen and questionnaire surveys were distributed to contractors and consultation companies. The cost was identified based on the elemental cost analysis of historic timber buildings. Findings – The restoration of historic timber buildings in Malaysia has grown rapidly, especially in the UNESCO world heritage sites, Melaka and Penang. Data obtained on the restorations of timber buildings show that the most influential elements were upper floors, roofs and walls. Termites’ invasions and the lack of building analysis were found to be the major issue in timber restoration works. In addition, the availability of timber material contributed significantly to the increase of cost for restoration works. Originality/value – The cost for every element was identified and was used as a reference for new restorations projects of historical, timber buildings. This paper also highlighted the causes for the problems and the factors affecting the cost of timber restoration works. These data are useful information, especially for surveyors and contractors who are involved in the restoration of historic timber buildings. Maintaining or replacing these elements with other material can help to minimise the restoration cost of timber buildings in Malaysia.
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Haralur, Satheesh B., Ghaseb Ahmed AL Ghaseb, Norah Ali Alqahtani, and Bader Alqahtani. "Comparison of microleakage between different restorative materials to restore marginal gap at crown margin." PeerJ 9 (February 25, 2021): e10823. http://dx.doi.org/10.7717/peerj.10823.
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Background An occurrence of secondary caries around the indirect restoration margin is reported to remain a leading cause of failures. Objective This study aimed to test the interfacial microleakage of conventional glass-ionomer (CGI), resin-modified glass ionomer (RMGI) and Nano-hybrid composite (CR) restorations at a full veneer margin crown. Methods Ninety human extracted molar teeth were divided into three groups (n = 30). Each group was subdivided into three subgroups (n = 10) according to the extent of the structural defects; The structural defect in G1 had a depth of 1.5 mm, width and length at 2 mm and 1 mm intrusion within the crown cervical margin. The corresponding structural defect dimension values for G2 were 2, 5, 4 and 2 mm with defects extending onto the root structure. Meanwhile, G3: structural deficiency of 2 mm depth, 3 mm width and 3 mm length and with 1.5 mm extension into the prepared teeth. These structural defects in each subgroup were restored with CGI, RMGI and CR. Artificial carious lesion formation was induced at the cervical finish line with a demineralizing solution. The artificial carious lesions were restored as per the group distribution. Subsequently, teeth samples were prepared and cemented with Nickel-chromium full coverage restorations utilizing glass-ionomer luting cement. Teeth samples were thermocycled, isolated with nail varnish, and immersed in 0.1% methylene blue for 24 h. The teeth samples were sectioned longitudinally, dye penetration was evaluated with a stereomicroscope. The data were analyzed with Kruskal–Wallis and Mann–Whitney U tests. Results CGI-G1 recorded the highest micro-leakage score at 1.450; while CR-G3 recorded the least score (0.350). At a cementum-restoration interface, CR-G1 (0.850) documented the lowest micro-leakage; RMGI-G3 had a greater value at 1.700. Conclusions The hybrid CR could be effectively used to restore the restoration of a marginal gap around crown margins.
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Georgiev, Kostadin G., Ivan A. Filipov, and Iliyan N. Dobrev. "In Vivo Collection and SEM Identification of Oral Biofilm Using Indirect Composite Prototype Restorations. Clinical and Laboratory Study." Folia Medica 60, no. 2 (June 1, 2018): 300–307. http://dx.doi.org/10.1515/folmed-2017-0092.
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Abstract Background: The oral ecosystem is a dynamic environment inhabited by more than 700 microbial taxa. Recent studies report that multispecies oral biofilms develop on the surface of resin composites leading to degradation of its organic matrix and altered structural stability of the restoration. Aim: To examine the efficacy of a novel clinical approach to investigating in vivo formed biofilms on resin composite surfaces. Materials and methods: The clinical protocol of this study implemented indirect composite molar restorations (from resin material Filtek Z250, 3M ESPE) as intraoral biofilm carriers (test devices). We recruited for the experiment 5 consenting adult subjects with indications for indirect molar restoration. For each subject we fabricated 4 indirect restorations, 3 of which dedicated to different intraoral duration – 3, 7, and 14 days. All composite carriers were fixed temporarily for the intended time period and consecutively replaced. The detached carriers were prepared for microscope analysis at each time interval. The fourth composite carrier was used as the definitive restoration. Results: The timeline of the biofilm formation and the microbial morphology were associated with previous studies of in vivo bacterial colonisation. A correlation between the plaque formation cycle and the DMFt indices of the subjects was established. Conclusions: The implementation of indirect composite restorations as intraoral biofilm carrier offers valuable contribution to the real time investigation of in vivo biofilm accumulation.
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Bel-Anzué, Pedro, Antonio Almagro, María Paz Sáez Pérez, and Carlos Rodriguez-Navarro. "Influence of the calcination process in traditional gypsum with structural behavior." Ge-conservacion 11 (June 30, 2017): 79–85. http://dx.doi.org/10.37558/gec.v11i0.456.
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Gypsum is used as a finishing material with a principal aesthetical purpose. It is assumed that this binder has a poor structural behavior. However, it is also found as a structural material in many ancient constructions. In Spain there are several examples of architectural heritage with structures, floors and façades made of pure gypsum. In the studied area (Teruel), traditional gypsum represents the main material used in its architectural heritage. Nowadays, commercial gypsum is being used in restorations, but the different behavior between current and traditional gypsum results in non-compatible restorations. Here, we analyze the traditional gypsum calcination process by building two traditional ovens, assisted by locals masons, and we study how the differences in the calcination procedure can generate different gypsum products, which can be used either as a finishing material or as a structural material with a high mechanical resistance.
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MacDonald, Justin, Guillaume Backé, Rosalind King, and Richard Hillis. "The Hammerhead Delta—deepwater fold-thrust belt, Bight Basin, Australia: 2D kinematic and geomechanical reconstructions." APPEA Journal 51, no. 2 (2011): 739. http://dx.doi.org/10.1071/aj10119.
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The Hammerhead Delta—deepwater fold-thrust belt is located in the Ceduna Sub-basin of the Bight Basin, offshore southern Australia. It is a short lived gravity gliding system, Late Santonian-Maastrichtian in age. It exhibits a distinctive spoon shape in cross-section and detaches on a master horizon above Santonian marine shales of the Tiger Supersequence. Here, we have interpreted a large seismic dataset—including the recently acquired regional two-dimensional seismic dataset provided by Ion Geophysical—to constrain the regional structural geometry of the Hammerhead Delta—deepwater fold-thrust belt. Two structural restorations were completed to quantify the amount of extension and shortening in the system. These restorations were: a two-dimensional kinematic restoration, using 2D MOVE; and a two-dimensional geomechanical restoration, using Dynel 2D. By comparing results from the two techniques we demonstrate that the amount of observed extension in the delta top is nearly balanced by the shortening in the delta toe. The near balance (< 2 % excess extension) of the system is a unique result. Other passive margin systems demonstrate larger amounts of extension compared to shortening, due to the regional-scale pro-gradational nature of the systems. These results suggest that the balanced geometry of the Hammerhead Delta—deepwater fold-thrust belt is consistent with either a sudden decrease in sediment supply during the upper Maastrichtian, resulting in a cessation of prograding fault activity, or a loss of extension to the underlying Cenomanian growth faults or some combination thereof. Thus, the system failed to develop into an extensive passive margin delta—deepwater fold-thrust belt.
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Couegnat, Guillaume, Siu L. Fok, Jonathan E. Cooper, and Alison J. E. Qualtrough. "Structural optimization of dental restorations using the principle of adaptive growth." Dental Materials 22, no. 1 (January 2006): 3–12. http://dx.doi.org/10.1016/j.dental.2005.04.003.
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Eliguzeloglu, Evrim, Oguz Eraslan, Huma Omurlu, Gurcan Eskitascıoglu, and Sema Belli. "Effect of Hybrid Layer and Thickness on Stress Distribution of Cervical Wedge-Shaped Restorations." European Journal of Dentistry 04, no. 02 (April 2010): 160–65. http://dx.doi.org/10.1055/s-0039-1697824.
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Objectives: The aim of this finite elemental stress analysis study was to evaluate the effect of a hybrid layer and the hybrid layer thickness on the shear stress distribution in mandibular premolar teeth under occlusal loading.Methods: The mandibular premolar tooth was selected based on the anatomical measurements suggested by Wheeler. The analysis was performed with a computer with the SAP 2000 structural analysis program. Three different mathematical models were evaluated; 1) composite restoration without a hybrid layer 2) composite restoration with a 1.5 μm thick hybrid layer and 3) composite restoration with a 3 μm thick hybrid layer. A total of 200 N of occlusal loading force was simulated from the buccal tubercule and central fossa of the premolar tooth. The findings were drawn by the Saplot program.Results: In model B, the output showed that hybrid layer reduced the shear stress concentration especially on gingival margin of the composite. Similarly shear stress intensity was decreased by a thick hybrid layer in model C, especially on the gingival margin of the composite.Conclusions: The hybrid layer and its thickness plays an important role on stress distribution and intensity in cervical restorations. (Eur J Dent 2010;4:160-165)
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Altunışık, Ahmet Can, and Ali Fuat Genç. "Earthquake response of heavily damaged historical masonry mosques after restoration." Natural Hazards and Earth System Sciences 17, no. 10 (October 20, 2017): 1811–21. http://dx.doi.org/10.5194/nhess-17-1811-2017.
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Abstract. Restoration works have been accelerated substantially in Turkey in the last decade. Many historical buildings, mosques, minaret, bridges, towers and structures have been restored. With these restorations an important issue arises, namely how restoration work affects the structure. For this reason, we aimed to investigate the restoration effect on the earthquake response of a historical masonry mosque considering the openings on the masonry dome. For this purpose, we used the Hüsrev Pasha Mosque, which is located in the Ortakapı district in the old city of Van, Turkey. The region of Van is in an active seismic zone; therefore, earthquake analyses were performed in this study. Firstly a finite element model of the mosque was constructed considering the restoration drawings and 16 window openings on the dome. Then model was constructed with eight window openings. Structural analyses were performed under dead load and earthquake load, and the mode superposition method was used in analyses. Maximum displacements, maximum–minimum principal stresses and shear stresses are given with contours diagrams. The results are analyzed according to Turkish Earthquake Code (TEC, 2007) and compared between 8 and 16 window openings cases. The results show that reduction of the window openings affected the structural behavior of the mosque positively.
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Chałas, Renata, Marta Jurczykowska, Rafał Marczyński, and Elżbieta Pels. "Composite Inlays as A Modern Way of Posterior Restorations in the Dental Arch." Polish Journal of Public Health 124, no. 2 (August 8, 2014): 99–102. http://dx.doi.org/10.2478/pjph-2014-0023.
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Abstract Modern restorative dentistry offers many methods of restoring qualitative cavities within the clinical crowns. Due to the concept of maintaining continuity of the dental arch and maintaining the correct plane of occlusion, for reconstruction of posterior teeth, there are especially recommended indirect restorations, which are made in the dental laboratory, i.e. crown inlays. The aim of the study was based on the literature to describe indications, classifications and advantages of indirect composite inlays. Additionally, factors affecting the durability of indirect composite inlays and the influence on stomatognathic system were noted. Authors concluded that composite inlays can be recommended restoration method, not only in situations of loss of clinical crown tissue, but also in situations where it is necessary as structural reinforcement, e.g., in the case of Cracked Tooth Syndrome or Molar Incisor Hypomineralization.
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Abdelraouf, Rasha Mohamed. "Could night-guards be used as a simple method to detect leached-elements from dental restorations intra-orally? A study on amalgam restorations." F1000Research 6 (October 2, 2017): 1786. http://dx.doi.org/10.12688/f1000research.12311.1.
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Background: Detection of leached-elements from dental restorations intra-orally has been a subject of prime importance in dental research. However, this is challenging as most of the present techniques have some limitations. In this study, a new simple method was proposed via using night-guards. Thus, the aim of the study was to verify if night-guards could detect leached-elements from restorations as dental amalgam. Methods: Ten upper custom-made night-guards were fabricated for patients suffering from bruxism, who had amalgam-restorations in their upper molars. The night-guards were delivered to the patients and they were instructed to wear the night-guards during when they were asleep. After six months, the night-guards were taken from the patients to be analyzed. A new unused night-guard was fabricated from the same material to be used as a control. In the used night-guards, two areas were studied: the fitting surfaces contacting the amalgam restorations and the fitting surfaces not contacting amalgam restorations. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Analysis (EDXA) were used to examine the structural and elemental changes in the night-guards. Results: SEM of the unused night-guard revealed a homogenous structure, and the composition was carbon and oxygen, as shown using EDXA (C=88.9wt% and O=11.1wt%). By contrast, the fitting surfaces of the night-guards contacting amalgam restorations showed numerous lustrous particles. Elemental analysis of these areas showed the presence of mercury and sulfur, in addition to carbon and oxygen (Hg=21.2wt%, S=2.5wt%, C=67.1wt% and O=9.2wt%). The night-guards’ fitting surfaces not contacting amalgam restorations showed slight cracking, and the composition was carbon and oxygen (C=88.3wt% and O=11.7 wt%). Conclusions: Analyzing fitting surfaces of night-guards contacting dental restorations, such as amalgam, could aid in understanding the nature of leached-elements from these restorations intra-orally. However, further studies about its application upon dental-restorations other than amalgam are recommended.
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Moussa, D. G., J. A. Kirihara, Z. Ye, N. G. Fischer, J. Khot, B. A. Witthuhn, and C. Aparicio. "Dentin Priming with Amphipathic Antimicrobial Peptides." Journal of Dental Research 98, no. 10 (July 17, 2019): 1112–21. http://dx.doi.org/10.1177/0022034519863772.
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The evolution of bonded restorations has undergone great progress over several decades. Nonetheless, life spans of bonded restorations are limited mainly because of the eventual incidence of recurrent caries. Over time, water and waterborne agents (acids, enzymes) degrade the components of the dentin/restoration interface, allowing bacterial colonization and dentin reinfection at the margins of the restoration. We developed a 2-tier protective technology consisting of priming/coating dentin with amphipathic and antimicrobial peptides (AAMPs) to obtain hydrophobic/water-repellent and antibiofilm dentin-resisting recurrent caries around bonded restorations. We tested a series of AAMPs to assess their structure-function relationships as well as the effects of different dentin-conditioning methods on the structural features of AAMP-coated dentin. We found relation between the secondary structure of AAMPs (high portion of β-sheet), the antimicrobial potency of AAMPs, and the AAMPs’ ability to form hydrophobic coatings on dentin. We also determined that AAMPs had preferential adsorption on the mineral phase of dentin, which suggested that peptides arrange their cationic and hydrophilic motifs in direct contact with the negatively charged minerals in the hydrophilic dentin. These results led us to explore different dentin-conditioning methods that would increase the mineral/collagen ratio and their effect on AAMP immobilization. We innovatively imaged the spatial distribution of the AAMPs in relation to the dentinal tubules and collagen network using a minimally invasive multimodal imaging technique: multiphoton–second harmonic generation. Using multiphoton–second harmonic generation imaging, we determined that partial deproteinization of dentin increased the amount of immobilized AAMPs as compared with the total etched dentin at the dentin surface and extended deeply around dentinal tubules. Last, we analyzed the release rate of AAMPs from dentin coatings in artificial saliva to predict their stability in the clinical setting. In conclusion, priming dentin with AAMPs is a versatile new approach with potential to fortify the otherwise vulnerable adhesive-based interfaces.
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Porojan, Liliana, Florin Topală, and Cristina Savencu. "Influence of the Veneering Thickness on Stresses in All-Ceramic Crowns." Applied Mechanics and Materials 835 (May 2016): 91–96. http://dx.doi.org/10.4028/www.scientific.net/amm.835.91.
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Brittle break downs are typical failures of ceramic materials. Chipping problems associated with all-ceramic zirconia restorations are studied and discussed at the moment. Factorial analysis showed that material and thickness of prosthetic crowns are of primary importance in stress magnitude. Laboratory tests such as finite element analysis (FEA) may help to predict the behaviour of different restorations during biomechanical simulation. The aim of this study was to evaluate by FEA stresses in all-ceramic crowns in regard to different veneer thicknesses. For the experimental analysis a first upper premolar was chosen. A static structural analysis was performed to calculate the stress distribution from different coping designs. FEA may help to predict the behaviour of all-ceramic bilayer crowns during biomechanical simulation. FEA investigations show that a constant veneering thickness of 1-1.8 mm doesn't affect the stress distribution and maximal stress values in the teeth structures and restorations.
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Podestà, S., F. Romis, and L. Scandolo. "CONSOLIDATION AND RESTORATION OF HISTORICAL HERITAGE: THE FLAVIAN AMPHITHEATER IN ROME." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIV-M-1-2020 (July 24, 2020): 543–50. http://dx.doi.org/10.5194/isprs-archives-xliv-m-1-2020-543-2020.
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Abstract. The recovery and retrofitting techniques adopted for historical structures and archaeological sites face an apparent dichotomy between conservation of constructions and the safety of users. Literatures show several examples where the current day structural safety of historical constructions, gets defined by the nature of past interventions, the compatibility of materials and elements used in retrofitting. The adopted interventions were, in their time, considered innovative, but over the years their compatibility and reversibility leave the historic constructions structurally vulnerable. For these reasons, a careful understanding of the structural systems is fundamental for the implementation of appropriate retrofitting solutions. Especially for monuments and Archaeological sites the objective to be achieved has to be clear, avoiding destructive investigation tests. In this work the instabilities caused by a consolidation intervention on some travertine columns in a sector of the Flavian Amphitheatre, better known as “Colosseum” in Rome, are critically analysed. The current consolidation operations are compared to the previous one. The restoration activity involves in-depth diagnosis process: the historical analysis of the failures and restorations of that area of the Colosseum, a survey of the crack pattern and an indirect investigation on the travertine of the columns. Subsequently the various data coming from the knowledge phase are elaborated, in order to have a correct interpretation of the causes triggering the failure and guide the choice of the most correct retrofitting techniques.
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Della Bona, Alvaro. "Characterizing ceramics and the interfacial adhesion to resin: I - The relationship of microstructure, composition, properties and fractography." Journal of Applied Oral Science 13, no. 1 (March 2005): 1–9. http://dx.doi.org/10.1590/s1678-77572005000100002.
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The appeal of ceramics as structural dental materials is based on their light weight, high hardness values, chemical inertness, and anticipated unique tribological characteristics. A major goal of current ceramic research and development is to produce tough, strong ceramics that can provide reliable performance in dental applications. Quantifying microstructural parameters is important to develop structure/property relationships. Quantitative microstructural analysis provides an association among the constitution, physical properties, and structural characteristics of materials. Structural reliability of dental ceramics is a major factor in the clinical success of ceramic restorations. Complex stress distributions are present in most practical conditions and strength data alone cannot be directly extrapolated to predict structural performance.
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Iringová, Agnes, and Dominika Vandličková. "Restorations of Historic Buildings Considering the Fire Safety in Model Solutions." Key Engineering Materials 808 (June 2019): 145–52. http://dx.doi.org/10.4028/www.scientific.net/kem.808.145.
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The paper deals with the theoretical analysis of physical, structural, and layout determinants affecting the design and restoration of historic buildings in terms of fire safety. Legislative requirements for fire safety of historic buildings in the Slovak Republic. Definition of the construction and layout limits in architectural solutions in model buildings in terms of optimizing the original function within the valid legislation. Construction possibilities considering the protection of building elements at higher fire load and layout changes in structures built to the original trusses.
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Giorgi, Luca, and Pietro Matracchi. "Architectural Evolution: Modifications, Alterations, and Restorations through Centuries." Journal of Performance of Constructed Facilities 31, no. 5 (October 2017): 04017046. http://dx.doi.org/10.1061/(asce)cf.1943-5509.0001014.
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Spikings, Allan L., David M. Hodgson, Douglas A. Paton, and Yvonne T. Spychala. "Palinspastic restoration of an exhumed deepwater system: A workflow to improve paleogeographic reconstructions." Interpretation 3, no. 4 (November 1, 2015): SAA71—SAA87. http://dx.doi.org/10.1190/int-2015-0015.1.
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The Permian Laingsburg depocenter, Karoo Basin, South Africa, is the focus of sedimentological and stratigraphic research as an exhumed analog for offshore hydrocarbon reservoirs in deepwater basins. Thin-skinned thrust tectonics during the Permo-Triassic Cape Orogeny result in postdepositional deformation of the Permian basin fill. Regional-scale cross sections reveal two structural domains: a southern domain in the Laingsburg depocenter comprising 8–11-km wavelength north-verging fault-propagation folding, driven by buried low-angle ([Formula: see text]) reverse faults that coalesce at depth as part of a megadetachment below the Lower Paleozoic Cape Supergroup; and a northern domain to the north of the Laingsburg depocenter of short-wavelength, low-amplitude, asymmetrical folding facilitated by a detachment within the Permian Ecca Group. Five detailed structural cross sections permit the palinspastic restoration, and a calculation of the amount of shortening, across a [Formula: see text] area in the Laingsburg depocenter. Average shortening across the study area is −16.9% (5.8 km), and it decreases south to north. Shortening estimates from the Upper Ecca Group increase from 4.3 km near Matjiesfontein in the west to 10.4 km near Prince Albert in the east. Three-dimensional restorations of stratigraphic surfaces are consistent with these figures (−17%), and they allow paleogeographic and isopach thickness maps to be resorted to their configuration at the time of deposition. Structural restoration can be routinely used in outcrop studies to improve the accuracy of dimensions (e.g., volumetrics) and reconstructions (e.g., sediment dispersal patterns) derived from ancient sedimentary systems. The workflow presented here will add value to exhumed basin analogs by presenting prekinematic configurations at the frontal margins of fold-thrust belts.
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Bencharit, Sompop, Michael B. Border, C. Russell Mack, Warren C. Byrd, and John T. Wright. "Full-Mouth Rehabilitation for a Patient With Dentinogenesis Imperfecta: A Clinical Report." Journal of Oral Implantology 40, no. 5 (October 1, 2014): 593–600. http://dx.doi.org/10.1563/aaid-joi-d-12-00217.
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Dentinogenesis imperfecta (DI) is a genetic disorder affecting the structural integrity of the dentin that can result in weakened dentin. The affected teeth, especially posterior teeth, often need to be extracted due to severe wear or fracture. This frequently yields a loss of posterior occlusion and occlusal vertical dimension. Besides wear and fracture, anterior teeth often have an unesthetic appearance because of discoloration. Current treatments of choice, including composite bonding restorations and, more recently, all-ceramic restorations, are typically suggested to preserve the remaining teeth and tooth structure. However, there are a limited number of studies on dental implants in patients with DI. The effectiveness of dentin bonding and dental implants in patients with DI is not known. This clinical report describes a 32-year-old Asian woman with DI who underwent full-mouth rehabilitation. The posterior occlusion, mostly in the molar areas, was restored with dental implants and ceramometal restorations. The anterior teeth and premolars were restored with bonded lithium disilicate glass-ceramic pressed veneers and crowns made with computer-aided design/computer-aided manufacturing. This case demonstrates that restoring functional occlusion and esthetics for a patient with DI can be completed successfully using contemporary implant therapy and adhesive dentistry.
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Beltrame, Ana Paula CA, Maíra Mery Rosa, Ricardo AT Noschang, and Izabel CS Almeida. "Early Rehabilitation of Incisors with Dentinogenesis Imperfecta Type II – Case Report." Journal of Clinical Pediatric Dentistry 41, no. 2 (January 1, 2017): 112–15. http://dx.doi.org/10.17796/1053-4628-41.2.112.
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Dentinogenesis imperfecta is an phenotypic alteration in the formation of the organic matrix. It causes the rapid and progressive wear of tooth structure, which may compromise tooth function and aesthetics. This is a case of a 1y, 8m-old child with dentinogenesis imperfecta. All teeth presented with an opalescent appearance and grayish color hue. Compromised structural integrity was noted as excessive wear and fracturing of the enamel from the dentin layer. With low doses of midazolam (oral) and chloral hydrate (rectal) administration, in a hospital environment, sedation was used to aid full mouth rehabilitation. Direct bonded restorations were performed on primary maxillary incisors and indirect restorations, pre-made on a plaster model using composite resin, were performed on primary mandibular incisors. After 32 months, we observed that diagnosis and early treatment allowed preventive maintenance of the patient's primary dentition, maintaining tooth function and esthetics.
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Sekundo, C., and C. Frese. "Underlying Resin Infiltration and Direct Composite Veneers for the Treatment of Severe White Color Alterations of the Enamel: Case Report and 13-Month Follow-Up." Operative Dentistry 45, no. 1 (January 1, 2020): 10–18. http://dx.doi.org/10.2341/18-242-l.
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SUMMARY Pronounced white color alterations due to structural anomalies of the enamel are often insufficiently masked by bleaching techniques or resin infiltration procedures alone. This frequently leads to the choice of more invasive prosthetic restorations in order to correct tooth color and form. This article describes a minimally invasive treatment option for esthetic and functional rehabilitation in the case of a 13-year-old female patient with suspected severe fluorosis and misalignment of the anterior teeth. The restorations were performed using underlying resin infiltration to homogenize the tooth shade. In a second step, direct composite veneers were applied on top to attain a natural tooth color and adjust tooth alignment and form. By joining the two minimally and noninvasive techniques, this treatment option combines the directive for preservation of hard tooth structure while treating adolescents with the benefits of easy adaptation and repair when the occlusion is still in adjustment.
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RICE, A. HUGH N., and MARK W. ANDERSON. "Restoration of the external Scandinavian Caledonides." Geological Magazine 153, no. 5-6 (July 13, 2016): 1136–65. http://dx.doi.org/10.1017/s0016756816000340.
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AbstractThree models are evaluated for restoring basement rocks coring tectonic windows (Window-Basement) in the Scandinavian Caledonides; parautochthonous (Model I) and allochthonous (models II/III), with initial imbrication of the Window-Basement post-dating or pre-dating, respectively, that in the external imbricate zone (Lower Allochthon). In Model I, the Window-Basement comes from the eastern margin of the basin now imbricated into the Lower Allochthon, while in models II/III it comes from the western margin. In Model II, the Window-Basement formed a basement-high between Tonian and Cryogenian sediments imbricated into the Middle and Lower allochthons; in Model III deposition of the Lower Allochthon sediments commenced in Ediacaran times. Balanced cross-sections and branch-line restorations of four transects (Finnmark–Troms, Västerbotten–Nordland, Jämtland–Trøndelag, Telemark–Møre og Romsdal) show similar restored lengths for the models in two transects and longer restorations for models II/III in the other transects. Model I can result inc.280 km wide gaps in the restored Lower Allochthon, evidence for which is not seen in the sedimentology. The presence of <3 km thick alluvial-fan deposits at the base of the Middle Allochthon indicates proximal, rapidly uplifting basement during Tonian–Cryogenian periods, taken as the origin of the Window-Basement during thrusting in models II/III. Model I requires multiple changes in thrusting-direction and predicts major thrusts or back-thrusts, currently unrecognized, separating parts of the Lower Allochthon; neither are required in models II/III. Metamorphic data are consistent with models II/III. Despite considerable along-strike structural variability in the external Scandinavian Caledonides, models II/III are preferred for the restoration of the Window-Basement.
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Rousseau, Maxime, and Jean-Marc Retrouvey. "Osteogenesis imperfecta: potential therapeutic approaches." PeerJ 6 (August 17, 2018): e5464. http://dx.doi.org/10.7717/peerj.5464.
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Osteogenesis imperfecta (OI) is a genetic disorder that is usually caused by disturbed production of collagen type I. Depending on its severity in the patient, this disorder may create difficulties and challenges for the dental practitioner. The goal of this article is to provide guidelines based on scientific evidence found in the current literature for practitioners who are or will be involved in the care of these patients. A prudent approach is recommended, as individuals affected by OI present with specific dentoalveolar problems that may prove very difficult to address. Recommended treatments for damaged/decayed teeth in the primary dentition are full-coverage restorations, including stainless steel crowns or zirconia crowns. Full-coverage restorations are also recommended in the permanent dentition. Intracoronal restorations should be avoided, as they promote structural tooth loss. Simple extractions can also be performed, but not immediately before or after intravenous bisphosphonate infusions. Clear aligners are a promising option for orthodontic treatment. In severe OI types, such as III or IV, orthognathic surgery is discouraged, despite the significant skeletal dysplasia present. Given the great variations in the severity of OI and the limited quantity of information available, the best treatment option relies heavily on the practitioner’s preliminary examination and judgment. A multidisciplinary team approach is encouraged and favored in more severe cases, in order to optimize diagnosis and treatment.
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Pilathadka, Shriharsha, and Dagmar Vahalová. "Contemporary All-ceramic Materials – Part 1." Acta Medica (Hradec Kralove, Czech Republic) 50, no. 2 (2007): 101–4. http://dx.doi.org/10.14712/18059694.2017.63.
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Over the past 35 years, multiple types of all-ceramic materials have been introduced as an ideal alternative for metal-fused to ceramic. This review covers state-of-the-art development of all-ceramic systems in terms of history, material composition, fabrication technologies, and structural and strength properties. These materials are proved to be ideal in terms of mechanical properties and biocompatibility, making metal-free ceramic restorations a realistic clinical alternative for conventional metal-fused-to ceramic.
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Almasi, Adrian, Liana Todor, Cristian Adrian Ratiu, Ramona Amina Popovici, Codruta Victoria Tigmeanu, Sergiu Alexandru Tofan, and Anca Porumb. "In Vitro Study of the Structure and Adhesive Interface in Direct Restorations with Commercial Nanocomposite Materials." Materiale Plastice 56, no. 1 (March 30, 2019): 277–81. http://dx.doi.org/10.37358/mp.19.1.5165.
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The purpose of this study was: Structural characterization of two commercial nanocomposite materials (Premise /Kerr Corp and Tetric EvoCeram�/ Ivoclar-Vivadent); Evaluation of the marginal adaptation and adhesive interface achieved with two commercial adhesive systems (Optibond SoloPlus /Kerr Corp and G-Bond /GC). Investigation was done using electronic scanning microscopy (SEM).
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Shuey, John, Paul Labus, Eduardo Carneiro, Fernando Maia Silva Dias, Luis Anderson R. Leite, and Olaf H. H. Mielke. "Butterfly communities respond to structural changes in forest restorations and regeneration in lowland Atlantic Forest, Paraná, Brazil." Journal of Insect Conservation 21, no. 3 (June 2017): 545–57. http://dx.doi.org/10.1007/s10841-017-9994-y.
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Tanase, Mihaela, Dan Florin Nitoi, Marina Melescanu Imre, Dorin Ionescu, Laura Raducu, Andrada Mihai, Andra Elena Balcangiu Stroescu, and Daniela Gabriela Balan. "Use of the Finite Element Analysis Method in Pedodontics." Materiale Plastice 55, no. 4 (December 30, 2018): 666–75. http://dx.doi.org/10.37358/mp.18.4.5097.
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The purpose of this study was to determinate , using the Finite Element Analysis Method, the mechanical stress in a solid body , temporary molar restored with the self-curing GC material. The originality of our study consisted in using an accurate structural model and applying a concentrated force and a uniformly distributed pressure. Molar structure was meshed in a Solid Type 45 and the output data were obtained using the ANSYS software. The practical predictions can be made about the behavior of different restorations materials.
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Papadopoulos, C., D. Dionysopoulos, K. Tolidis, P. Kouros, E. Koliniotou-Koumpia, and EA Tsitrou. "Structural Integrity Evaluation of Large MOD Restorations Fabricated With a Bulk-Fill and a CAD/CAM Resin Composite Material." Operative Dentistry 44, no. 3 (May 1, 2019): 312–21. http://dx.doi.org/10.2341/18-013-l.
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SUMMARY Aims: To evaluate the effect of two composite restorative techniques (direct bulk fill vs indirect CAD/CAM) on the fracture resistance and mode of fracture of extended mesio-occlusal-distal (MOD) cavity preparations. Methods: Fifty-one sound human mandibular third molars were divided into three groups (n=17). Extended bucco-lingual MOD cavities were prepared. Teeth in group 1 were restored with a bulk-fill resin composite (Filtek Bulk-Fill Posterior Restorative), teeth in group 2 were restored with composite computer-aided design/computer-aided manufacturing (CAD/CAM) inlays (Lava Ultimate), and teeth in group 3 served as control and remained intact. All specimens were submitted to thermocycling, and a fracture resistance test was performed using a Universal testing machine (0.5 mm/min). Mode of fracture was classified into five types. One-way analysis of variance and the Duncan test were used to analyze the fracture load data at a significance level of α = 0.05. A chi-square test was used for the analysis of fracture mode between the restorative groups. Results: Statistical analysis showed significant differences in fracture resistance among the experimental groups. The teeth restored with the bulk-fill composite exhibited lower fracture resistance (1285.3±655.0 N) when compared to the teeth restored with the composite CAD/CAM inlays (1869.8±529.4 N) (p<0.05). Mode of fracture showed the same distribution between the restorative groups. Conclusions: Although both types of restorations failed at loads larger than those found in the oral cavity, the CAD/CAM composite inlays increased the fracture resistance of teeth with large MOD cavities when compared to direct bulk-fill composite restorations. The majority of fracture types were intraorally repairable for both restorative techniques.
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Correa, Santiago, Juliana Ivancik, Juan Felipe Isaza, and Mauricio Naranjo. "Evaluation of the structural behavior of three and four implant-supported fixed prosthetic restorations by finite element analysis." Journal of Prosthodontic Research 56, no. 2 (April 2012): 110–19. http://dx.doi.org/10.1016/j.jpor.2011.07.001.
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Guzofski, Chris A., Joachim P. Mueller, John H. Shaw, Pierre Muron, Donald A. Medwedeff, Frank Bilotti, and Carlos Rivero. "Insights into the mechanisms of fault-related folding provided by volumetric structural restorations using spatially varying mechanical constraints." AAPG Bulletin 93, no. 4 (April 2009): 479–502. http://dx.doi.org/10.1306/11250807130.
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Karl, Matthias, Horst Fischer, Friedrich Graef, Manfred G. Wichmann, Thomas D. Taylor, and Siegfried M. Heckmann. "Structural changes in ceramic veneered three-unit implant-supported restorations as a consequence of static and dynamic loading." Dental Materials 24, no. 4 (April 2008): 464–70. http://dx.doi.org/10.1016/j.dental.2007.03.012.
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Böttger, H. M., C. J. Arce Bazán, and N. P. Saarman. "3D LASER SCANNING FOR PRESERVATION AND STRUCTURAL MONITORING OF HISTORIC CALIFORNIA ADOBE MISSIONS." Journal of Green Building 11, no. 4 (September 2016): 1–14. http://dx.doi.org/10.3992/jgb.11.4.1.1.
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INTRODUCTION At the University of San Francisco Architecture & Community Design Program, the Architectural Engineering curriculum utilizes a Leica ScanStation C10 3D Laser Scanner to document historic structures and monitor their structural behavior. Some of the oldest structures in the State of California are the historic adobe missions built by Native Americans and Spanish Catholic missionaries between 1769 and 1833. California is a region of very high seismic activity, and the adobe structures have withstood significant earthquakes and other erosive or destructive forces over their lifetime. However, they are sensitive structures in need of active preservation and very few original adobe buildings remain. Working together with local structural engineers who specialize in seismic restoration of historic adobe structures, USF students have conducted laser scanning at Mission Santa Cruz and Mission San Miguel Arcángel, creating extensive 3D point cloud records, and developing architectural drawings which establish the current state of these structures for the purposes of historic preservation and structural study. Because of the delicate and irregular nature of these structures, the 3D laser scanner is the most appropriate tool for detailed yet non-invasive documentation. Completed in 1821, Mission San Miguel Arcángel suffered significant damage in the nearby 2003 San Simeon earthquake. The original adobe structure has undergone partial repairs such as banding at the top of the walls of the Sacristy. Using the 3D laser scanner, thorough scans are stitched together to create full interior and exterior 3D point cloud files, which are processed in Leica Cyclone and Autodesk Recap, and then imported into AutoCAD to create detailed line drawings of plans, elevations and sections of significant areas. Wall lean and other indicators of crack progress and deterioration are areas of special focus. With these records, a structural monitoring program has begun to document the condition of the buildings in wet seasons and dry seasons, and to determine the long-term effect of seismic restorations which have been implemented. This paper presents a detailed account of the process, pedagogical value and structural and architectural lessons learned over the course of the 3D scanning of these valuable heritage landmarks.
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Sanders, Carlo, Massimo Bonora, David Richards, Estanislao Kozlowski, Claudio Sylwan, and Marcos Cohen. "Kinematic structural restorations and discrete fracture modeling of a thrust trap: a case study from the Tarija Basin, Argentina." Marine and Petroleum Geology 21, no. 7 (August 2004): 845–55. http://dx.doi.org/10.1016/j.marpetgeo.2003.09.006.
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Deliperi, S. "Functional and Aesthetic Guidelines for Stress-Reduced Direct Posterior Composite Restorations." Operative Dentistry 37, no. 4 (July 1, 2012): 425–31. http://dx.doi.org/10.2341/11-082-t.
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SUMMARY Amalgam has been used in the restoration of structurally compromised posterior teeth for many years. When placing large amalgam restorations, replacement of weak cusps with restorative material is recommended to prevent tooth fracture. This recommendation can be modified with new guidelines using modern adhesive techniques. Semidirect and indirect inlay/onlay composite restorations have progressively replaced amalgam restorations over the past 20 years. Lately, single visit direct resin-bonded composite (RBC) restorations have also been used as a viable alternative to conventional indirect restorations. This paper is intended to introduce a step-by-step protocol for the direct restoration of structurally compromised posterior teeth using RBCs with stress-reducing protocols.
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Coşkun, Burcu Selcen. "Scraping the layers: Tahsin Öz and his stylistic restorations in Topkapı Palace Museum." A/Z : ITU journal of Faculty of Architecture 15, no. 3 (2018): 1–12. http://dx.doi.org/10.5505/itujfa.2018.41033.
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Koutsioubas, Alexandros, Sebastian Jaksch, and Javier Pérez. "DENFERT version 2: extension of ab initio structural modelling of hydrated biomolecules to the case of small-angle neutron scattering data." Journal of Applied Crystallography 49, no. 2 (March 24, 2016): 690–95. http://dx.doi.org/10.1107/s1600576716003393.
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Following the introduction of the program DENFERT [Koutsioubas & Pérez (2013). J. Appl. Cryst. 46, 1884–1888], which takes into account the hydration layer around solvated biological molecules during ab initio restorations of low-resolution molecular envelopes from small-angle X-ray scattering data, the present work introduces the second version of the program, which provides the ability to treat neutron scattering data sets. By considering a fully interconnected and hydrated model during the entire minimization process, it has been possible to simplify the user input and reach more objective shape reconstructions. Additionally, a new method is implemented for the subtraction of the contribution of internal inhomogeneities of biomolecules to the measured scattering. Validation of the overall approach is performed by successfully recovering the shape of various protein molecules from experimental neutron and X-ray solution scattering data.
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Cozza, Lucos. "Mura di Roma dalla Porta Latina all'Appia." Papers of the British School at Rome 76 (November 2008): 99–154. http://dx.doi.org/10.1017/s006824620000043x.
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The stretch of the Aurelianic Walls from the Porta Latina to the Porta Appia comprises twelve towers linked bv curtain walls with covered walkways. The surviving state of the monument is described in detail. The individual phases (from AD 275 to the present) are distinguished through the analysis of their construction techniques, archive drawings and photographs of vanished sections, papal coats of arms, and inscriptions (in pencil or graffito) recording more recent events. When the entire circuit was doubled in height during the Honorian phase (AD 401–3), the floors of the towers were built at a considerably higher level than the rampart walkways, so as to exploit fully the type of siege machinery(halhstae)located in the towers' upper chambers. The Honorian loopholes, for the use of archers, reveal a long and complex history: undergoing modifications during construction, they were subsequently blocked to prevent the illegal traffic of goods (and the avoidance of customs dues), and were finally reopened and modified once again for the defence of papal Rome. The modern restorations of 1930–67 are examined critically. The need for immediate restoration and sustained maintenance to guarantee the monument's structural integrity is now clear. It is to be hoped that a direct link (with visitor access) will be provided with the ‘Museo delle Mura’, which was set up in the neighbouring Porta Appia in 1970.
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Ломиашвили, Лариса, Larisa Lomiashvili, В. Сидельников, V. Sedelnikov, А. Постолаки, and A. Postolaki. "FROM UNITY TO THE VARIETY OF FORMS IN NATURE." Actual problems in dentistry 11, no. 3 (June 25, 2015): 4–13. http://dx.doi.org/10.18481/2077-7566-2015-11-3-4-4-13.
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<p>The questions of unity and variety of forms in nature are discussed In the presentpaper. Refers to the process of shaping the teeth, structural and functional unit of the tooth is determined: canine module – odontomer. The common structure of the tooth, hand and foot is demonstrated, moreover the morphological similarity is manifested at the stage of human embryo – histogenesis. Thus, at the stage of bookmarks, formation, growth and development of certain organs of a human embryo (hands, feet and teeth) one can see some similarity of their structure, the internal order of the morphological units (fingers, enameldentinal rollers), which describes the universal law of creation – "the golden proportion" . Dentists have to know the anatomy of the organs and tissues of the oral cavity very well when restoring the teeth. Also dentists should study their phylogeny, anthropogeny,ontogeny in order to reconstruct the missing tissue in their original form, in harmony. The stages of dental restorations made of composite materials based on modular technology are shown.</p><p>We have proposed a matrix model for shaping the crown of a tooth. At the base of a tooth crown several modules – odontometrs are laid, which are directed to the fissure of the first order. A doctor deliberately puts missing edges, filling empty spaces with composite material, thus performing a specific algorithm of a tooth construction. While restoration the missing tissue you operate with the canine tooth module and composite material and fill a tooth crown.</p><p>Thus, we consider a canine tooth as the initial unit, fractal part of ontogenesis of dento-facial system of a person in accordance with the set laws which are typical for the modular (fractal) structural organization.</p>
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Sun, X. J., and J. Y. Chang. "Re-formation of disulphide bonds in reduced antithrombin III." Biochemical Journal 269, no. 3 (August 1, 1990): 665–69. http://dx.doi.org/10.1042/bj2690665.
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Human antithrombin III (AT-III) contains three disulphide linkages (Cys-8-Cys-128, Cys-21-Cys-95 and Cys-247-Cys-430), and two of them (Cys-8-Cys-128 and Cys-21-Cys-95) are situated near the heparin-binding domain of the inhibitor. We demonstrate in this paper that: (i) partially reduced AT-III (with Cys-8-Cys-128 and Cys-21-Cys-95 quantitatively reduced) could be re-oxidized in air to regain 70-80% of its heparin cofactor activity and thrombin-inhibitory activity; (ii) completely reduced AT-III was re-oxidized under similar conditions and recovered 30-35% of it biological activities. Structural analysis of refolded AT-IIIs indicates that restorations of their disulphide contents and conformations (evaluated by chemical modification) are congruent with recoveries of their biological activities.
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Bertolini-Cestari, Clara, Stefano Invernizzi, Tanja Marzi, and Steni Rolla. "Preservation of the Large Timber Roof of the Porta Nuova Railway Station in Torino." Advanced Materials Research 778 (September 2013): 951–58. http://dx.doi.org/10.4028/www.scientific.net/amr.778.951.
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Torino, in 1861, was the first capital of the just unified Reign of Italy. In the same year, Eng. A. Mazzucchetti was charged for the design of the railway station of Porta Nuova in Torino, in correspondence of the arrival of the railway connecting Genova. The original conception resembles the bilateral scheme of the King Cross station in London, which is few years older. The design and construction of the station deserved contributions from the most outstanding scientists of that time, including R. Sephenson who provided the details of the lateral roof structures of the station, and the young Eng. A. Castigliano who defended his thesis on the design of the great steel vault above the rails. The two main branches were conceived with masonry bearing structure and a wide span timber roof covered with stone plates. The station, during the years, was object of several interventions, including restorations, dismantling of parts, and changes in the destination of use. Nowadays, the roof structure needs for important maintenance interventions due to the water leaking which caused the deterioration of the beneath timber structure. The present holders are considering the replacement of the entire roof. This solution is not respectful for conservation criteria, nor is affordable from an economical point of view. The present study describes the correct and sustainable approach for the structural assessment, restoration and maintenance program for the preservation of this important structure belonging to cultural heritage.
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Palacios, Teresa, Sandra Tarancón, Cristian Abad, and José Ygnacio Pastor. "Saliva Influence on the Mechanical Properties of Advanced CAD/CAM Composites for Indirect Dental Restorations." Polymers 13, no. 5 (March 6, 2021): 808. http://dx.doi.org/10.3390/polym13050808.
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This study aims to evaluate the microstructural and mechanical properties of three commercial resin-based materials available for computer-aid design and manufacturing (CAD/CAM)-processed indirect dental restoration: LavaTM Ultimate Restorative (LU), 3M ESPE; Brilliant Crios (BC), COLTENE and CerasmartTM (CS), GC Dental Product. The three types of resin-based composite CAD/CAM materials were physically and mechanically tested under two conditions: directly as received by the manufacturer (AR) and after storage under immersion in artificial saliva (AS) for 30 days. A global approximation to microstructure and mechanical behaviour was evaluated: density, hardness and nanohardness, nanoelastic modulus, flexural strength, fracture toughness, fracture surfaces, and microstructures and fractography. Moreover, their structural and chemical composition using X-ray fluorescence analysis (XRF) and field emission scanning electron microscopy (FESEM) were investigated. As a result, LU exhibited slightly higher mechanical properties, while the decrease of its mechanical performance after immersion in AS was doubled compared to BC and CS. Tests of pristine material showed 13 GPa elastic modulus, 150 MPa flexural strength, 1.0 MPa·m1/2 fracture toughness, and 1.0 GPa hardness for LU, 11.4 GPa elastic modulus; 140 MPa flexural strength, 1.1 MPa·m1/2 fracture toughness, and 0.8 GPa hardness for BC; and 8.3 GPa elastic modulus, 140 MPa flexural strength, 0.9 MPa·m1/2 fracture toughness, and 0.7 GPa hardness for CS. These values were significantly reduced after one month of immersion in saliva. The interpretation of the mechanical results could suggest, in general, a better behaviour of LU compared with the other two despite it having the coarsest microstructure of the three studied materials. The saliva effect in the three materials was critically relevant for clinical use and must be considered when choosing the best solution for the restoration to be used.
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Yadav, Sukriti, and Swati Gangwar. "Long-term solubility and sorption characteristics of novel dental restoratives." International Journal of Engineering, Science and Technology 13, no. 1 (July 8, 2021): 17–24. http://dx.doi.org/10.4314/ijest.v13i1.3s.
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Sorption and solubility are the unfavorable conditions for the dental restorative composites (DRCs). It can be precursor of various physical and chemical phenomenon that may lead to structural deterioration and minimizes the endurance of restorations. This study sought to evaluate the sorption and solubility features of MPTS (M)/APTES(A) treated n-HAPs filled dental composite in distilled water and artificial saliva medium. In this experiment, 7 different compositions of disc-shaped specimens of Φ15mm×1mm (n=3) of dental composites were prepared and tested under distilled water and artificial saliva medium for 35 days according to ISO 4049 method. The dental material shows relatively higher sorption and solubility in the artificial saliva medium as compared to distilled water. However, at higher wt.% (DRCs-12M & DRCs-12A), it shows minimum solubility (i.e.) and sorption characteristics. The results indicate that there was significant variation regarding storage medium and time to saturation but still these values are within the limit of the ISO 4049 standards, which is 40 μg/mm3 for sorption and 5μg/mm3 for Solubility.
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Albertão, Gilberto Athayde, Thierry Mulder, and Rémi Eschard. "Impact of salt-related palaeotopography on the distribution of turbidite reservoirs: Evidence from well-seismic analyses and structural restorations in the Brazilian offshore." Marine and Petroleum Geology 28, no. 5 (May 2011): 1023–46. http://dx.doi.org/10.1016/j.marpetgeo.2010.09.009.
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Baggio, Carlo, Valerio Sabbatini, Silvia Santini, and Claudio Sebastiani. "Comparison of different finite element model updates based on experimental onsite testing: the case study of San Giovanni in Macerata." Journal of Civil Structural Health Monitoring 11, no. 3 (April 5, 2021): 767–90. http://dx.doi.org/10.1007/s13349-021-00480-1.
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AbstractUnderstanding the behavior of historic structures that have undergone structural changes, restorations, and damage over time is still a significant challenge for structural engineers, particularly in those countries subject to high seismic risk, such as Italy. The study of built heritage for its prevention and conservation is an active research topic, due to the numerous uncertainties present in historic structures. Finite element modelling has become the most common and accessible method to study the behavior of complex masonry structures, however, the gap between numerical and experimental analysis may lead to erroneous results. Model updating techniques can reduce the discrepancy between the behavior of the numerical models and the testing results. The goal of this work is to illustrate a methodology to integrate the information derived from local, global, and geotechnical investigations into the finite element model of the masonry historical church of San Giovanni in Macerata, considering the Douglas–Reid model updating method. The PRiSMa laboratory of Roma Tre University carried out local investigations such as sonic tomography, video endoscopy and double flat jack tests, along with five ambient vibration tests that were processed through the operational modal analysis to extrapolate the dynamic properties of the building (modal frequency, modal shape vector and modal damping). The combined use of global, local and geotechnical information implemented in the methodology effectively reduced the uncertainties of the model and led the refinement and validation of the most relevant structural parameters.
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Öztürk, Caner, and Gülşen Can. "Effect of Sintering Parameters on the Mechanical Properties of Monolithic Zirconia." Journal of Dental Research, Dental Clinics, Dental Prospects 13, no. 4 (December 25, 2019): 247–52. http://dx.doi.org/10.15171/joddd.2019.038.
Full textAbstract:
Background. Zirconia restorations with high mechanical properties are the current treatment options for fixed restorations with advantages of high biocompatibility and low pulp irritation. Although the effect of sintering time and temperature on the optical and mechanical properties of zirconia core material were investigated, the effect of these parameters on the translucent monolithic zirconia is still uncertain. This study aimed to evaluate the effect of the changes in sintering temperature and holding time on the mechanical and structural properties of monolithic zirconia. Methods. Totally, 340 self-colored (A2) zirconia specimens from two different monolithic zirconia groups (n=170) were prepared, measuring 15.5×12.5×1.2 mm. Then, 17 subgroups (n=10), including the control groups, were sintered according to sintering parameters. XRD analysis was used to determine phase transformations. The surface roughness of the specimens was evaluated using profilometry, and the flexural strength of the specimens was evaluated by the three-point bending test. The data were analyzed using three-way ANOVA and post hoc multiple comparison test with Bonferroni correction (a=0.05) at a significance level of 0.05. Independent-samples t-test was used to compare the subgroups between the control groups (P˂0.05). Results. No tetragonal-to-monoclinic phase transformation was observed in the groups. Changes in the sintering parameters did not significantly affect the surface roughness and flexural strength of monolithic zirconia. Surface roughness values for all the subgroups were above the clinically critical limit. Conclusion. According to the results of this study, changes in the sintering parameters did not affect the surface phase transformation, surface roughness, and flexural strength of monolithic zirconia.
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Tomo, Saygo, Nagib Pezati Boer, Jussara Barbosa Fortunato, and Adriana Sales Cunha Correia. "Molar-incisor hypomineralization (MIH): report of a severe case." Revista de Odontologia da Universidade Cidade de São Paulo 28, no. 1 (January 1, 2016): 58. http://dx.doi.org/10.26843/ro_unicid.v28i1.233.
Full textAbstract:
The term molar-incisor hypomineralization describes an uncommon pathological entity characterized by the hypomineralization of permanent first molars and commonly affecting permanent incisors. In this paper we describe a case of a 9 years old female patient attended with severe dental sensibility, masticatory and phonetic difficulties. Clinical examination revealed severe enamel structural defects affecting all four permanent first molars and opaque stains affecting permanent incisors, besides caries lesions on posterior teeth and severe osseous basis discrepancy. Radiographic examination evidenced permanent first molars imbrication and shallow lesions on the enamel of these teeth. Therefore, molar-incisor hypomineralization was defined. After fluoride varnish applications, glass ionomer cement restorations and home performed fluoride mouthwash, patient continued to report dental sensibility. Molar-incisor hypomineralization is capable of led the affected patient through morbidity which results on quality of life decrease. Due to severe dentin exposure, therapeutic interventions aiming to reduce dental sensibility are not always effective.