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Biomedical subjects

D A Tyndall

Publications and source records attributed to D A Tyndall.

At least 37 records · Page 2Linked to original sources
PubMed1998

Periodontitis detection efficacy of film and digital images.

OBJECTIVE: The objective of this study was to evaluate the accuracy of alveolar crestal bone detection in a comparison of unenhanced and enhanced Sidexis (Siemens Medical Systems, Inc., Bensheim, Germany) digital images with Ektaspeed Plus (Eastman Kodak, Rochester, N.Y.) films by means of receiver operating characteristic analysis. STUDY DESIGN: More than 100 proximal and furcal areas in the anterior and posterior areas of the mandible and maxilla of each of three tissue-equivalent human skull phantoms were imaged with film, direct digital images, and contrast- and brightness-enhanced digital images. Alveolar crest status was assessed by a consensus panel of three experts who used the Delphi method and evaluated information from all of the imaging modalities concurrently. Five observers assessed all images for the presence or absence of crestal bone loss using a five-point confidence scale. Receiver operating characteristic curves were generated, and calculated areas (Az) were analyzed by means of analysis of variance. RESULTS: The expert panel determined that of 106 crestal areas, 48 were disease free and 58 exhibited bone loss greater than 2 mm apical to the cemento-enamel junction. Analysis of variance of observer Az scores showed significant differences among readers (p < 0.001) and among readings (p = 0.027), but not among modalities (p = 0.435). Mean Az values for the different modalities were as follows: Sidexis, 0.70; enhanced Sidexis, 0.71; Ektaspeed Plus films, 0.735. CONCLUSION: The Sidexis digital imaging system was not significantly different from Ektaspeed Plus film for crestal bone evaluation in this in vitro study.

Alveolar Bone Loss↗
PubMed1998

A comparison of Kodak Ektaspeed Plus film and the Siemens Sidexis digital imaging system for caries detection using receiver operating characteristic analysis.

OBJECTIVE: To evaluate the accuracy of proximal caries detection comparing enhanced and unenhanced Siemens Sidexis CCD-based digital images with Ektaspeed Plus films utilizing receiver operating characteristic analysis. STUDY DESIGN: Sixty extracted teeth (24 posterior and 36 anterior) were imaged under identical standardized geometric and exposure conditions. Six observers, using a 5-point confidence scale, rated 120 proximal surfaces for the presence or absence of carious lesions by means of three image modalities: (1) observer enhanced and (2) unenhanced Sidexis displays, and (3) Ektaspeed Plus films. The ground truth was determined by microscopic analysis of ground sections. Receiver operating characteristic curves were generated with calculated areas (AZ) analyzed with analysis of variance for effect of reader, reading, and modality. RESULTS: Analysis of variance demonstrated significant differences among readers, readings and modalities (mean square values of 0.012, 0.005, 0.004, F ratios of 13.604, 5.329, 5.100; p = values of 0.001, 0.043, and 0.030, respectively). Post-hoc paired comparisons of modalities using Tukey's statistic demonstrated that only film and enhanced Sidexis images were different from each other (p = 0.024). AZ scores were 0.7650, 0.7499, and 0.8008 respectively, for unenhanced Sidexis, enhanced Sidexis, and Ektaspeed Plus film. CONCLUSION: Unenhanced digital Sidexis images were equivalent to film for the detection of proximal caries in this in vitro study. Observer enhanced Sidexis images exhibited a statistically significant lower diagnostic accuracy than the unenhanced digital and film images.

Analysis of Variance↗
PubMed1998

The effects of restorative material and location on the detection of simulated recurrent caries. A comparison of dental film, direct digital radiography and tuned aperture computed tomography.

OBJECTIVES: To explore the effects of restorative material and lesion location on the detection of recurrent caries using intra-oral film, direct digital radiography and unprocessed and iteratively restored tuned aperture computed tomography (TACT) images. METHODS: An in vitro model with simulated lesions in half the surfaces studied was used. Lesions of varying sizes were created at either the intersection of the facial or lingual wall and the gingival floor or on the gingival floor midway between the facial and lingual walls in the proximal boxes of 24 molar teeth with MOD inlay preparations that had been restored with amalgam, radiopaque composite or radiolucent composite. RESULTS: Sensitivity and specificity values based on restoration were: amalgam: 59 and 87%; radiopaque composite: 68 and 78%; radiolucent composite: 36 and 93%; based on lesion location, mid-cervical floor region: 51 and 97%; point angle region: 44 and 90%; based on imaging modality, film: 40 and 85%; digital: 44 and 76%; unprocessed TACT slices: 50 and 87%, iteratively restored TACT images: 83 and 96%. Iteratively restored TACT images had the best intra- and inter-reader agreement. CONCLUSIONS: The use of restorative materials with a density approximating that of enamel is more effective for the detection of recurrent caries. Lesions located at the buccal point angle or mid-gingival floor are more easily detected than at the lingual point angle region. The sensitivity and specificity of TACT and iteratively restored TACT images were superior to those of film and direct digital images.

Analysis of Variance↗
PubMed1998

Extraoral radiographic imaging of primary caries.

OBJECTIVE: To evaluate three extra-oral radiographic imaging modalities as alternatives to conventional intra-oral film for the detection of primary caries. METHODS: Sixty-four extracted primary molar teeth with eighty-five carious lesions were radiographed using D-speed film (N = 8), panoramic imaging (N = 8), multidirectional tomography (N = 8), and linear tomography (N = 8). Eight trained observers were asked to identify the presence or absence of caries on each surface using a five point scale. Ground sections were viewed microscopically to determine truth. ROC curve areas (Az) were generated from observer responses and assessed with ANOVA. RESULTS: Average of Az for the detection of combined results for proximal and occlusal lesions were 0.70 for D-speed, film, 0.58 for linear tomography, 0.64 for both multidirectional tomography, and panoramic film. Turkey's pairwise comparisons of Az revealed that D-speed film was significantly better than linear tomography (P = 0.0039). When data were divided into proximal and occlusal surfaces the variability due to modality remained significant (P = 0.0003 and P = 0.0024 respectively). Turkey's comparisons for proximal surfaces revealed that D-speed film was significantly better than linear tomography (P = 0.0007), multidirectional tomography (P = 0.0010) and panoramic radiography (P = 0.0100). For detection of occlusal lesions, multidirectional tomography was significantly better than linear tomography (P = 0.0075) and panoramic radiography (P = 0.0034), but not significantly different from D-speed film (P = 0.2337). CONCLUSIONS: Multidirectional tomography and panoramic radiography performed as well as intra-oral D-speed film for the combined assessment of proximal and occlusal caries in the model used. when proximal surfaces were evaluated alone, D-speed film was significantly better. For occlusal caries there was no statistically significant difference between multidirectional tomography and D-speed film.

Analysis of Variance↗
PubMed1998

Tuned aperture computed tomography and detection of recurrent caries.

This study compared the diagnostic efficacy of four imaging modalities for the detection of artificially induced recurrent caries: intraoral film, direct digital bitewing images, tuned apertuce computed tomography (TACT) slices and iteratively restored TACT images using an in vitro model. Twenty-four posterior teeth were prepared for MOD inlay restorations. These were then restored with different restorative materials (amalgam, Herculite and Durafill). Lesions were simulated in half the number of surfaces studied. These lesions were created either at the intersection of the facial or lingual walls and the gingival floor or on the gingival floor midway between the facial and lingual walls in the proximal boxes of the MOD restorations. Analysis of observations from 8 observers using ROC curve reveal the superior diagnostic efficacy with TACT iteratively restored images (Az for TACT iteratively restored images = 0.9171, TACT slices = 0.7052, Film = 0.6608, direct digital images = 0.5979). ANOVA revealed significance with respect to the imaging modality used (p < 0.0001). The results suggest that TACT images hold promise as a more effective imaging modality than film or direct digital systems for detection of recurrent caries.

Analysis of Variance↗
PubMed1997

TACT imaging of primary caries.

OBJECTIVE: Tuned-aperture computed tomography, a new method for creating 3-D radiographic information based on optical aperture theory, was evaluated for diagnostic efficacy in primary caries detection. STUDY DESIGN: Sixty-four extracted teeth with 89 carious lesions were imaged with D-speed film, direct digital, and TACT modalities. A commercially available, 8-bit, charge-coupled device was used in the later two modalities. Six trained observers were asked to identify the presence or absence and depth of interproximal and occlusal lesions for all three modalities. The teeth were sectioned and examined microscopically to determine ground truth. Logistic regression analysis was performed for all three imaging systems for the detection task. Analysis of variance was used for depth determination. Detection of lesion, depth of lesion accuracy, and time for diagnosis were also examined. RESULTS: For caries detection TACT and film were not different (p = 0.2216) with the Wald statistic. Film and TACT were significantly more accurate than the digital system (p = 0.0001). Scheffe's post hoc test revealed that TACT and film were more accurate than the direct digital system for determining lesion depth (p = 0.05) but not statistically different when compared with each other. The detection data were substantiated further by receiver operating characteristic analysis that demonstrated similar statistical relationships. Time required per diagnosis was not shown to be statistically different among the three imaging modalities. CONCLUSIONS: We conclude for caries detection and depth determination that TACT could not be distinguished from film despite the significant relative loss of information capacity in the charge-coupled device receptor. The relatively poorer performance yielded by the digital control images suggests that increased information capacity associated with more modern charge-coupled device detectors may improve diagnostic performance for both direct digital and TACT displays over that demonstrated in this investigation.

Analysis of Variance↗
PubMed1997

Tuned-aperture computed tomography (TACT). Theory and application for three-dimensional dento-alveolar imaging.

OBJECTIVES: To introduce a new method for creating three-dimensional (3-D) radiographic displays based on optical aperture theory known as tuned-aperture computed tomography (TACT). With a number of advantages over conventional plain film and tomographic imaging. METHODS: The TACT algorithm and some of its capabilities are explained and published with results of in vitro simulations produced from a well-tested multi-tube tomosynthetic x-ray system. Examples of TACT reconstructions of a tooth with naturally occurring caries which were produced from multiple projections and generated with a new servo-controlled single-tube prototype are illustrated. Current imaging strategies in dentistry and their shortcomings in the detection of dento-alveolar disease are reviewed. Pertinent theoretical aspects of the TACT reconstruction algorithm are described and dental applications discussed in light of these limitations. RESULTS: Results of several published in vitro investigations derived from a prototype TACT system are referenced. Sample images of a tooth with naturally occurring caries derived from an even newer system are displayed. All data are consistent with the hypothesis that TACT imaging yields diagnostic performance either comparable, or superior, to that obtainable from conventional control modalities depending on the diagnostic task. Moreover, all investigations cited demonstrated conclusively the obvious theoretical benefits associated with the acquisition of multiple projections in three dimensions. CONCLUSIONS: TACT shows promise as a supplement to film-based dental radiography and as a digital alternative to conventional tomographic systems used in dento-alveolar applications.

Algorithms↗
PubMed1996

Comparison of film, direct digital, and tuned-aperture computed tomography images to identify the location of crestal defects around endosseous titanium implants.

This study compared diagnostic performance obtained from two-dimensional and three-dimensional x-ray images. The latter were produced with a new tomosynthetic method based on aperture theory called tuned-aperture computed tomography. Seven human cadaver mandibular segments containing a total of 20 endosseous implants with a small randomly positioned alveolar crestal defect at each implant site were imaged in two dimensions with periapical film and with a charge-coupled digital detector, and digitally with the same detector in three dimensions with tuned-aperture computed tomography and subtracted tuned-aperture computed tomography techniques. Seven trained dentists viewed randomized displays of all modalities. Outcomes of the diagnostic task of identifying the locations of crestal defects were quantified with accuracy, confidence, and time performance measures. Analyses of variance demonstrated that differences between either three-dimensional technique and either two-dimensional modality were significant for all measures (p < 0.001). These findings suggest that clinically applied TACT methods hold promise as an improvement over the status quo.

Alveolar Bone Loss↗
PubMed1995

Video-based teleradiology for intraosseous lesions. A receiver operating characteristic analysis.

Immediate access to off-site expert diagnostic consultants regarding unusual radiographic findings or radiographic quality assurance issues could be a current problem for private dental practitioners. Teleradiology, a system for transmitting radiographic images, offers a potential solution to this problem. Although much research has been done to evaluate feasibility and utilization of teleradiology systems in medical imaging, little research on dental applications has been performed. In this investigation 47 panoramic films with an equal distribution of images with intraosseous jaw lesions and no disease were viewed by a panel of observers with teleradiology and conventional viewing methods. The teleradiology system consisted of an analog video-based system simulating remote radiographic consultation between a general dentist and a dental imaging specialist. Conventional viewing consisted of traditional viewbox methods. Observers were asked to identify the presence or absence of 24 intraosseous lesions and to determine their locations. No statistically significant differences in modalities or observers were identified between methods at the 0.05 level. The results indicate that viewing intraosseous lesions of video-based panoramic images is equal to conventional light box viewing.

Analysis of Variance↗
PubMed1995

Temporomandibular joint imaging: a comparative study of diagnostic accuracy for the detection of bone change with biplanar multidirectional tomography and panoramic images.

This in vitro investigation compares biplanar (sagittal and coronal) temporomandibular joint images produced by multidirectional tomographic and panoramic techniques for diagnostic accuracy in the detection of simulated degenerative lesions. A series of dentin chips placed at four locations on the head of a temporomandibular joint condyle in a dried human skull were imaged with tomographic and panoramic modalities. Equal numbers of images with and without chips were scored by four examiners with the use of confidence levels for presence or absence of the lesion. To assess intra-examiner reliability, each examiner viewed one of the modalities twice. Responses were assessed by generating receiver operating characteristic curves and analyzing the area (A(z)) under the curves with analysis of variation methods. Biplanar tomography provided significantly more accurate assessment of condylar lesions than biplanar panoramic images (p = 0.007). No statistical difference by location (p = 0.592) was found. The effects of observer and repeated observation were marginally significant at p = 0.046 and p = 0.030, respectively.

Analysis of Variance↗
PubMed1995

Analysis of condylar position change on digitally subtracted Orthophos P-4 and Sectograph zonogram images.

The purpose of this study was to compare the accuracy of two single-image techniques that provide parasagittal views of the temporomandibular joint. Orthophos program 4 and Sectograph zonographic techniques were evaluated using digital subtraction to measure 1-, 2-, and 3-mm shifts of condylar position in horizontal or vertical planes. Precise repositioning of a human skull was facilitated by laser alignment beams. Statistically significant differences between radiographic techniques reflected the tendency for overestimating of shifts with program 4 and underestimation with zonographic techniques. Pooled mean difference values were 0.12 mm for program 4 images of -0.17 mm for zonograms. Program 4 images and zonograms produced with precise repositioning of anatomy approached the accuracy of tomograms and may prove useful for evaluating parasagittal alterations in condylar position in pretreatment and posttreatment radiographs.

Analysis of Variance↗
PubMed1995

A comparison of zonography, multidirectional tomography, and biplanar panoramic images for detection of simulated condylar arthropathy of the temporomandibular joint.

Three imaging modalities were compared for diagnostic efficacy in the detection of simulated osteoarthritic lesions created by a series of dentin chips placed at four locations on the head of a temporomandibular joint condyle in a dry human skull. The modalities included panoramic-based biplanar temporomandibular joint views, parasagittal linear zonography, and sagittal-view, computer-controlled, multidirectional tomography. Equal numbers of images with and without chips were viewed by six examiners. Observers recorded the presence or absence of lesions on a 100-point confidence scale. Responses were used to construct ROC curves. Pooled data sorted by modality produced areas under the curves of 0.7421 (zonography), 0.6627 (panoramic imaging), and 0.7478 (tomography). No statistically significant difference in lesion detection was found among the three modalities, between observers, or within observers.

Analysis of Variance↗
PubMed1994

Analysis of condylar position changes: a test of validity of posteroanterior cephalometric and 20-degree lateral cephalometric techniques enhanced by digital subtraction.

This preclinical study was designed to evaluate 20-degree lateral cephalometric and posteroanterior cephalometric techniques with digital subtraction enhancement for their ability to detect 1-, 2-, and 3-mm shifts in condylar position in two of three planes of space (horizontal or transverse and vertical). The model used was a dry human skull with a complete mandible mounted on a microscopic stage with positioning accuracy to 0.1 mm in x, y, and z planes. Analysis of variance showed no significant difference from expected values in the transverse plane (posteroanterior cephalogram only). There were significant differences in the sagittal plane (20-degree lateral cephalogram only) for the 2- and 3-mm shifts (P < .001). There were no significant differences among expected values in the vertical plane for individual increments or for increment comparisons. The magnitude of standard deviations and of the absolute value of differences indicates markedly increased variability for both techniques as compared to tomograms produced with cephalostat repositioning. The authors conclude that even with precise repositioning and digital subtraction enhancement, cephalometric radiographs are inadequate for clinical monitoring of condylar position.

Analysis of Variance↗
PubMed1993

MRI effects on craniofacial size and crown-rump length in C57BL/6J mice in 1.5T fields.

Previous studies have shown magnetic resonance imaging to be potentially teratogenic for eye development. An investigation was undertaken to ascertain the effects of 1.5 Tesla magnetic resonance imaging fields on crown-rump length and craniofacial perimeter, two less sensitive teratologic end points of the C57BL/6J mouse. A sham control and two experimental groups of dams (N = 12, 11, 12) placed in different magnet locations were exposed to magnetic resonance imaging fields under clinically realistic conditions. A T-2 weighted spin-echo technique of 36-minutes duration was used on each dam. Crown-rump length was chosen because it is a standard measure of embryotoxicity. Craniofacial perimeter was evaluated because of its relationship to the anterior neural plate, the same region in the developing embryo that gives rise to the eyes. Magnetic resonance imaging fields were found to produce crown-rump and craniofacial perimeter measures smaller than control animals (p < 0.05) when exposed at the isocenter (p = 0.038 and 0.008 respectively). Groups exposed to magnetic resonance imaging fields at the magnet entrance showed p values of 0.004 and 0.053 respectively. The results confirmed magnetic resonance imaging teratogenicity in the C57BL/6J mouse and demonstrates the need for further experimental investigation to ascertain the clinical safety of magnetic resonance imaging for humans.

Abnormalities, Radiation-Induced↗
PubMed1993

Assessing condylar changes with digital subtraction radiography.

Transcranial radiographs of the temporomandibular joint with and without simulated pathology were compared with digital subtracted and histogram equalized images of the same joints. Subtracted images had specificity and sensitivity values of 0.83 and 0.76 respectively, compared with values of 0.42 and 0.54 for conventional radiographs. It was concluded that digital subtraction radiography has the potential to increase the diagnostic yield of transcranial temporomandibular radiography for bony changes to the condylar head.

Chi-Square Distribution↗
PubMed1992

Positional changes of the mandibular condyle assessed by three-dimensional computed tomography.

This investigation was designed to test the validity and reliability of three-dimensional computed tomography (3-D CT) for quantification of positional changes of the condyle in a laboratory model. The model consisted of a mounted dried human skull and a mandibular condyle attached to a micromanipulator. Controlled changes in condylar position were made and the condyle/fossa was imaged. Positional changes were measured by triangulation methods based on specific 3-D CT landmarks. The data were analyzed using descriptive statistics, analyses of variance to evaluate the sources of variability, and linear contrasts to evaluate the differences between observed and expected values. The results indicated that selection of appropriate anatomic landmarks for assessment of movement influences technique accuracy. The data also indicate that 3-D CT is most accurate in detecting inferior condylar movements. Lateral and posterior movements were assessed with less accuracy than the inferior positional changes. The clinical significance of these differences has yet to be determined.

Analysis of Variance↗
PubMed1992

Assessment of external root resorption using digital subtraction radiography.

Digital subtraction radiography was investigated for its capability to detect and quantify experimentally produced external root resorptive defects in teeth. Using a long source to object X-ray technique and E-speed film, serial radiographs of teeth with artificial lesions in a dry human skull (soft tissue simulated) were obtained. Receiver operating characteristic analysis was used to evaluate the diagnostic performance for each imaging system (conventional versus subtraction). To explore the quantitative assessment potential of digital subtraction radiography, images were produced after sequential demineralization by HCl. The acid solution was analyzed for calcium concentration by atomic absorption spectrophotometry. Three-dimensional histogram quantification for each subtracted image was performed. In overall performance for detecting experimentally produced external root resorption, digital subtraction radiography was found to be significantly superior to conventional radiography. In addition, digital subtraction radiography can provide quantification of experimentally produced external root resorptive defects.

Humans↗