bluuebunny/crossref_metadata_2025 huggingface dataset:
Breaking the Barriers—The Integrated Asset Model
Authors: Tesaker Øystein , Øverland Alf Midtbø , Arnesen Dag , Zangl Georg , Al-Kinani Andreas , Torrens Richard , Bailey William , Couët Benoît , Pecher Radek , Rodriquez Nelson
Published: February 2008

The objective of this paper is to highlight the necessary steps for the successful use of integrated asset modeling. It presents the full workflow for optimzing production and injection cycle times with the help of a simplified reservoir model (SRM) through the set up of an integrated asset model (IAM) to validate the SRM results and control the actual production performance.

A discusson of the theory of the IAM as well as the steps to set up a SRM and IAM are presented in this paper. The steps are described in context of an actual field operation. A WAG cycle optimization workflow for the Snorre field has been created to demonstrate the advantages of using the SRM and IAM technology. The optimization process is performed using a SRM able to run a simulation run in a matter of minutes and hence being suitable for sensitivity analysis and optimization. The optimized WAG injection and production cycle is then carried forward to an IAM in order to accurately determine the well performance and the reservoir production. The IAM couples the modeling results from reservoir and well model with the surface facility network and process plant model. The coupling and integration allows investigating the impact of changes in one model to all the other models and hence also handles the proper propagation of constraints throughout the system.
Valuation Models for Intelligent Strategies
Authors: Govia Delfina , Carpenter Kevin
Published: February 2008

There is intrinsic value in the application of intelligent strategies. Pockets of "value" have been calculated in isolated situations. Yet the resistance to change has created a strong barrier to execution. Robust models for valuing intelligent strategies do not appear to be prominent. At the Digital Energy Conference in Houston in April, several presenters from large oil companies publicly admitted to not having a process in place to quantify the results of their efforts. This paper seeks to provide suggested models to pave the path forward.

This paper will especially highlight the critical success factors for effective valuation: ➢Valuation that supports integrated decision management➢Valuation that takes into account uncertainties➢Valuation that clearly models risk vs. reward➢Valuation that speaks to the organizations multiple levels of stakeholders (Executive/ Investor, Mid-level management, Field Operators)
Real Time Optimisation Approach for 15,000 ESP Wells
Authors: Zdolnik Sergey , Pashali Alexander , Markelov Dmitry , Voklov Maksim
Published: February 2008

In Rosneft Oil Company 90% of production is provided by 15 000 ESP wells. That is why monitoring and efficiency increasing of those wells are of current importance. Up to recent time, analysis and optimisation were done regularly on monthly basis, while real time monitoring systems were oriented mainly to keep books of oil production.

In our opinion implementation of real time monitoring and control systems and reducing analysis and optimisation cycle to days may increase production by the means of rate increase and downtime reduction.

Research in this area started in Rosneft in late 2006 in the framework of New Technologies System. Currently there are solutions for data gathering and proceeding, worked out information use in business processes, has practice in production increase and well downtime reduction, started company-wide application of system.

Paper includes cases of well regime analysis done with the described system.

An important question of quantative evaluation of system applicability for certain conditions was examined. This paper may help to take decision on application of this type of systems for other companies.
Drilling Better Wells Cheaper and Faster
Authors: Brooks Robin , Wilson John
Published: February 2008

The control of a drill in realtime is demanding on the skills and experience of the drill operator and is variable across operating shifts because different operators have different levels of skill and experience. A mathematical model that could be shared by operators would eliminate this variability but few, if any, exist because of the mathematical difficulty and considerable expense of creating such a model in the first place and then of updating it as geology and hole depth and the type of drilling changes.

This paper describes and demonstrates a radically different approach and a solution to the problem by modelling the operating envelope of the drill operation as a multi-dimensional solid object so that the operating problem becomes a geometric problem of operating always as an interior point of the envelope. The beauty of this approach is that the model developers and maintainers do not need any mathematical knowledge or the ability to describe problems with algebraic or differential equations. The method is able to create models of high dimensionality using the original process variables only so is easily understood and accepted. It is well-placed for realtime exploitation of the increasing number of down-hole measurements. The geometric basis of the model makes the operating advice that it generates intrinsically safe. A realtime operator guidance model will be developed and shown during the presentation to show the concepts, mechanics and possibilities of the method.

The method is part of the overall technology known as Geometric Process Control (GPC) which is becoming well-established in downstream process industries and has already achieved success in problem-solving and offshore process improvement applications with several major North Sea operators. It has won awards for Innovation from EPSC, IChemE, IET and the CIA (Chemical Industries Association).
Alto do Rodrigues GeDIg Pilot—Case Study for Continuous Steam Injection Recovery Combined with Real-Time Operation
Authors: Lacerda G. M. , Patriota J. H. , Pereira J. I. , Torres J. S. , de Lima L. A.
Published: February 2008

Alto do Rodrigues (ARG) is an onshore heavy oil brownfield with continuous steam injection recovery located in the Rio Grande do Norte and Ceara Business Unit in the Northeast of Brazil and it was chosen as a pilot in Petrobras corporative program for Digital Integrated Field Management - GeDIg.

The ARG pilot consists of on-line monitoring of bullhead temperature of producers and injector of five spot networks connected with steam facilities measurements such as pressure and steam quality. The real time operation is combined with two collaborative environments integrated with SOLAR, an in-house development collaboration software.

Reservoir heterogenerity analysis like steam channeling is provided when steam generators parameters, well instrumentation, and historical data are combined in new workflow processes of steam analysis. Change management associated to process mapping guided the pilot implementation to minimize the side-effects of new process absorption.

The objective of this paper is to present the methodology and results from Digital Integrated Field Management in the onshore heavy oil brownfield of Alto do Rodrigues.
Application of Intelligent Well Completion for Controlled Dumpflood in West Kuwait
Authors: Rawding J. , Al Matar B. S. , Konopczynski M. R.
Published: February 2008

This paper describes the philosophy and design of an intelligent well installation in a water dumpflood well in Kuwait and analysis of data gathered. The paper examines the reservoir management capabilities of intelligent wells can lead to significant value in terms of reservoir management in this application.

Dumpflooding, the method by which fluids from one formation are allowed to flow into another formation, has been used for several years in Kuwait as a means of providing reservoir pressure support. Typically, a well is drilled to penetrate both a prolific aquifer and a producing oil reservoir. Under the right conditions, with a higher pressure aquifer, significant quantities of water flow from the aquifer to the oil reservoir.

As production from the oil reservoirs matures, this uncontrolled method of pressure support has led to several reservoir management challenges, including difficulties with flood front control, water breakthrough, conformance management, and inability to quantify the crossflow rate in each well. With declining oil reservoir pressure, the pressure differential between the aquifer and the oil reservoir has increased, leading to destabilization of the aquifer reservoir clastic matrix from excessive drawdown and high flow rates during perforating operations.

In early 2007, a West Kuwait well was completed as a controlled dumpflood well utilizing intelligent well technology. Water from the Zubair aquifer formation flows to the Minagish Oolite oil formation in a controlled and monitored dumpflood process. Utilizing a variable interval control valve, the amount of injection fluid is regulated, while permanent downhole monitoring devices transmit pressure data to surface, enabling evaluation of the flow rate. The intelligent well also permits "soft starts" of the dumplood to avoid borehole destabilization.

The methods described in the paper may be considered for improved reservoir management on a field wide basis wherever dumpflooding is used for pressure maintenance.
Reservoir Surveillance, Production Optimisation and Smart Workflows for Smart Fields—A Guide for Developing and Implementing Reservoir Management Philosophies and Operating Guidelines in Next Generation Fields
Authors: Konopczynski M. R. , Ajayi A.
Published: February 2008

Many oil and gas companies are joining the wave of forward looking operators implementing intelligent well and smart field technologies to improve their ability to optimise production, minimize expenses, and improve reserve recovery. Much has been written about the application of these technologies and steps to successful installation of the hardware. But the real value of intelligent wells and smart field systems come from the ongoing exploitation of the new technology in day to day operations. This paper compares the methods of reservoir surveillance and production optimisation in the "old world" to those of the next generation intelligent fields. Successful exploitation of the new technologies requires an understanding of information flow, control and automation capabilities, knowledge management, interpersonal communications, and decision processes to develop performance indicators, workflows, philosophies and protocols suitable for the fields of the future.

Three core elements are explored in the intelligent field workflow: the reservoir management philosophy, the production surveillance capabilities, and the operating guidelines. The requisite components of these elements are reviewed in the context of intelligent field capabilities. The concept of intelligent well and intelligent field optimization is explored examining the most recent developments in proxy modeling and feed-forward control technologies applied to well and reservoir management.

The value of these new optimisation tools will come not just from fine tuning of steady state conditions, but more likely from being able to react quickly to changes in operating conditions, whether reservoir, well or facilities related, to find optimum production solutions in near real time.

The concepts discussed in this paper are applicable to all intelligent well and smart field applications, particularly to those planning to implement "real-time" reservoir optimisation strategies. The information presented will provide a roadmap for the development of these strategies and protocols in the context of the smart field environment.
Rapid Model Updating with Right-Time Data—Ensuring Models Remain Evergreen for Improved Reservoir Management
Authors: Webb Stephen J. , Revus David E. , Myhre Angela M. , Goodwin Nigel H. , Neil K. , Dunlop B. , Heritage John R.
Published: February 2008

History matching reservoir models to production data has been a challenge for asset teams since the early days of reservoir simulation. Keeping these models evergreen as production data continues to arrive, knowing when a re-history match is required and being able to re-history match easily and efficiently is also a major challenge which is often not addressed in a timely manner. This need is becoming even more pressing as real-time reservoir performance data is increasingly available. Decisions can now be made with the support of the good quality real-time data from the reservoir usually in the form of pressure data from downhole gauges and rate data from multiphase meters.

With the recent integration of existing technologies, a rapid model updating workflow is now possible. The history matching workflow that was once a discrete process can now be a computer assisted continuous process. Using statistically-based assisted history-matching technology in conjunction with real-time data acquisition, data monitoring, and reservoir simulation software, new production data can be quickly assimilated into the reservoir model. Real-time data from the field measurement devices is filtered for consumption by the reservoir modeling software and compared with the forecasts from the reservoir simulator to determine if re-history matching is required. The new data can be added to the history file and the model (revised if necessary) can be used in operational performance optimization.

This rapid model updating workflow can be run semi-automatically on a continuous basis as new production data is gathered, thereby keeping reservoir models evergreen and providing the most up-to-date basis for the making of important reservoir management decisions.
Tap into the "Creativity of the Crowd"!
Authors: Paylow K. , Guidry A. , Braley N.
Published: February 2008

Many papers inside and outside our industry have discussed tapping into the ‘wisdom of the crowd' to meet organizational needs. Many papers have also discussed the need – and methods – to innovate. So perhaps we need to ask ourselves how we can tap into the ‘creativity of the crowd' to better understand what needs to change, identify opportunities for improvement or new market spaces to explore, share technologies across disciplines and industries and attract new types of talent.

Cultivating and supporting innovation can be a significant challenge within any organization. Empowering people to generate new ideas should be a part of successful business organization. One should be mindful that innovation knows no boundaries and can happen for anyone at anytime. This becomes apparent within each of us when we ask "What if…?"

There are several challenges in capturing these innovative thoughts in the proper context and putting them in front of the appropriate audience. This includes creating a mechanism for stakeholders to share their ideas, a process for management review and monitor submissions, the ability to bounce ideas off the ‘wisdom of the crowd' and tools to connect the R&D effort to stakeholders throughout the development process.

We have addressed this challenge through the creation of an IDEA system and using existing knowledge management tools to affect the development and commercialization process. The approach allows the entry and tracking of submissions through the process while maintaining intellectual property security.

This paper discusses cases where these new tools and processes effectively managed and nurtured innovation within and between product service lines. Typical barriers that have hindered end users from sharing innovative ideas will be highlighted along with solution measures utilized. Finally, areas of future exploration related to the effort will be identified.
Real-time Access to Expertise: Improving decision making and collaboration through unified communications
Authors: Munro Michael
Published: February 2008

The days of easy oil have gone. It is harder and harder to replace world oil reserves, requiring all the skills possible to find and extract hydrocarbons. Now, more than ever, decision making is critical to the success of exploration and production. And decisions made by experienced people who understand the complexities of each situation, colored by their years of activity and exposure to global conditions are the best suited for making those decisions. The expertise that they bring, coupled with a nuanced view of their current environment allows them to make better decisions, bringing reserves online faster with less cost, and improves ultimate field efficiency.

But the people with the best skills and experience, the ones that can best make those decisions at the point of activity are becoming scarce. Additionally, an expertise gap exists between the experienced workers who are getting ready to retire and new workers the industry has hired. This gap, plus shortages of rigs and crews to support the rigs are requiring new ways to staff them, a way to "virtualize" the expertise by placing them in centralized operations centers and have them support multiple physical operations.

So this brings us to the overarching question: "How do we connect the experts to the problem, provide them with complete awareness of the remote environment, and let them collaborate and share information in real-time with those who need that expertise?"

The answer to this lies in the ability to create a platform of connectivity that enables you to bring the problem to the expert, provides a complete picture of the context of the situation, and ensures seamless collaboration between participants regardless of their location. We call this platform, Unified Communication…the ability to transform the collaboration experience and provide real-time access to expertise.

This paper will explore that capability and provide examples of how exploration and production companies are leveraging convergence in communications to allow data voice and video collaboration between experts and explore the value that it brings. Specifically: Improving ad-hoc interaction by identifying expertise in real-time, connecting with them in the context of the operational workflowExtending transactions to interactions to allow transformation of workflows that have person-to-person collaboration inherent to their performanceIntroducing real-time decision making and new business models by leveraging this new platform of communication and collaboration

This paper will include various case examples of where exploration and production companies are creating these experiences, as well as examples from other relevant industries.
Decision Support System for Economic Analysis of E&P Projects under Uncertainties
Authors: Túpac Y. J. , Lazo J. G. , Faletti L. , Pacheco M. A. , Vellasco M. M. B. R.
Published: February 2008

This work presents the conception, modeling and development of an E&P projects economical analysis system under uncertainty that integrates the following modules: –an optimization hybrid system for oilfields development based in evolutionary algorithms with distributed evaluation, proxies and use of quality maps to optimize the place and quantity of wells in a delimited petroleum field to maximizing the NPV of the alternative. Also, this system considers some technical constrains as the minimum wells distance and maximum wells trajectory.–a model based on Genetic Algorithms and Monte Carlo simulation designed to find an optimal decision rule for some oil field development alternatives obtained from previous module, considering market uncertainty (oil price), that may help decision-making with regard to: developing a field immediately or waiting until more favorable market conditions.

In the economic analysis also is considered, for each alternative under evaluating, the option of investment in information taking in account interactions of different uncertainties types. This analysis considers the option of future production expansion by installing an additional well under reserve volume uncertainties in the in the area to be drained by the additional well.

Some computational intelligence techniques were applied in this system as: evolutionary algorithms, neural networks and fuzzy numbers; also, the system uses other techniques as Real Options and Monte Carlo Simulation to treat uncertainties.

The obtained outcomes show the benefits to have an integrated decision support system to the decision-making in the economic analysis of oilfields development.
Semantic Web Technologies for Smart Oil Field Applications
Authors: Soma Ramakrishna , Bakshi Amol , Prasanna Viktor , DaSie William J. , Bourgeois Birlie
Published: February 2008

In model based oil field operations, engineers rely on simulations (and hence simulation models) to make important operational decisions on a daily basis. Three problems that are commonly encountered in such operations are: on-demand access to information, integrated view of information and knowledge management. The first two problems of on-demand access and information integration arise because a large number of, and different kinds of simulation models, each modeling a different facet of the oil-field, are used. An engineer is generally an expert in one aspect of oil-field modeling and trained to use a few tools; therefore, accessing information captured in models that do not lie in an engineer's area of expertise is not easy. Moreover, since these models are created by different processes and people, the same information is represented differently across models. A unified view of the models and their simulations is desirable for decision making, and thus the necessity for information integration. In the third problem- knowledge management problem, we address the situation in which an engineer performs many analyses before making a decision. A systematic way to capture the rationale (knowledge) behind the various decisions is needed for audit tracking purposes as well as for future references. We examine the application of semantic web technologies to address these three problems, present a prototype implementation which addresses them and provide an evaluation of the technology.
A Framework for Design Space Exploration in Oilfield Asset Development
Authors: Zhang Cong , Bakshi Amol , Prasanna Viktor , Da Sie Will , Bourgeois Birlie
Published: February 2008

Design space exploration (DSE) is a common yet complex workflow in oilfield asset development. The "design" of an oilfield refers to a set of decisions about aspects ranging from well locations and number to facility sizing for optimum production. Evaluation of alternate designs – based extensively on reservoir simulations – corresponds to the evaluation of alternate development scenarios in face of uncertainty about subsurface structure and properties. The outputs of DSE influence many decisions in the development phase of an oilfield as well as operational decisions in a producing asset. In this work, we design and implement a generic framework to support DSE workflows in oilfield asset development. Our framework provides tools and services to allow rapid specification and evaluation of multiple design candidates using multiple realizations. The framework also supports hierarchical DSE workflows that allow users to first explore a large design space using proxy models and selectively refine the simulation quality of a smaller subset of designs via fine grained, detailed simulations. The usefulness of this framework is demonstrated through a case study that considers the design problem of selecting a drilling schedule for wells in an offshore oil and gas field.
IT Security and Architecture for Integrated Operations: Examples from deliveries to Ormen Lange and Draugen
Authors: Aarset Marius F. , Mo Olav
Published: February 2008

The introduction of Integrated Operations causes a demand for integrating process control systems with office systems. A secure and reliable connection between these systems enables considerable cost savings related to: Process OptimizationMaintenanceCollaborationRemote support

Shell operates two oil fields on the Norwegian Continental Shelf; Draugen and Ormen Lange. Draugen is an established oilfield having been in operation since 1993. Ormen Lange is a new gas-field based on subsea installations remotely operated from an onshore process plant.

In implementation of a technological basis for IT Architecture and Security supporting Integrated Operations, certain products and services are essential for achieving the ambitious expectations. The technological basis may be separated in three fundamental areas: Establishment of plant Security Policies, a management tool for establishing plant security.Design of a Plant Network, which will facilitate communication between the office and process control networks, and communication with other subsystem networks.Implementation of Remote Services, a solution for a secure connection between the Plant Network and the office network.

IT security is a major issue when integrating office systems with process control systems. Corporate, national and international standards must be adhered to, and good technical and procedural solutions must be developed. The technological nature of the underlying process control systems must be addressed when an architecture for integration is created.

Both Draugen and Ormen Lange have recently been designed to facilitate Integrated Operations according to Shell requirements, integrating information from various subsystems and making real-time data available in Shell's newly developed collaboration centre in Kristiansund, Norway. The collaboration centre will provide operational support to Draugen and Ormen Lange, and is part of a collaboration network in Shell Europe. Remote services are established enabling remote access towards vendor support centers, as the ABB remote operations rooms for Ormen Lang and Draugen.
The Use of Integrated Operations in Order to Improve Quality of Health Care and Medical Evacuations from Offshore Installations
Authors: Evensen Arne M. C. , Fjærtoft Inger
Published: February 2008

Since the early 1970s, thousands of patients offshore have been treated on board by our medical staff, in cooperation with our on-call onshore doctors. Several hundred patients have been evacuated to hospitals due to acute illness and serious injuries. Our present standards will be described, as will our perspectives on the future treatment of, for instance, acute cardiac disease and pre-hospital diagnosis through the transfer of electrocardiograms (ECG) and the use of telemedicine to obtain a medical diagnosis directly from the receiving hospital's emergency care unit.

Norwegian regulations require nurses to be present on all installations, with doctors available on call onshore. Compared with ordinary nurses onshore, offshore nurses have wider responsibilities in normal diagnostic consultations and in emergency situations. Today, doctors and nurses discuss specific patients and cases by telephone, and they exchange photos.

We wanted to use our experiences from integrated operations (IO) and from telemedicine to improve the offshore health care services, in order to provide better quality and integration of the people and organisations involved.

Together with the NST (Norwegian Centre for Telemedicine), we studied the possibility of providing medical advice and support through the use of Telemedicine. Valuable experiences from Telemedicine projects, such as expert opinions in training and diagnosis, and follow-up of patients in rural areas and surgery, were collected.

The use of IO for training, diagnostics and emergency situations will improve communication and cooperation between nurses offshore and doctors onshore. It may also enable advice to be given through video conferencing.

The NST conducted a risk assessment of these new work processes, with special attention being devoted to the electronic transfer of sensitive information (photos/videos and other personal health data). Thirty threats were identified. None of them had an unacceptable risk level given the recommended solutions and the information management system applied. No corrective actions need to be taken, but some small changes in the procedures were suggested in order to reduce risks related to confidentiality, integrity and availability.

We have recently started pilot projects on several platforms involving the extensive use of videoconferencing and sharing of real-time data. The equipment supports direct communication between the patient and nurse on the offshore installation and the doctor or hospital onshore.

The results of the pilot tests will be presented, as will perspectives on future development and the relevance of the risk assessment.
Management of Ectopic Maxillary Canines
Authors: Bjerklin Krister , Bondemark Lars
Published: February 2008

Objective: To document and analyze factors involved in decision-making by orthodontists in managing disturbances of eruption of maxillary canines.

Materials and Methods: The participants comprised orthodontic specialists and active members of the Swedish Orthodontic Society. Those selected for the study sample were under 65 years of age or younger and had been treating orthodontic patients for at least 1 year as a specialist. Three typical cases were presented for treatment proposals. The case notes, including radiographs and specific background data, were sent to the 182 selected orthodontists. The orthodontists were also requested to complete a questionnaire about practice profile, comprising eight questions.

Results: The response rate was 86.3%; yielding 157 participants (mean age 53.8 years, SD 8.12). Analysis disclosed no differences between responders and nonresponders regarding age, gender, and years of specialist practice. For treatment plans based on panoramic radiographs, intraoral radiographs, and status and anamnesis, there was general consensus. However, when supplementary information from computer tomography (CT) was provided, disclosing root resorption half-way to the pulp or more on the lateral incisor, the orthodontists' treatment proposals varied. Gender, age, and practice profile of the orthodontists had little association with the decision-making.

Conclusions: Supplementary CT information led to variations in decision-making with respect to treatment of eruption disturbances of maxillary canines. This lack of consensus among specialist orthodontists can have negative implications for patients.
Masseter Muscular Weakness Affects Temporomandibular Synovitis Induced by Jaw Opening in Growing Rats
Authors: Ozaki Miho , Kaneko Sawa , Soma Kunimichi
Published: February 2008

Objective: To evaluate the influence of impaired masseter function during growth on the development of temporomandibular synovitis.

Materials and Methods: Sixteen 3-week-old male Wistar rats were classified into four groups. The first group served as control; and in the second group, jaw opening was forced for 3 hours when the rats were 9 weeks old. In the third and fourth groups, the masseter muscles were bilaterally resected at 3 weeks of age, and the rats in the fourth group were additionally forced to open their jaw at 9 weeks of age. All rats were sacrificed at 9 weeks. Temporomandibular joint (TMJ) tissue samples were processed for histology, and evaluated for cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expressions by immunohistochemistry to examine the inflammatory changes in the synovial membrane.

Results: The control group showed noninflammatory changes. In the jaw-opening group, vascular dilation and weak COX-2 immunoreactivity were induced by jaw opening in the synovium. In the masseter-resection group, the masseter-resected rats exhibited moderate synovial changes while in the resection with opening group, the masseter-resected rats revealed more significant inflammatory changes including synovial hyperplasia, dilated vasculature, fibrin deposits, and intense immunoreactivity for COX-2 and iNOS, all caused by jaw opening.

Conclusions: These results suggest that masseter activity in the growth period is an important factor in the induction of temporomandibular synovitis.
Cytotoxicity of Two Autopolymerized Acrylic Resins Used in Orthodontics
Authors: Siqueira Gonçalves Tatiana , Minghelli Schmitt Virgínia , Thomas Melissa , Lopes de Souza Maria Antonieta , Macedo de Menezes Luciane
Published: February 2008

Objective: To test in vitro the null hypothesis that the toxic effect of different acrylic resins used in orthodontics cannot be reduced when a prior elution is performed.

Materials and Methods: Three established cell lines were used (HeLa, NIH3T3, and Hep2) and cultured under standard conditions. Resin segments were immersed in a culture medium and left to elute for 24 and 48 hours. Cells were exposed to medium containing eluates for 24 or 48 hours. The 3-(4,5 dimethyl-2-thiazolyl)-2.5-diphenyl-2H-tetrazolium bromide (MTT) assay was used as the cytotoxicity test. Control cells contained standard medium with no eluate. Analysis of variance and Tukey test were used for statistical analysis.

Results: Fibroblastic viability was not affected when the elution time was 24 hours, but treatments showed higher cell viability than controls when the elution time was 48 hours. When left to elute for 24 hours, both resins had a cytotoxic effect on epithelial cells, but this effect was not observed when the elution time was 48 hours.

Conclusions: The hypothesis was rejected as both tested materials showed lower cytotoxic effect when treated with 48-hour elutes compared with 24-hour elutes, which indicates that a longer elution time reduces resin toxicity.
Different Lingual Retainer Composites and the Microleakage between Enamel-Composite and Wire-Composite Interfaces
Authors: Uysal Tancan , Ulker Mustafa , Baysal Asli , Usumez Serdar
Published: February 2008

Objective: To assess microleakage of enamel-composite and wire-composite interfaces when retainer wires were bonded with two orthodontic and a flowable composites.

Materials and Methods: Forty-five freshly extracted human mandibular canine teeth were used in this study. Teeth were separated into three groups of 15 teeth each. Round stainless-steel wire of 0.36-in. diameter in three groups was bonded to enamel by Transbond XT (3M Unitek), Transbond LR (3M Unitek), and Venus Flow (Heraeus Kulzer) composites. Specimens were further sealed with nail varnish, stained with 0.5% basic fuchsine for 24 hours, sectioned and examined under a stereomicroscope, and scored for microleakage for the enamel-composite and wire-composite interfaces from mesial and distal margins. Statistical analysis was performed by Kruskal-Wallis and Mann-Whitney U-tests.

Results: Little or no microleakage was determined at the mesial and distal sides for three composites in two different interfaces, and these findings were not statistically significant (P > .05). No statistically significant differences were observed among all composite groups for the microleakage with either of the interfaces. Venus Flow in the enamel-composite interface and Transbond LR in the wire-composite interface exhibited no microleakage.

Conclusion: The presence of wire in the mesial portion of the lingual retainer did not increase the microleakage at the enamel-composite and wire-composite interfaces in all groups. The microleakage results in this study support the use of all these composites in routine orthodontic practice.
Clinical Evaluation of Bracket Bonding Using Two Different Polymerization Sources
Authors: Koupis Nikolaos S. , Eliades Theodore , Athanasiou Athanasios E.
Published: February 2008

Objective: To comparatively assess clinical failure rate of brackets cured with two different photopolymerization sources after nine months of orthodontic treatment.

Materials and Methods: The sample of this study comprised 30 patients who received comprehensive orthodontic treatment by means of fixed appliances. Using the same adhesive, 600 stainless steel brackets were directly bonded and light cured for 10 seconds with the light-emitting diode (LED) lamp or for 20 seconds with the conventional halogen lamp. A split-mouth design randomly alternated from patient to patient was applied. Failure rates were recorded for nine months and analyzed with Pearson χ2 test, and log-rank test at α = .05 level of significance.

Results: The overall failure rate recorded with the halogen unit (3.33%) was not significantly different from the failure rate for the LED lamp (5.00%). Significantly more failures were found in boys compared with girls, in the mandibular dental arch compared with the maxillary arch, and in posterior segments compared with anterior segments. However, no significant difference was found between the right and left segments.

Conclusion: Both light-curing units showed sufficiently low bond failure rates. LED curing units are an advantageous alternative to conventional halogen sources in orthodontics because they enable a reduced chair-time bonding procedure without significantly affecting bond failure rate.
Glenoid Fossa Position in Class II Malocclusion Associated with Mandibular Retrusion
Authors: Giuntini Veronica , Toffol Laura De , Franchi Lorenzo , Baccetti Tiziano
Published: February 2008

Objective: To assess the position of the glenoid fossa in subjects with Class II malocclusion associated with mandibular retrusion and normal mandibular size in the mixed dentition.

Materials and Methods: A sample of 30 subjects (16 male, 14 female), age 9 years ± 6 months, with skeletal and dental Class II malocclusion associated with mandibular retrusion, normal skeletal vertical relationships, and normal mandibular dimensions, was compared with a matched group of 37 subjects (18 male, 19 female) with skeletal and dental Class I relationships. The comparisons between the Class II group and the control group on the cephalometric measures for the assessment of glenoid fossa position were performed by means of a nonparametric test for independent samples (Mann-Whitney U-test, P < .05).

Results: Subjects with Class II malocclusion presented with a significantly more distal position of the glenoid fossa, when compared with the control group as measured by means of three parameters (GF-S on FH, GF-Ptm on FH, and GF-FMN).

Conclusions: A posteriorly displaced glenoid fossa is a possible diagnostic feature of Class II malocclusion associated with mandibular retrusion. An effective cephalometric measurement to evaluate glenoid fossa position is the distance from the glenoid fossa to the frontomaxillonasal suture (GF-FMN).
Relative Esthetic Importance of Orthodontic and Color Abnormalities
Authors: Lawson Jessica , Warren John J. , Levy Steven M. , Broffitt Barbara , Bishara Samir E.
Published: February 2008

Objective: To assess the relative importance of an orthodontic esthetic index, dental fluorosis and nonfluoride opacities, with respect to parents' satisfaction with their children's dental esthetics.

Materials and Methods: Dental examinations of Iowa Fluoride Study participants assessed fluorosis and nonfluoride opacities in the mixed dentition. Dental casts of 200 randomly selected subjects were scored using the Dental Aesthetic Index (DAI) criteria. Parent satisfaction was assessed via multiple items on a questionnaire. Associations were evaluated using logistic regression.

Results: Nineteen percent of parents were somewhat or very dissatisfied with their children's dental esthetics. Overall DAI score was positively associated with dissatisfaction (P < .001), as was fluorosis (P = .003).

Conclusions: In addition to changes related to DAI scores, parent esthetic satisfaction decreased with the presence of fluorosis. Dental professionals should address both the issues of tooth positioning and color aberration with respect to dental esthetics.
Porcelain Refinishing with Two Different Polishing Systems after Orthodontic Debonding
Authors: Karan Sevinc , Toroglu Mustafa Serdar
Published: February 2008

Objective: To compare the effects of two polishing systems on the surface roughness of three types of porcelain after orthodontic debonding.

Materials and Methods: A total of 90 porcelain discs were fabricated from feldspathic (n = 30), leucite-based (n = 30) or lithia disilicate–based (n = 30) ceramics. Ten samples in each group served as the control and received no surface treatment. The remaining 60 samples in three of the porcelain groups were bonded with lower incisor brackets and debonded using a testing machine in shear mode at a rate of 1 mm/minute crosshead speed. After debonding, the remaining adhesive resin was removed with a tungsten carbide bur. Then, two experimental subgroups (10 each) in each porcelain group were treated as follows: in the first subgroup, porcelain polishing wheel and polishing paste were applied, whereas in the second, polishing was performed using a series of Sof-Lex discs. The average surface roughness (Ra) of the all samples was evaluated using SPM/AFM (surface probe microscope/atomic force microscope). Data were statistically analyzed by analysis of variance for each porcelain material and polishing method.

Results: The polishing techniques affected surface roughness significantly. There were significant differences between the groups; higher Ra values were obtained with the use of porcelain polishing wheel and polishing paste (P < .001).

Conclusion: The application of Sof-Lex discs can produce smoother porcelain surfaces than porcelain polishing wheel and polishing paste.
Stability of Zygomatic Plate-Screw Orthodontic Anchorage System
Authors: Veziroglu Firdevs , Uckan Sina , Ozden Utku Ahmet , Arman Ayca
Published: February 2008

Objective: To evaluate the biomechanical properties of a standard and a newly designed plate-screw orthodontic anchorage system.

Materials and Methods: A three-dimensional model of the posterior maxilla, including the zygomatic buttress region, was prepared. Insertion of standard and newly designed plates was simulated on the three-dimensional model. The effect of 200 g of orthodontic force on the plate, screws, and zygomatic bone was evaluated in three-dimensional models by finite element analysis. To determine the force distribution, Von Mises stress, principal maximum and minimum stress, and principal maximum and minimum elastic strain values were evaluated.

Results: In all plate models the highest stresses occurred on the threaded bone site where the force application unit was attached.

Conclusion: Changing the plate configuration did not affect the stress distribution in the newly designed plates. To equalize the force distribution, new plate designs that change the location of the force application unit are required.
Taurodontism and Van der Woude Syndrome
Authors: Nawa Hiroyuki , Oberoi Snehlata , Vargervik Karin
Published: February 2008

Objective: To report the occurrence of taurodontism in a clinical sample of Van der Woude syndrome (VWS) and describe its association with hypodontia and cleft type.

Materials and Methods: This retrospective, cross-sectional study was carried out on chart reviews and radiographs of 13 persons with VWS. Mean age was 10 years 11 months ± 1 year 5 months. Panoramic radiographs were used to confirm the presence or absence of teeth and to measure crown body and root lengths of mandibular first molars. Three-dimensional cone beam computed tomography (CT) scans were available on two persons with VWS. Both volumetric and linear measurements were obtained.

Results: The occurrence of taurodontism of the mandibular first molar was 35%: 27% hypodont and 8% mesodont. Of the 13 subjects with VWS, 6 (4 males and 2 females) had at least one tooth identified with taurodontism. Half of the cases were unilateral and half were bilateral, and all of the unilateral cases were on the left side. Five of the six subjects with taurodontism had missing incisors and premolars. Taurodontism was two times more frequent in those who were missing their second premolars than in those who had their second premolars. There was no correlation between cleft type and presence of taurodontism. The cone beam CT pilot study on two persons showed very abnormal morphology of both crown and roots, which was not apparent on the standard panoramic radiograph. Both the volumetric and linear measurements of the ratio of crown body to root were highly indicative of taurodontism. Further genetic studies are needed.

Conclusion: There is a likely association between VWS and taurodontism.
Malocclusion Traits and Orthodontic Treatment Needs in Prematurely Born Children
Authors: Paulsson Liselotte , Söderfeldt Björn , Bondemark Lars
Published: February 2008

Objective: To evaluate if prematurely born children have higher prevalence of malocclusion traits and greater orthodontic treatment need than matched full-term born controls.

Materials and Methods: Seventy-three preterm children were selected from the Medical Birth Register and divided into two subgroups according to their gestational age. One group consisted of 37 very preterm children (VPT), born in gestational week 29–32, and the other of 36 extremely preterm children (EPT), born before the 29th gestational week. The subjects were compared with a control group of 41 full-term children, who were matched for sex, age, and nationality. Data from clinical examinations, study casts, and panoramic radiographs were used to determine malocclusion traits. The dental health component of the index of orthodontic treatment need (IOTN) was used to rank the treatment need.

Results: Two or more malocclusion traits occurred significantly more often among EPT (83.3%) and VPT children (73.0%), compared with the full-term children (51.2%). Significantly higher prevalence of deep bites and was found in EPT and VPT groups compared with the full-term control group. Deep bite was the most common malocclusion trait in the EPT and VPT group. Higher orthodontic treatment need was found for the preterm children but no differences in prevalence of malocclusion traits and treatment need were found between VPT and EPT children.

Conclusion: The clinician should be aware of the potential for a higher number of malocclusion traits and greater orthodontic treatment need in prematurely born children compared with full-term children.
Maxillary Canine-First Premolar Transposition in the Permanent Dentition
Authors: Babacan Hasan , Kiliç Banu , Biçakçi Altuğ
Published: February 2008

Maxillary canine premolar transposition is the most frequently reported transposition type, which many orthodontists face. Although correcting the transposed tooth order is not advised after the eruption of the permanent tooth, several articles published in the last decade demonstrated nonextraction treatment of transposition using fixed mechanics. This article describes the nonextraction treatment of a complete transposition between a maxillary left canine and a first premolar, using similar mechanics as suggested earlier. The correct tooth order was established with a functional Class I canine and molar relationship at the end of treatment. Although triangular cortical bone resorption at the vestibule of the canine root was detected on computed tomography at the end of treatment, spontaneous regeneration of bone tissue at the resorption area was present on the postretention computed tomography scan.