bluuebunny/crossref_metadata_2025 huggingface dataset:
Problems in the Analysis of a Shock Sequence with Application to Gunfire Analysis and Simulation
Authors: Sherf Z. , Hopstone P. , Ostrovski G. , Klein R. , Yehuda D.
Published: April 2015

In the planning of a laboratory simulation based on a transient sequence, non-conventional techniques must be applied to the analysis of the sequence, due to the non-stationary character of the signals. This paper deals with the specific analysis problems of a transient sequence. The RMS and spectral content analysis of a single transient elucidates the distortion in the characterization of the sequence, when stationary time-series analysis methods are implemented. The way this distortion affects the simulation of the sequence is presented next. From this presentation, it can be concluded that the best method for the laboratory simulation of a transient sequence is the application of a measured time-history, while preserving the statistical features of the sequence. This conclusion has been implemented in the planning of the laboratory simulation of a gunfire-generated sequence of transients, produced by a gun installed on a helicopter. Statistics of the maximum values of each transient were calculated, for the sequences measured under changing firing conditions. Based on these statistics and on the knowledge of the total number of rounds, the number of transients of different maxima during the entire life cycle could be evaluated. Also a life-cycle representative sequence that could be simulated by a shaker was generated. A second method for the gun firing sequence simulation was also tested. In this case, the shot with maximal peak value was used and the number of equivalent shocks representing the entire lifecycle calculated, using a fatigue accumulation model. The weakness of the method is in the fatigue model.
Uncharted Waters: Vibration Measurement in Thermal Chambers
Authors: Merrick Alan
Published: April 2015

Most space flight structures typically are tested for thermal and vacuum survivability, cycled initially at the component level to relieve internal strains and as an end product to verify thermal balance and operation as a complete system. Dynamic testing is generally performed on the individual components and as a complete system prior to the thermal vacuum test. This paper discusses a test requiring vibration data measurement in a thermal environment. Vibrations were induced internally by the thermal cycling of the structure (internal stress relief) as well as input with a shaker system capable of operating at cryogenic (LN2) temperatures. The intent of this vibration input was to characterize the structure rather than performing a qualification vibration environment. Requests for vibration measurements in thermal and vacuum environments are becoming more common, although this is the first test completed at Lockheed Martin Sunnyvale.
The Relationship Between the Variance of Energy Estimates and the Uncertainty Parameter
Authors: Smallwood David
Published: April 2015

The relationship between the uncertainty (4π times the product of rms duration, Dt, and rms bandwidth, Df) and the variance of energy estimates of random transients is examined. If a transient can be modeled with the product model, it is shown that for many cases the normalized error in the energy estimate, as measured by the uncertainty, is approximately the same as the normalized error determined from the more exact statistical duration and bandwidth. The uncertainty is a quantitative measure of the expected energy estimate errors. If the transient has a significant random component, a small uncertainty parameter implies a large error in the energy estimate. Attempts to resolve a time/frequency spectrum near the uncertainty limits of a transient with a significant random component will result in large errors in the spectral estimates.
Ceramic Chemical Filter for Removal of Organic Contaminants
Authors: Sakata Soichiro , Takahashi Hideto , Sato Katsumi , Takahashi Atsushi
Published: April 2015

A recently developed nonflammable ceramic chemical filter1 provides an alternative to conventional charcoal filters for removing organic airborne molecular contamination2 in cleanroom applications. The ceramic chemical filter is applicable in mini-environments and clean enclosures to handle manufacturing processes of less than 0.1 μm design and 300 mm wafer.
Probabilistic Numerical Analysis of Large, Complex, Structural Dynamic System Models
Authors: Urbina Angel , Paez Thomas
Published: April 2015

In recent years, great progress has been made in the construction and solution of large finite element models of complex structural dynamic systems. For example, structural models with millions of degrees of freedom are being built and used to approximate responses of structural systems. Further, great progress is being made in stochastic system analysis. Techniques for the construction of stochastic system models have been developed and solution techniques proposed. However, the two areas have not been combined, on a large scale, because stochastic finite element approaches appear very intrusive in their pure form. That is, substantial modifications of deterministic finite element codes are required to accommodate stochastic analysis. In view of this, a technique that uses the techniques of stochastic finite elements in a non-intrusive manner is required. This research provides one such approach. Specifically, the problem is divided into three parts: (1) model structural dynamic excitations using traditional approaches, and model physical system randomness using techniques of stochastic finite elements, namely, the Karhunen-Loeve expansion and polynomial chaos; (2) generate stochastic structural realizations and realizations of the random excitation using a Monte Carlo approach, and analyze structural responses with parallel computation in a suitable, large-scale finite element code; and (3) analyze structural dynamic responses using the techniques of stochastic finite elements, namely, the Karhunen-Loeve expansion and polynomial chaos. This paper supplies the details of the analytical approach. A numerical example is presented.
Modal Survey Testing and Vibration Qualification Testing: The Integrated Approach
Authors: Peeters Bart , Van der Auweraer Herman , Guillaume Patrick
Published: April 2015

In the assessment of the structural integrity and launch-environment survivability of satellite structures, dynamic mathematical models are used for load prediction. These analytical models are test-verified by a modal survey test. Once the vibration environment is specified, the satellite equipment is subjected to shaker excitation in order to reproduce this environment. This paper investigates the possibilities to integrate both the modal survey and the vibration qualification test.
Rectangular Control of Multi-Shaker Systems: Theory and Practical Results
Authors: Underwood Marcos , Keller Tony
Published: April 2015

Most current multi-shaker, Multiple Input Multiple Output (MIMO), tests are performed on the basis of a "square" arrangement, in which the number of control accelerometers equals the number of controlled exciters. However, in some cases more control accelerometers than exciters may be desirable. This arrangement is referred to as "rectangular" control. Recent advances in digital control of multi-shaker and multi-axes systems have made rectangular control an achievable, if not a simple, reality.

This paper examines the theory behind this approach and also gives some practical results. Some unexpected benefits resulting from this new control approach are included.
Accelerated Testing for Demonstration of Product Lifetime Reliability
Authors: Krasich Milena
Published: April 2015

This test is designed with the assumption that product reliability is a combination of its individual reliabilities under various operational and environmental stresses and of the undetermined interaction among these stresses. A well-designed reliability test accounts for all cumulative operational and environmental exposures to the stresses that the product will encounter in field use. To determine the level and duration of each of the individual stresses to be applied in the test, it is assumed that the stresses are independent, and a separate factor is added to make up for any unknown stress interactions. The synergism or the test sequence is not disregarded, as it might be the factor contributing to lower demonstrated reliability. The individual stresses are accelerated to allow for reasonable and cost-effective test duration. This test design cannot be accomplished without detailed knowledge of the product's usage profile, sequence of operation, and expected use environments.

The choice of test data analysis technique will depend on whether there were any test failures and on the type of failures. Where failures occur, acceleration factors are applied to determine the corresponding times to failure in field use. The test may be conducted as a reliability growth or a fixed duration test by applying the appropriate analytical techniques. The reliability growth technique may be preferred, as it normally yields tests of shorter duration.

Accelerated reliability testing provides realistic lifetime reliability demonstration or validation and, if performed early enough, allows for design changes to improve product reliability.

In designing any accelerated life test, caution should be exercised to avoid exceeding the environmental rating of the tested product, as high test acceleration can also induce failures that would normally not be expected to occur in the field life of the product. Also, acceleration factors must be carefully determined, preferably through accelerated testing to the failure mode of interest. Acceleration factors (their constants) may be different for different components of the tested products, thus care must be taken in their selection.
The Feasibility of Differential Flow Velocity Dividing Working Areas in a Cleanroom
Authors: Chen Juhn-Jie , Jeng Ming-Shan , Lan Chao-Ho , Lee Yan-Ching
Published: April 2015

The possibility of dividing working areas by airflow velocity differences in a cleanroom with fan-filter unit (FFU) systems was investigated. Without physical partitions, the cleanroom area was divided into working and non-working areas defined by the FFU exit flow velocities, which were maintained at constant value in the working areas and reduced in the non-working areas. As uniform micro-sized particles were released from a particle generator in the non-working area, the concentrations of particles in the working area were monitored by a particle counter. The results showed that high downward flow velocity in the working area can effectively prevent particles from spreading. The results also suggested an optimum velocity ratio of 20% between adjacent flow regions, in terms of the balance between energy savings and the effective partition insulation.
A Process for Estimating Component Life in Support of Reliability Predictions for Present and Future Military Combat Vehicles
Authors: De Porter William
Published: April 2015

The manufacture of future military combat vehicles faces a number of challenges. One of those challenges is to balance producibility, reliability, and weight. An additional challenge is the military's frequent need to extend the life of its current combat vehicles. Imperfections resulting from the manufacturing process may contribute to both of these challenges by shortening the fatigue life of the vehicle structure or components. Use of an assessment fatigue process can help meet these manufacturing challenges. Established technologies can extract past life events and anticipated extended life events. These combined life events can then be compared to the vehicle life boundaries. The results can be used to extend combat vehicle life or to pursue new challenges such as improved weight balance.
Application of a Real-time Process Simulator to PLC Programming for a Satellite Thermal Vacuum Chamber
Authors: Shin Younggy , Choi Seok-Weon , Moon Guee-Won , Seo Hee-Jun , Lee Sang-Hoon , Cho Hyokjin
Published: April 2015

A thermal vacuum chamber is used to simulate thermal environments of a test satellite in orbits where daily temperature variations range from 80 K to above 400 K. The test facility is complex and consists of expensive parts. Modification of control software is discouraged as the modification may cause unexpected system failure. This paper describes a study that develops a real-time dynamics model of the thermal vacuum chamber that can be used to create control algorithms and simulate electrical inputs and outputs for interface with a programmable logic controller (PLC). The dynamics model is represented by simulation software and exported to a target PC in the Microsoft® Disk Operating System (DOS) mode to exploit the real-time kernel of the DOS software. The model is executed in real-time and communicates with a microprocessor-based input/output (I/O) board via a serial port to emulate electrical inputs and outputs.

The target process to model is the gaseous nitrogen (GN2) mode in which GN2 circulates in a closed loop through thermal shrouds encompassing a test object. A blower boosts the GN2. Injected liquid nitrogen (LN2) and an electric heater control the set temperature of the GN2. The realized simulator dynamics are quite similar to those of the thermal vacuum chamber and serve as an appropriate system to verify the control performance of a programmed PLC.
Maturation of the Vibration Environment in Advanced Technology Facilities
Authors: Gendreau Michael , Amick Hal
Published: April 2015

Semiconductor production and other advanced technology facilities are often designed in two states, the "base-build" state and the "hook-up" state. The base-build state, which after completion is termed "as-built" by the International Organization for Standardization (ISO)1, includes the design and construction of the shell structure and all architectural, mechanical, electrical, and process systems needed for building operation. The hook-up state includes the installation of the production tools and their local support equipment (dry pumps, piping attachments, etc.). During the project design, cleanroom environment vibration and noise requirements are often assigned for compliance in the as-built state only (before tool hook up), since often a different design team or construction team or both is involved in the hook-up state and the base-build design team has little control of operational vibration and noise levels. This paper discusses typical changes, or maturation, in the production vibration environment after the as-built state. In these mature states, identified by ISO as "at rest" and "operational," there is usually an increase in environmental vibration and noise levels with the addition of tools and tool support equipment. This paper also discusses the role of maturation in building mechanical equipment as well as the means of controlling the increase in vibration.
ColumbiaAccident Investigation and Return-to-Flight Effort
Authors: Melis Matthew , Pereira Mike , Revilock Duane , Carney Kelly
Published: April 2015

On February 1, 2003, the Space Shuttle Columbia broke apart during reentry, resulting in the loss of seven crewmembers. For the next several months an extensive investigation of the accident involved a nationwide team of experts from the National Aeronautics and Space Administration (NASA), industry, and academia, spanning dozens of technical disciplines.
Investigating Rigidity of Military Vehicle Body Using Operating Deflection Shape (ODS) Analysis
Authors: Bounds Mark , White George
Published: April 2015

The Army has many rigid-body dynamic models of various vehicle platforms. The adequacy of these rigid-body models has been questioned. In an effort to gain insight into the significance of flexibility in the development of dynamic vehicle models, operating deflection shape (ODS) techniques were applied to acceleration data gathered from the body of a wheeled military vehicle. The data were analyzed in an effort to determine a specific frequency range over which the assumption of rigidity would be valid. For the particular platform examined in this study, the assumption of rigidity would apply up to approximately 14 Hz. Future efforts include using operational modal analysis (OMA) to further examine the problem.
Automated Sorting of Mixed Mode Environment's Data
Authors: Roberts Nathan , Cap Jerry
Published: April 2015

Transportation of sensitive flight hardware requires information about the expected transportation environment as well as the actual transportation environment during the part's movement—typically vibration with superimposed intermittent shocks. Each data type has different sampling, processing, and specification requirements. Analyzing shock data requires high sampling rates and leads to large file sizes. A barrier to analyzing data has been the vast quantity of information acquired. Previous approaches have focused either on manually separating data or on selectively recording extreme data. The use of an automated approach allows for quickly verifying vibration and shock levels while retaining the robustness of the underlying data set. Further, the automated approach allows the environments engineer to select criteria for shock/vibration sorting, which removes the subjectivity associated with visual differentiation. This automated technique evaluated several vehicles over four different road conditions in the same time that one data set could have been processed using visual discrimination. Automated processing of satellite shipment vibration and shock data is made thoroughly and objectively vs. traditional shock and tilt indicators. The automated technique could also be useful in processing large amounts of on-orbit data for changes in vibration signature.
Design of a Zero-Failure Reliability Test Plan Based on Customer Usage and Bench Life Test Data
Authors: Chen Jianxiong , Yan Wenzhen
Published: April 2015

Reliability tests are mandatory to evaluate new products prior to their release. The proper determination of a reliability test plan is crucial because an erroneous test plan can be very costly and misleading. This paper describes a probability-based method of designing a reliability demonstration test plan using both field customer usage and historical bench life test data. Statistical distribution analysis, Monte Carlo simulation (MCS) technique, and zero-failure test method are integrated into the probability-based method to create test plans that can more accurately evaluate product reliabilities for the required product service life using a small number of test samples.
Accelerated Reliability Growth Testing and Data Analysis Method
Authors: Krasich Milena
Published: April 2015

Traditionally, a reliability growth test was performed at the levels of various operational and environmental stresses, often at a level equal to that expected in use. Other than formal failure modes and effects analysis, reliability growth tests were often the only practical means for identification and mitigation of failure modes of a newly designed product.

With the present high reliability requirements and long product useful life, the length of reliability growth tests may become cost and schedule prohibitive; therefore, accelerated testing is taking the place of prior testing at the use levels. This practice, however, does not address the dilemma of possibly unrealistically skewed test results highly dependent on the sequence of individually applied stresses as, unfortunately, it is often difficult to impossible to apply all of the environmental and operational stresses simultaneously. An example of this problem would be a case where the majority of failure modes in a product are a result of or are related to a specific stress, and this test was performed early in the program. These early failures would then produce a high growth rate and an incorrect estimate of the product achieved reliability if the analysis were done by standard analytical models. The test data also may be skewed in the opposite way, producing little or no reliability growth. This concern has been addressed as a serious caution in Edition 2 of the International Electrotechnical Commission (IEC) 61014 Programmes for reliability growth.

This study shows how data analysis applied to an accelerated life test based on reliability growth methodology may produce a viable solution to the calculation problems. The stresses applied in this test are an accelerated application of most of the stresses expected to take place during product use. Each of the tests represents a lifetime exposure to an individual stress. If those stresses are applied individually and in sequence, they are considered to be equivalent to being applied in parallel with one another, as the duration of each stress is calculated to represent life of the product.

Time to failure in each test is re-calculated to represent time to failure in real life. Failure occurrences are then sorted in their increasing order and analyzed using one of the reliability growth test analytical methods.
Microstructural-Based Physics of Failure Models to Predict Fatigue Reliability
Authors: Tryon Robert , Dey Animesh , Krishnan Ganapathi
Published: April 2015

The fatigue life of materials is strongly influenced by their microstructure. The scatter in fatigue life is caused by the scatter in grain size, grain orientation, and stresses induced in each grain of the material due to external loading. A novel microstructural fatigue crack growth model that accounts for real-life variability in the material is presented in this study. Ti-6Al-4V, a common aerospace titanium alloy used in numerous turbine engines, has been studied to predict its fatigue life and scatter at load ratios of 0.1 and -1.0. The predictions have been compared with experimental data. Results indicate that the microstructural material models accurately predict the behavior of Ti-6Al-4V.
Forging New Frontiers
Authors: Granitto Diana
Published: April 2015

By 1958, the nascent environmental engineering profession had moved from wartime activities into the space age, and this journal began documenting the evolution of an industry. Over the past five decades and under as many titles, the Journal has witnessed advances into contamination control, ecological sciences, and nanotechnology, to name a few.
Evaluation of a Wafer Fab AMC Monitoring and Control Program
Authors: Muller Chris , Tan See
Published: April 2015

An air monitoring program is in place at a wafer fab to characterize outdoor air quality and its potential impact on manufacturing processes. Airborne molecular contamination (AMC), and specifically acid contamination, was of particular concern as the facility incorporated 90-nanometer (nm) manufacturing technology. Impinger ionic analysis, passive and real-time reactivity monitoring, and litmus paper hue readings were among the techniques used to assess air quality. Historical data for each monitoring technique was evaluated and compared to determine the applicability of each monitoring technique for these purposes. Data from this monitoring program also offered an opportunity to evaluate the performance of chemical filters installed in makeup air handling units for their ability to remove AMC. This study presents the results of air monitoring, detailing outdoor air quality and how that air quality compares to established specifications; comparison of different monitoring techniques used in the study; performance of installed chemical filter systems; recommendations for improving acid contamination control and evaluation of selected options; and recommendations for overall AMC monitoring and control programs.
Optimal Utilization of Test Facilities to Replicate Operational Environments
Authors: Hoy Timothy , Herrmann Jeffrey
Published: April 2015

Useful system endurance tests require operating a system in settings similar to operational environments. However, existing test facilities may not be good replicas of the operational environment, especially for systems with long life cycles that are being used in new and unforeseen situations. Because constructing new test facilities can be expensive and time-consuming, it is desirable to use the existing test infrastructure to replicate the operational environment as closely as possible. This study presents an optimization model that determines the most appropriate amount of testing to conduct using each existing test facility. A multi-objective model is also presented, and the application of this work to two military vehicle tests is discussed.
Acceleration-Based Remaining Life Prognostics for Terrain-Loaded Components on an Army Ground Vehicle System
Authors: Heine Richard , Barker Donald
Published: April 2015

Use of a health and usage monitoring system (HUMS) is one method the Department of Defense is investigating to meet conflicting cost and performance goals for Army wheeled vehicles. One area where a HUMS would be of great benefit is monitoring critical components vulnerable to terrain-induced fatigue. While strain is typically the desired input to a fatigue model, acceleration sensors are less susceptible to damage from the military ground vehicle environment and provide more reliable data over long periods of usage. The feasibility of using vibratory inputs from an accelerometer to make component fatigue predictions for a military wheeled vehicle system is explored in this study, and the use of limited subsets of data for algorithm training are evaluated. An example component is used to demonstrate that the proposed HUMS algorithms are appropriate and provide suitably accurate fatigue predictions.
Vibration with Non-Gaussian Noise
Authors: Smallwood David
Published: April 2015

Three methods are introduced for generating realizations of time histories with a specified auto-spectral density while controlling the kurtosis. One of the methods also allows the skewness to be specified. A second method allows large excursions (that produce large kurtosis) to be randomly distributed or almost periodic. In addition, the second method allows the average number of large excursions per unit of time to be specified. All the methods are variations of the inverse Welch method. The shape of the discrete Fourier magnitude is specified for a frame of data, thus controlling the shape of the auto-spectral density. The phase of the frame of data or the magnitude of the amplitude spectrum is modified to control the kurtosis or the skewness. The frames of data are multiplied by a window and overlapped and added to produce the realization.
Facts and Fiction in Cleanroom Metrology
Authors: Gail Lothar , Stanischewski Dirk
Published: April 2015

This article discusses a number of cleanroom qualification parameters in terms of their proper specification. A critical analysis reveals that the useful operating range of some parameters is not appropriately considered by some early standards and guidelines, which are still used by regulatory authorities (the US Food and Drug Administration (FDA) and the European Union (EU)) and industry professionals. In practice, the windows of safely controlled cleanroom operation prove to be considerably larger than anticipated by existing regulations, especially with regard to unidirectional airflow velocity, pressure difference, and other parameters. Many measuring techniques, such as installed HEPA filter integrity testing and recovery time testing, are also regulated more strictly than necessary. Modern cleanroom testing requires more carefully defined targets and more flexibility in using advanced test procedures.
Using a Modified Harmonic Wavelet Transform to Characterize Mechanical Shock
Authors: Smallwood David
Published: April 2015

A modified harmonic wavelet transform is used to estimate a time varying spectral density. The resolution of the estimate has an approximate constant time-frequency product. The estimation error is directly related to this time-frequency product. Unwanted cross product terms are effectively minimized. Several examples are given: White random, two sine waves, chirps, impulses, sums of exponentially decaying sinusoids, and a pyroshock. It is also shown how realizations can be generated from the modified harmonic wavelet transform estimate of the time varying spectral density.
Prediction Model for Particle Fallout in Cleanrooms
Authors: Parasuraman Dinesh , Kemps Antonius , Veeke Hans , Lodewijks Gabriel
Published: April 2015

Particle fallout in cleanrooms is a primary concern for industries manufacturing super critical products with surfaces highly susceptible to particulate contamination. Limited research has been conducted to predict the contribution of particulate contamination by production activities in cleanrooms. This paper describes a prediction model that utilizes the relationship between airborne particulate contamination and particle fallout, and the relationship between particle fallout and spatial variations, to predict the level of particle fallout on product surfaces in the cleanroom. Experimental modeling and statistical process control techniques were employed in establishing the above relationships and validation was performed by comparing the predictions from the model with actual observations at production cleanrooms.
Relationship between Strain and Velocity for Ground Vehicle Vibration
Authors: White George
Published: April 2015

This paper uses experimental vibration data to evaluate the relationship between strain and velocity on a ground vehicle platform. The data also are used to compare the acceleration and the strain. Comparisons are made in the time, frequency, and damage domains. The results clearly show the strain data are more closely related to the vibratory velocity than to the acceleration, but the analysis is complicated somewhat by characteristics of the experimental data set.
Contamination of Ultra-High-Purity (UHP) Gas Distribution Systems by Back Diffusion of Impurities
Authors: Dittler Roy , Kishore Jivaan , Geisert Carl , Shadman Farhang
Published: April 2015

A combination of experimental investigation and process simulation was used to analyze the effect of various operational parameters on impurity back diffusion into ultra-high-purity (UHP) gas distribution systems. The process model developed in this work was validated by comparing its predictions with data from the experimental test bed. Surface diffusion as well as convection and dispersion in the bulk fluid played a strong role in the transport of moisture from vents and lateral branches into the main line. Parametric studies on the effect of key operational and design parameters were performed experimentally and with the application of a process simulator. In this analysis, a dimensionless number (Peclet Number) was derived and applied as the key indicator of the relative significance of various transport mechanisms in moisture back diffusion. Guidelines and critical values of Peclet Number were identified for assuring the operating conditions meet the purity requirements at the point of use while minimizing UHP gas usage. These guidelines allowed the determination of lateral lengths, lateral diameters, flow rates, and restrictive flow device configurations to minimize contamination.
Comparative evaluation of marginal integrity of two new fissure sealants using invasive and non-invasive techniques: a SEM study
Authors: Vineet Dhar , Tandon Shobha
Published: April 2015

In this era of preventive dentistry, many dental materials used for prevention of dental diseases are available. Since last few decades efforts are being directed towards prevention of dental caries which is one of the major dental diseases tormenting mankind. The main avenues available are plaque control, use of systemic and local fluorides and use of fissure sealants. There are many factors that contribute towards a successful sealant restoration such as properties of enamel, duration of etching, acid used for etching, manipulative variables. However, one of the prime factors governing the efficacy and life expectancy of a sealant is the marginal adaptability. This study was carried out on a total of 40 intact premolar teeth, which were divided in four main groups and subjected to evaluation under Scanning Electron Microscope. The parameters checked were the width and the number of marginal gaps. The results obtained showed that Teethmate had better marginal integrity and favored the use of invasive technique over non-invasive technique.
Enameloplasty effects on microleakage of pit and fissure sealants under load: an in vitro study
Authors: Zervou Christina , Kugel Gerald , Leone Cataldo , Zavras Athanasios , Doherty Eileen , White George
Published: April 2015

Enameloplasty has been implicated in the successful application of pit and fissure sealants. The present study aimed to evaluate the effect of enameloplasty technique on microleakage of sealants when occlusal force was applied on the teeth. The study also allowed a direct comparison of the effectiveness of enameloplasty, when two different burs were used. Six groups of ten human extracted wisdom teeth were tested. Group A: no load, conventional (no enameloplasty - control); Group B: no load, enameloplasty 1/2 round bur (Brasseler USA); Group C: no load, enameloplasty diamond fissure bur REF/UP 791( Ultradent); Group D: load 500 N, conventional , Group E: load 500 N, 1/2 round bur; Group F: load 500 N, diamond fissure bur. Specimens were thermocycled for 500 cycles at 5° and 55° with a dwell time of 30 seconds after load application. Microleakage was scored as distance of dye penetration with 0 = no microleakage and 3 = microleakage to underling fissure. The Kruskal-Wallis One Way Anova and Mann -Whitney U test showed group D having the greatest degree of microleakage statistically significant (p<0.05) comparing with other groups. Sealants prepared with the conventional technique (A, D) had statistically significant differences in microleakage with those prepared with enameloplasty (B,C,E, F) (p = 0.01). Enameloplasty in groups with no load (B, C) did reduce microleakage, but not significantly (p = 0.3) However, loaded teeth with enameloplasty appeared to perform superior, as compared to those without (p=0.005) Regarding the effect of load, teeth without load (Groups A,B, C) were found to have significantly less microleakage than teeth where mechanical force had been applied (Groups D, E, F), (p = 0.01). Microleakage in Group A (conventional technique without load) was significantly less than microleakage in Group D (conventional technique with load), (p = 0.04). However, load did not seem to influence microleakage when enameloplasty had been performed. This finding was true for both round bur enameloplasty (p = 0.29), and fissure bur enameloplasty (p = 0.26). There was no statistically significant difference between Groups B, E (round bur) and C, F (fissure bur) (p > 0.05), or between Groups B and C (p > 0.05) and between Groups E and F (p > 0.05). The results of the study indicated that enameloplasty reduced microleakage of pit and fissure sealants, especially when load was applied to teeth, irrespective of what bur was used to enlarge the fissure, as there was no statistical significant differences between the round and fissured diamond burs. The application of occlusal force to the tooth produces significantly more microleakage, unless enameloplasty is performed.
Hurler syndrome: a case report
Authors: Thomas S. , Tandon S.
Published: April 2015

Hurler syndrome is an inherited disorder of mucopolysaceharide metabolism, which is caused by a defect in genetically controlled pathways of lysosomal degradation. It represents the classical prototype of mucopolysaccharide disorder. An interesting case of a three and a half-year old boy with a rare combination of skeletal, neurological, ophthalmologic, and dental findings is presented. It is a rare syndrome with a very low prevalence of 1:100000 births and as such the clinician should be aware of this syndrome.
Child behavior in a private pediatric dental practice associated with types of visits, age and socio-economic factors
Authors: Brill Warren
Published: April 2015

The purpose of this study was to describe child patient behavior patterns seen in a private pediatric dental practice. Patient behavior for every individual visit was recorded over a span of 3 consecutive months using the Sarnat Behavior Scale as the descriptive measurement device. Behavior during 5 categories of procedures was recorded: new patient examination / introduction to the office, periodic recare, restorative dentistry, orthodontic adjustment and quick check observation. Socio-demographic variables such as age, sex, method of payment as an indicator of socio-economic status, prior dental experience and referral source were also recorded. The results of this study showed: 1. the younger the child and the more threatening the procedure, the more often negative behavior was noted, 2. patients whose dental treatment was paid for by Medicaid and who are likely to be in a lower socio-economic strata, often exhibited more negative behavior than the fee-for service counterparts, 3. in general, there was no difference in the behavior between males and females, although males age 8 to 12 had a higher incidence of negative behavior than females when undergoing restorative dental procedures. There are trends between age, type of procedure, source of patient referral, method of payment and familiarity with the office, that may be able to used as behavioral predictors in a private pediatric dental office.
The effect of caries detector dyes and a cavity cleansing agent on composite resin bonding to enamel and dentin
Authors: El-Housseiny Azza , Jamjoum Hana
Published: April 2015

This study was undertaken to evaluate the effect of caries detector dyes and/or cavity cleanser on composite bonding and etching patterns of enamel and dentin. One hundred and eight non-carious premolars were divided into six groups according to the enamel and dentin pretreatment investigated. The different pretreatment were as follows: Group I: teeth with prophylaxis only, Group II: Sable seek caries detector dye,Groups III: chlorhexidine cavity cleanser,Group IV: the caries detectors dye followed by prophylaxis, Group V: the cavity cleanser followed by the caries detector dye, and Group IV: Snoop caries detector dye. The shear bond strength of composite resin bonded to enamel and dentin was evaluated by the Instron Universal testing machine while, the topographic details of enamel and dentin were examined by the SEM following the different pretreatment and acid etching. Results of the shear bond strength showed no statistically significant difference among the six groups, with no substantial differences in SEM results. It is concluded that using the caries detector dyes and/or chlorhexidine cavity cleanser before acid etching does not significantly affect composite bonding to enamel and dentin.
Clinical evaluation of the efficacy of anesthesia and patient preference using the needle-less jet syringe in pediatric dental practice
Authors: Munshi A. , Hegde Amitha , Bashir Nyla
Published: April 2015

Most dentists are aware that local anesthetic injections produce the highest incidence of disruptive behavior in children. Both psychological and physiological monitoring of the response of children to dental injection, support empirical observations of clinicians. The needle-free injector delivers local anesthesia without the use of a needle. This is accomplished by delivering the anesthetic solution under high compressive forces. One hundred children between the ages of 3 to 13 years underwent operative procedures using Madajet XL. There was a statistically significant difference in favor of the instrument. The instrument was completely successful in providing anesthesia.
Riga-Fede disease: report of a case and review
Authors: Baghdadi Ziad
Published: April 2015

Self-mutilation of tongue is a type of self-injurious behavior. Ulcers of the lingual frenum in neonates with natal lower incisors are referred to as Riga-Fede disease. In this paper a case of Riga-Fede disease in a ten-month infant male with lower central incisors is reported. The ulcer resolved after the sharp incisal edges were smoothened and topical triameinolone was applied. As this lesion may be confused or associated with other serious disorders, a review of medical and dental literature was included.
Attention-deficit/hyperactive disorder: making a case for multidisciplinary management
Authors: Ramanathan Guru , White George
Published: April 2015

Attention Deficit/Hyperactivity Disorder (AD/HD) is characterized by a cluster of age-inappropriate behavioral abnormalities comprising inattentivity, hyperactivity and impulsivity. The definition is controverisal and without an accurate diagnosis. Therefore, it seems prudent that a multidisciplinary treatment protocol should begin with non-drug psychological and behavioral strategies plus nutritional intervention.
Eruption process of upper permanent canine
Authors: Tsai Hung-Huey
Published: April 2015

The purpose of this study was to investigate normal eruptive pattern of upper permanent canine. One hundred and fifty-one panoramic radiographs were used. Inclination of upper canine and lateral incisor, length and horizontal and vertical positions of cusp and root apex of the canine were evaluated. The canine erupted with increasing distal inclination and with no significant changes of the lateral incisor. Developmental changes of the canines relative to palatal plane and midline were shown by figures.
Pseudo-class III treatment with reverse traction: case report
Authors: Santos-Pinto Ary dos , Fabris Paulin Ricardo , Moreira Melo Ana Cláudia
Published: April 2015

The pseudo-Class III can be defined as a functional reflex of an anterior positioning of the mandible, an acquired muscular position that simulates a mesiocclusion. The diagnosis and treatment plan of this condition must be based on a cephalometric evaluation that provides information about the relative contributions of the skeletal and dental components to the malocclusion. There is still great controversies about when is the best moment to start the Class III treatment. The purpose of this article is to describe a case report in which a Class III patient was successfully treated with reverse traction.
pH changes in dental plaque after using sugar-free pediatric medicine
Authors: Mentes Ali
Published: April 2015

The aim of this study was to compare the pH changes in the dental plaque after rinsing with sugared- (sucrose) or sugar-free (saccharine, cyclamate and sorbitol) versions of the same pediatric acetaminophen solution (ekosetol®) up to one hour. Twenty-nine undergraduate dental students (17 girls and 12 boys) collected plaque for 48 hours by abstaining from oral hygiene, during which period they maintained normal dietary habits. Plaque sampling was done in two subsequent days before and 2, 5, 10, 15, 20, 25, 30, 40, 50 and 60 minutes after rinsing with both solutions. Measurements of pH were done within one hour using a micro pH electrode and a pH meter. All experiments were finished in 6 days by dividing the group to three. Results showed a significant difference between groups in respect to pH values and pH drops after rinsing. Mean pH values were below 5.70 for one hour in sugared solution, whereas no mean pH value was detected below 5.80 for one hour with the sugar-free solution. Minimum pH values (sugar-free: 5.62±0.36; sugared: 5.00±0.33, p<0.001) and maximum pH drops (sugar-free: -0.57±0.26; sugared: -1.16 ± 0.44, p<0.001) were also significantly different. No difference was found between genders. We concluded that changing of sucrose to non-acidogenic sweeteners was essential to prevent the cariogenic potential of the pediatric medicines.
Oligodontia: a case report
Authors: Ünalan Fatma , Ulukapi Işin , Bakirgil Juliana
Published: April 2015

Oligodontia is the agenesis of numerous teeth, and is commonly associated with specific syndromes and / or severe systemic abnormalities. In this paper a patient with 14 missing permanent teeth is presented clinically with her conservative and prosthetic treatments.
Penetration of the mandibular condyle into the middle cranial fossa: report of a case in a 6-year-old girl
Authors: DeFabianis Patricia
Published: April 2015

Reported cases of dislocation of the mandibular condyle into the middle cranial fossa are rare. Treatment of this injury should be individualized and should take in account the age of the patient, growth potential, the degree of glenoid fossa destruction, the risk of ankylosis and the risk of further cranial injury. In children, functional therapy is aimed at helping the restoration of posterior facial height, good occlusal relations and function. Long-term follow-up is mandatory. Surgery may be required later to correct asymmetrical growth or developing ankylosis. This article describes a case of condylar penetration into the middle cranial fossa in a six-year-old child and the treatment performed to minimize consequences on occlusion and facial development.
Clinical evaluation of carisolv® in the chemico-mechanical removal of carious dentin
Authors: Munshi A. , Hegde Amitha , Shetty Priya
Published: April 2015

The Chemo-mechanical caries removal technique involves the application of chemical agents, to cause a selective softening of the carious dentine and facilitate removal by gentle excavation. Carisolv® is one such new chemical agent used in this minimal invasive technique of carious dentine removal. The present study was, therefore, undertaken to evaluate the efficacy of Carisolv® in the chemo-mechanical removal of carious dentine, the time taken for caries removal, the perception of the treatment by the patient, and to evaluate the restorations, radiographically. Accordingly, fifty primary and permanent molars with dentinal carious lesions were excavated using this technique of caries removal. The chemo-mechanical caries removal technique using Carisolv® proved to be an effective atraumatic treatment modality with potential interest for use in clinical pediatric dentistry.
Class II division 1 malocclusions: the subdivision problem
Authors: Alkofide Eman
Published: April 2015

The purpose of this study was to determine the frequency of occurrence of subdivisions, in Class II division 1 malocclusions. Sixty patients seeking orthodontic treatment at the dental college of King Saud University were selected. The results revealed that 45% of Class II division 1 patients examined had subdivisions. The most commonly affected side was the right (66.7%). Mandibular shift upon closure was noted in 36% of the subdivision cases. Mandibular asymmetry was noted in 62.6% of the patients. It can be concluded from this study that subdivisions are a frequent finding in Class II division 1 malocclusions. Appropriate diagnosis of these cases should be done early in the mixed dentition phase, to avoid developing dental or skeletal asymmetries that can persist throughout adulthood.