A comparative evaluation of the efficacy of manual, magnetostrictive and piezoelectric ultrasonic instruments: an in vitro profilometric and SEM study

OBJECTIVES: The debridement of diseased root surface is usually performed by mechanical scaling and root planing using manual and power driven instruments. Many new designs in ultrasonic powered scaling tips have been developed. However, their effectiveness as compared to manual curettes has always been debatable. Thus, the objective of this in vitro study was to comparatively evaluate the efficacy of manual, magnetostrictive and piezoelectric ultrasonic instrumentation on periodontally involved extracted teeth using profilometer and scanning electron microscope (SEM). MATERIAL AND METHODS: 30 periodontally involved extracted human teeth were divided into 3 groups. The teeth were instrumented with hand and ultrasonic instruments resembling clinical application. In Group A all teeth were scaled with a new universal hand curette (Hu Friedy Gracey After Five Vision curette; Hu Friedy, Chicago, USA). In Group B Cavitron(TM) FSI - SLI(TM) ultrasonic device with focused spray slimline inserts (Dentsply International Inc., York, PA, USA) were used. In Group C teeth were scaled with an EMS piezoelectric ultrasonic device with prototype modified PS inserts. The surfaces were analyzed by a Precision profilometer to measure the surface roughness (Ra value in µm) consecutively before and after the instrumentation. The samples were examined under SEM at magnifications ranging from 17x to 300x and 600x. RESULTS: The mean Ra values (µm) before and after instrumentation in all the three groups A, B and C were tabulated. After statistically analyzing the data, no significant difference was observed in the three experimental groups. Though there was a decrease in the percentage reduction of Ra values consecutively from group A to C. CONCLUSION: Within the limits of the present study, given that the manual, magnetostrictive and piezoelectric ultrasonic instruments produce the same surface roughness, it can be concluded that their efficacy for creating a biologically compatible surface of periodontally diseased teeth is similar

Hydrophone design utilising Spectral-Shifts from Strain-Optic Interactions

Alternative technologies for the production of hydrophones using optical sensing are reviewed with respect to performance and manufacturability. Sensor designs utilising spectral shifts as a result of strain-optic interactions are uncommon, and we believe they merit further investigation as geophysical sensors due to good sensitivity and relative ease of manufacture Specifically, a Long Period Fibre Grating placed onto a mandrel appears to be as promising candidate as a future compact hydrophone sensor. A mathematical model has been created for a compliant mandrel coupled with a Long Period Fibre Grating inscribed into plastic fibre. The modelling results indicate that such a sensor should provide a sensor of minimal size, with desirable sensitivity characteristics. Compared to the Rayleigh based optical fibre sensors being evaluated in geophysical applications currently the modelled sensor is predicted to have significantly greater sensitivity, with the mandrel acting as a mechanical amplifier. The main limitation of the spectral shift method is the number of sensors that can be multiplexed on a single fibre. However, a combination of time-domain and wavelength domain multiplexing could significantly increase the number of sensors per fibre to usable numbers for geophysical applications

A new approach provides opportunities for spectral gamma analysis in boreholes for mineral exploration

Wide-spread application of gamma ray logging system in mineral exploration has long been desired by the mining industry, but not achieved. New developments in borehole logging approaches the Deep Exploration and Technologies Commonwealth Research Centre (DET CRC) have recently created Logging-While-Drilling tools, named the Autosonde and Shuttle, to measure natural gamma ray activity during drilling process. The Shuttle in particular will allow the collection of high quality natural gamma spectra by placing a sensor on the core-barrel and logging whilst drilling; a much slower process than wireline logging. Thus, a new approach collecting gamma data provides opportunities to use natural gamma radiation data in ways not normally done with conventional wireline tools. We have used a prototype spectral gamma sensor using BGO crystal on a wireline to simulate the data that will be collected by a shuttle system to demonstrate the data quality and to test whether more sophisticated data analysis of spectral attributes such as the ratio of Photo-electric to Compton gamma bands, or "heavy minerals indicator", will further lithological information than the standard K, U, Th analysis. Our preliminary results indicate that spectral data collected by the Shuttle will allow the heavy mineral indicator to be used and opens the possibility of better lithology identification tools

Cross-hole reflection seismic to delineate a relatively thin volcanogenic massive sulphide deposit in shale hosted environment

The seismic reflection method is a high resolution technique that can be used in many exploration environments including mineral exploration. However, mountainous terrain, depth of burial and the steepness of ore bearing structures pose a challenge to the application of surface seismic in mineral exploration. The cross-hole seismic method may present an alternative approach under such conditions. Presented here is a synthetic study examining the capability of the cross-hole seismic method to delineate a volcanogenic massive sulphide ore body in a shale hosted environment. A simple model typical for volcanogenic massive deposits in Tasmania has been considered. There, an elongated steeply dipping volcanogenic massive sulphide deposit with an average thickness of 10 m is seated within a shale rock. The primary aim of the modelling is to test the capability of the technique to delineate relatively medium sized, steeply dipping volcanogenic massive sulphide lens in shale hosted environment. A second objective is to use the technique to prospect for extensions to mineralization along steeply dipping reflectors. Synthetic cross-hole seismic records were generated using a 120 Hz energy source. Kirchhoff VSP migration was applied to wavefield separated shot records and Pre-stacked Depth Migrated images created. The resulting migrated images correlate well with the position and dip of the ore body demonstrating the potential of the cross-hole reflection technique to delineate steeply dipping ore structures in challenging environments

Seismic Exploration of Ore Deposits in Western Australia

ABSTRACT Exploration for mineral deposits in a predominatel

. Logging during diamond drilling?: Autonomous logging integrated into the Bottom Hole Assembly

Logging total count gamma data while diamond drilling an HQ borehole has been achieved using an autonomous shuttle. The shuttle is integrated into the Bottom Hole Assembly (BHA) prior to drilling. Logging is initiated at the beginning of each core run and the shuttle unit continuously logs at 1 second intervals. Continuous logging combined with the relatively slow rate of penetration of diamond drilling results in high fidelity logs at 1-5 cm intervals. The data is collected by the drilling crew, who download and email the data at the end of each core run for near real time analysis. Little to no interruption to the normal drilling process is experienced once the Shuttle has been integrated into the BHA. Autonomous logging while diamond drilling enables the collection of in-situ rock property measurements, without the risks and costs associated with later wireline logging. This value is added to the drilling process at little expense

Cutting the line in wireline with an Autonomous Sonde

Rock core has long been one of the pillars of mineral exploration strategy. This strategy, however, is becoming less viable as the depth of exploration targets continue to increase. Exploration strategies based on physical and chemical attributes of the rock-mass measured in-situ have the best chances to deliver efficient exploration programs by providing new data channels that can be used to improve the models of the deposits. Unfortunately, the logistic costs of acquiring these data using conventional wire-line methods have precluded their widespread use in the mineral industry. The autonomous sonde concept presented in this work drastically reduces the logistics costs of acquiring in-situ measurements. The autonomous sonde has been developed to integrate fully with the normal operations of current drill rigs. As such, it requires no specialised operator or equipment and no rig modifications. In this work, we present the results of field trials of the autonomous sondes at two Australian field sites. In the first experiment, we show that a pressure transducer can be used to evaluate the position of the sonde and to depth register the natural gamma data. In the second experiment, we show data acquired when the autonomous sonde protrudes through the bottom of the drill string and is brought back to surface by pulling up the rods. The results show a good repeatability between logging runs and data quality compares favourably to traditional wireline data