Biomedical subjects

J B Ludlow

Publications and source records attributed to J B Ludlow.

At least 37 records · Page 2Linked to original sources

PubMed2001

Generation of TACT image slices using different reconstruction algorithms: effects on natural caries detection.

OBJECTIVE: The purpose of this study was to determine whether the method of reconstruction of tuned-aperture computed tomography (TACT) slices has an influence on observer performance in caries detection. STUDY DESIGN: Eight images of each of 40 extracted posterior teeth were acquired by using a solid state intraoral detector. Stacks of tuned-aperture computed tomography slices were generated by using the minimum and average reconstruction methods. Slices of the 2 experimental conditions were presented to 8 observers in a balanced order. Images were viewed on a high-resolution 21-in color monitor. Observers scored the presence/absence of caries by using a 5-point confidence scale. Observers' assessments were compared with histologic examinations of tooth sections. Receiver operating characteristic curves measured observers' diagnostic performance. Analysis of variance was used to test for possible significant differences between observers and between experimental conditions. Sensitivity, specificity, accuracy, and interobserver reliability were also calculated. RESULTS: No statistically significant differences between the 2 methods of reconstruction were found for the detection of either occlusal (P =.07) or proximal (P =.52) caries. Interobserver reliability was similar for both experimental conditions. CONCLUSIONS: The minimum and average methods of TACT reconstruction provide comparable performances for caries detection tasks.

Algorithms↗

PubMed2001

Evaluation of a bioadhesive device for the management of aphthous ulcers.

BACKGROUND: Aphthous ulcers are common and painful. Current treatments are palliative and focused on pain reduction. This article reports on the clinical trials of a novel, bioadhesive treatment modality. METHODS: Formulations of 2-octyl cyanoacrylate, or 2-OCA, tissue adhesive were tested in two blinded, sham-controlled studies. A total of 200 patients with a single, painful aphthous ulcer were entered. In the first study, the investigators applied the tissue adhesive to the aphthous ulcers; in the second trial, the subjects themselves applied the tissue adhesive to their ulcers. The authors evaluated the safety, pain reduction and healing times associated with the bioadhesive. RESULTS: The bioadhesives were found to be safe with no significant adverse events. The short- and long-term pain reduction achieved with an investigator-applied adhesive was significant compared with that achieved with a sham device (P = .024 and P = .036, respectively). The investigator-applied adhesive also demonstrated a significant reduction in healing time over the sham device (P = .021). In the definitive trial, in which the subjects themselves applied the tissue adhesive, pain reduction with a predicate device approved by the U.S. Food and Drug Administration and with the bioadhesive was significantly better than with a sham application (P < .05). The active devices were not statistically different from each other (P = .37). No difference in healing time was evident between devices and the sham. CONCLUSIONS: The formulations of 2-OCA tissue adhesives tested were safe and demonstrated statistically significant pain reduction when applied by either the investigators or the subjects. CLINICAL IMPLICATIONS: Our clinical trials indicate that these novel tissue adhesives could be used as nonprescription, over-the-counter devices to provide significant pain relief for patients suffering from aphthous ulcers.

Administration, Topical↗

PubMed2000

Updated quality assurance self-assessment exercise in intraoral and panoramic radiography. American Academy of Oral and Maxillofacial Radiology, Radiology Practice Committee.

This updated self-assessment exercise for the dental team by the Radiology Practice Committee of the American Academy of Oral and Maxillofacial Radiology is intended to produce the highest quality diagnostic radiographs while keeping patient exposure as low as is reasonably achievable. To continue to provide the best radiographic services to patients, those involved in dental radiography need to be aware of the latest changes and advances in dental radiography and need to use them in their practice.

Credentialing↗

PubMed2000

Intraoral digital imaging documenting recurrent aphthous ulcer healing in 2-octyl cyanoacrylate versus sham-treated lesions.

OBJECTIVE: A device to standardize imaging was coupled with a digital intraoral camera to investigate the efficacy of 2-octyl cyanoacrylate (OC) tissue adhesives on the healing of minor aphthous ulcers. STUDY DESIGN: Forty-two subjects were enrolled in a patient-blinded, sham-controlled study assessing the effects of 2-OC formulations on ulcer size and healing time. Daily images were made until ulcers were healed. Ulcer image outlines were traced by using a mouse, and ulcer areas were automatically calculated. RESULTS: A mean difference of -0.15 mm(2) was seen between baseline and next-day measurements (P =.48). The cumulative ulcer area was meaningfully reduced in one OC group compared with the sham group (P =.04). Time to healing was reduced by 1.9 days in the same group compared with the sham group (P =.02). CONCLUSIONS: The use of digital intraoral images with an integrated measurement reference enhances the accuracy and reproducibility of measurements. 2-OC adhesives hold promise as devices to promote healing of recurrent aphthous ulcers.

Cyanoacrylates↗

PubMed2000

A comparison of Web page and slide/tape for instruction in periapical and panoramic radiographic anatomy.

Self-guided slide/tape (ST) and web page (WP) instruction in normal radiographic anatomy of periapical and panoramic images is compared using objective test performance and subjective preference of freshman dental students. A class of seventy-four students was divided into a group studying anatomy in periapical images using WP and a group studying similar ST material. In a modified cross-over design the groups switched presentation technologies to learn anatomy in panoramic images. Students completed self-administered on-line quizzes covering WP materials and conventional quizzes for ST material. Students also completed a voluntary survey. Mean quiz performance identifying matched anatomic features in PA (n = 26) and panoramic images (n = 35) was excellent (96.9%) and not different between image types (p = 0.12) or presentation technologies (p = 0.81). Students preferred WP for accessibility, ease of use, freedom of navigation, and image quality (p < .01). Student comfort level with the quiz formats of the two technologies was not different (p = 0.11). Students experienced a higher rate of mechanical and logistical problems with ST than with WP technology. While 71 percent of the students preferred WP technology, this preference appears to be related to ease of use and facilitation of flexible learning styles rather than improved didactic performance.

Audiovisual Aids↗

PubMed1999

Detection of caries with conventional digital imaging and tuned aperture computed tomography using CRT monitor and laptop displays.

OBJECTIVE: The purpose of this study was to compare the diagnostic performance of conventional digital images and tuned aperture computed tomography (TACT) slices in caries detection through use of cathode-ray tube monitor and laptop displays. STUDY DESIGN: Forty-two extracted posterior teeth were mounted and imaged with a direct digital radiography system. Conventional digital bitewing projections and TACT slices were acquired. Images were viewed on a high-resolution cathode-ray tube monitor and on an active-matrix laptop display. Eight observers assessed caries status of occlusal and proximal surfaces of the teeth using all combinations of image and display modality. Observers' assessments were compared with the results of histologic examination of tooth sections. Possible differences in receiver operating characteristic curve areas among displays, image modalities, observers, and surfaces were analyzed by means of analysis of variance. RESULTS: There was no statistically significant difference between the diagnostic performances provided by the cathode-ray tube monitor and laptop displays in caries detection (P = .588). In addition, the performances of digital images and TACT slices were not significantly different (P = .843). CONCLUSIONS: Modern active-matrix laptop displays provide diagnostic quality for caries detection comparable to that obtainable with cathode-ray tube monitors.

Analysis of Variance↗

PubMed1999

Clinical and in vitro film quality comparison of manual and automatic exposure control in panoramic radiography.

OBJECTIVE: Automatic exposure control has been used successfully in medicine to improve image quality and reduce the number of retakes necessitated by inadequate operator selection of exposure factors. The purpose of this study was to assess the influence of automatic exposure control on panoramic image quality. STUDY DESIGN: A total of 352 patients were imaged with either the OP 100 or the Orthophos Plus panoramic machine. An expert consensus panel judged film quality using a 5-point scale. Differences in quality that would have resulted from the use of operator-determined exposures were calculated through use of an algorithm validated with test images of a human phantom. RESULTS: McNemar's test demonstrated significant improvements in quality with automatic exposure control (P = .001) in comparison with manual exposure control. No quality difference was found between the 2 machines (P = .9661). Manual exposure selection by oral and maxillofacial radiology residents was better than selection by technologists and assistants (P = .006). CONCLUSIONS: This study confirms the utility of automatic exposure control for panoramic radiography.

Adult↗

PubMed1999

Performance of film, desktop monitor and laptop displays in caries detection.

OBJECTIVES: To compare film, desktop monitor and laptop displays of digitized film images for accuracy of caries detection. METHODS: Sixty-four extracted teeth were mounted in eight models and radiographed with E-speed bitewing film. Films were digitized and displayed on a desktop monitor and a laptop display. Six observers scored the presence or absence of enamel and dentinal caries for each proximal surface for film, desktop and laptop displays. Results were compared with the histology of ground sections. ROC curve areas for each display mode and observer were assessed for significant differences with ANOVA. RESULTS: Diagnostic accuracy for proximal surface caries detection was not significantly different for conventional film or desktop monitor and laptop displays for detection of enamel caries (P = 0.9112) or dentin caries (P = 0.2796). CONCLUSIONS: Current laptop active matrix liquid crystal displays provide diagnostic quality for caries detection comparable with conventional film and desktop monitor displays.

Analysis of Variance↗

PubMed1999

Two- and three-dimensional imaging modalities for the detection of caries. A comparison between film, digital radiography and tuned aperture computed tomography (TACT).

OBJECTIVES: To compare the diagnostic performance provided by two- (film and digital radiography) and three-dimensional imaging modalities (TACT slices and TACT pseudoholograms) in the detection of primary caries. METHODS: Forty-two extracted human posterior teeth were mounted and imaged with conventional film and direct digital radiography. Free-hand positioning of a dental X-ray source was used for all exposures. From the digital images, iteratively restored TACT slices and TACT pseudoholograms were generated. Film images were viewed on a viewbox. Digital format images were viewed on a high-resolution monitor. Eight observers used a five-point scale to score the presence or absence of occlusal and proximal caries using the four image modalities. Observers' assessments were compared with the histological examination of tooth sections. Possible differences in ROC curve areas among image modalities, observers, and surfaces were assessed by ANOVA. Intra- and interobserver reliability as indicated by intraclass correlation was also calculated. RESULTS: There were no statistically significant differences between the diagnostic performances of film, digital radiography, TACT slices and TACT pseudoholograms in the detection of caries (P = 0.310). Intraclass correlation indicated the highest concordance both within and between observers when film was used for the evaluation. CONCLUSIONS: Under the experimental conditions of this study, three-dimensional TACT images did not improve caries detection over film or digital radiography. Further research should investigate the effects of imaging variables on TACT's diagnostic efficacy.

Analysis of Variance↗

PubMed1999

Cross-sectional presurgical implant imaging using tuned aperture computed tomography (TACT).

OBJECTIVES: To investigate tuned aperture computed tomography (TACT) as an alternative to conventional tomography for cross-sectional imaging of potential implant sites. METHODS: Twenty potential implant sites in three dry human mandibles were selected. Sixteen TACT basis projections were recorded on film using a linear array of source positions. Films were scanned and 20 TACT and iterative TACT slices were reconstructed using TACT Workbench software. Maximum height and width were measured on one representative slice of each site. Results were compared with the ground truth using ANOVA and Wilcoxon signed rank tests. RESULTS: The means of relative difference in maximum height were 1.55 and 1.56% for TACT and iterative TACT respectively (P = 0.8643). The means of relative difference in width were 5.96 and 6.36% for TACT and iterative TACT respectively (P = 0.4845). More than 75% measurements were within +/- 1 mm of ground truth for both modalities. CONCLUSIONS: TACT may provide an alternative to conventional tomography for dental implant imaging. Further investigations should be performed to explore factors affecting image quality.

Anatomy, Cross-Sectional↗

PubMed1999

The influence of storage conditions on film characteristics of Ektaspeed plus and Ultra-speed films.

BACKGROUND: Dental professionals were reluctant to accept Ektaspeed (Eastman Kodak Co.) intraoral film despite its X-radiation dose-sparing advantages for patients. One reason may have been Ektaspeed film's known sensitivity to long-term storage as compared with that of Ultra-speed film (Eastman Kodak Co.). In 1995, Kodak replaced Ektaspeed with Ektaspeed Plus, claiming it had better resolution and higher stability than Ektaspeed, as well as equal exposure radiation. The authors compared film response to storage condition and time for Ultra-speed and Ektaspeed Plus films. METHODS: The authors stored 10 boxes of newly produced Ultra-speed and Ektaspeed Plus film in five locations. They conducted 23 image trials over a 26-month period, exposing each film with an aluminum step-wedge under controlled conditions. After processing the film, they measured density to calculate the film's base + fog and contrast index values. RESULTS: The authors found significant differences in film type (P = .0002), processing status (P < .0001), storage location (P < .0001) and month of storage (P < .0001). They also found a film-type-by-location interaction (P < .0001) but did not find a film-type-by-processing interaction (P = .3271). Regression lines suggested that the optical density of base + fog levels rose more steeply for Ultra-speed film than they did for Ektaspeed Plus film. A significant association of decreasing contrast with increasing months of storage was seen with Ultra-speed film (P < .0001). There was a small increase in base + fog levels resulting from the use of used solutions over the course of the study. CONCLUSIONS: Ektaspeed Plus film compared favorably with Ultra-speed film under all conditions. CLINICAL IMPLICATIONS: The authors recommend the use of Ektaspeed Plus film for intraoral imaging, as its performance is comparable to that of Ultra-speed film while requiring half the X-radiation exposure to patients. Clinicians must ensure that the correct safelights and processing solutions are used before switching to the new film.

Analysis of Variance↗

PubMed1998

Quantitative radiographic follow-up of apical surgery: a radiometric and histologic correlation.

The objective of this study was to establish an objective method for evaluating the treatment outcome of apical periodontitis (AP). AP was induced in the mandibular premolars of beagle dogs and apicoectomies were performed with retrofilling. Standardized periapical radiographs were taken immediately after completion of treatment and at 6 months. Ten pairs of standardized radiographs of 33 treated roots were analyzed. Radiographs were digitized and subtracted after warping and gamma correction. Areas of AP and adjacent normal areas (N) in digitized original and subtraction images were analyzed using eight radiometric computations. These computations were compared with subjective histologic evaluation and objective quantitative histomorphometry of the periapical condition at 6 months. The average gray value for AP on the subtraction images was found to have significant correlation with both objective (multiple regression p < 0.01) and subjective histology (logistic regression p < 0.01). Digital subtraction may be a useful tool in endodontic apical surgery assessment.

Absorptiometry, Photon↗

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↗