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Biomedical Engineering, IEEE Transactions on

Issue 4 • Date April 1991

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Displaying Results 1 - 15 of 15
  • CAD/CAM for dental restorations-some of the curious challenges

    Page(s): 314 - 318
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1046 KB)  

    The current state of the art for production of dental restorations is reviewed, and DentiCAD, a system being developed by Maryland University and Minnesota University which is capable of producing dental crowns, is described. DentiCAD can produce dental restorations that fit at least as well as those that are cast. Some of the challenges and difficulties that have arisen during development are addressed. Some of the questions that, because of the new technology, can now be addressed and that are presenting new challenges are discussed. View full abstract»

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  • Computer-controlled differential scanning calorimetry of dental composites

    Page(s): 319 - 325
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    Computer-controlled differential scanning calorimetry that has been used to evaluate the heat liberated and the temperature rise associated with the light cure of selected dental composites is described. The effect of postcure heating and the increased ambient temperature of the light cure are examined in terms of a potential secondary cure. The results indicate significant differences between the mean heats of cures of different composites, primarily reflecting the filler fraction variations of the composites. Increased cure activity appears to result from postcure heating as well as thermal activation due to higher ambient temperature of the light cure. The results are analyzed and attributed to variations in resin phase composition and resin content per unit weight of composite as well as to thermally induced enhancement of cure. View full abstract»

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  • Nonlinear interpolation of mandibular kinesiographic signals by applying sensitivity method to a GMDH correction model

    Page(s): 326 - 329
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    An improved nonlinear interpolation method for estimating distorted kinesiographic recording of interlattice points in space is proposed, and its correction accuracy is evaluated. The group method of data handling (GMDH) correction method reported previously by the authors (1984, 1986) can be adapted to a measurement environment in which kinesiographic signals are subject to ferromagnetic interferences, but it was restricted to kinesiographic signals representing lattice points in space. The sensitivity method for GMDH correction modeling is explored. This provides for nonlinear interpolation of kinesiographic signals for lattice points. Nominals, i.e., true values, of 3-D coordinates of the interlattice points were determined by means of a mandibular jaw movement simulator together with simultaneous recording of distorted kinesiographic signals which correspond to the nominals. Distorted signals were corrected by the new method of correction modeling. A mean estimation error of 0.16 mm (SD 0.19 mm) was determined for 24 interlattice coordinates. Thus, nonlinear interpolation by the sensitivity method is confirmed to be effective. View full abstract»

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  • A periodontal probe with automated cemento-enamel detection-design and clinical trials

    Page(s): 330 - 334
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    An automated periodontal probe has been developed to measure pocket depth and attachment loss in a single measurement under controlled force conditions. A natural anatomic landmark, the cemento-enamel junction (CEJ), is used as a reference for attachment-level measurements. The CEJ is detected automatically by immediate digital postprocessing of simultaneous measurements of probe-tip acceleration and displacement during probing. Clinical trials in the beagle dog model for naturally occurring periodontitis have shown that the automated probe, when used with 35-g probing force, has a repeatability of 0.13 mm and a bias of 0.09 mm, indicating that the automated periodontal probe is capable of attachment-level measurements with a high degree of repeatability and validity. View full abstract»

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  • Computer-aided interpretation and quantification of angular periodontal bone defects on dental radiographs

    Page(s): 334 - 338
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    The evaluation of a computer-aided procedure for the interpretation and quantification of angular periodontal bone defects on dental radiographs is described. The computer-aided procedure was able to rank a series of artificial periodontal bone lesions as accurately as experienced clinicians. A comparison of data from clinical inspections of lesions during surgery with quantitative results of the digitized procedure shows that the latter produced reliable information on lesion size. Reproducibility is satisfactory. It is concluded that computer-aided detection and description of periodontal bone defects decreases the interobserver variability in general and the time-dependent variability in repeated assessments of a single observer. View full abstract»

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  • An artificial oral environment for testing dental materials

    Page(s): 339 - 345
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    An artificial oral environment which closely matches the conditions of human mastication for dental materials testing is described. Two servo-hydraulic actuators were combined to produce the force movement cycle of human mastication. A closed-loop method of control which functions in a manner similar to the human neuromuscular system was used. The horizontal closed loop used a linearly variable differential amplifier (LVDT) to monitor the position. The vertical closed loop used an LVDT to monitor position and a load cell to monitor force, with a 'mode switch' being made between the two mechanisms of control. A function generator was used to produce a sinewave that was modified to produce the movement and force programs for the two servo-hydraulic actuators. An acrylic chamber which contains the test samples and maintains an environment similar to that of the mouth was constructed. Natural or artificial saliva maintained at 37 degrees C is continuously circulated through the chamber. The time to complete a single chewing cycle was decreased by eliminating that part of the cycle where no force is produced. This enables the chewing rate to be increased to 4 cycle/s. The wear produced in the artificial mouth was found to have a high correlation with clinical wear if 250000 cycles in the artificial mouth are assumed to be equivalent to one year in the human mouth. View full abstract»

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  • Optical determination of dental pulp vitality

    Page(s): 346 - 352
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    The feasibility of employing photoplethysmography and pulse oximetry to assess the status of blood circulation in dental pulp was explored. A simple photometer that measures diffuse light transmission at 575 nm was built to record tooth plethysmograms and the ability to distinguish the vital from the surgically devitalized teeth of a dog using plethysmography was demonstrated. As an extension of the photoplethysmographic technique, red-infrared pulse oximetry applied to the measurement of the oxygen saturation (SO 2) of blood in the pulp was examined using an in vitro test setup. Results suggest that the measurement of relative SO 2 changes is feasible, but standard dual-wavelength pulse oximetry does not allow determination of SO 2 independent of tooth geometry and sensor placement. Practical issues concerning the design of an optical vitalometer capable of reliably detecting the tooth pulp plethysmogram are discussed. View full abstract»

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  • pH measurements with an ion sensitive field effect transistor in the mouth of patients with xerostomia

    Page(s): 353 - 356
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    A transistor pH electrode (ion-sensitive field-effect transistor), placed in the upper dentures of xerostomia patients and five healthy volunteers, was used to register pH changes in five-, six-, and seven-day-old dental plaque. A mouth rinse with a 10% sucrose solution caused a pH fall of about three-decades. A significant difference in the duration of critical plaque pH was observed; in xerostomia patients, a 10% longer period of pH <5.7 was registered during 60 min following a sucrose rinse. Normal oral functions were not influenced by the denture containing the integrated electrode. Both in vitro and in vivo tests showed remarkable electrode stability. Materials and measurement methods are described. View full abstract»

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  • Application of digital image analysis in dental radiography for the description of periapical bone lesions: a preliminary study

    Page(s): 357 - 359
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    The use of digital image analysis in dental radiography for the description of periapical bone lesions is described. This technique circumvents the problem of observer variability and can eventually be used for the quantitative assessment of bone lesions. Since periapical bone lesions appear on a radiography as dark areas compared to the surrounding tissues, an edge-detection method was developed to extract the boundaries between anatomy and pathology. The original data were transformed in such a way that only the outlines remained. The lesion was assumed to be demarcated by a continuous outline, so all the contour points not being part of a continuous outline were excluded. With only limited operator interaction, the lesion contour could be projected successfully onto the original image. The result was a simplified diagnostic examination process promising a higher degree of objectivity in periapical bone lesion detection. It is concluded that the results encourage further development of image processing techniques that would yield definitive detection and diagnosis of periapical bone lesions. View full abstract»

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  • Measurements of dental cast profile and three-dimensional tooth movement during orthodontic treatment

    Page(s): 360 - 365
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    A system developed for measuring three-dimensional profiles of dental casts and three-dimensional tooth movement during orthodontic treatment is described. The profile measurement is based on a triangulation method which detects a laser spot on a cast using an image sensor. The system is computer-controlled and designed to achieve the depth and lateral resolutions of 0.05 mm and 0.1 mm, respectively, within a depth range of 25 mm. The movements of teeth, including rotations, were obtained by means of three-dimensional registration of tooth profiles using a computer between casts that were serially taken at different stages of the treatment. Measurements on patients over periods of 70 to 190 days revealed that this technique is capable of quantifying the difference in movements due to orthodontic therapeutics. View full abstract»

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  • Real-time sensing of tooth position for dental digital subtraction radiography

    Page(s): 366 - 378
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1228 KB)  

    Dental digital subtraction radiography and accurate repositioning of the patient and X-ray source in order to facilitate correct diagnostics of bone loss are considered. Present mechanical repositioning systems do not allow radiography of posterior teeth and are uncomfortable for the patient. A repositioning system having a six degree-of-freedom position sensor and a robot arm with an X-ray source is proposed. A mathematical model for the system is given, and the robot arm solution is obtained based on patient position. An error analysis is performed in order to determine the influence of sensor and robot errors on system accuracy. A series of experiments to determine sensor noise and accuracy are described. These tests showed relatively small errors over the work envelope of the sensor. Further tests showed that there is no adverse effect due to the presence of metal work in the patient's mouth. The high bandwidth of the sensor may allow real-time tracking of small movements of the patient's head. View full abstract»

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  • A beamformer for the acquisition of evoked potentials

    Page(s): 379 - 382
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    Evoked potential (EP) measurements using a delay and sun beamformer acquisition system are described. This system has the potential for significantly improving the signal/noise ratio (SNR) in EP measurements. The performance of the beamformer is characterized in terms of the number of electrodes and cross-channel correlation. When compared to conventional ensemble averaging, the beamformer reduces the number of response repetitions required to achieve a given SNR by a factor which approaches the number of channels in the acquisition system. View full abstract»

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  • Reconstruction of out-of-plane cardiac displacement patterns as observed on the chest wall during various phases of ECG by capacitance transducer

    Page(s): 383 - 385
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    The out-of-plane displacements due to cardiac action were measured on the chest wall by an electronic distance measurement technique which is based on the variation of the capacitance between the probe and moving surface. The displacements were measured at 36 locations over the entire cardiac region along with ECG (electrocardiogram) measurements and were directly fed to an IBM PC/AT computer after analog-to-digital conversion. From these data, the displacement patterns for the whole region during the complete cardiac cycle could be reconstructed in a perspective view. The sequential analysis of the displacements shows the details of the cardiac events. and the results obtained are in agreement with other techniques. The averaged displacements over various regions of the heart for normal subjects are also presented. The data acquisition system and measurement results are presented and discussed. View full abstract»

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  • A qualitative approach to cell growth modeling and simulation for cancer chemotherapy

    Page(s): 386 - 389
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    A qualitative model of cell growth that is based on qualitative process theory is presented. The model can be used to analyze the effects of the interaction of antiproliferative drugs on cells when the effects of each specific drug are known, which is useful when designing multidrug protocols for optimal cancer treatment. This model encompasses both structural and behavioral aspects. This makes it suitable for drawing conclusions about differences among different types of cell growth and about system behavior under different situations. adding some significant options with respect to closed-form cell cycle models. Moreover, qualitative modeling, unlike closed-form modeling, allows causal explanations of events: in this respect, the qualitative simulation presented-based on reasoning in terms of processes, individual views. and history limits-makes causes of specific behaviors even clearer than qualitative simulation based on constraints. This model is able to adapt to the amount of information supplied by the user: if this is scarce (only relating to the cell cycle phase on which each drug acts), the model will produce a simulation in which only cell cycle phase information for the combination is present; if the information supplied is more detailed, the simulation output will be more detailed as well. View full abstract»

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  • Comments, with reply, on "Point source nerve bundle stimulation: effects of fiber diameter and depth on simulated excitation" by K.W. Altman and R. Plonsey

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    The commenter questions some assertions made in the above-mentioned work by K.W. Altman and R. Plansey (see ibid., vol.37, p.688-98, 1990), which describes a simulation study relating the electrical excitability of nerve axons to their diameter and depth in the bundle. The commenter also points out the lack of experimental validation of their simulation work as well as their ignoring the membrane capacitance and strength/duration relationship. In their reply, the authors make clear that in the paper they evaluated a strength/diameter relationship that describes a measure of the relative propensity for activation and they examined how this relationship changes as a function of depth within the nerve bundle.<> View full abstract»

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Aims & Scope

IEEE Transactions on Biomedical Engineering contains basic and applied papers dealing with biomedical engineering. Papers range from engineering development in methods and techniques with biomedical applications to experimental and clinical investigations with engineering contributions.

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Editor-in-Chief
Bin He
Department of Biomedical Engineering