Radiographic endodontic working length estimation: comparison of three digital image receptors.

OBJECTIVE: This in vitro study was conducted to evaluate the accuracy of the Schick wireless image receptor compared with 2 other types of digital image receptors for measuring the radiographic landmarks pertinent to endodontic treatment. STUDY DESIGN: Fourteen human cadaver mandibles with retained molars were selected. A fine endodontic file (#10) was introduced into the canal at random distances from the apex and at the apex of the tooth; images were made with 3 different #2-size image receptors: DenOptix storage phosphor plates, Gendex CCD sensor (wired), and Schick CDR sensor (wireless). Six raters viewed the images for identification of the radiographic apex of the tooth and the tip of a fine (#10) endodontic file. Inter-rater reliability was also assessed. RESULTS: Repeated-measures analysis of variance revealed a significant main effect for the type of image receptor. Raters' error in identifying structures of interest was significantly higher for Denoptix storage phosphor plates, whereas the least error was noted with the Schick CDR sensor. A significant interaction effect was observed for rater and type of image receptor used, but this effect contributed only 6% (P < .01; eta(2) = 0.06) toward the outcome of the results. CONCLUSIONS: Schick CDR wireless sensor may be preferable to other solid-state sensors, because there is no cable connecting the sensor to the computer. Further testing of this sensor for other diagnostic tasks is recommended, as well as evaluation of patient acceptance.

How does signal fade on photo-stimulable storage phosphor imaging plates when scanned with a delay and what is the effect on image quality?

OBJECTIVE: The goals of this in vitro study were to determine the effect of signal fading of DenOptix photo-stimulable storage phosphor imaging plates scanned with a delay and to determine the effect on the diagnostic quality of the image. In addition, we sought to correlate signal fading with image spatial resolution and average pixel intensity values. STUDY DESIGN: Forty-eight images were obtained of a test specimen apparatus and scanned at 6 delayed time intervals: immediately scanned, 1 hour, 8 hours, 24 hours, 72 hours, and 168 hours. Six general dentists using Vixwin2000 software performed a measuring task to determine the location of an endodontic file tip and root apex. One-way ANOVA with repeated measures was used to determine the effect of signal fading (delayed scan time) on diagnostic image quality and average pixel intensity value. RESULTS: There was no statistically significant difference in diagnostic image quality resulting from signal fading. No difference was observed in spatial resolution of the images. There was a statistically significant difference in the pixel intensity analysis of an 8-step aluminum wedge between immediate scanning and 24-hour delayed scan time. CONCLUSION: There was an effect of delayed scanning on the average pixel intensity value. However, there was no effect on image quality and raters' ability to perform a clinical identification task. Proprietary software of the DenOptix digital imaging system demonstrates an excellent ability to process a delayed scan time signal and create an image of diagnostic quality.

The use of radiation dose-reduction techniques in the practices of dental faculty members.

X-ray exposure to dental patients has been significantly reduced by the introduction of speed group E intraoral film, rectangular beam limitation, long position indicating devices (PIDs), and rare-earth intensifying screens for extraoral radiography. Research indicates that many dentists do not use these techniques. However, schools of dentistry have implemented them to varying degrees for many years, so this investigation was conducted to determine the extent to which dental school faculty members use these materials and techniques in their own practices. Comparisons were made between full- and part-time instructors, those in practice for fifteen years or less and those in practice for more than fifteen years, and those with postgraduate education versus those with no formal education beyond dental school. The significance of differences was measured with chi-square analysis. The results indicate that dentists with faculty appointments utilize dose-reducing techniques to degrees that are comparable to or greater than reported usage by non-dental faculty practitioners. Faculty dentists in practice fifteen years or less are more likely than their older colleagues to use E-speed film (p = 0.001), whereas those in practice more than fifteen years are more likely to use longer PIDs (p = 0.049). Greater acceptance of these practices by faculty may lead to reinforcement of their use in the clinical education of dental students.

Comparison of panoramic radiography and panoramic digital subtraction radiography in the detection of simulated osteophytic lesions of the mandibular condyle.

OBJECTIVE: The aim of this study was to compare panoramic temporomandibular joint radiography, unenhanced and color-enhanced digital-subtraction radiography with respect to detectability of simulated osteophytic lesions of the mandibular condyle. METHODS: Three dry human skulls with no obvious temporomandibular joint pathology were selected. Four sizes of bone chips were placed on the anterior aspect of the condyle at medial, central, and lateral locations. Panoramic radiographs were made with and without the chips in place. These paired radiographs were digitized, and unenhanced and color-enhanced digital-subtraction images of the original panoramic images were obtained. Eight observers evaluated 72 randomized images of each modality for the presence or absence of simulated osteophytic lesions of the mandibular condyle, grading the images on a 100-point scale. RESULTS: A(z) values for overall diagnostic accuracy of the three imaging modalities were 0.5376 for panoramic radiography, 0.7861 for unenhanced digital subtraction radiography, and 0.7923 for color-enhanced digital-subtraction radiography. Digital-subtraction radiography improved the detection accuracy of the original panoramic films. CONCLUSION: Panoramic radiographs were significantly less accurate in the detection of simulated osteophytic lesions of the mandibular condyle than the two digital-subtraction techniques.

Radiation dose-reduction techniques in North American dental schools.

OBJECTIVE: The purpose of this investigation was to describe the extent to which dental schools use materials, equipment, and quality-assurance protocols that reduce radiation exposure to patients. STUDY DESIGN: Questionnaires soliciting information regarding intraoral and extraoral radiographic practices and quality-assurance procedures were sent to the directors of oral and maxillofacial radiology (OMR) at the 65 schools of dentistry in the United States and Canada. RESULTS: The response rate was 100%. E-speed film is used at 86% of institutions. Direct digital radiography is used at 58% of institutions for intraoral imaging and 11% for extraoral radiography. Other dose-reducing techniques include long source-film distances (88%), rectangular beam limitation (47%), leaded aprons (95% for extraoral films; 85% with thyroid collars for intraoral films), and rare earth intensifying screens (100%). The most commonly used tube potential is 70 kVp (88%). The director of OMR is solely responsible for radiographic policies at approximately 75% of institutions. Regular tests for film fog, speed, and contrast are done at roughly 75% of schools, while over 90% test darkroom lighting and x-ray equipment. CONCLUSIONS: Some dose-reducing strategies are commonly used in dental schools, while others have not gained wide acceptance.

Comparative radiographic study of human and animal long bone patterns / Estudo comparativo do padrão radiográfico de ossos longos humanos e animais

The objective of this study was to test the hypothesis that certain radiographic features can be found to distinguish between human and animal long bone fragments, and therefore would be useful as an adjunct in forensic science identification. Using proposed radiographic criteria, 13 archeologists and 12 dentists were asked to identify 20 radiographic samples as representing human or animal bone. Results showed that archeologists correctly identified 86.8 percent of the samples, and dentists correctly identified 81.9//. Based on the results of this study, it was conclueded that radiographic interpretation of long bone fragments may be a useful aid in a forensic science investigation of human and animal remains