Effect of 3 different disinfection methods on the image quality of photostimulable phosphor plates.

OBJECTIVE: The aim of this study was to assess the effects of 3 disinfection protocols on the quality of images acquired with a photostimulable phosphor (PSP) plate system. STUDY DESIGN: Thirty DIGORA Optime PSP plates were divided into 3 groups of 10. Group 1 was disinfected with 95% ethanol. Group 2 was disinfected using germicidal disposable wipes. Group 3 was disinfected with 95% ethanol, followed by hydrogen peroxide gas sterilization. Images of a quality assurance phantom were acquired on each plate before disinfection (baseline images). Disinfection and imaging cycles were repeated 45 times for each plate. Changes in image quality were assessed between baseline and final images. Image quality was evaluated for dynamic range, spatial resolution, and contrast perceptibility. The Fisher exact test was used to detect statistically significant differences among the 3 disinfection methods relative to decreases in image quality parameters between the baseline and final radiographs. Additionally, for each group, the Z-test was used to detect statistically significant decreases in image quality parameters between baseline and final images. The significance level was established at P < .05. RESULTS: No statistically significant differences were detected among the disinfection groups or relative to baseline values for any group at a 5% significance level. CONCLUSIONS: Hydrogen peroxide gas may be considered to prevent cross-contamination while preserving image quality. Regular quality assurance testing is recommended to maintain image quality over time.

Comparison of gray-level detectability on computer monitors among several dental specialties: A web-based study.

BACKGROUND: Diagnosis in dentistry begins with the correct reading and interpreting of the dental radiograph. OBJECTIVES: The aim of the present study was to examine the effects of the imaging technique used, the dentistry specialty and the years of experience on the gray-level perception among dentists. MATERIAL AND METHODS: A custom web application was developed. Dentomaxillofacial radiologists (DentRads), endodontists (Ends) and general dental practitioners (GDPs) were invited via e-mail to participate in the study. A total of 46 participants met the requirements of the test. The test comprised 2 webpages. On the 1st page, the participants were asked for information such as gender, specialty, the years of experience, and the imaging techniques they used. Then, on the 2nd page, they were welcomed with instructions and directions, and asked to rearrange 85 gray color tones represented by square bars of equal dimensions. These mixed gray bars were placed in 4 rows according to the principles of the FarnsworthMunsell 100-hue test (FM). Each clinician's test results were recorded in a database. The individual's level of recognition of gray tones was evaluated through the total error score (TES), which was calculated using a web-based independent scoring software program. Lower TES values were a desirable result, indicating fewer misplacement, while higher scores indicated more misplacements of gray tones. The testing time (TT) was recorded automatically. RESULTS: The years of the participants' experience as dentists or specialists did not affect TES or TT. The dentists who used the charge-coupled device-complementary metal oxide semiconductor (CCD-CMOS) had lower TES values than those who used analog radiographs (p < 0.05). CONCLUSIONS: While the specialty and the years of experience did not affect the clinicians' ability to recognize gray tones, the digital imaging techniques (photostimulable phosphor (PSP) and CCD/CMOS) could improve the clinicians' gray-level perception.

DICOM file format has better radiographic image quality than other file formats: an objective study.

This study aimed to assess the influence of the file format on the image quality parameters (image noise, brightness, and uniformity) of periapical radiographs acquired with different digital systems. Radiographic images of an acrylic phantom were acquired with two digital systems - Digora Toto and Express, and exported into five different file formats - TIFF, BMP, DICOM, PNG, and JPEG. Image noise, image brightness (mean of gray values), and image uniformity (standard deviation of gray values) were evaluated in all images. A two-way analysis of variance with Tukey's test as a post-hoc test was used to compare the results, considering the file formats and radiographic systems as the studied factors. A significance level of 5% was adopted for all analyses. The DICOM image file format presented lower image noise, higher brightness (higher mean gray values), and greater image uniformity (p<0.001) than the other file formats, which did not differ from each other for both digital radiography systems (p>0.05). The Express system revealed lower image noise and greater image uniformity than the Digora Toto system regardless of the image file format (p<0.001). Moreover, the Express showed higher brightness than the Digora Toto for all image file formats (p<0.001), except for the DICOM image file format, which did not significantly differ between the digital radiography systems tested (p>0.05). The DICOM image file format showed lower image noise, higher brightness, and greater image uniformity than the other file formats (TIFF, BMP, PNG, and JPEG) in both digital radiography systems tested.

Evaluation of soft tissue and crestal bone changes around non-submerged implants with and without a platelet-rich fibrin membrane: A randomized controlled clinical trial.

BACKGROUND: Platelet-rich fibrin (PRF) membranes are known to enhance wound healing after periodontal surgeries and dental implant procedures. OBJECTIVES: The aim of the present study was to examine the effect of PRF on soft tissue healing and the crestal bone level (CBL) around non-submerged dental implants. MATERIAL AND METHODS: A total of 40 patients, aged 20-60 years, with partially edentulous posterior mandibular sites were divided into 2 groups of 20 patients each: group I received non-submerged implants with a PRF membrane; and group II was treated with non-submerged implants alone. The examined parameters included the modified plaque index (mPI), the gingival index (GI), the width of keratinized tissue (WKT), the thickness of keratinized tissue (TKT), and CBL, assessed using digital intraoral periapical radiography (IOPA). All parameters were measured at baseline (immediately post-op), and at 3-month and 6-month follow-ups. RESULTS: In comparison with baseline, statistically significant increases in WKT and TKT were observed in both groups at 3 and 6 months post-op (p < 0.05). Also, significant gains were noted in group I vs. group II (p < 0.05). The CBL increased significantly in both groups at 3 and 6 months post-op (p < 0.05), with no remarkable differences from 3 to 6 months. A decreased CBL was observed in group I vs. group II at the 3- and 6-month intervals (p < 0.05). CONCLUSIONS: The PRF membrane enhances peri-implant tissue wound healing, with gains in soft tissue width and thickness around non-submerged implants.

Fundamental research for dose control during supine dental panoramic radiography.

OBJECTIVE: This study aimed to control radiation doses when using a portable supine dental panoramic radiography system by measured the scattered doses. METHOD: The study used LPX7007 (Asahi Roentgen) for the panoramic radiography system. The subjects comprised a cylinder phantom (QualitA) and a RANDO Phantom (Alderson). The semiconductor dosimeter was an X2 survey sensor (RaySafe). The phantom was set at a height of 1 m from the floor, and the sensor was set at 1 m from the floor at the genital level and 1.5 m at the lens level. Measurements were taken at 30°intervals clockwise from 0°at distances of 0.5 m and 1 m in radius around the phantom. The occupational exposure range was defined as 0 ± 30° and the public exposure range was defined as the occupational exposure range and 30° to 150° and 210° to 330° as the public exposure range. RESULT: The highest doses were observed in the 120° and 240° directions, and the lowest in 0° ± 30° range. The lowest limit number of images taken in the occupational exposure range was 130 images at a distance of 0.5 m, 452 images at 1 m at the lens level for the cylinder phantom, and 320 images at 0.5 m and 1098 images at 1 m for the RANDO Phantom. In the public exposure range at the genital level, there was one image at 0.5 m and six images at 1 m for the cylinder phantom, and two images at 0.5 m and eight images at 1 m for the RANDO Phantom. CONCLUSION: We found that radiation exposure can be reduced by keeping a distance from the subject, avoiding working at 120° and 240° and staying within 0° ± 30° behind the panoramic radiography system.

Computed vs. film-based radiographs' contour artifacts influence diagnosis of secondary caries.

To test local grey-scale changes on dental bitewing radiographs near filling margins for image acquisition. Forty approximal preparations in caries-free amalgam filled teeth and bitewing radiographs were acquired under standardized conditions applying four techniques. Film-based analog radiographs were digitized using flat-bed scanner (FDR). Phosphor-plate computed radiographs (PCR) were directly acquired by scanning VistaScan imaging plates. Image quality was tested using Preset Filter (PF) or manually applied IntraOral Fine Filter (IF) to enhance digital images. Local changes from digital imaging processing were assessed by comparing the margin-near (MN) and margin-far (MF) zone by a multivariate repeated measurements analysis. All images were acquired with 8-bit depth (256 shades). Dentine was displayed in 79 shades for FDR and 54 shades for PCR. PF or IF locally modify bitewing radiographs by darkening marginal dentine by 8 or 29 shades, respectively. The sharpest display of the margin (shades per pixel) from dentine to filling was found for IF (26.2), followed by FDR (23.2), PF (15.3) and PCR (8.3). Computed radiography with phosphor plates generate more homogeneous images compared to flatbed-digitized film-based radiographs. The filling margin was sharpest represented with the IF filter at the detriment of an artificial darkening of the dentine near the margin of the filling. Contour artifacts by filters have the potential to confound diagnosis of secondary caries. Algorithms and filters for sensor data processing, causing local changes above 2% of the dynamic range by non-continuous mathematical functions, should only be applied with caution, manually when diagnosing and reversibly.

Avaliação da profundidade da cárie proximal nos exames radiográfico convencional e digitalizado / Evaluation of the size of proximal caries in radiography and digitized

Introdução: A cárie dentária é uma doença multifatorial que compreende vários fatores biológicos e sociais. A superfície proximal dos dentes é uma região de difícil visualização que pode esconder pequenas lesões cariosas no esmalte dentário, impossibilitando o diagnóstico através de inspeções visuais e táteis. Objetivo: O objetivo deste trabalho foi avaliar a profundidade da cárie proximal nos exames radiográficos convencionais e digitais, comparando as profundidades das lesões consideradas nestes exames às do exame histológico. Método: Foram utilizados exames radiográficos interproximais de 40 dentes humanos, 20 pré-molares e 20 molares, com alterações clínicas em uma das superfícies proximais, como lesões de mancha branca ou acastanhada e pequenas cavitações. Três profissionais especializados em radiologia odontológica com mais de cinco anos de experiência clínica mediram a profundidade das lesões pelos exames radiográfico e digital das amostras. Para obter os resultados, utilizou-se a técnica de análise de variância (ANOVA). Resultados: Constatou-se um nível de significância de 5% nas mensurações dos exames radiográficos convencionais e digitalizados, mostrando a fidelidade das imagens radiográficas em relação a real profundidade da lesão. Conclusão: Conclui-se que os exames de imagem avaliados foram eficientes na determinação da profundidade das lesões de cárie proximal.

Introduction: Dental caries is a multifactorial disease that comprises several biological and social factors. The proximal surface of the teeth is a region of difficult visualization that can hide small carious lesions in the dental enamel, making diagnosis through visual and tactile inspection infeasible. Objective: The objective of this study was to evaluate the depth of proximal caries in the conventional and digitized radiographic examinations, comparing the depths of the lesions considered in these examinations to those of the histological examination. Method: Interproximal radiographic examinations of 40 human teeth, 20 premolars and 20 molars, with clinical alterations on one of the proximal surfaces, such as white or brown spot lesions and small cavitations, were used. Three professionals specialized in dental radiology with more than five years of clinical experience measured the depth of the lesions by radiographic examination of the samples. To obtain the results, we used the technique of analysis of variance (ANOVA). Results: A level of significance of 5% was found in conventional and digitized radiographic measurements, showing the fidelity of the radiographic images in relation to the actual depth of the lesion. Conclusion: It was concluded that the imaging tests evaluated were efficient in determining the depth of proximal caries lesions.

The effect of different spatial resolutions and enhancement filters on radiographic detection of simulated furcation defects with intraoral digital radiography.

OBJECTIVE: The objective of this study was to evaluate the effects of spatial resolution and the application of enhancement filters in the diagnosis of simulated furcation defects and image quality with intraoral radiographs. STUDY DESIGN: Periapical images were acquired with photostimulable phosphor plates of molars in dry skulls (n = 8) and mandibles (n = 10) with 4 stages of furcation defect simulation. The plates were scanned in fast scan and high resolution modes to produce different spatial resolutions. Four image filters were applied. Six observers scored the detection of furcation defects. Mean values of area under the curve in receiver operating characteristic evaluation, accuracy, sensitivity, and specificity were calculated. Mean gray value (brightness), noise, and contrast-to-noise ratio (CNR) were calculated for enamel, dentin, and alveolar bone to evaluate image quality. Analysis of variance compared the values between the different spatial resolutions and filters. The significance of difference was established at P < .05. RESULTS: There were no significant differences in overall diagnostic values comparing image spatial resolutions and filters. Diagnostic outcomes were significantly better for the largest defects than the smallest lesions but were generally poor in detecting lesions. All structures showed greater brightness in high resolution. . Noise was greater in all structures with all enhancement filters except inversion. Dentin and alveolar bone exhibited more noise and lower CNR in high resolution. CONCLUSIONS: Varying spatial resolution and applying enhancement filters did not significantly affect the diagnosis of furcation defects.

Ambient light exposure of photostimulable phosphor plates: is there a safe limit for acceptable image quality?

OBJECTIVES: To subjectively assess radiographs obtained with photostimulable phosphor (PSP) plates exposed to clinical levels of ambient light prior to read-out to potentially set a safe limit for acceptable image quality. METHODS AND MATERIALS: Six dental regions of a dry human skull were X-rayed using PSP plates from VistaScan and Express under four exposure times: 0.1, 0.2, 0.32, and 0.4 s. Before read-out, the PSP plates were exposed to ambient light for 0, 5, 10, 30, 60, and 90 s. Six observers were asked to classify the 288 resulting radiographs as acceptable or unacceptable based on the identification of anatomical structures and global image quality. The number of answers classifying radiographs as unacceptable was used to calculate a rejection rate; a pairwise comparison for better image quality was further conducted among radiographs considered acceptable. Reproducibility was tested by having 25% of all experimental groups reassessed. RESULTS: Intra- and interobserver agreement ranged from 0.87 to 1.00 and from 0.81 to 0.92, respectively. Exposure of PSP plates to ambient light increased rejection rates mostly as of 10 s. In the pairwise comparison, subtle differences were observed between radiographs obtained with PSP plates not exposed and those exposed to ambient light for 5 s. CONCLUSIONS: Ambient light exposure of PSP plates impairs the image quality of radiographs. A safe limit of ambient light exposure of 5 s for VistaScan and Express should be considered. Ambient light exposure of PSP plates within safe limits can avoid retakes and reduce unnecessary patient exposure to X-rays.

Panoramic errors in pediatric patients with special needs.

This study aimed to analyze the types and frequencies of panoramic technical errors in pediatric patients with special needs, as compared to matching images of patients with normal developmental patterns. Panoramic images of 100 pediatric patients, with equal numbers of either special needs or healthy controls, referred to our Oral Maxillofacial Imaging unit, were retrospectively examined by four blinded observers for the presence of four common technical errors: palatoglossal air space, movement, positioning errors, and foreign bodies appearance. In addition, they subjectively determined the image quality on an ordinal scale. The statistical examination included inter-observer correlation and correlations between demographic factors (age, gender, developmental status) and the number and types of errors. The frequencies of demonstrated errors were, in descending order: movement, positioning, palatoglossal air space, and foreign bodies' appearance. The special needs group images showed significantly more errors and were rated as low-quality radiographs. Younger patients in both groups showed more movement and positioning errors. Technical errors in panoramic images of patients with special needs were more frequently found. Therefore, increased awareness of the staff and appropriate pre-imaging instructions to the patients, are required when imaging pediatric patients, especially those with special needs.

Influence of binarization methods on the fractal dimension of alveolar bone using digital radiographs.

OBJECTIVE: The aim of this study was to evaluate the influence of binarization methods (BnMs) on the fractal dimension (FD) of the alveolar bone in digital radiographic images. STUDY DESIGN: Five identical periapical radiographs were obtained from each of 20 anatomic regions. Using ImageJ/Fiji software, a standardized region of interest was positioned in the trabecular bone of all radiographs, 14 BnMs were independently applied, and FD was calculated. The Friedman test and Dunn post hoc tests were used to evaluate the influence of BnMs on FD (α = 0.05). The intraclass correlation coefficient (ICC) was used to assess correlation among BnMs. RESULTS: No significant differences were observed in the threshold value between the BnMs. No significant differences in FD were observed among 9 BnMs (Default, Huang, Iso Data, Li, Mean, Min Error[I], Moments, Otsu, and Shanbhag). These methods presented significantly higher FDs than those from 3 other BnMs (Max Entropy, Renyi Entropy, and Yen), which did not significantly differ from each other. The Triangle method significantly differed from all BnMs, and the Percentile method produced significantly higher FDs than Huang, IsoData, Li, Moments, Otsu, and Shanbhag. Most BnMs presented good or excellent correlation (ICC ≥ 0.76). CONCLUSIONS: Binarization methods influence FD of the alveolar bone from digital periapical radiographs; thus, this technical aspect is relevant for comparison purposes and should be standardized. For comparison of published FD research, the Default method is recommended.

Disinfection of intraoral photostimulable phosphor plates with 70% ethyl alcohol and 70% isopropyl alcohol alters image contrast and produces image artifacts.

OBJECTIVE: This study evaluated changes in image quality and the presence and size of artifacts on radiographs obtained with photostimulable phosphor (PSP) plates after disinfection with 70% ethyl alcohol and 70% isopropyl alcohol. STUDY DESIGN: Eight PSP receptors (4 Express and 4 VistaScan) were used for the investigation. Two Express and 2 VistaScan receptors were disinfected with 70% ethyl alcohol, and 2 Express and 2 VistaScan receptors were disinfected with 70% isopropyl alcohol. Before disinfection and after every 5 disinfections, 2 radiographs of an aluminum stepwedge and 2 radiographs of an acrylic block were acquired using each receptor. The gray values of the radiographs were analyzed regarding contrast, density, uniformity, and noise. Four oral radiologists evaluated the images for the presence of artifacts, and 2 measured the artifacts. RESULTS: Differences in image contrast were significantly larger with isopropyl alcohol (P < .0001). Artifact size was significantly greater with the VistaScan system when isopropyl alcohol was used as the disinfectant (P < .0001). The correlation between the number of disinfections and artifact size was moderately positive with the Express system (P < .05) and strongly positive with the VistaScan system (P < .05) with both disinfectants. CONCLUSIONS: Small artifacts restricted to the edges of the image were observed with disinfection using both types of alcohol, and a positive correlation was found between artifact size and the number of disinfections. However, artifacts appeared earlier and of greater size with the VistaScan system when disinfected with 70% isopropyl alcohol. Thus, we recommend using 70% ethyl alcohol to disinfect PSP receptors, with attention placed on its action and evaporation times.

Evaluation of diagnostic accuracy of CBCT and intraoral radiography for proximal caries detection in the presence of different dental restoration materials.

PURPOSE: This study aimed to assess the diagnostic accuracy of cone-beam computed tomography (CBCT) and digital intraoral radiography for the detection of proximal caries adjacent to amalgam, e.max porcelain, and metal-ceramic restorations (MCRs). MATERIALS AND METHODS: Parallel intraoral radiographs were obtained from 40 posterior teeth using PSP sensors. To obtain CBCT scans, the teeth were first radiographed alone, and were then positioned next to a tooth with an amalgam restoration, MCR, and e.max porcelain crown, and radiographed again. Two blinded observers scored radiographs using a four-point scale (0: absence of proximal caries, 1: enamel caries, 2: carious lesion extending to the outer half of dentin, 3: carious lesion extending to the inner half of dentin). Tooth sections were made, and the grade of caries was determined under a light microscope at x12 magnification. The sensitivity, specificity, and accuracy of CBCT and intraoral radiographs were then calculated. RESULTS: Artifact-free CBCT scans and intraoral radiographs had the highest diagnostic accuracy (0.826 and 0.657, respectively) while CBCT images of the teeth next to the amalgam restorations (0.526) had the lowest accuracy. The diagnostic accuracy of CBCT images of the teeth next to the porcelain crowns and MCRs was 0.613 and 0.601, respectively. CONCLUSION: Artifact-free CBCT images had higher diagnostic accuracy than intraoral radiography for the detection of all grades of proximal caries. The diagnostic accuracy of CBCT images of teeth adjacent to amalgam, porcelain, and MCRs was lower compared to intraoral radiographs and artifact-free CBCT images.

Validation of radiographic visibility of root pulp in mandibular first, second and third molars in the prediction of 21 years in a sample of south Indian population: A digital panoramic radiographic study.

This study examines the radiographic visibility of root pulp (RPV) in lower first, second and third molars to validate the completion of 21 years. RPV in all lower three molars of both sides was assessed using a sample of 930 orthopantomograms of individuals aged between 15 and 30. The scoring of RPV was done using the Olze et al. four-stage classification (Int J Legal Med 124(3):183-186, 2010). Cut-off values were determined for each molar using the receiver operating characteristic (ROC) curve and the area under the ROC curve (AUC). The selected cut-off values were stage 3 for the first molar, stage 2 for the second molar and stage 1 for the third molar. For lower first molar, the AUC was 0.702, and the sensitivity, specificity and posttest probability (PTP) were 60.1%, 98.8% and 98.1% in males, and 64.5%, 99.1% and 98.6% in females. For lower second molar, the AUC was 0.828, and the sensitivity, specificity and PTP were 75.5%, 97% and 96.2% in males, and 74.4%, 96.3% and 95.3% in females. For the lower third molar, the AUC was 0.906; the sensitivity was 74.1% and 64.4% in males and females, while specificity and PTP were 100% in both sexes. The accuracy of predictions for the completion of 21 years was high. However, the greater percentage of false negatives and inapplicability of this method in one-third of lower-third molars have been recommended for using this method in conjunction with other dental or skeletal methods.

Does endodontics influence radiological detection of external root resorption? an in vitro study.

BACKGROUND: External root resorption (ERR) has a multifactorial etiology and is difficult to diagnose, which means that is continues to be of research interest. This work mainly aims to determine whether external root resorption can be differentially detected in root-filled versus non-endodontically treated teeth using digital periapical radiography (DPR) and cone-beam computed tomography (CBCT). METHODS: The Checklist for Reporting In-vitro Studies (CRIS) guidelines were followed throughout this study. This experiment highlights the preparation and generation of standardized synthetic teeth measured on three-dimensional records converted into Digital Imaging and Communication on Medicine (DICOM) file format. Twelve replicate maxillary incisors were randomized into two groups: (G1) six non-endodontically treated, and (G2) six endodontically treated teeth. In both groups, actual tooth lengths of all specimens were measured and compared with measurements obtained using DPR and CBCT. Simulated ERR lesions [0.12, 0.18, 0.20 mm × 0.5 mm depth in the mesial, distal and palatal apical regions] were created progressively, radiographic images were recorded, and 24 DPRs and 96 CBCTs were obtained in total. Eight blinded, previously calibrated researchers made a total of 1920 measurements (using Horos Software). Data were analyzed using the Shapiro-Wilk, ANOVA, Kruskal-Wallis and Wilcoxon rank post-hoc tests [Bonferroni correction in multiple comparison tests (p < 0.05)]. RESULTS: ICC values for intra- and inter-examiner agreement were appropriate. DPR overestimated ERR detection compared to the actual and CBCT measurements [Mean diff = 0.765 and 0.768, respectively]. CBCT diagnosis of ERR lesions in specimens without root canal treatment was significantly more accurate than DPR diagnoses on both non-endodontically and endodontically-treated specimens [p = 0.044; p = 0.037, respectively]. There was an 18.5% reduction in sensitivity in all DPR diagnoses made on endodontic teeth versus those made on non-endodontically treated teeth. For the smallest ERR lesions, this sensitivity was even more marked, with 27.8 and 25% less sensitivity, respectively. CONCLUSIONS: The results of this study highlight that both CBCT and DPR are good diagnostic methods for ERR. Nevertheless, root canal filling material influences diagnostic capability in ERR. The clinical significance was that the presence of intracanal material reduces the detection and diagnosis of ERR by DPR in teeth with root canal treatment.

Revisiting dynamic range and image enhancement ability of contemporary digital radiographic systems-part 2: a subjective assessment.

OBJECTIVE: To assess the subjective image quality of original and manually enhanced radiographs acquired at different X-ray exposure times and using different digital systems. METHODS: A total of 500 radiographs obtained under 10 exposure times, 5 digital systems, and 2 enhancement conditions were assessed by 5 observers, who were asked to categorize each radiograph into acceptable or unacceptable. A radiograph was considered to be acceptable when at least four out of five observers found it acceptable. Descriptive analysis was used to summarize the outcomes and compare the subjective image quality of original and manually enhanced digital radiographs among different X-ray exposure times and digital systems. RESULTS: Express had six exposure times producing acceptable original images within a range from 0.063 to 0.4 s, followed by Digora Toto, which had five within a range from 0.063 to 0.32 s, Digora Optime, which had four within a range from 0.063 to 0.2 s,and SnapShot and VistaScan, which had 2 (0.2 and 0.32 s) and 1 (0.63 s), respectively. Image enhancement turned unacceptable images into acceptable ones in four digital systems: SnapShot at three exposure times, Digora Toto at two exposure times, Express at one exposure time, and VistaScan at four exposure times. CONCLUSION: Image enhancement based on brightness and/or contrast adjustments may be necessary to reveal the useful dynamic range of some digital radiographic systems and PSP-based systems may not necessarily have a wider range than sensor-based systems.

Development of formulae for dental age estimation using digital radiographs in the Mongolian population.

This study aimed to examine the applicability of the pulp/tooth ratio (PTR) method for age estimation in Mongolian populations using panoramic radiographs and derive new regression formulae. Moreover, we aimed to assess the accuracy of these formulae in other subjects from the Mongolian population and compare them with the other formulae derived from different Asian populations. The total sample size of the study was 381. The formulae were derived from the examination of panoramic radiographs of 271 individuals aged 15-62 years. Following Cameriere's method, PTR was calculated for the upper and lower canine teeth. Linear regression analyses were performed between the actual age and that obtained from upper-lower canine PTR and established formulae for age estimation. To verify the formulae, two types of test samples were collected: 73 panoramic radiographs and 37 periapical radiographs. The estimated age was calculated using our new formulae and three other formulae derived from Asian populations. The correlation coefficient between the actual age and that obtained by PTR was significantly negative for both canines. According to our new regression formulae, the differences between the estimated age and actual age showed a bell-shaped curve distribution in both test groups. While using the other formulae derived from the Asian population, the distribution patterns obtained were significantly different in the Mongolian population. This study was the first to examine the relationship between actual age and PTR in Mongolian population, and these results advance the field of forensic science in Mongolia.

Radiopacity evaluation of different types of resin restorative materials using a digital radiography system.

OBJECTIVES: The aim of the study was to evaluate and compare the radiopacity of 20 current dental resin composites with digital radiography. METHODS: Ten specimens, 10-mm in diameter and 1-mm thickness, were prepared and radiographed using phosphor plates close to Al step wedges and tooth sections. The mean grey values (MGVs) were measured using an ImageJ software program and converted to equivalent Al thickness. Data were analyzed using one-way analysis of variance (ANOVA) and Tamhane post hoc test (p < 0.05). Correlation between mean radiopacity and filler content (wt% and vol%) of the tested materials was analyzed with linear regression analysis. RESULTS: The radiopacity of all composites ranged from 1.32 mm Al (Estellite Flow Quick) to 3.41 mm Al (Charisma Classic). All the tested materials, except four restorative materials, had a radiopacity equal or higher than the enamel (p < 0.05). Linear regression revealed low correlation between the radiopacity and filler content of the composite. CONCLUSION: Majority of the materials has appropriate radiopacity for dental restorations. There was great variation in radiopacity level, may clinically affect the diagnosis.

Could the radiographic image quality be affected by the excessive use of the photostimulable phosphor plate?

The study aimed to assess the influence of excessive use of a photostimulable phosphor plate (PSP) on the density, image noise, and contrast of radiographs. For that, radiographs of an acrylic block were acquired with a PSP of the Express intraoral system to assess the density and image noise. Initially, five images were obtained and exported (first group). After 400 exposures to X-rays and scannings of PSP, other five images were obtained and exported (second group). The same procedure was done after 800 (third group), 1200 (fourth group), 1600 (fifth group), and 2000 acquisitions (sixth group), resulting in 30 images to be evaluated. The mean and standard deviation of the gray values were calculated for the images using the ImageJ software. For contrast analysis, radiographs of an aluminum step-wedge were acquired with a new PSP following the same acquisition intervals. The percentage of contrast variation was calculated. Another two unused PSP receptors were employed to evaluate the method's reproducibility. The comparison of the results among the acquisition groups was performed with one-way Analysis of Variance (α=0.05). Intraclass Correlation Coefficient (ICC) assessed the reproducibility of the receptors. Image noise did not differ among the groups (p>0.05). There was a slight increase in density after 400 acquisitions and a slight difference in contrast for all acquisition groups without a pattern of increase or decrease (p<0.05). ICC showed excellent reliability for the methods. Therefore, excessive PSP use slightly affected the radiograph's density and contrast.

[Intraoral radiography: qualitative study]. / Radiographies intraorales : étude de qualité.

When taking intraoral X-rays with a round collimator, the salivary glands and the thyroid gland are exposed to ionizing radiation. The rectangular collimator reduces the patient's radiation dose. This study aims to analyze the impact of the rectangular collimator on the quality of intraoral X-rays taken by students of the University Clinics of Dental Medicine (Geneva, Switzerland). Intraoral X-rays, performed by 8 students with digital intraoral phosphor plates, were collected and a quality score was assigned to each X-ray. A total of 130 intraoral radiographs were analyzed. Half of the radiographs were taken with a rectangular collimator and 24.6% (32/130) were bitewings. The mean quality score of bitewings taken with or without a collimator was 11 ± 1.8 and 10.3 ± 0.9, respectively. The mean quality score of apical X-rays taken with or without collimator was 11.6 ± 1.0 and 11.5 ± 2.1, respectively. X-rays taken with a rectangular collimator were of excellent or sufficient diagnostic quality for 95% of the bitewings and 100% of the periapical radiographs. This quality control study showing that students perform quality intraoral X-rays with a rectangular collimator could encourage clinicians to use this device as ameans of radiation protection in their daily practice.