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Coals were used in two different grain size types: pulverised and granular ones. Experimental results were used for the mathematical modelling. Effect of char on the cohesive zone thickness and permeability could be simulated.
Next, industrial trials were performed to evaluate the extent of char transfer within the BF shaft and of the raceway characteristics at high PCI rates. Several techniques for shaft and raceway measurements were applied for these studies at two blast furnaces. The results of gas and temperature measurements gave new insights regarding the impact of high coal injection rates on the BF inner state and showed that fine dust was actually carried out with the gas, but was condensed in the gas sampling pipe.
In addition, several measurement techniques were developed and applied for raceway monitoring. Measurements of temperature distribution in the raceway were done under various blast furnace conditions including changing coal injection rate at an industrial BF. Abstract: Among numerous measures to accelerate the PC conversion within the blast furnace BF raceway, local increase of oxygen concentration is the most common one.
On the other hand, the presence of cold media oxygen in the vicinity of the coal stream might affect its ignition and combustion negatively. A minor amount of coke oven gas COG may increase the temperature and hence improve the coal conversion.
To examine this effect, laboratory trials were performed using the Multifunctional Injection Rig for Ironmaking MIRI under blast furnace simulating conditions. The results testified an improved conversion degree of coal while adding the COG. The temperature increase is measurable in the reaction chamber and the off-gas stream. Optical microscopy of the original PC particles and residues after reaction confirm the findings of the off-gas analysis and the increase in temperature during the experiments with addition of COG.
The thermogravimetric analysis was applied to determine and to compare the behavior of coal in different atmospheres including an atmosphere with COG. Furthermore, a stand at one tuyere at a modern BF was erected and tests were performed targeting the observation of the ignition behavior of coal at different COG rates, using a camera image analysis system.
Abstract: The hot blast system is key ancillary plant equipment with respect to safe and stable operations during a long blast furnace campaign. Hot blast stove designs have been optimized to such an extent that in some cases, their lifetimes have surpassed the campaign lengths of the associated blast furnaces by a substantial margin, with the exception of the burner and a few critical areas.
This article presents recent developments with respect to designing, building new and operating existing hot blast systems for a long lifetime and at optimized performance. These developments include fundamental improvements such as dome combustion designs as well as increasingly comprehensive packages for inspection, assessment and maintenance techniques. Examples of such techniques are burner replacement with the hot blast system at operating temperature, improved double shell approaches and TOFD measurement applications.
Abstract: Steel production generates vast amounts of by-products e. The ever-stronger regulation regarding disposal and the potential benefit from recovering valuable elements iron, lime, magnesia, zinc, … contained in the by-products, some of them being considered as Critical Raw Materials in Europe, have driven steelmakers to develop processes to turn waste into source of raw materials and approach the goal of a zero-waste practice.
Due to their powdery nature, some by-products can hardly be introduced in a furnace as secondary raw materials without pre-agglomeration. Traditional agglomeration technologies briquetting, pelletizing require a binder to provide the agglomerates the adequate mechanical resistance and enable their handling without generating large amounts of fines. Aside from their costs, binders reduce by-products recycling efficiency rate, can require curing time hence handling and storage costs.
They also require supplemental energy for their burn-up and generate environmental problems. Binder-free compaction technology relies on subjecting a powder without any additive to uniaxial punching efforts up to MPa, leading to agglomerates called tablets. In this paper, EAF by-products slags, dust and refractory fines behavior under compression is studied using binder-free compaction technology.
Based on the provided by-products compositions, several mixes are elaborated to aim at reducing the amount of primary raw materials lime, magnesia , at proceeding to iterative zinc enrichment and at extending the refractory walls lifetime by achieving MgO saturation of the slag.
Results demonstrate that any of the three studied by-products can be combined in optimized and valuable mixes yielding binder-free compaction tablets whose mechanical resistance, assessed by crushing and drop tests, is in accordance with the requirements of the metal making industry. Abstract: M. Javurek1, P. The complexity of the casting process and the ever-increasing quality demands require a well-founded knowledge of the interaction between the electromagnetic actuators and the liquid steel flow.
Plant trials are not sufficient to build up this knowledge. Numerical modelling and simulations provide a better and more detailed view and are therefore crucial for understanding the interaction between the electromagnetic fields and the liquid steel flow. The work presented here is part of an on-going research to bridge the gap between the liquid steel flow and the grain structure of the end product.
The focus of this paper lies on the liquid steel flow modified by the employed traveling magnetic fields and the investigations rely mainly on numerical simulations. Various modelling approaches with differing complexities are used to simulate linear electromagnetic stirring in the secondary cooling zone of a slab caster. These models are then ranked in terms of accuracy and computational effort. The best model is chosen to investigate the influence of various stirring parameters, stirring modes and stirring positions onto the liquid steel flow.
With these results, further conclusions for the real casting process can be drawn. In contrast to many other simulation systems this new modular approach is able to bring together process data and new enhancements in physically based and empirical microstructure simulations. The system is designed to be easily extendable to new data sources, processes and products. A modern web application makes the simulations usable for a wide range of user groups e.
The combination of physical approaches and data driven modelling makes well-founded estimates and optimization of alloy concepts and process parameters for improved material properties of hot rolled strips possible. Compared to state of the art process controls with neural network this approach gives insight to the microstructure in every single process step like, reheating, rolling, cooling and coiling. Here we will demonstrate the validity of the system for a wide range of steels from deep drawing steels over carbon steels to complex phase steels.
Abstract: The blast furnace is the most important aggregate for hot metal production. In around 1. A modern blast furnace is equipped with hundreds of sensors delivering information about local temperatures, pressures, gas compositions, etc. Nevertheless, even after more than hundred years of blast furnace ironmaking, it is not possible to directly measure information about the current process state like position of process zones, homogeneity of gas flow through the whole stack, etc.
In consequence it is task of the operators to interpret all available data and to deduce to the inner stack state. With the raising number and complexity of measurement data this task gets more challenging. Furthermore, with increasing number and quality fluctuations of charged raw materials the stack processes are more and more difficult to control.
The soft sensor concept has been developed to deduce the internal process parameters, which are of real interest, by exploitation of numerous measurements of auxiliary quantities. During the last years measuring techniques like 2D measurement of top gas temperatures, 3D burden surface radar, etc. These techniques enable together with innovative simulation methods like CFD-DEM modelling to compute a far more accurate insight in the current blast furnace stack state.
During actual research projects, BFI has developed models basing on the soft sensor concept, in cooperation with steel plant operators and measurement technique providers. They interpret e. These tools are designed to support the blast furnace operators in their daily challenge of correctly interpreting the multitude of available data series. Abstract: Operation managers are constantly assessing the productivity of their processes.
Variations in mineralogy and the presence of impurities, not only influence on the effectiveness of the processes, but also increase production costs. Online chemical analysis of material flows directly on site is critical for timeous interventions to improve process performance and eliminate the need for laboratory analysis, often involving hours of delay and potential human error. Lyncis, using knowledge and experience accumulated in the industrial applications, offers the solution for stable accurate online measurements under production conditions, where many factors such as mineralogy, grain size, moisture, etc.
Our analyzers use fully safe laser optical emission technology without hazardous radiation, provide long-term stable calibration, easy and low-cost maintenance. Abstract: In , Already today in China, many integrated mills partially convert their operations to EAF technology. EAF operations are very flexible in terms of raw material used and steel grades produced. In order to be competitive a good material efficiency metallic yield, but also process material consumptions like electrodes or refractories and a good energy efficiency electrical and chemical energy are essential.
This paper gives an overview of the latest global EAF performances in terms of material and energy efficiency in the different regions and for different technologies e. Furthermore, it describes several industry examples how to improve material and energy efficiency in EAF operations based on new methodologies e.
Finite Network Method or by applying profound process and technology expertise for optimization. In conclusion, an outlook about future EAF operations and performance will be given. Abstract: Almost the entire steel industry is currently driven by initiatives and CAPEX projects for improving operational competitiveness, safety levels and environmental footprint. Industry 4. In fact, skilled people will become even more important in the future, in order to understand, maintain and improve the new technologies and complex systems.
By experience, BSW is convinced that the road to success is a well-qualified and motivated workforce. This paper describes the history and the outlook of a unique system for qualifying steelmakers: The Badische Training Model. Established in in a rural area, the mini-mill had a design capacity of , tpy. An unskilled and inexperienced workforce initially operated it. Today, BSW is one of the most productive and efficient mini-mills in the world with a current crude steel capacity of 2.
Today, BSW has established a sophisticated and nationwide-awarded training concept for newcomers, while it also strongly focuses on the continuous multi-skilling of its workforce. To cope with future workforce requirements and to overcome the issue of decreasing birth rates, BSW applies several innovative concepts.
Since , more than 8, steelmakers from different countries were trained in the Badische mini-mill philosophy in order to learn and create their own success story. Abstract: In the past years, Tenova has launched a number of pilot projects to identify opportunities for applications of artificial intelligence techniques to find new ways of bringing value to its customers.
One project was carried out using the data from a BOF furnace in a customer plant. The goal was to predict the final steel temperature based on the composition and temperature of the input material hot metal, scrap, additions in the BOF vessel, in order to make optimal use of the charged material and improve the efficiency of the downstream steel process.
Another project aimed at controlling cassette penetration and strip tension in a tension leveler machine for an Aluminum annealing and chemical treatment line, to improve product quality and system availability as well as reduce roll wear. Yet another project for a steel making plant was to classify scrap material automatically from incoming truck images and images of the load on the ground, according to specifications.
The goal was to speed up the classification process and improve its accuracy. For these and other projects different machine learning algorithms were used, from convolutional neural networks to support vector regression and random forest regression. This paper discusses the results obtained as well as the insight that came from the experience.
The conclusion is that there is definitely scope for applying machine learning models in steel plants with benefits limited only by the quality of the ideas and the availability of data. Abstract: It has been long recognized that conducting a unit operation in closed circuit enhances its efficiency.
This concept also applies to the agglomeration of green balls in the iron ore pelletizing industry. Metal7 has relied on classification principles to develop an array of solution to address some limiting constraint of pelletizing plants.
Those principles had conducted more recently to the development of Triple Deck , a breakthrough technologies in the world of iron ore pelletizing plant. This presentation outlines the theoretical basis for the development of this new screening process and exposes the benefits for the end-user.
From increases in production, his positive impact in bed permeability resulting in higher pellet quality, as well as energy savings. This revolutionary technology has been developed in partnership with Corem and operated with success in one benchmark pelletizing plant in the Americas. Results of this industrial trial will be share through the presentation, as well as operating experience.
Abstract: Environmental emission limits are getting more stringent all over the world since years. In order to fulfill local emission requirements and even surpass them, modern electric arc furnaces have to consequently monitor and treat their off-gas emissions accordingly.
This paper outlines the differences of conventional electric arc furnaces and shaft furnaces in terms of environmental emissions. Emission generation within the furnace as well as different technical solutions for off-gas cleaning and monitoring will be presented. The different approaches and technical solutions for both furnace types will be highlighted from the emission source to the stack. The conclusion of this paper will show, that differences in final emissions of the two furnace technologies are minimal.
Abstract: Since several months, the worldwide scrap availability is getting better and better. The prices for electrical energy are rising thus the efficiency of electric arc furnaces is getting more important. Possible upgrades to pre heating furnaces very often are limited due to scrap yard and meltshop logistics, meltshop heights above the EAF area, and crane heights as well as lifting capacities.
The biggest challenge of a brownfield integration of shaft furnace technologies is to reduce the shaft height without losing the efficiency of the scrap pre heating. Existing meltshop bay as well as crane heights usually limit the possibilities for shaft furnace integrations. Furthermore, the scrap logistics and the shorter tap to tap times have to be considered. This paper will outline the available technical solutions, offered by PT, and will show the benefits in terms of OPEX and productivity increase by using latest shaft furnace technologies with minor changes to the existing meltshop.
The layout was designed with the support of CRM Group and the full engineering and implementation at industrial scale was carried out by ArcelorMittal Fos itself. The installation was built by Azur Industries. WGR layouts have to be optimised in terms of many targets and constraints reduced emission of specific pollutants, reduced off-gas flow rate, energy savings, productivity and sinter quality, limited available space… which may widely differ from one plant to another.
Furthermore, the performances vs costs to be expected for one given WGR layout may depend on local conditions raw materials used, energy costs…. CRM has therefore developed a complete set of tools its sinter model, a flexible sintering pilot station and industrial measurement capacities in order to help its affiliated steel companies to make the best choice and optimise layouts in terms of local objectives and payback time. The selected final layout could even allow a productivity increase.
Simulations results supported also the pre-engineering and economical assessment. First industrial results confirmed the reduction of NOx emissions and showed also a significant improvement in terms of dust emission. Abstract: Sectional strip tension meter - Shapemeter roll Sectional strip tension meter is designed for evaluating of metal strip flatness in cold rolling mills. The principle of the flatness evaluation is based on measuring of pressure forces of a metal strip in the individual zones of the measuring roll.
A visual unit displays measured tensions across the strip in real time on monitor in the form of a column and flat graphical mapping. Depending on the graph shape on the monitor, the operator can make the adjustment of the rolling mill. Abstract: For years, digitization has affected each industry and Industry 4.
With Bilfinger Digital Next and the competence gained from decades of experience as industrial services provider , Bilfinger has set out to make its digital solutions for the optimization of maintenance and operations available to the steel industry. The potential of optimization is undoubtedly present: with the help of the latest artificial intelligence and machine learning technology, individual use cases can be defined within the steel industry.
Models are developed to monitor the condition of individual machines with the help of virtual sensors that combine and evaluate all relevant plant data with cloud solutions. Asset health monitoring, among a variety of additional solutions, allows deep insights improving quality, reducing waste, emissions and energy consumption.
Eventually, Bilfinger Digital Next is dedicated to this goal. Abstract: In cold rolling, tribological effects prevailing at the interface of the work roll and strip surface greatly influence the rolling process and the quality of the final cold rolled product. In particular, the amount of iron fines generated in the roll gap significantly influences strip surface cleanliness. Research work done on this topic has shown that improving the lubrication efficiency especially in the early mill stands helps to avoid excessive wear generation and thus allows to improve the surface quality of the final product.
This paper explains the wear mechanism and the influence of strip, process and lubricant parameters on the generation of strip wear in cold rolling. The system is currently operated based on a lubrication table depending on the steel grade and process parameters. Operational results are presented that demonstrate a reduction of the required rolling forces and power consumptions by improved roll-gap friction.
Measurements of the strip surface cleanliness after cold rolling have shown a significant improvement compared to the previously installed conventional emulsion lubrication system. Currently, intelligent model-based lubrication control concepts are being investigated that allow to influence crucial process parameters such as the coefficient of friction or the forward slip. In the production of ULC steel grades via the RH-process route, Al is first added for deoxidation after the end of decarburization and FeTi after a certain period of separation of alumina particles and the related reduction of the total oxygen content.
The FeTi-addition is well known to cause clogging problems in the following casting process. These particles are comparably smaller as the alumina particles and even if thermodynamically unstable, they still exist as a large population of small particles in samples taken from the tundish.
The local supersaturation of Ti and O during the dissolution of the FeTi-particles seems to be the main reason for the nucleation of these inclusions. Sessile drop experiments indicate that the wetting angle between these Ti-containing alumina particles and ULC steel is at the same level as for pure alumina particles. However, due to only moderate convection of the melt in the ladle after the FeTi-addition, the agglomeration tendency for these particles is low and as previous work has shown, a large number of non-wetting small particles is most critical for clogging.
Laboratory experiments and plant observations are in correspondence and indicate some countermeasures for the better control of clogging. Co-Authors: M. Ringhofer, K. Herzog, E. Tatschl-Unterberger, W. Oberaigner, P. Pennerstorfer, J. Plaul, K. Abstract: A vast amount of companies in the steel industry started digitalization initiatives in the past years. First implementations of those initiatives had been already commissioned successfully.
During the implementation process of such systems it was identified that technology is essential as enabler, however, to make full use of the implemented systems the cultural aspects in a company need to be considered in an equal manner. Especially when software systems are being installed, they also trigger changes in the ways of working in order to untap the full potential of the installed systems.
Software systems supporting business processes are already around for decades and the critical success factors had been researched already quite well thus such implementation challenges are not a novelty to the current digitalization initiatives. Nevertheless, the learning from those past installations is not always considered to the extent required. This paper shows in a few case studies the critical success factors in selected digitalization projects. One of the digitalization projects shows how the acceptance of the digital twin in a continuous casting machine increased over the years.
First installations of digital twins were commissioned decades ago and had basic functionalities to offer. Over the past years the functionalities of the digital twin developed further providing now plant operators, plant designers and start-up engineers with a package to model, simulate, optimize and control the machine. Another example describes that a Through-Process Optimization system brought transparency along the whole value chain allowing to optimize and control a plant in a holistic manner, making strong cross departmental alignment and top management attention to critical success factors.
A further case study shows that the available process know-how became a critical success factor when installing and optimizing a production management systems to be accepted and fully used by the operators. Abstract: Up until recently ironmaking process optimization systems focused on the production processes of stand-alone operations such as individual sinter plants, pelletizing plants and blast furnaces. This control has been based on locally-stored recent — and therefore limited — data.
Process models convert data into usable information, expert systems judge the process conditions and derive required actions by rule based decision support systems to achieve a standardized operation strategy. These systems provide a digital assistant to supervise the overall plant and to offer decision-making solutions to meet the required KPIs of for example productivity, cost and quality.
Automatic control and decision support systems naturally rely on data: The integration of innovative data sources as Acoustic Measurements, Tuyere Optics and Intelligent Staves into the automation landscape and related benefits are discussed. Together with the individual process optimization systems Holistic Ironmaking offers an increased degree of transparency and standardization in order to orchestrate the ironmaking plants closer to the optimal operational setpoint.
The interaction of these systems with the local optimization systems is described in this paper: Together with the individual process optimization systems Holistic Ironmaking offers an increased degree of transparency and standardization in order to orchestrate the ironmaking plants closer to the optimal operational setpoint.
Co-Authors: H. Fritschek, N. Laister, R. Lamplmayr, M. Lehner, H. Lindbichler, B. Schwarzbauer, D. Ulrich, W. Abstract: Higher demands regarding flexibility is a key request of modern plant operation and hence for the respective automation system. At the same time any downtime of a production facility causes loss of production and can even harm your plant.
Especially the complex processes of ironmaking — in particular in blast furnaces and direct reduction plants — require a reliable and highly available automation backbone. This system has to control the process at any time, deliver sound performance in daily operation and guarantee easy and flexible maintainability.
A clearly structured system based on proper system design, advanced programming tools and software management , flexible communication and interfaces, inclusion of smart sensors, simulation with a digital twin for operator training and development of software modifications, online documentation to support the operating and maintenance personnel as well as virtualization concepts, belong to the cornerstones of digitalization — features that are offered by state-of-the-art automation systems.
Abstract: Waste products are actually raw materials in disguise, waiting for a smart person to identify them and put them back into use by an appropriate process. This groundbreaking process is designed to recycle all possible raw material wastes RMWs from an integrated steel plant to produce direct reduced iron DRI. The reduced briquettes with high metallic iron are excellent high-value intermediate products to sell to mini-mills having electric arc furnaces EAF , or to charge in the blast furnace to lower the coke rate as much as possible.
The process is also able to generate power as the by-product. This work presents the development and the technical background of this novel process, which has been developed partially in India and partially in Austria patent application in Austria. This work also explores the possibility of installing this new technology in Europe as well as in global context. Abstract: The properties of coke play a crucial role in the blast furnace process.
Coke, a highly cost intensive raw material, is the most important reducing agent for the furnace. During the burden descend inside a blast furnace, coke undergoes several macro and microscopic changes in its structure due to the combined effect of chemical and mechanical process conditions inside the furnace. A strong and stable structure of coke is necessary in order to secure smooth movement of the burden as well as to maintain the bed permeability.
The surface properties of coke play an important role to influence coke properties. Previous research works have demonstrated the effect of slag penetration in the coke structure due to the change of coke surface caused by Boudouard reaction. In this work, several blast furnace coke samples of different qualities in terms of their CRI and CSR values are investigated microscopically in order to characterize the topographic nature of their surface.
Coke samples before and after CRI tests have been tested and their surface roughness and other topographic parameters are measured along with successive correlation to their reactivity indices. The samples are also analyzed using BET technique to measure their specific surface areas and these values are correlated with the topographic parameters.
The results reveal a better understanding of the changes of surface properties of coke caused by similar conditions as blast furnace. Applications for steel powders include forging tools and structural components for various industries. For large parts, the choice of tool-paths influences the build-rate, the part performance and the distortions in a highly geometry-dependent manner.
With weld-path lengths in the range of hundreds of meters, a reliable, automated tool path generation is essential for the usability of LMD processes. In this contribution, automated tool-path generation approaches are shown and their results are discussed for arbitrary geometries. After generation, the tool-paths are automatically formatted into g-code for experimental build-up and ASCII for a numerical simulation model.
Finally, the tool paths are discussed in regards to volume-fill, microstructure and porosity for the experimental samples and temperature flow for the numerical model. Guidelines are presented for the geometry-dependent selection of path-strategies. Abstract: Paul Wurth works on the advancement of durable engineering concepts and design solutions for BF-hearth side walls since many decades. Preventing structural failures in BF-hearth lining already in the early BF campaign on the one hand and avoiding accelerated hearth lining wear on the other hand will be discussed in the paper as well.
Different classical BF-hearth lining concepts and designs will be compared and judged regarding their success. Is it necessary to change the mind-set and develop new BF-hearth lining concepts for high specific hot metal production rates and significantly prolonged BF-hearth lining life campaigns? Abstract: The metal industry is facing ever stringent environmental regulations leading to more and more efficient off-gas systems. These new off-gas systems generate additional by-products in the form of dusts and sludges.
At the same time, the quality and scarcity of raw materials is becoming a real issue and metal producers have to maximize their resource efficiency in order to maintain their competitiveness. Its objective is to synergistically combine by-products from different sectors in view of their recycling in the production of FeMn alloys. This paper presents the different cold and hot stage pre-processing steps required before recycling. Indeed, to be recyclable the by-products mix has to comply with process requirements such as mechanical strength.
Several binders have been tested and optimised in order to minimize the cost of cold pre-processing while providing the required mechanical properties. The final feasibility assessment will be done in during a semi-industrial campaign using a kW Smelting Arc Furnace. Abstract: Materials and processes for the third-generation advanced high strength steels W.
Bleck1, F. Ma1, C. AHSS have been developed in recent years. The innovation and development of the new generation AHSS brings ecological and economic potential in the automotive industry for reducing automotive weight, improving fuel efficiency, and decreasing CO2 emission.
The microstructure design concepts of the 3. To achieve the sophisticated microstructure, multi-step thermal processing routes are employed. In this case, the manganese partitioning plays an essential role in stabilizing austenite. As a consequence, the combination of the unique characteristics of each microstructural component contributes to the extraordinary mechanical properties of the 3. Specifically, the transformation-induced-plasticity TRIP effect in the metastable austenite improves the strain-hardening rate effectively, leading to an excellent combination of high strength and good ductility.
In the current paper, the alloy design concept, microstructure characteristics, mechanical properties as well as potential applications of the 3. AHSS are summarized. The critical aspects in controlling stability and fraction of retained austenite in the new generation AHSS are explained. The requirements for the process design and the new annealing concepts are emphasized. They consist of a number of high-speed, intelligent and yet inexpensive cameras that are arranged closely next to each other in groups — the clusters.
The distance between two cameras is 20mm, each cluster consists of 16 cameras, cameras are used for two-meter inspection. By lining up multiple cluster modules next to each other, it is possible to measure foil, strip and plate of any width as well as long products. The innovative technology makes the clusters highly interesting for a number of measurement tasks in the steel, aluminium and nonferrous metal industries for cold and hot applications.
Information on defects is extremely important not only for quality assurance, but also to avoid broken strip. Due to the high resolution and steep angle of sight, the technology can also be used economically for the first time for inline measurement of slit strip width in slitting lines. Especially for tinplate and aluminium packaging material camera cluster systems are applicable for detection of pinholes in the size of several micrometer. Wherever the flatness, levelness, contour is necessary to be measured, the camera cluster technology in combination with laser line projection laser triangulation principle is used.
In cut-to-length lines this technology is applicable for sheet and plate dimension measurement such length, width, out of squareness, diagonals and camber. IMS also uses the innovative technology for surface inspection as well. For long products camera cluster are used for straightness measurement. This development raises increasing demands on avoiding surface defects during the production of strip steel, which is typically used by OEMs for outer panel applications.
Aim of this presentation is to illustrate how thyssenkrupp Steel Europe AG tkSE meets this requirement by the example of using a contactless cleaning device at the in-line skin-pass mill SPM of its continuous annealing line CAL : This SPM operates without using any liquid medium for cleaning neither working nor back-up rolls in order to avoid rust dots on the uncoated steel surface. Due to that, dirt appears and may result in dents into the strip surface, which represent major quality defects.
To reduce surface defects caused by dirt while keeping the SPM operating in the wanted dry mode a contactless cleaning device has been developed by tkSE. In recent years, this procedure of contactless cleaning was successfully implemented and industrially tested at the tkSE's CAL in Dortmund. Today, an automatized contactless cleaning device is continuously operating in this line with a positive effect on dirt-related surface defects. Abstract: Primetals Technologies has developed a new vertical sinter shaft cooler that is not only highly energy-efficient but is also much more environmentally friendly than conventional circular sinter coolers.
It is based on a counter-flow cooling process, so heat transfer efficiency is significantly higher than in a conventional sinter cooler. The shaft cooler design allows the optimized utilization of sensible heat contained in the hot sinter.
With this approach the temperature of the cooling air exiting the shaft can be maximized and more efficiently applied for the generation of steam. The total cooler off air of the process is finally cleaned in a dedusting unit which gives the environmental benefit of zero diffuse dust emissions.
The system consists of a pan conveyor for charging the shaft cooler, the shaft cooler, a heat recovery system and a bag filter unit. Operational results and achievements of the first installed shaft cooler will be presented.
The aim of the paper is to illustrate a continuous processing route for AM metal powders production developed to maximize productivity rates, efficiency and flexibility while minimizing production costs and environmental impact. Together with other benefits, this processing system is designed to face the challenge of the industrialization phase relevant to AM Powder production processes.
Abstract: Descaling is an important step in the rolling process. The oxide is removed from the surface of the product to improve surface quality and maintain the rolls. Nozzle selection and header design are important parts of an effective descaling system. The nozzles need to be sized and placed, so they provide sufficient impact force to remove the oxide with the minimal amount of water possible.
Headers need to be sized to maximize the impact performance of the nozzles. Impact testing along with CFD analysis can help to determine if a header has been properly designed to provide maximum impact force. CFD analysis can determine the fluid approach velocity along with the turbulence level in the header. The spray pattern of the nozzle can then be measured for impact force and distribution under different approach velocities and turbulence levels.
Comparing these to a nozzle tested under an ideal no turbulence condition can determine minimum header size requirements based on nozzle capacity and pressure. Optimizing the header can help to improve performance and minimize energy costs. This paper will show the results of several existing installations where both CFD and impact testing was used to optimize a descaling operation in hot strip mills and plate mills.
Abstract: With the mainstream adoption of technologies, such as Machine Learning, Artificial Intelligence, Data Analytics and Digitalization, many industries are exploring these areas to understand how each solves unique challenges in their operational value chain.
This paper explores non-steel producing industries to see what solutions are being adopted, problems they are solving, and how this relates to the steel industry. Further, this paper discusses how Midrex is making these technologies available in Midrex Connect, a connected services platform, designed to help customers understand Industry 4. Abstract: Blast furnace hearth lifetime extension remains one of the biggest challenges within the whole integrated steelmaking system.
Savings associated with a long hearth campaign are difficult to estimate but are huge. The eternal hearth goal may appear impossible today but our current path holds promise. Hearth lifetimes over recent decades have increased incrementally from around 5 years to over 20 years. We are now looking for stepwise improvements. Saint-Gobain Ceramic Cup technology has been one of the key factors in hearth lifetime extension especially following adoption of sialon bonded corundum in There is already very clear evidence that the first two sialon bonded corundum qualities have lasted 8 to 10 years before the self-protecting layer on carbon needs stabilising.
Saint-Gobain announces the launch of a new quality for Ceramic Cup. This last generation of Alumina Sialon Bonded material was especially developed to withstand the severe and extreme conditions existing inside the hearth. This new enhanced quality exhibits outstanding properties, surpassing the good and proven performances of former products. Major optimizations were necessary to reach this result from recipe to reactive sintering process, making this material perfectly designed to protect the hearth carbon lining.
The corrosion resistance to iron and slag has been significantly improved to reduce kinetic and chemical erosion of the refractory including the critical interface iron - slag - refractory. In addition, the excellent refractoriness of Al2O3 Sialon bonded materials is maintained with resistance to CO environment and high thermo-mechanical stability. Finally, the resistance to chemical attacks and oxidation has been improved.
In this paper, this new material will be benchmarked against other materials, tested or currently used in the blast furnace to highlight the main technical advantages. Such emissions may involve complicated relationship with neighbourhood of steel Plants.
Important expenses may be due to local or international regulations regarding the finest dust particles emitted in the atmosphere. The solutions cover the full range of particle size, from the coarsest particles involving dust deposition on the ground within the first kilometres around the steel plants to the finest visible particles emitted by the roofs and other diffuse sources of the Steel process.
The WEB monitoring interface delivers Alarm and important information such as the location of the main sources. The sensor samples the deposition for accurate analysis. It is optimized for steel shop, electric furnace, blast furnace and coke plant. A dashboard gives the opportunity to edit statistics for ISO management. Abstract: Even today, no one in the world can precisely quantify ASIS performance for the whole running production as in contrast to common measuring systems where the accuracy of the measurement is well defined, it is almost impossible for the user to determine comparable quantities for an ASIS.
This guideline should lead to comparable ASIS results of proven reliability as a first step towards real measurement of surface quality. This paper discusses the project results and the concepts developed for ASIS stability testing. In order to extend the product range further especially in terms of grades and sizes, NLMK DanSteel decided to revamp and expand the heavy-plate rolling mill. The large-scale expansion and modernization comprises a new laminar plate cooling system with water treatment equipment, new heavy plate cooling bed and a revamp of the existing cold-plate leveler.
The new plate cooling system will allow NLMK DanSteel to produce high-strength plate for various applications, like e. The new water treatment system will filter and cool the cooling water and feed it back into the process in a closed circuit. A new cooling bed for thick plate is to be installed downstream of the laminar cooling system and existing hot-plate leveler.
The plate will be delivered automatically to the cooling bed, which will be able to handle plate weights of up to 40 tons and more. The existing cold-plate leveler will also undergo a comprehensive revamp. In order to reduce shutdown times to a minimum, suitable installation strategies and optimized erection schedules were developed on the basis of a 3D laser survey.
The paper will provide insights in the partly highly complex modifications and implementation strategy. Abstract: In steel production we often encounter special steel grades having increased requirements in terms of the surface quality.
The fulfillment of such quality requirements can be achieved by a suitable choice of cooling intensities in individual loops of the secondary cooling zone. This preserves a final product with a minimum number of defects.
The developed 3D transient solidification model BrDSM is applicable to monitor and control the evolution of temperature distribution of the cast strand. The solidification model is coupled with the fuzzy-based regulator, which controls and adjusts cooling intensities in the secondary cooling zone to maintain surface temperatures of the strand in specified temperature intervals ensuring a low occurrence of defects and a good final quality.
The aim of the paper is to investigate an optimum design of the secondary cooling zone, which allows for sufficiently smooth regulation, but with regard to a minimal cost of the zone number of pumps, valves, electronics. Therefore, the objective is to optimally split a secondary cooling zone into proper number of cooling loops.
The paper presents results for an optimal number of cooling loops for a case of dynamic process fluctuations with abrupt changes of the casting speed. Results demonstrate that the proposed coupled system is an efficient tool capable for the design optimization of the secondary cooling zone. HTT developed the new technology to significantly improve efficiency of burner flame as well as of injected oxygen. It enables controlled wide range motion of the flame and supersonic oxygen jet inside the furnace area, while burner body remains static and sealed in the furnace wall.
This brings substantial advantages of EAF operation as volume of the scrap preheated by flame increase due to flame ability to move and flame can be better directed to the required spots in the furnace. Further to this, ability to move supersonic oxygen jet speed up scrap cutting in period of transition from solid the liquid phase.
These benefits are reached while furnace is still tight sealed and burner body inside the furnace is not moving. The paper will describe technological principles as well as practical results and experience gained during EAF operation with HTT OxymoTM technology in these two plants. Abstract: In order to control and investigate all major steps of metal additive manufacturing, SMS group has set up a 3D Competence Center at their location in Moenchengladbach, Germany.
A full scale powder atomization plant for the production of high-grade metal powders has been built to gain detailed operator know-how and production expertise to develop and produce different AM powders. A fully equipped laboratory guarantees high qualities for the further processing using a laser based powder bed fusion printer.
The main goal is to analyze and develop the different influencing factors during atomization and further powder processing and the correlating properties during the downstream processing steps. By this full liner approach for the entire value chain of additive manufacturing, SMS can bring the best value to customers. In this paper, the Powder Atomization Plant and its technical features are described in detail to show the correlations of the powder processing and best results of the laser based powder bed fusion printer.
To realize highest cleanness of the powder, the melting and refining of metals and alloys is taken place under vacuum or inert gas atmosphere. The atomizing process with argon or nitrogen, using the close-coupled principal, guarantees defined grain sizes and distribution of metal powders.
An anti-satellite system is used for the needed spherical particles shapes which guarantee good flow properties during the 3D printing process. Combining a high utilization grade of metal powder and the right particle size and shape for additive manufacturing at highest quality, the new plant concept of SMS group demonstrates customers how to become the leading supplier of the AM industry.
Abstract: Reducing CO2 emissions by around 80 percent to is the central climate goal, and requires both energy suppliers and industry to prepare themselves and explore new pathways together. For the industry, transport, and energy sectors, CO2-free hydrogen is an important source of energy for sector coupling and can significantly contribute to achieving the climate goals. The vision is to move away from carbon via bridging technologies based on natural gas, as is already the case at the direct reduction plant of voestalpine in Texas and finally on to the greatest possible use of green hydrogen in steelmaking.
The prerequisite is the provision of sufficient energy from renewable sources and at competitive prices. Construction of the new PEM pilot plant for the production of CO2-free hydrogen together with research on other breakthrough technologies like hydrogen plasma smelting reduction is a step further towards the long-term realization of a technology transformation in the steel industry in the next couple of decades.
This calls for flexible and well-designed production plants with reduced maintenance and longer equipment lifetime. Centre segregation and porosity, in high quality blooms and billets, can cause inconsistent mechanical properties and potential failure of the final product.
Additionally, introduction of DynaPhase model influences further improvement of thermal tracking, resulting superb quality of the cast product. Abstract: Addition of directed reduced iron DRI or hot briquetted iron HBI to blast furnaces has been studied for decades and has well known benefits for increasing productivity and decreasing coke rate.
In the last few years, it has been of interest as a means to reduce ironmaking carbon dioxide emissions. Despite the technical benefits, DRI or HBI addition to the blast furnace is rarely done due to economic reasons or issues related to low top-gas temperatures. Operational issues related to top gas temperature constraints will be discussed.
The practical limits for addition and potential ability to shut down a blast furnace at a multiple blast furnace facility will be explored. Carbon dioxide savings will be estimated. Part 3 of this paper will consider hot gas addition to the mid-stack of the blast furnace in order to increase top gas temperature to allow for higher DRI or HBI addition.
The hot gases can be generated via plasma torches to further reduce CO2 emissions from the ironmaking area. Co-Authors: R. Albanese, J. Grindey, J. Busser, M. Sukhram, I. Cameron, R. Pula, M. Abstract: Leaking tuyeres damage hearth refractories, chill the hearth and cause production losses. Steel and Hatch implemented a soft sensor at Blast Furnace No. The soft-sensor statistically compares inlet and outlet water flows for each tuyere.
Leaks are found quickly by tracking fast and slow drifts in the differential water flowrates. This paper will discuss the development of the soft-sensor and present examples of the leak events that were successfully detected. Co-Authors: P. Ghosh , D. Srivastava, A. Chatterjee , A. Bajaj, R. Ghosh , A. Garg, F. Garbugino, M. Bassetti, L. Spadoni, K. At Bhilai Steel Plant where the existing BF plant consists of seven mid-size furnaces of Soviet design built in the ies , this new unit was to become Blast Furnace No.
The paper will highlight the latest technological solutions adopted and the main challenges met during the project, in particular all the required plant units had to be arranged within the allocated area for this brownfield installation and especially the layouts of the main charging conveyor, of the racks for utilities pipes and cable and of the railway tracks had to be finalized with unconventional solutions.
This was to ensure the maintainability and accessibility of the surrounding areas during construction and for the future operations of the plant. With an inner volume of 4, m3, a hearth diameter of Abstract: The goal of this study is to forecast the electrical energy consumption of an Electric Arc Furnace using historical data from a steel mini-mill producing clean steel.
Machine learning models are created, specializing on three of the main types of steel grades produced in the steel plant. The goal is to predict the electrical energy consumption for the next heat. The results from the interpretability algorithms are then compared to previous research results on the dynamics of the Electric Arc Furnace energy consumption to achieve a model-to-application-domain transparency.
Abstract: Bragg grating optical fibers can replace, with significant advantages, the temperature measurements previously performed by thermocouples. This paper describe, from a pratical point of view, the first results of the conversion.
Abstract: A demand for high quality steels is growing around the world. The RH vacuum degasser is one of the equipment used to refining these steels. The common clinical problems about distally extended RPDs are lack of retention and stability due to the movement around the rotational axis.
Dental implant placement to the distal edentulous site minimizes the potential dislodgement of the RPD is popular. Implant-supported RPD can be suggested as an advantageous and cost-effective treatment option for the partially edentulous patients. Introduction The use of removable partial denture RPD is considered as low-cost and common treatment option to rehabilitate edentulous areas. Aim This study aimed to investigate the epidemiological data of patients rehabilitated with removable partial denture RPD in order to assess treatment survival rate and failures.
Factors such as gender, age, presence of systemic disease, main complaint, edentulous arch, period and cause of denture replacement and the prosthesis characteristics were recorded. The chi-square test was used to assess the differences between the variables and the Kaplan Meyer to assess the survival of the RPDs evaluated.
Most of the patients were women aging 41 to year-old. In patients with a limited number of remaining teeth, bruxism force can be destructive for both the remaining teeth and periodontal structures. This paper reports the successful management of four such patients with severe sleep bruxism, using conventional removable partial dentures and specially designed, splint-like removable partial dentures called a night denture.
The night denture was fabricated in two different designs, which depended upon the pattern of the remaining tooth contacts. The patients were followed up for years using a night denture in either of the two designs. Within the limitations of these four reports of clinical cases, the night denture appeared to be effective in managing the problems related to sleep bruxism.
Influence of length and diameter of implants associated with distal extension removable partial dentures. The aim of this study was to evaluate the influence of the length and diameter of the implant incorporated under the saddle of a distal-extension removable partial denture , acting as support.
Six hemi-mandibular models were made with the presence of left inferior cuspid and first bicuspid, with the following differences: model A, without removable partial denture ; model B, removable partial denture only; model C, removable partial denture and implant of 3. The loads applied were 50 N vertical on each cuspid point. It was noted that the presence of the removable partial denture overloaded the supporting tooth and other structures.
The introduction of the implant reduced tensions, mainly at the extremities of the edentulous edge. Both the length and diameter tended to reduce tensions as their dimensions increased. Increasing the length of the implant had a great influence on the decrease of displacement and von Mises tension values.
Increasing the diameter of the implant had a great influence on the decrease of von Mises tension values, but did not influence the displacement values. According to the results of this study, it is a good choice to use the greater and larger implant possible in the association between implant and distal extension removable partial denture. Effect of complete and partial removable dentures on chewing movements. Partial or complete edentulism impairs mastication.
However, it is unclear how the chewing cycle is affected by prosthetics. We evaluated the chewing movements of patients fitted with complete CD or removable partial denture RPD. A total of 29 subjects were kinesiographically evaluated during chewing of peanuts and Optocal portions in a random sequence. The subjects were divided into two groups according to prosthesis type.
Opening, closing, occlusal and masticatory cycle times, movement angle opening and closing , maximum velocity opening and closing , total area and chewing cycle amplitudes were evaluated. RPD wearers use a faster chewing sequence with greater vertical and lateral jaw excursions compared with CD wearers. Removable partial denture alloys processed by laser-sintering technique.
Removable partial dentures RPDs are traditionally made using a casting technique. New additive manufacturing processes based on laser sintering has been developed for quick fabrication of RPDs metal frameworks at low cost. The objective of this study was to characterize the mechanical, physical, and biocompatibility properties of RPD cobalt-chromium Co-Cr alloys produced by two laser-sintering systems and compare them to those prepared using traditional casting methods.
L-1 and L-2 techniques were 8 and 3. To quantify effects on occlusion and temporomandibular function of mandibular distal extension removable partial dentures in shortened dental arches. Data were collected at baseline and at 3-, 6-, and 9-year observations. Occlusal activity in terms of reported awareness of bruxism and occlusal tooth wear of lower anterior teeth did not differ significantly between the groups. In contrast, occlusal tooth wear of premolars in shortened dental arches with or without extension dentures was significantly higher than in the controls.
Differences amongst groups with respect to signs and symptoms related to temporomandibular disorders were not found. Occlusal support of the dentures did not influence anterior spatial relationship. Mandibular distal extension removable partial dentures in moderate shortened dental arches had no effects on occlusion and temporomandibular function.
Removable partial denture supported by implants with prefabricated telescopic abutments - a case report. Implants have been designed to rehabilitate edentulous patients with fixed prosthesis or implant supported overdentures. Implant-supported single crowns and fixed partial dentures have become successful treatment alternatives to removable and fixed partial dentures. However, it is common to have clinical situations which make it impossible to use conventional as well as implant supported fixed partial dentures.
The implant supported removable partial dentures can be a treatment modality that offers the multitude of benefits of implant-based therapy-biologic, biomechanical, social, and psychological to such patients. The aim of this article is to present a case report describing the fabrication and advantages of removable partial denture supported by teeth and implants for a patient with long edentulous span.
The patient was satisfied with his dentures in terms of function and aesthetics. Regular follow-up visits over a period of three years revealed that the periodontal condition of remaining natural dentition and peri-implant conditions were stable. There was no evidence of excessive residual ridge resorption or mobility of the teeth, nor were any visible changes in the bone levels of the natural teeth or implants noted on radiographs.
Reestablishment of occlusion through overlay removable partial dentures : a case report. Loss of posterior teeth may cause an imbalance in the stomatognathic system. Overlay removable partial dentures ORPD are a reversible and relatively inexpensive treatment for patients with severely worn teeth. This paper presents a treatment with ORPD in a year-old male patient who had severe attrition in the maxillary and mandibular teeth, temporomandibular joint pain and reduced vertical dimension of occlusion VDO.
The treatment consisted in the reestablishment of the VDO using Lucia's jig, fabricating removable partial denture with reconstruction of the worn teeth without preparation. This therapy can be used as an alternative treatment to provide esthetic, function and stable occlusion in patients with severely worn teeth.
Posterior open occlusion management by registration of overlay removable partial denture : A clinical report. This clinical report describes prosthetic rehabilitation of posterior open bite relationship in a patient with several missing teeth and skeletal Class III malocclusion. Primary diagnostic esthetic evaluations were performed by mounting casts in centric relation and estimating lost vertical dimension of occlusion.
Exclusive treatments were designated by applying overlay removable partial denture with external attachment systems for higher retentions. Maxillary overlay removable partial dentures for the restoration of worn teeth. Prolonged tooth maintenance by a more aged population considerably increases the probability of dentists having to treat patients with high levels of tooth wear. Pathological tooth wear, caused primarily by parafunction, seems to be a growing problem that affects a large number of adult patients.
The clinical report presents a case of a partially edentulous patient with an elevated degree of wear in the upper jaw caused by attrition and erosion, rehabilitated with a maxillary overlay removable partial denture ORPD consisting of a chrome-cobalt Cr-Co framework with anterior acrylic resin veneers, posterior cast overlays, and acrylic resin denture bases. Removable partial prosthesis is a treatment alternative when teeth are found to be severely worn or when the patient needs a simple and economical option.
Because economics is a conditional factor of the treatment, the clinician should present different treatment alternatives to the patient, in which the overlay prosthesis can be considered. The aim of this systematic review was to evaluate the functionality of fixed and removable partial dentures as test interventions in relation to variations in the opposing dentition and their prosthetic restoration.
The abstracts identified in the respective databases were screened independently by two investigators. RCTs and uncontrolled studies were considered, provided the patients were included consecutively and the confounding variables were adequately monitored. Seventeen papers were included.
The reported outcomes, such as survival rates, were in each case obtained from a single study. Two possible trends could be deduced for the endpoint longevity: a the first trend in favor of removable partial dentures , compared to fixed partial dentures , with a fully edentulous opposing arch fitted with a removable prosthesis; b the second trend in favor of implant-supported partial dentures , compared to conventionally fixed partial dentures , with natural opposing dentition or with a removable partial denture in the opposing arch.
No evidence could be generated as to whether, and if so how, variations in the opposing dentition have a bearing on the decision to fit a partially edentulous arch with a fixed or removable partial denture. The decision as to whether to retain or extract a single remaining natural tooth prior to the provision of dentures can be a difficult one.
If the tooth is left in situ, the development of an adequate peripheral seal around the denture is not possible thereby compromising the appliance' retention. If the tooth is extracted the possibility of gaining direct retention with the use of clasps or attachments is lost. This paper aims to illustrate the use of windowed removable partial denture design and review the literature relevant to this area.
The present clinical report describes the prosthodontic management for a patient with uncontrolled bleeding and diabetes mellitus treated with a maxillary complete denture and a mandibular partial fixed dental prosthesis designed to interface with a removable cast framework partial denture retained by 2 ERA attachments.
This approach was undertaken to improve both retention and stability of the distal extension Kennedy Class I removable partial denture. The rehabilitation provided better anterior esthetics than if treated with a conventional clasp retained removable partial denture , by employing a simple, practical design and offering a significant biomechanical advantages, restoring both oral health and function. Thus, this treatment modality, involving an ERA system and transfixation in fixed crowns, is an effective treatment and can be indicated as a clinical alternative for edentulous and partially edentulous patients with systemic disorders or for patients in economic situations that might preclude implant-based rehabilitation.
Three-dimensional finite element analysis of implant-assisted removable partial dentures. Whether the implant abutment in implant-assisted removable partial dentures IARPDs functions as a natural removable partial denture RPD tooth abutment is unknown.
Finite element models of the partial maxilla, teeth, and prostheses were generated on the basis of a patient's computed tomographic data. The teeth, surveyed crowns, and RPDs were created in the model. Oblique loading of N was applied on the crowns and denture teeth.
The von Mises stress and displacement of the denture abutment tooth and implant system were identified. Among the 4 models, the highest maximum displacement value was observed in the model TT and the lowest value was in the model IB. When implants are used for RPD abutments, more consideration concerning the RPD design and the number or location of the implant is necessary.
Published by Elsevier Inc. All rights reserved. Final-impression techniques and materials for making complete and removable partial dentures. Edentulism is relatively common and is often treated with the provision of complete or partial removable dentures. Clinicians make final impressions of complete dentures CD and removable partial dentures RPD using different techniques and materials.
Applying the correct impression technique and material, based on an individual's oral condition, improves the quality of the prosthesis, which may improve quality of life. To assess the effects of different final-impression techniques and materials used to make complete dentures , for retention, stability, comfort, and quality of life in completely edentulous people. To assess the effects of different final-impression techniques and materials used to make removable partial dentures , for stability, comfort, overextension, and quality of life in partially edentulous people.
No restrictions were placed on language or publication status when searching the electronic databases, however the search of Embase was restricted by date due to the Cochrane Centralised Search Project to identify all clinical trials and add them to CENTRAL. We included randomised controlled trials RCTs comparing different final-impression techniques and materials for treating people with complete dentures CD and removable partial dentures RPD.
For CD, we included trials that compared different materials or different techniques or both. In RPD for tooth-supported conditions, we included trials comparing the same. Measurements were carried out on 60 teeth of 28 patients 28 teeth and 12 patients of TTSD group, 32 teeth and 16 patients of TSD group who had not worn any type of removable partial dentures before, had no systemic problems and were non smokers.
PBF values were recorded by LDF before insertion day 0 and after insertion of dentures at day 1, day 7 and day Statistical analysis was performed by student t test and covariance analyses of repeated measurements. This clinical report described the oral rehabilitation of a cleft lip and palate patient with removable partial denture. Although implant-supported fixed treatment was presented as part of the optimum treatment plan to achieve the best result, the patient declined this option due to the significant financial burden.
Persons with a congenital or craniofacial defect are unique, and oral problems must be evaluated individually to the most ideal treatment. The changes in appearance, function, and psychological wellbeing have an enormous impact on patients' personal lives and are rewarding for the maxillofacial prosthodontist providing this care.
Effect of oral hygiene education and motivation on removable partial denture wearers: longitudinal study. The purpose of this study was to determine the effect of two different preventive oral hygiene education and motivation programmes on the plaque and gingival index, as well as denture hygiene of patients provided with removable partial denture RPD during a month follow-up.
A total of 53 partially edentulous patients were recruited for this study. The presence or absence of plaque and gingival bleeding by gentle probing was scored on all tooth surfaces at the preliminary visit. Following treatment, the patients were randomly divided into three groups.
In Control Group I, subjects were instructed to continue their personal oral hygiene routine. In Group II, participants were given verbal instructions and a self-educational manual on oral hygiene without illustrations. In Group III, oral hygiene guidance was delivered using a combination of verbal instructions and a self-teaching manual.
To evaluate the effect of the different modes of instruction, the presence or absence of plaque and gingival bleeding was scored on all tooth surfaces day zero examination and re-examined 7, 15 and 30 days, 3, 6 and 12 months following RPD placement.
The state of denture hygiene was evaluated 7, 15 and 30 days and 3, 6 and 12 months following rehabilitation. Parametric statistics was applied to dental plaque and gingival indexes. For accumulation of plaque and calculus on the RPD, non-parametric statistic was applied. The frequency of plaque found during the preliminary visit was higher than that found in the other periods.
With regard to gingival index, significant difference was found between the preliminary visit examination and other periods. There was a significant difference in the plaque accumulation on the denture surface between groups I and III. The different methods of oral hygiene instruction used in this study indicate that the type of education was not of significant importance.
Clinical and microbiologic effects of lingual cervical coverage by removable partial dentures. The effect of gingival coverage by removable partial dentures RPDs on bacterial accumulation has not been sufficiently established. The aim of this study was to evaluate the periodontal and microbiologic reactions to mandibular major connectors. It was hypothesized that the use of a lingual plate increases the risk of periodontal disease. Fourteen subjects mean age: Each subject received an experimental RPD incorporating either a lingual bar or lingual plate for the first 8 weeks and was then switched to the other option for the next 8 weeks.
Clinical parameters Plaque Index, Gingival Index, probing depth, and tooth mobility were recorded. Subgingival plaque samples were collected from the periodontal pocket in the test site to measure the colonization of periodontal pathogens after the use of each denture. The mean probing depth was significantly greater after use of the lingual plate compared to the lingual bar P denture hygiene are carefully monitored. Laser welding of a cobalt-chromium removable partial denture alloy.
The electric alloy brazed joints of removable partial denture alloys have failed frequently after routine usage. A technique providing higher joint strengths was investigated. This investigation compared the tensile strengths of electric-brazed and laser-welded joints for a cobalt-chromium removable partial denture alloy. Twenty-four cobalt-chromium standard tensile testing rods were prepared and divided into three groups of eight.
All specimens in the control group group 1 were left in the as-cast condition. Groups 2 and 3 were the test specimens, which were sectioned at the center of the rod. Eight specimens were joined by using electric brazing, and the remaining specimens were joined by using laser welding.
After joining, each joint was ground to a uniform diameter, then tested to tensile failure on an Instron universal testing machine. Failure loads were recorded and fracture stress calculated. Statistical analysis was applied. The student-Newman-Keuls test showed a highly significant difference between the joint strengths of the as-cast control specimens, the electric-brazed and laser-welded joints.
The tensile strengths of the as-cast joints were higher than those for the laser-welded joints, and both were higher than the electric-brazed joint strengths. This in vitro study investigates how unilateral and bilateral occlusal loads are transferred to an implant assisted removable partial denture IARPD.
Materials and Methods. A duplicate model of a Kennedy class I edentulous mandibular arch was made and then a conventional removable partial denture RPD fabricated. Two Straumann implants were placed in the second molar region, and the prosthesis was modified to accommodate implant retained ball attachments.
Statistical analysis was carried out using SPSS version Unilateral loading resulted in a twisting of the structure and generated a strain mismatch between the metal and acrylic surfaces. The curvature of the dental arch resulted in a twisting action which intensified as the unilateral load was moved anteriorly. Maxillary rehabilitation using fixed and removable partial dentures with attachments: a clinical report.
Despite requiring dental crown preparation and possible root canal treatment, besides the difficulty of clinical and laboratory repairs, and financial burden, the association between fixed FPD and removable partial dentures RPD by means of attachments is an important alternative for oral rehabilitation, particularly when the use of dental implants and FPDs is limited or not indicated. Among the advantages of attachment-retained RPDs are the improvements in esthetics and biomechanics, as well as correction of the buccal arrangement of anterior teeth in Kennedy Class III partially edentulous arches.
Removable partial dentures vs overdentures in children with ectodermal dysplasia: two case reports. Ectodermal dysplasia ED represents a disorder group characterised by abnormal development of the ectodermal derivatives. Removable partial dentures RPD , complete dentures CD or overdentures OD are most often the treatment of choice for young affected patients.
Prosthetic intervention is of utmost importance in the management of ED patients, as it resolves problems associated with functional, aesthetic, and psychological issues, and improves a patient's quality of life. However, few studies present the principles and guidelines that can assist in the decision-making process of the most appropriate removable prosthesis.
The purpose of this study was to suggest a simple treatment decision-making algorithm for selecting an effective and individualised rehabilitative treatment plan, considering different parameters. Periodic recalls were employed to manage problems, and monitor the changes associated with occlusion and fit of the prostheses in relation to each patient's growth.
The main factors guiding the decision process towards the choice of an RPD or an OD are the presence of posterior natural teeth, facial aesthetics, lip support, number and size of existing natural teeth, and the occlusal vertical dimension. Additive manufacturing AM often referred to as 3D printing 3DP has shown promise of being significantly viable in the construction of cobalt-chromium removable partial denture RPD frameworks.
The current paper seeks to discuss AM technologies photopolymerization processes and selective laser melting and review their scope. The review also discusses the clinical relevance of cobalt-chromium RPD frameworks. All relevant publications in English over the last 10 years, when the first 3D-printed RPD framework was reported, are examined.
The review notes that AM offers significant benefits in terms of speed of the manufacturing processes however cost and other aspects of current technologies remain a hindrance. The technique in this article was developed to provide a means to create prepared guide planes of proper dimension to ensure a more stable and retentive removable partial denture prosthesis RPDP framework when providing this service for a patient. Using commonly found clinical materials, a paralleling device can be fabricated from the modified diagnostic cast of the patient's dental arch requiring an RPDP.
Polymethyl methacrylate or composite added to an altered thermoplastic form can be positioned intraorally and used as a guide to predictably adjust tooth structure for guide planes. Since it can potentially minimize the number of impressions and diagnostic casts made during the procedure, this can help achieve the desired result more efficiently and quickly for the patient. Designing cobalt chromium removable partial dentures for patients with shortened dental arches: a pilot survey.
The aim of this survey was to investigate the quality of prescription for the fabrication of cobalt chromium removable partial dentures RPDs that are used to extend the shortened dental arches SDAs. A survey of four commercial dental laboratories located in northern England was conducted. The target of this survey was cobalt chromium RPDs that were requested to restore SDAs comprising the anterior teeth and premolars.
Dentists' prescriptions were scrutinised, and a special data collection form was completed accordingly. A total of 94 dentists' prescriptions and associated SDA casts were examined. This finding has an ethical and clinical bearing and does not fit with current legal guidelines relevant to designing RPDs.
The influence of heat treatments on several types of base-metal removable partial denture alloys. Fe-Cr alloy , Durallium L. Co-Cr-Ni alloy , and Ticonium Ni-Cr alloy , were evaluated in the as-cast condition and after heat treatment for 15 minutes at 1, degrees, 1, degrees, 1, degrees, and 2, degrees F followed by quenching in water.
The following properties were determined and compared for each alloy at each heat treatment condition: the yield strengths at 0. The results were statistically analyzed. Photomicrographs were examined for each alloy and test condition. The following conclusions were made: 1. The "highest values" were exhibited by the as-cast alloy. Heat treatment of the partial denture alloys tested resulted in reductions in strength, while the elongations varied.
This study demonstrates that, in practice, one should avoid a prolonged "heat-soaking" while soldering and b grinding or polishing of the casting until the alloy is "red hot". Durallium L. Conventional reporting of the yield strength at 0. The reporting of the yield strength at 0. The process of tooth loss throughout life associated with severe occlusal wear may pose a challenge in the rehabilitation of partially edentulous arches.
In these cases, many therapeutic procedures are necessary because each tooth must be restored to obtain the correct anatomical contour and recover the occlusal vertical dimension OVD. This clinical report reviews the principles involved in the clinical indication for an overlay RPD, as well as the necessary planning and execution, to discuss the feasibility and clinical effectiveness of this treatment, identifying the indications, advantages, and disadvantages of this procedure through the presentation of a clinical case.
The main advantages of this type of treatment are its simplicity, reversibility, and relatively low cost; however, further studies are needed to ensure the efficacy of this treatment option. An ontology-driven, case-based clinical decision support model for removable partial denture design. We present the initial work toward developing a clinical decision support model for specific design of removable partial dentures RPDs in dentistry. During the case-based reasoning process, a cosine similarity algorithm was applied to calculate similarity values between input patients and standard ontology cases.
A group of designs from the most similar cases were output as the final results. To evaluate this model, the output designs of RPDs for randomly selected patients were compared with those selected by professionals. An area under the curve of the receiver operating characteristic AUC-ROC was created by plotting true-positive rates against the false-positive rate at various threshold settings. The precision at position 5 of the retrieved cases was 0.
The mean average of precision MAP was 0. All the metrics demonstrated the efficiency of our model. This methodology merits further research development to match clinical applications for designing RPDs. This paper is organized as follows. After the introduction and description of the basis for the paper, the evaluation and results are presented in Section 2. Section 3 provides a discussion of the methodology and results. Section 4 describes the details of the ontology, similarity algorithm, and application.
Influence of implant inclination associated with mandibular class I removable partial denture. The aim of this study was to use two-dimensional finite element method to evaluate the displacement and stress distribution transmitted by a distal extension removable partial denture DERPD associated with an implant placed at different inclinations 0, 5, 15, and 30 degrees in the second molar region of the edentulous mandible ridge.
Six hemimandibular models were created: model A, only with the presence of the natural tooth 33; model B, similar to model A, with the presence of a conventional DERPD replacing the missing teeth; model C, similar to the previous model, with a straight implant 0 degrees in the distal region of the ridge, under the denture base; model D, similar to model C, with the implant angled at 5 degrees in the mesial direction; model E, similar to model C, with the implant angled at 15 degrees in the mesial direction; and model F, similar to ME, with the implant angled at 30 degrees in the mesial direction.
The force applied was vertical of 50 N on each cusp tip. The results showed that the introduction of the RPD overloaded the supporting structures of the RPD and that the introduction of the implant helped to relieve the stresses of the mucosa alveolar, cortical bone, and trabecular bone. The best stress distribution occurred in model D with the implant angled at 5 degrees.
The use of an implant as a support decreased the displacement of alveolar mucosa for all inclinations simulated. The stress distribution transmitted by the DERPD to the supporting structures was improved by the use of straight or slightly inclined implants.
According to the displacement analysis and von Mises stress, it could be expected that straight or slightly inclined implants do not represent biomechanical risks to use. We developed an ontological paradigm to represent knowledge of a patient's oral conditions and denture component parts.
To introduce a method of digital modeling and fabricating removable partial denture RPD frameworks using self-developed software for RPD design and rapid manufacturing system. The three-dimensional data of two partially dentate dental casts were obtained using a three-dimensional crossing section scanner.
Self-developed software package for RPD design was used to decide the path of insertion and to design different components of RPD frameworks. The components included occlusal rest, clasp, lingual bar, polymeric retention framework and maxillary major connector. The design procedure for the components was as following: first, determine the outline of the component. Second, build the tissue surface of the component using the scanned data within the outline.
Third, preset cross section was used to produce the polished surface. Finally, different RPD components were modeled respectively and connected by minor connectors to form an integrated RPD framework. The finished data were imported into a self-developed selective laser melting SLM machine and metal frameworks were fabricated directly. RPD frameworks for the two scanned dental casts were modeled with this self-developed program and metal RPD frameworks were successfully fabricated using SLM method.
The finished metal frameworks fit well on the plaster models. The self-developed computer aided design and computer aided manufacture CAD-CAM system for RPD design and fabrication has completely independent intellectual property rights. It provides a new method of manufacturing metal RPD frameworks.
Microbiological analysis of biomaterial surface in dental prosthesis showed the most common colonizing gram-positive species to be S. The highest concentration of C. Impact of implant support on mandibular free-end base removable partial denture : theoretical study. This study investigated the impact of implant support on the development of shear force and bending moment in mandibular free-end base removable partial dentures RPDs.
Three theoretical test models of unilateral mandibular free-end base RPDs were constructed to represent the base of tooth replacement, as follows: Model 1: first and second molars M1 and M2 ; Model 2: second premolar P2 , M1, and M2; and Model 3: first premolar P1 , P2, M1, and M2. The implant support located either at M1 or M2 sites. The occlusal loading was concentrated at each replacement tooth to calculate the stress resultants developed in the RPD models using the free-body diagrams of shear force and bending moment.
There was a trend of reduction in the peak shear force and bending moment when the base was supported by implant. However, the degree of reduction varied with the location of implant support. The shear forces and bending moments subjected to mandibular free-end base RPDs were found to decrease with the addition of implant support. However, the impact of implant support varied with the location of implant in this theoretical study. Numerical simulation of the casting process of titanium removable partial denture frameworks.
The objective of this work was to study the filling incompleteness and porosity defects in titanium removal partial denture frameworks by means of numerical simulation. Two frameworks, one for lower jaw and one for upper jaw, were chosen according to dentists' recommendation to be simulated. Both mold filling and solidification of the castings with different sprue designs e.
The shrinkage porosity was quantitatively predicted by a feeding criterion, the potential filling defect and gas pore sensitivity were estimated based on the filling and solidification results. A satisfactory sprue design with process parameters was finally recommended for real casting trials four replica for each frameworks.
All the frameworks were successfully cast. Through X-ray radiographic inspections it was found that all the castings were acceptably sound except for only one case in which gas bubbles were detected in the grasp region of the frame. It is concluded that numerical simulation aids to achieve understanding of the casting process and defect formation in titanium frameworks, hence to minimize the risk of producing defect casting by improving the sprue design and process parameters.
Recent advances in dental titanium casting machines allow for the use of titanium for crowns, fixed partial dentures By the end of the s, titanium found a niche in dental implantology In the field of dental implantology , evidence suggests that metal corrosion and allergenicity may be important. Finite element analysis of an implant-assisted removable partial denture. Standard RPDs are not originally designed to accommodate a posterior implant load point.
The null hypothesis is that the introduction of posteriorly placed implants into an RPD has no effect on the load distribution. A Faro Arm scan was used to extract the geometrical data of a human partially edentulous mandible. A standard plus regular neck 4. The model incorporated an RPD and was loaded with a bilateral force of N. FEA identified that the metal framework developed high strain patterns on the major and minor connectors, and the acrylic was subjected to deformation, which could lead to acrylic fractures.
The ideal position of the neutral axis was calculated to be 0. A potentially destructive mismatch of strain distribution was identified between the acrylic and metal framework, which could be a factor in the failure of the acrylic. The metal framework showed high strain patterns on the major and minor connectors around the teeth, while the implant components transferred the load directly to the acrylic.
The aim of this study was to evaluate the effectiveness of team-based learning TBL methodology on dental students' retention of knowledge regarding removable partial denture RPD treatment. The process of learning RPD treatment requires that students first acquire foundational knowledge and then use critical thinking skills to apply that knowledge to a variety of clinical situations. The traditional approach to teaching, characterized by a reliance on lectures, is not the most effective method for learning clinical applications.
To address the limitations of that approach, the teaching methodology of the RPD preclinical course at the University of Florida was changed to TBL, which has been shown to motivate student learning and improve clinical performance. A written examination was constructed to compare the impact of TBL with that of traditional teaching regarding students' retention of knowledge and their ability to evaluate, diagnose, and treatment plan a partially edentulous patient with an RPD prosthesis.
Students taught using traditional and TBL methods took the same examination. The mean score for the TBL class 0. The results of the study suggest that TBL methodology is a promising approach to teaching RPD with successful outcomes. Comparative study of circumferential clasp retention force for titanium and cobalt-chromium removable partial dentures.
The interest in using titanium to fabricate removable partial denture RPD frameworks has increased, but there are few studies to support its use. Each group was divided into 2 subgroups, corresponding to. No polishing procedures were performed to ensure uniformity.
Only nodules and burs were carefully removed with tungsten burs under magnification when necessary. With ever-growing aging population and demand for denture treatments, pressure-induced mucosa lesion and residual ridge resorption remain main sources of clinical complications. Conventional denture design and fabrication are challenged for its labor and experience intensity, urgently necessitating an automatic procedure.
This study aims to develop a fully automatic procedure enabling shape optimization and additive manufacturing of removable partial dentures RPD , to maximize the uniformity of contact pressure distribution on the mucosa, thereby reducing associated clinical complications. A 3D heterogeneous finite element FE model was constructed from CT scan, and the critical tissue of mucosa was modeled as a hyperelastic material from in vivo clinical data.
A contact shape optimization algorithm was developed based on the bi-directional evolutionary structural optimization BESO technique. Both initial and optimized dentures were prototyped by 3D printing technology and evaluated with in vitro tests. In vitro tests verified the effectiveness of this procedure, and the hydrostatic pressure induced in the mucosa is well below clinical pressure-pain thresholds PPT , potentially lessening risk of residual ridge resorption.
The integration of digitalized modeling, computational optimization, and free-form fabrication enables more efficient clinical adaptation. An analytical model to design circumferential clasps for laser-sintered removable partial dentures. Clasps of removable partial dentures RPDs often suffer from plastic deformation and failure by fatigue; a common complication of RPDs.
A new technology for processing metal frameworks for dental prostheses based on laser-sintering, which allows for precise fabrication of clasp geometry, has been recently developed. This study sought to propose a novel method for designing circumferential clasps for laser-sintered RPDs to avoid plastic deformation or fatigue failure.
An analytical model for designing clasps with semicircular cross-sections was derived based on mechanics. The Euler-Bernoulli elastic curved beam theory and Castigliano's energy method were used to relate the stress and undercut with the clasp length, cross-sectional radius, alloy properties, tooth type, and retention force.
Finite element analysis FEA was conducted on a case study and the resultant tensile stress and undercut were compared with the analytical model predictions. Pull-out experiments were conducted on laser-sintered cobalt-chromium Co-Cr dental prostheses to validate the analytical model results. The proposed circumferential clasp design model yields results in good agreement with FEA and experiments.
The results indicate that Co-Cr circumferential clasps in molars that are 13mm long engaging undercuts of 0. However, shorter circumferential clasps such as those in premolars present high stresses and cannot avoid plastic deformation or fatigue failure.
Laser-sintered Co-Cr circumferential clasps in molars are safe, whereas they are susceptible to failure in premolars. Effect of different cleansers on the surface of removable partial denture. Removable partial dentures RPD demand specific hygienic cleaning and the combination of brushing with immersion in chemical solutions has been the most recommended method for control of biofilm.
However, the effect of the cleansers on metallic components has not been widely investigated. This study evaluated the effect of different cleansers on the surface of RPD. The surface changes and tarnishes were examined with a scanning electronic microscopy SEM. In addition, energy dispersive x-ray spectrometry EDS analysis was carried out at representative areas. EDS analysis revealed the presence of oxygen for specimens in contact with both MI and NaOCl solutions, which might suggest that the two solutions promoted the oxidation of the surfaces, thus leading to spot corrosion.
A critical review of selected relevant publications assessed clinical efficacy and effectiveness of implant-assisted removable partial dentures IARPDs with implant survival and failure rates, biologic and technical complications, and maintenance and patient satisfaction after rehabilitation as outcomes. Reports on outcomes from human studies conducted between 1 January and 31 May were considered. A quality assessment of the identified full-text articles was performed to assess risk of bias and to evaluate heterogeneity.
Only nine studies were included, and all nine demonstrated high risk of bias. The mean observation period ranged from 1 to 10 years, and only four studies included at least one control group. The studies reported implant survival rates of IARPDs were associated with a higher frequency of technical complications and maintenance interventions than biologic complications.
Only two question-based studies assessed patient satisfaction before and after treatment, and both reported marked improvement. A meta-analysis was not possible because of substantial heterogeneity in study design. Limited availability of robust publications related to the selected review topic precluded significant conclusions. Nonetheless, the preliminary assessment suggests that IARPDs are a simple and cost-effective approach to providing symmetric prosthesis support and stability, plus improved patient satisfaction.
Why do dentists struggle with removable partial denture design? An assessment of financial and educational issues. Published studies in the international dental literature illustrate that the quality of prescription and fabrication of cobalt-chromium removable partial dentures CCRPDs by general dental practitioners frequently fail to comply with ethical and legal requirements. The reasons cited for this in the past have broadly related to either financial or educational issues.
The aim of this investigation is to determine the effect of financial and educational factors on the quality of CCRPD design and fabrication by general dental practitioners. This investigation was completed in two parts. These sought information relating to the quality of written instructions for CCRPDs received by these laboratories, and details of the remunerative scheme under which they were being provided. This sought information relating to their attitudes, opinions, and educational and clinical experiences of CCRPD design and fabrication.
One-fifth of respondents n. Managing the maxillary partially edentulous patient with extensive anterior tooth loss and advanced periodontal disease using a removable partial denture : a clinical report. The treatment modality, a continuous occlusal rest removable partial denture , not only restored missing teeth but also stabilized the remaining dentition in a patient with advanced periodontal attachment loss.
By engaging the guiding planes at the mesial surfaces of the abutments anteriorly and also the distal surfaces of the abutments posteriorly, the remaining teeth, with varying amounts of mobility, were splinted together by the framework. This conservative treatment option allows flexibility for easy repair during the life span of the prosthesis. Consecutive patients with shortened dental arches were recruited from the Department of Prosthodontics, Foshan Chancheng Hospital of Stomatology.
The Chinese version of OHIP was administered to each subject before treatment and after treatment. The subjective outcomes of removable partial dentures therapy on SDA were collected and the pre- and post-treatment scores of the Chinese version of OHIP were compared. The main impacts of shortened dental arch with intact anterior region affecting patients' OHRQOL are physical disability.
Composite resin root coping with a keeper for magnetic attachment for replacing the missing coronal portion of a removable partial denture abutment. Numerous methods for replacing missing removable partial denture abutments have been introduced, however, most of them are time consuming and require several visits to complete the procedure.
Since magnetic attachments can provide support and bracing as well as retention for overdenture abutments, the remaining tooth root structure can be used to support the coping with the keeper. Through the use of composite resin and adhesive material, improved retention of the keeper to the root may be achieved, along with improved esthetics.
This article describes a method for replacing the missing abutment of a removable partial denture with a magnetic attachment, and a composite resin coping with a keeper. Management of long span partially edentulous maxilla with fixed removable denture prosthesis. Restoration of a long span partially edentulous maxilla with tooth supported prosthesis is challenging because of inherent anatomic limitations and unfavourable biomechanics present after the loss of teeth. A tooth supported fixed- removable prosthesis is a treatment option for restoration of such long span partially edentulous maxillary arches.
This prosthesis meets the requirements for esthetics, phonetics, comfort, and hygiene, as well as favourable biomechanical stress distribution to the remaining natural tooth abutments. This article presents a procedure for fabrication of a fixed- removable prosthesis that has cement-retained custom cast bar metal substructure and a ball attachment retained removable superstructure prosthesis. Maxillary rehabilitation using a removable partial denture with attachments in a cleft lip and palate patient: a clinical report.
CLP patients often need multidisciplinary treatment to restore oral function and esthetics. This paper describes the oral rehabilitation of a CLP adult patient who had maxillary bone and tooth loss, resulting in decreased occlusal vertical dimension.
Functional and cosmetic rehabilitation was achieved using a maxillary removable partial denture RPD attached to telescopic crowns. The influence of removable partial dentures on the periodontal health of abutment and non-abutment teeth. The aim of this study was to evaluate the influence of removable partial dentures RPD on the periodontal health of abutment and non-abutment teeth. A total patients with RPD participated in this study. These clinical measurements were taken immediately before insertion the RPD, then one and 3 months after insertion.
The level of significance was set at P 0. With carefully planned prosthetic treatment and adequate maintenance of the oral and denture hygiene, we can prevent the periodontal diseases. Microbiological and clinical assessment of the abutment and non-abutment teeth of partial removable denture wearers.
The aim of this study was assessing the changes in both clinical and microbiological parameters of healthy individuals after rehabilitation with removable partial denture RPD. Clinical and microbiological parameters of abutment, non-abutment, and antagonist teeth were assessed at baseline RPD installation and after 7, 30, 90, and days of function. The Checkerboard DNA-DNA hybridization technique was used to identify and quantify up to 43 different microbial species from subgingival biofilm samples.
Probing depth, gingival recession, and bleeding on probing were also investigated over time. The total and individual microbial genome counts were shown significantly increased after days with no significant differences between abutment, non-abutment, or antagonist teeth. Streptococcus spp. Abutment teeth presented higher values of gingival recession when compared with non-abutment or antagonist teeth, irrespectively time of sampling p denture loading for both abutment and non-abutment teeth with no significant differences regarding the microbial profile over time.
Bleeding on probing and probing depth showed no significant difference between groups over time whereas gingival recession increased in the abutment teeth. Objective: The aim of this study was to evaluate the influence of removable partial dentures RPD on the periodontal health of abutment and non-abutment teeth.
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