Schick CDR Research Articles

Spatial frequency domain analysis of a commercially available digital dental detector

X-ray detectors are used in medical imaging for the representation of diagnostic information. Digital detector performance is evaluated through appropriate parameters in the spatial domain (i.e. contrast, noise or resolution) and in the frequency domain. Dental radiography is a domain of medical imaging. The purpose of this work is the examination of a commercially available digital dental imaging detector through spatial frequency domain parameters. The available detector was a commercially available image receptor SCHICK CDR, working in indirect mode that is a scintillator coupled to a Complementary Metal Oxide Semiconductor (CMOS) photoreceptor. The detector was irradiated at an X-ray system with 60 kVp and 70 kVp tube voltages utilized in intraoral radiography. The detector linearity, Modulation Transfer Function (MTF), Normalized Noise Power Spectrum (NNPS) and Detective Quantum Efficiency (DQE) were measured according to literature. The Entrance Surface Air Kerma (ESAK) was measured with an RTI PIRANHA X-ray multimeter. The images were evaluated as presented to the dentist by the detector software, in 12bit format. The resolution of the detector was found better than 100 μm. The DQE curves suggested optimum exposure conditions below 133 μGy.

Effect of different exposure times on caries detection and pixel value in a wireless digital system.

: The aim of this study was to assess, using the CDR Wireless®, the effect of different exposure times on caries detection and pixel intensity values. Forty teeth were x-rayed using a Schick CDR Wireless sensor at eight different exposure times - 0.06, 0.10, 0.13, 0.16, 0.20, 0.25, 0.30, and 0.32 s. Four observers evaluated the images for presence of carious lesions scoring proximal surfaces of each tooth on a 5-point scale. Scores were compared to histological sections of the teeth. Accuracy was evaluated by means of ROC curve analysis. Radiographs of an aluminum step wedge were obtained using the same eight exposure times. Pixel intensity measurements were obtained, and mean pixel values were statistically analyzed using linear regression. The Az for each exposure time varied from 0.53 to 0.62. Two-way analysis of variance and Tukey test demonstrated that the exposure time of 0.25 s presented the best result and was significantly higher than 0.30 s and 0.35 s. In regard to mean pixel values, two different behaviors were observed, and the exposure time of 0.20 s presented mean pixel values in both phases. The performance of the exposure times from 0.06 s to 0.25 s was satisfactory for proximal caries detection, and 0.25 s is the best as indicated for this finality. Considering that a reduction of exposure time represents a reduction of patient exposure dose, and this reduction cannot neglect image quality, the behavior of any digital system must be carefully evaluated.

Examining the Spatial Frequency Components of a Digital Dental Detector

Digital X-ray detectors are widely used in dental radiography. The scope of this work is the examination of the spatial frequency component of a dedicated dental CMOS detector. A commercially available SCHICK CDR CMOS detector was irradiated at a Del Medical Eureka X-ray system at 60kVp and 70kVp. The irradiation setup included images of an edge, for Modulation Transfer Function (MTF) calculation. The air-KERMA was measured with an RTI PIRANHA X-ray multimeter. The images were evaluated in ‘for presentation’ format with the use of ImageJ software. The linear range of the detector was found in the range 13μGy-183μGy at 60 kVp and 18μGy-180μGy at 70 kVp. By inspecting the MTF curves it was found that MTF(6lp/mm)60kVp=0.29 and MTF(6lp/mm)70kVp=0.25. The inspection of the Normalized Noise Power Spetrum (NNPS) showed similar low noise components. Our results indicate that this detector presents comparable performance at both kVp, although its X-ray response (pixel value vs air KERMA) was not equal to previously published results, for the same detector type.

Radiopacity of Resin Cements Using Digital Radiography.

Monitoring performance of glass-ceramic based indirect restorations using radiographic imaging might be difficult due to their low radiopacity. Therefore, materials used for their cementation must possess adequate radiopacity. This study determined radiopacity of a group of resin-cements used for adhesive-cementation of glass-ceramic-based restorations using digital radiography. Two specimens were prepared from a group of resin cements (VariolinkII-opaque, VariolinkII-opaque (base), VariolinkII-Transparent, VariolinkII-Transparent (base), Nexus, RelyX Unicem, RelyX ultimate, Duolink, Monocem and Resinomer) and longitudinal sections of same thickness were obtained from molar and premolar. Specimens were assigned to two groups one had molar section with 10 specimens whereas other had premolar with remaining 10 specimens. Each group was placed on digital radiograph sensor (Schick CDR, size 2) together with aluminum step-wedge. Sensor was exposed to X-ray using standard technique. Two images were obtained for each group. Pixel measurements were made using NIH Image-J software. Mean pixel measurements were converted into aluminum thickness equivalents. Data were statistically-analyzed using one-way ANOVA and Tukey's tests. ANOVA revealed significant difference in mean pixel values among cements (p < 0.001). VariolinkII-opaque showed highest mean aluminum equivalent (4.6 mm Al/1 mm) followed by VariolinkII-opaque-Base (4.5 mm Al/1 mm), VariolinkII-transparent (4.45 mm Al/1 mm), VariolinkII-transparent-Base (4.45 mm Al/1 mm), Nexus (2.95 mm Al/1 mm), Duolink (2.7 mm Al/1 mm), RelyX Unicem (2.2 mm Al/1 mm) and finally RelyX ultimate (2 mm Al/1 mm). All cements had mean radiopacity values higher than that of enamel whereas Monocem (1.25 mm Al/1 mm) and Resinomer (1.2 mm Al/1 mm) had means between those of enamel and dentin. All tested resin-cements showed radiopacity values higher than that of dentin which is adequate for diagnostic purposes according to ISO recommendation. The use of resin cement with adequate radiopacity for adhesive cementation of glass-ceramic based restorations enables their radiographic monitoring. (J Esthet Restor Dent 29:215-221, 2017).

X-ray response of a digital detector for dental radiographs

Introduction Current dental imaging technology offers indirect detectors capable of digital imaging. These detectors incorporate a scintillator coupled to a photoreceptor. Purpose The purpose of this work is to study the X-ray response of a commercially available SCHICK CDR CMOS detector for dental radiography, in terms of detector response (mean pixel value and standard deviation) per incident air-kerma and the spatial resolution. Materials and methods The detector was uniformly exposed at a Del Medical Eureka X-ray radiographic system at high voltages of 60 kV and 70 kV. The range of the incident air-kerma, measured with the RTI PIRANHA X-ray multimeter, was varying between 0.047 mGy and 0.225 mGy. The mean pixel value and the standard deviation of the derived DICOM images were measured with RadiAnt (Medixant) available software. Spatial resolution was optically estimated by visualizing the image of an irradiating Type1-83 bar pattern. All images were evaluated in ‘for presentation’ format, in 8 bit format. Results The detector shows linear response up to 0.170 mGy for 60 kV and up to 0.145 mGy for 70 kVp. For higher air-kerma, mean pixel values tend to saturated at 255 grey level value. The saturation was faster at 70 kV. The coefficient of variation, as well as the standard deviation was found to reduce with respect to incident air-kerma for both X-ray tube voltages. Spatial resolution was observed approximately 10 lp/mm at 60 kVp and 9 lp/mm at 70 kVp. Conclusion The observed digital detector was found to have better resolution and dynamic range characteristics at 60 kVp. Disclosure No disclosure.

In vitro comparison of three different image receptors for determining the length of endodontic files

Background/purposeThe aim of this study was to evaluate the accuracy of endodontic file length measurements of E-speed radiographs, Digora storage phosphor plates, and Schick charge-coupled device sensors, with a secondary aim of assessing the influence of image enhancement on the measurement accuracy. Materials and methodsForty-seven extracted mandibular first premolar teeth were selected. ISO size 8, 10, and 15 files were inserted into each canal, and the files were fixed when the tip was seen at the apical foramen. The teeth were mounted in acrylic blocks and exposed using E-speed films, Digora storage phosphor plates, and Schick charge-coupled device sensors. Two radiologists and two endodontists measured the length of each file between the file stopper and tip on each image. Measurements were carried out on original and magnified images as well as on revealer images for Schick CDR. The actual lengths of the files were measured using a calipers to the nearest 0.01 mm and served as the “true length”. Repeated measures analysis of difference and Tukey honestly significant difference tests were used to analyze the data (P < 0.05). ResultsE-speed films were superior to digital systems for the measurement accuracy of the size 08 file (P < 0.05). Revealer images gave equivalent results with E-speed films for the measurement of the size 10 file (P > 0.05). The most accurate results were obtained with the size 15 file regardless of the image receptor (P > 0.05). ConclusionSize 15 or larger files should be used for endodontic working length determinations. Revealer images gave equivalent results with E-speed films and may be utilized for determining the file length of size 10 files.

Comparison of conventional and digital radiography systems with regard to radiopacity of root canal filling materials

To compare the radiopacity of five root filling materials as measured on digitized E-speed films, storage phosphor plate and CCD sensor images. Radiopacity of Resilon cones and Epiphany, MM-Seal, EndoREZ and AH Plus sealers were investigated. Ten acrylic plates were prepared and filled with the materials. Samples were radiographed together with samples of dentine and an aluminium stepwedge. Images were obtained using E-speed films, Digora storage phosphor plates and Schick CDR CCD sensor. Conventional radiographs were digitized using a desktop scanner. Mean grey values of the materials, stepwedge and dentine were measured using the histogram analysis function of Photoshop 7.0. A graph of radiographic density versus thickness of the aluminium was drawn for each image from which the radiographic densities of the materials were determined in relation to the aluminium thickness. The mean was calculated, and the data were analysed using repeated measures anova and Bonferroni tests (P<0.05). There were significant differences between different imaging modalities (P=0.018) and root filling materials (P<0.001). A statistically significant interaction between imaging modality and material was also observed (P<0.001). All materials had radiopacity above 3mm of aluminium regardless of the imaging technique. The radiopacity of Resilon and Epiphany was significantly higher on digital images compared with digitized E-speed film images (P<0.001). The choice of imaging system may effect radiopacity measurements. It is possible that radiopacity as recorded on traditional or digitized films is not indicative of the radiopacity as recorded on a digital sensor.

An audit of intra‐oral digital radiographs for endodontics

Aim The aim of this study was to improve the quality of digital radiographs taken during endodontic treatment at King's College Hospital Dental Institute, UK. There were three phases. The first phase compared the Schick CDR system with Digora Optime. The second and third phases involved ways of improving the quality of the digital radiographs produced by the Schick CDR system.Methodology The Faculty of General Dental Practitioners Royal College of Surgeons of England (FGDP) guidelines on Selection Criteria for Dental Radiography and Guidance Notes for Dental Practitioners on the Safe Use of X‐Ray Equipment‐National Radiological Protection Board enabled the use of a three point quality scale (one excellent, two diagnostically acceptable, three unacceptable), which took into consideration sensor angulation, positioning, contrast and focusing. The recommended FGDP guidelines are not less than 70% images scoring excellent. For the first phase 50 exposures recorded with the Schick CDR system were compared with 50 recorded using Digora Optime. For the second and third phases 50 radiographs for each phase were evaluated with images generated by the Schick system with training provided between the phases.Results Images produced by the Schick system showed an inferior quality compared with the images generated by the Digora method. Both systems failed to reach the desired quality FGDP standard of 70% excellent (Schick 55% Digora 69%). Comparison of the results in the second and third phases showed that training the operator improved the quality but recommended the purchase of a size 1 or 0 Schick sensors to improve positioning errors.Conclusions This study was carried out in order to minimise the ionising radiation dose to patients and to maximise the clinical and administrative benefits of using a digital system. It demonstrated an improvement in the quality of radiographs across all criteria measured up to and beyond the desired standard, from 55% of radiographs scoring excellent in the first phase to 80% in the third phase. As a result of the study it was decided to install the Schick CDR system because of the speed it produced images even though the first phase of this study demonstrated inferior image quality. The audit had clear, measurable standards with explicit targets. The audits have been through the entire audit cycle, data collection, change and a further data collection to provide evidence of the benefit of the change. A third data collection, demonstrated an ongoing commitment to quality.

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

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. 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. 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. 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.

A Comparison of Five Radiographic Systems to D-Speed Film in the Detection of Artificial Bone Lesions

The purpose of this study was to compare three direct digital sensors (Kodak 6100 [Rochester, NY], Schick CDR [Long Island City, NY], and Dexis PerfectSize [Alpharetta, GA]), a phosphor plate system (OpTime; Milwaukee, WI), and F-speed film to standard D-speed film in the detection of artificial bone lesions prepared in mandible bone sections. Artificial bone lesions were prepared at varying depths in the cortical bone. Radiographs were randomly presented to nine different observers. Logistic regression analysis indicated significant differences in lesion detection among the radiographic systems at the mean percentage of cortical bone remaining. The Kodak filtered, Schick filtered, OpTime unfiltered, Schick unfiltered, and Dexis filtered images were significantly better at lesion detection compared with D-speed film.

A comparison of older and newer versions of intraoral digital radiography systems: Diagnosing noncavitated proximal carious lesions

The authors conducted a study to compare the accuracy of an older and newer version of two intraoral digital systems in terms of radiographic detection of proximal carious lesions. Under in vitro and standardized conditions, the authors obtained radiographs of 160 noncavitated proximal surfaces using the Digora FMX (Soredex, Tuusula, Finland), the Digora Optime, the Schick CDR (Schick Technologies, Long Island City, N.Y.) and the Schick CDR Wireless (Schick Technologies) systems. Eight observers recorded proximal carious lesions on a five-point confidence scale. The presence of caries was validated histologically. The new digital systems (Digora Optime and Schick CDR Wireless) had significantly higher sensitivities than their predecessors. The authors found no significant differences in specificity among the Digora FMX, Schick CDR and Schick CDR Wireless systems, all of which had a significantly higher specificity than did the Digora Optime system (P < .02). The positive predictive value for the Digora Optime system was affected by its high sensitivity and low specificity, and it was lower than that for the two CDR systems (P < .02). Regarding overall accuracy, the difference between the older and newer versions of the photostimulable storage phosphor and complementary metal oxide semiconductor systems was not statistically significant. However, the authors found more false-positive diagnoses made with the Digora Optime system than with the Digora FMX system. Though the difference in specificities was statistically significant, the authors question whether the difference between the Digora Optime and the other systems is clinically relevant. Therefore, dentists can purchase any of these systems after considering factors other than those evaluated in this study.

Schick CDR® for a film-free practice

Schick CDR® for a film-free practice

In Vitro Radiographic Determination of Distances from Working Length Files to Root Ends Comparing Kodak RVG 6000, Schick CDR, and Kodak Insight Film

Previous studies suggest that digital and film-based radiography are similar for endodontic measurements. This study compared the accuracy and acceptability of measured distances from the tips of size #10 and #15 files to molar root apices in cadaver jaw sections using the newly developed Kodak RVG 6000, and the Schick CDR digital systems to digitized Kodak film. Standardized images were taken of files placed 0.5 to 1.5 mm short of true radiographic lengths. Images were imported into Adobe PhotoShop 7.0, thereby blinding observers who measured distances from files to root apices and assessed images for clarity (acceptability). Repeated measures ANOVA and Tukey-Kramer post hoc tests demonstrated that Kodak RVG 6000 images with enhanced contrast produced significantly less measurement error than unenhanced contrast Schick CDR images (p < 0.05) and significantly higher acceptability ratings than all other systems (all p < 0.002). Among these conditions, the newly developed Kodak RVG 6000 system provided the best overall images.

Comparison of Two Different Direct Digital Radiography Systems for the Ability to Detect Artificially Prepared Periapical Lesions

The purpose of this study was to compare Schick CDR and Trophy RVGui direct digital radiography (DDR) systems for the ability to detect periapical lesions in human cadaver mandibles. Digital radiographs were exposed of teeth with normal periapical areas and of teeth with artificially prepared periapical lesions using both DDR systems. Three examiners independently viewed the images at two different time periods and estimated which bony state was present. The resulting data were subjected to statistical analysis using a two-way ANOVA. Interexaminer variability was statistically analyzed using Spearman’s rho. There was no significant difference in the level of accuracy between the two different DDR systems at either observation period. There was a statistically significant high level of agreement between examiners (p < 0.01). In conclusion, there was no significant difference in the accuracy of detecting artificially prepared periapical lesions between Schick CDR and Trophy RVGui DDR systems.

A comparison of 18 different x-ray detectors currently used in dentistry

Purpose There has been a proliferation of available dental x-ray detectors over the recent past. The purpose of this short technical report is to provide a basic comparison of spatial resolution, contrast perceptibility, and relative exposure latitudes of 18 current dental x-ray detectors, including solid-state systems (CCD and CMOS), photostimulable phosphors, and analog film. Methods Spatial resolution was measured using a 0.025 mm Pb phantom test grid with a measurement range from 1.5 to 20 lp/mm. For contrast perceptibility, a 7-mm thick aluminum perceptibility test device with wells of 0.1-0.9 mm depth at 0.1 mm intervals and 1 defect of 1.5 mm was used. The relative exposure latitude was determined by expert consensus using clear discrimination of the enamel-dentin junction as the lower limit and pixel blooming or unacceptable levels of cervical burnout as the upper limit. Results The highest spatial resolution was found with Kodak InSight film, RVG-ui (CCD), and RVG 6000 (CMOS) detectors, each of which achieved 20 lp/mm, followed by the Planmeca Dixi2 v3 at ≥16 lp/mm. Contrast resolution was at least to 0.2 mm through 7 mm aluminum for all 18 detectors, with the best results being found for the Visualix HDI, RVG-ui, RVG 5000, and RVG 6000 detectors and the Schick CDR wired and wireless systems. The greatest exposure ranges were found with photostimulable phosphors and the Kodak RVG 6000 and RVG 5000 detectors. Conclusions Most current x-ray detectors generally perform well in terms of spatial and contrast resolutions, and in terms of exposure latitude. These findings were independent of the modality applied.

The impact of image compression on diagnostic quality of digital images for detection of chemically-induced periapical lesions.

To test the hypothesis that there is no significant difference in the detectability of chemically-induced periapical lesions between a non-compressed image and one subjected to a Joint Photographic Experts Group (JPEG) lossy compression technique at a ratio of 23:1 or less. Chemically-induced periapical lesions were created by placing a solution of 70% perchloric acid at the apex of extracted teeth in 13 human jaw cadaver specimens. Acid was applied in seven incremental time periods from 0-32 h. Extracted teeth were replaced in the socket and images were made using the Schick CDR digital sensor. Using a JPEG lossy compression algorithm, five compression ratios of 2:1, 14:1, 23:1, 28:1 and 47:1 were applied to the images. Images were viewed three times by three observers who ranked the presence or absence of a lesion at three sites, the mesial area, distal area and apex of the tooth, on a 5-point confidence scale. Intraobserver and interobserver agreement and agreement between the compressed and the original images were assessed with intraclass correlation coefficients (ICCs). Overall ICCs for measuring intraobserver agreement using all images were 0.77, 0.84, and 0.50 for the three observers, respectively. The overall ICC for assessing agreement between observers was 0.57. There was no significant difference (P>0.05) between compressed and original images for any site at compression ratios of 2:1, 23:1 and 28:1. There were significant differences for a compression ratio of 47:1. JPEG compression does not impact detectability of artificial periapical lesions at low and moderate compression ratios up to and including 28:1.

Measurement of the Distance Between the Minor Foramen and the Anatomic Apex by Digital and Conventional Radiography

The purpose of this study was to determine the distance between the minor foramen and the anatomic apex from digital and conventional radiographs. Thirty permanent single-canal teeth with mature root apex were used. After access preparation, a K-file was inserted into the canal until the tip of the file was just seen at the minor foramen under a x40 stereomicroscope. The file was fixed in the canal by filling the access with composite resin. The teeth with files in the canals were radiographed using a Schick CDR digital system and conventional radiography with E-speed film. For digital radiographs, the distance between the file tip and the center of radiographic apex was directly measured from the computer screen by using Schick CDR measurement software. For conventional radiographs, the distance was measured under a stereomicroscope at a magnification of x10 with a calibrated millimeter ruler. The mean distance was 0.494 mm measured from conventional radiographs and 0.594 mm from digital radiographs. These results agree with the current conception that endodontic working length should terminate 1 mm from the radiographic apex. There was a significant difference between the measurements on digital radiographs and those on conventional radiographs (p < 0.05, paired t test). However, the 0.1-mm difference has no clinical significance, because clinically, the working length is generally measured to the nearest 0.5 mm.

Measurement of Endodontic File Lengths: A Density Profile Plot Analysis

The purpose of this study was to evaluate measurements of endodontic files of known length and diameter using a density profile plot analysis of digital images. Ten single-rooted teeth with relatively straight roots in cadaver specimens were used. The crowns of the teeth were removed and a rectangular orthodontic wire, 5.13 mm in length, was placed horizontally on the occlusal surface to serve as a calibration reference point. The #8, #10, #15, and #20 FlexOFiles were measured to the nearest 0.5 mm and then placed to four working lengths that terminated within the apical third of each root. A GE X-ray unit and a Schick CDR #2 sensor were used to digitally acquire 160 images. The digital images were placed in random order and an independent, blinded investigator determined the file length using a density profile plot analysis. The measurements generated by the histogram analysis (experimental) were compared with the original clinical measurements. The paired t test, intraclass correlation coefficient, and the Bradley-Blackwood test were used to assess reliability. The results revealed that the means of the experimental measurements of all file sizes were within 0.5 mm of the known lengths and were always shorter than the known lengths. Also, the larger the file size the less deviation from the known lengths: #20, -0.16 mm (p = 0.0001); #15, -0.21 mm (p = 0.0001); #10, -0.34 mm (p = 0.0001); and #8, -0.45 mm (p = 0.0001). This study demonstrated that the density profile plot analysis might be a useful adjunct for the measurement of endodontic file lengths on a digital image.