Direct digital radiography for the detection of periapical bone lesions: a clinical study

Detection of Simulated Periapical Lesion in Intraoral Digital Radiography with Different Brightness and Contrast

Objective:

To assess the detection of simulated periapical lesions in digital intraoral radiography with different levels of brightness and contrast combinations, and to investigate the observers’ preference of image quality for this diagnostic task.

Methods:

Digital radiographs were acquired prior to periapical lesion simulation and after each one of four defects enlargement. Original images were adjusted in 4 brightness and contrast combinations. Five observers evaluated the images according to the presence of periapical lesion on a 5-point scale. In a second moment, the observers ordinated the images subjectively, according to quality, from the best to the worst to detect the bone defect. The area under the receiver operating characteristic curve was calculated for the diagnostic values and compared by two-way ANOVA. The significance level was set at 5% (P<0.05).

Results:

No differences were found between the diagnostic values of the five combinations of brightness and contrast (P>0.05). The overall results showed low values of area under the Receiver Operating Characteristic (ROC) curve and sensitivity of the periapical radiography in the detection of periapical lesions of sizes from 1 to 3, which rose substantially in size 4. For image quality, combinations with the lowest brightness and highest contrast were preferred by the observers in 58% of the cases.

Conclusion:

Brightness and contrast adjustments do not influence the detection of simulated periapical lesions in digital intraoral radiography. Lower brightness and higher contrast images were preferred for this diagnostic task.

Influence of VistaScan image enhancement filters on diagnosis of simulated periapical lesions on intraoral radiographs

OBJECTIVE:

To evaluate whether image enhancement filters of VistaScan system improve the diagnostic accuracy of simulated periapical lesions.

METHODS:

10 sockets were prepared on bovine ribs to fit a bovine tooth. Bone defects were created and successively enlarged providing four groups (n = 10): Group 0, absence of lesions; Group 1, periapical lesions with 1.6  mm in diameter; Group 2, with 1.8  mm in diameter; and Group 3, with 2.1  mm in diameter. Periapical radiographs were taken using a photostimulable storage phosphor plate and DBSWIN software. VistaScan filters were applied and the images were allocated into seven groups: Nonfiltered, Fine, Caries 1, Caries 2, Endodontic, Periodontal and Noise Reduction. All the 280 images were assessed about the presence or absence of periapical lesions. Pixel intensities standard deviation were compared between nonfiltered and filtered images. Two-Way Analysis of Variance and the post hoc Tukey's test were used to compare area under the ROC curve, sensitivity and specificity.

RESULTS:

VistaScan filters showed no significant difference for area under receiver operating characteristic curve (p = 0.124), sensitivity (p = 0.835) and specificity (p = 0.832). Area under receiver operating characteristic curve (p = 0.000) and sensitivity (p = 0.000) in 2.1  mm lesions size were significantly higher than in 1.6  mm and 1.8  mm lesions size. Pixel intensities standard deviation was significantly changed in the filtered images compared to nonfiltered ones (p < 0.01), except for Fine in the bone region (p > 0.05).

CONCLUSION:

VistaScan enhancement filters do not influence the diagnostic accuracy of simulated periapical lesions. On the other hand, larger lesions were more frequently detected. The filters change the pixel intensities reducing or intensifying the differences between similar regions.

A comparative study on diagnostic accuracy of colour coded digital images, direct digital images and conventional radiographs for periapical lesions - an in vitro study

OBJECTIVES

The identification and radiographic interpretation of periapical bone lesions is important for accurate diagnosis and treatment. The present study was undertaken to study the feasibility and diagnostic accuracy of colour coded digital radiographs in terms of presence and size of lesion and to compare the diagnostic accuracy of colour coded digital images with direct digital images and conventional radiographs for assessing periapical lesions.

MATERIALS AND METHODS

Sixty human dry cadaver hemimandibles were obtained and periapical lesions were created in first and second premolar teeth at the junction of cancellous and cortical bone using a micromotor handpiece and carbide burs of sizes 2, 4 and 6. After each successive use of round burs, a conventional, RVG and colour coded image was taken for each specimen. All the images were evaluated by three observers. The diagnostic accuracy for each bur and image mode was calculated statistically.

RESULTS

Our results showed good interobserver (kappa > 0.61) agreement for the different radiographic techniques and for the different bur sizes. Conventional Radiography outperformed Digital Radiography in diagnosing periapical lesions made with Size two bur. Both were equally diagnostic for lesions made with larger bur sizes. Colour coding method was least accurate among all the techniques.

CONCLUSION

Conventional radiography traditionally forms the backbone in the diagnosis, treatment planning and follow-up of periapical lesions. Direct digital imaging is an efficient technique, in diagnostic sense. Colour coding of digital radiography was feasible but less accurate however, this imaging technique, like any other, needs to be studied continuously with the emphasis on safety of patients and diagnostic quality of images.

Image enhancement of digital periapical radiographs according to diagnostic tasks

Purpose

This study was performed to investigate the effect of image enhancement of periapical radiographs according to the diagnostic task.

Materials and Methods

Eighty digital intraoral radiographs were obtained from patients and classified into four groups according to the diagnostic tasks of dental caries, periodontal diseases, periapical lesions, and endodontic files. All images were enhanced differently by using five processing techniques. Three radiologists blindly compared the subjective image quality of the original images and the processed images using a 5-point scale.

Results

There were significant differences between the image quality of the processed images and that of the original images (P<0.01) in all the diagnostic task groups. Processing techniques showed significantly different efficacy according to the diagnostic task (P<0.01).

Conclusion

Image enhancement affects the image quality differently depending on the diagnostic task. And the use of optimal parameters is important for each diagnostic task.

A Subjective Assessment of Perceived Clarity of Indirect Digital Images and Processed Digital Images with Conventional Intra-oral Periapical Radiographs

OBJECTIVES

To compare and analyze the perceived clarity and diagnostic value of Conventional periapical Radiographs (CRs) with those of their Digitized Periapical Images (DIs) and Processed Digitized Periapical Images (PDIs) counterparts.

MATERIAL AND METHODS

Forty two intraoral periapical radiographs of patients with clinically suspected periapical pathosis were made to constitute the group of CRs. These were photographed by using a Canon Power Shot SD500 (7.1 Megapixel) digital camera and the unaltered images were transferred to a computer laptop, to form the group of DIs. Subsequently, the contrast and brightness of these images were modified to represent the group of PDIs. Two experienced oral radiologists independently evaluated 5 specific apical and periapical region parameters of all the 42 CRs, DIs and PDIs for perceived image quality and diagnostic value and graded them on a three point grading scale. Conventional radiographs served as the control. Data were analyzed by using paired t-test and Kappa analysis.

RESULTS

The clarity and diagnostic quality of the PDIs were statistically significant as compared to those of their conventional counterparts. In comparison, the DIs group fared badly, with deterioration of the image quality. The interobserver agreement was good and all the results were statistically significant.

CONCLUSION

Indirectly digitizing the radiographs by employing a digital camera and further digitally processing the images resulted in an improvement in their perceived clarity and they enhanced their diagnostic properties.

Carious lesions: diagnostic accuracy using pre-calibrated monitor in various ambient light levels: an in vitro study

OBJECTIVES

This study investigated the effect of different monitor calibration modes under various ambient lighting conditions on the ability of observers to recognize proximal carious lesions of varying depths.

METHODS

7 observers evaluated 100 teeth for proximal carious lesions on standardized digital radiographs using 3 set-ups: (1) pre-calibrated monitor for high ambient light (higher than 1000 lux), (2) pre-calibrated monitor for low ambient light (less than 50 lux) and (3) Barten calibration (Digital Imaging and Communication in Medicine) on the monitor in dimmed ambient light (less than 50 lux). Receiver operating characteristic curves were plotted for all observations. The criterion standard was histological examination of the teeth. The effects of three conditions were compared using a paired t-test. The level of significance was set to p < 0.05.

RESULTS

No significant difference was found in diagnostic accuracy for the detection of any type of proximal carious lesions between the different calibration modes of the monitor according to different ambient light levels.

CONCLUSIONS

There is no evidence that any difference between ambient light levels affects the ability to detect carious lesions in digital radiographs as long as the monitor was calibrated in accordance with the surrounding light level.

Clinical applications of digital 2-D and 3-D radiography for the periodontist

CONTEXT

Although there has been rapid development of imaging technology within dentistry, there has been limited evidence-based research documenting the benefits of digital radiography.

EVIDENCE

We searched MEDLINE for relevant studies and review papers demonstrating clinical applications, limitations, and advancements within digital radiography.

EVIDENCE SYNTHESIS

Two-dimensional (2-D) and 3-D digital radiography has become a powerful diagnostic tool for simple and complex procedures, including implant reconstruction. Recent advancements have reduced radiation exposure, increased resolution, and improved detection capabilities of complementary metal oxide semiconductor (CMOS) and cone-beam computed tomography (CBCT) sensors. The current review summarizes such advances and outlines advanced CBCT implant-planning techniques.

CONCLUSIONS

While evidence-based research grows, the logistic, diagnostic, and planning improvements of 2-D and 3-D digital radiography are irrefutable with the potential to supplant conventional techniques.

Radiological diagnosis of periapical bone tissue lesions in endodontics: a systematic review

This systematic review evaluates the diagnostic accuracy of radiographic methods employed to indicate presence/absence and changes over time of periapical bone lesions. Also investigated were the leads radiographic images may give about the nature of the process and the condition of the pulp in nonendodontically treated teeth. Electronic literature search included the databases PubMed, Embase and CENTRAL from January 1950 to June 2011. All languages were accepted provided there was an abstract in English. The MeSH terms were 'Cone beam computed tomography (CBCT)', 'Radiography, panoramic', 'Periapical diseases', 'Dental pulp diseases', 'Sensitivity and specificity', 'receiver operating characteristics (ROC) curve', 'Cadaver', 'Endodontics' and 'Radiography dental'. Two reviewers independently assessed abstracts and full text articles. An article was read in full text if at least one of the two reviewers considered an abstract to be potentially relevant. Altogether, 181 articles were read in full text. The GRADE approach was used to assess the quality of evidence of each radiographic method based on studies of high or moderate quality. Twenty-six studies fulfilled criteria set for inclusion. None was of high quality; 11 were of moderate quality. There is insufficient evidence that the digital intraoral radiographic technique is diagnostically as accurate as the conventional film technique. The same applies to CBCT. No conclusions can be drawn regarding the accuracy of radiological examination in identifying various forms of periapical bone tissue changes or about the pulpal condition.

Effect of ambient light level at the monitor surface on digital radiographic evaluation of approximal carious lesions: an in vitro study

OBJECTIVES

This study investigated how ambient light affects the diagnostic accuracy of dental carious lesions on monitors used in dental practice. Specifically, the aim was to evaluate whether a monitor hood for blocking excess ambient light increases practitioners' ability to accurately diagnose carious lesions on digital radiographs under bright ambient light conditions.

METHODS

7 observers evaluated approximal carious lesions on standardized digital radiographs of 100 teeth under 3 ambient light conditions: bright light (> 1000 lx) and dim light (<50 lx) with no monitor hood; and bright light with a hooded monitor. Receiver operating characteristic curves were plotted for all observations. The criterion standard was a histological examination of the teeth. A paired t-test compared the effects of the three lighting conditions. The level of significance was set to p <0.05. Weighted kappa statistics estimated intraobserver agreement.

RESULTS

The diagnostic accuracy for dentine lesions was significantly higher in ambient light<50&hairsp ;lx than on monitors with and without a hood in ambient light>1000 lx. For all observers, diagnostic accuracy of dentine lesions under bright light was higher on a hooded monitor than on a monitor without a hood, but this difference was not significant. Intraobserver agreement varied from moderate to good.

CONCLUSION

Diagnostic accuracy of those carious lesions that reached into the dentine was significantly higher in ambient light<50 lx than in ambient light>1000 lx. A hooded monitor in bright light was not as effective as a monitor without a hood in dim light.

Comparison of the efficacy of conventional radiography, digital radiography, and ultrasound in diagnosing periapical lesions

OBJECTIVES

The aim of this study was to evaluate the efficacy of conventional radiography, digital radiography and ultrasound imaging in diagnosing periapical lesions.

STUDY DESIGN

Twenty-one patients aged between 15 and 45 years with well defined periapical radiolucency associated with anterior maxillary or mandibular teeth requiring endodontic surgery or extraction were selected and consented to the study. Preoperative intraoral periapical radiographs and digital images using charge-coupled device obtained by paralleling technique were assessed by 3 specialist observers who gave their diagnosis of the periapical lesions. Then ultrasound examination was performed and the images were assessed for size, contents, and vascular supply by 3 ultrasonographers. It was followed by curettage of periapical tissues to enable histopathologic investigation, which is the gold standard in diagnosis. The data were statistically analyzed using SPSS, analysis of variance, and kappa statistics.

RESULTS

The percentage accuracy of diagnosing periapical lesions using conventional radiography was 47.6%, digital radiography 55.6%, and ultrasound 95.2%. Ultrasound had the highest sensitivity and specificity: 0.95 and 1.00, respectively.

CONCLUSION

Conventional and digital radiography enable diagnosis of periapical diseases, but not their nature, whereas ultrasound provides accurate information on the pathologic nature of the lesions, which is of importance in predicting the treatment outcome. Therefore ultrasound can be used as an adjunct to conventional or digital radiography in diagnosing periapical lesions.

Digital radiography in general dental practice: a field study

OBJECTIVES

The aim of this study was to conduct a field study to survey the performance of digital radiography and how it was used by dentists in general dental practice.

METHODS

19 general dental practitioners were visited at their clinics. Ambient light (illuminance) was measured in the rooms where the monitors were placed. Different technical display parameters were noted. Test images and two phantoms--one low-contrast phantom and one line-pair resolution phantom--were used to evaluate the digital system. How the dentists used the enhancement program was investigated by noting which functions were used.

RESULTS

Average illuminance in the operating room was 668 lux (range 190-1250 lux). On radiographs of the low-contrast phantom taken at the clinic, the ability to observe the holes decreased as illuminance increased. On average, the "light percentage" initially set on the monitor had to be decreased by 17% and contrast by 10% to optimize the display of the test images. The general dental practitioners used the enhancement programs most often to alter brightness and contrast to obtain the subjectively best image. Large differences between the clinics were noted.

CONCLUSION

Knowledge of how to handle digital equipment in general dental practice should be improved. A calibrated monitor of good quality should be a given priority, as should proper ambient light conditions. There is a need to develop standardized quality controls for digital dental radiography.

Imaging of root canal fillings: a comparison of subjective image quality between limited cone-beam CT, storage phosphor and film radiography

AIM

To compare the subjective quality of limited cone-beam computed tomography (LCBCT), storage phosphor plate (SPP) and F-speed film images for the evaluation of length and homogeneity of root fillings.

METHODOLOGY

Root canals of 17 extracted permanent mandibular incisor teeth were filled. With the teeth placed in their jaws, images were obtained with Accu-I-Tomo LCBCT, Digora Optime image plate system and F-speed film using exposure parameters yielding 'clinically' acceptable density and contrast. Three radiologists and three endodontists independently rated the quality of all images in respect to homogeneity and the length of root fillings using a 3-graded scale. Evaluations were undertaken in two sessions. In the first, the coronal LCBCT images were not included. In the second, both coronal and sagittal LCBCT images were rated along with F-speed film and SPP images.

RESULTS

were compared using the Friedman test (P < 0.05). Pair-wise comparisons of systems were completed using the Wilxocon signed-ranks test (P < 0.05). Kappa was used to measure interobserver agreement. Results Digora images were rated superior, consecutively followed by F-speed films and LCBCT images, for the evaluation of both homogeneity and length of root fillings in both the evaluation sessions (P < 0.05). Kappa ranged from slight to moderate for the length evaluation of root fillings and from poor to fair for the evaluation of homogeneity of root fillings.

CONCLUSION

Image quality of storage phosphor images was subjectively as good as conventional film images and superior to LCBCT images for the evaluation of both homogeneity and length of root fillings in single-rooted teeth.

Comparison of ultrasound, digital and conventional radiography in differentiating periapical lesions

OBJECTIVES

To carry out an in vivo comparative pilot study to evaluate the efficacy of ultrasound, digital (DR) and conventional plain film-based imaging (PF) in the differential diagnosis of periapical lesions.

METHODS

Fifteen patients aged between 13 years and 40 years with periapical lesions associated with anterior maxillary or mandibular teeth requiring endodontic surgery were selected and consented for the study. Pre-operative periapical radiographs (PF) and charge coupled device (CCD) DR were obtained. Measurements and provisional diagnoses of the apical areas were made by three specialist observers (two dental radiologists and one endodontist) on three separate occasions. Pre-operative ultrasound examinations were then performed and the images assessed by two specialist observers (ultrasonographer and endodontist) for the size, contents, vascular supply and a provisional diagnosis made as to whether the lesion was a cyst or granuloma. Endodontic surgery was performed including curettage of the apical tissues to enable histopathological investigation, which provided the gold standard diagnosis. All measurements and findings were compared and statistically analysed.

RESULTS

On PF and DR the periapical lesions were readily identified but observers were unable to differentiate granuloma from cyst using either modality. Dimensional measurements were subject to greater interobserver variation on DR than on PF. Where sufficient buccal cortical bone had been resorbed, ultrasound imaging was straightforward but underestimated the size of the lesions compared with PF and DR. In all 15 cases, the ultrasound diagnosis agreed with the histopathological gold standard.

CONCLUSIONS

PF and DR enable diagnosis of periapical disease existence, but not of its nature; while ultrasound underestimates the extent of disease, but can provide accurate information on the pathological nature of the lesion.

Conventional and indirect digital radiographic interpretation of oral unilocular radiolucent lesions

OBJECTIVES

To compare the diagnostic processes for the main unilocular radiolucent lesions of the mandible in the presence of the following variables: conventional and digital radiography, specialization of the examiner and type of lesion.

METHODS

Twenty-four panoramic radiographs were selected from the archives of the AC Camargo Hospital (São Paulo, Brazil), aiming at comparing the diagnostic processes for similar unilocular radiolucent lesions of the mandible, with the following histopathological diagnosis: six ameloblastomas, six dentigerous cysts, six keratocysts and six traumatic bone cysts. The radiographs were scanned and processed using the Trophy 2000 software. Three specialists, each from four related areas (pathologists, stomatologists, radiologists and oral surgeons), randomly evaluated the radiographs before and after digitalization.

RESULTS

The kappa statistic showed a high level of agreement between results obtained using the two radiographic techniques. This means that, in general, the examiners diagnosed the same cases correctly or incorrectly regardless of the method used.

CONCLUSIONS

Based on generalized estimating equations, it was concluded that the probability of correct diagnosis does not depend on the kind of lesion, on the radiographic technique or on the specialization of the examiner. In view of the differing opinions of the specialists regarding the diagnostic validity of some software features available and of the results obtained in indirect digital technique, it may be reasonable to reconsider its use for diagnosis of bone pathology.

Survey of dental radiological practice in Turkey

OBJECTIVES

The aim of this study was to determine the dentist's knowledge about dose reduction techniques, radiographic equipment and quality of dental radiographic service in general dental practice in Turkey.

METHODS

The survey was performed on 636 dentists who attended the 11th International Congress organized by the Turkish Dental Association. Information on the demographic characteristics of the dentists, radiographic equipment, techniques and processing they used and radiation protection was obtained with a 32 point questionnaire.

RESULTS

The respondents' knowledge concerning the technical details of their equipment was limited, with 512 (86.9%) not knowing the kilovoltage peak (kVp) of their machine. Only 34 (5.5%) respondents reported having rectangular collimators. The dentists had little knowledge about the speed of film they used. D-speed film was the most preferred one with 21.6%. Fifty-eight (10.2%) dentists used E-speed film and the F-speed film was used only by 13 (2.3%) dentists. The most preferred technique (62%) for periapical radiography was the bisecting angle technique. Four hundred and eighty five (82.5%) of the dentists reported that they took the radiographs by themselves.

CONCLUSIONS

In the present study, the results indicate that for minimizing any unnecessary radiation, attempts should be made to improve dentists' knowledge about radiation dose reduction techniques.

Effects of the automatic exposure compensation on the proximal caries diagnosis

OBJECTIVE

To elucidate the effect of automatic exposure compensation (AEC) on the diagnostic accuracy of proximal caries by comparing several digital intraoral imaging systems with a film.

MATERIALS AND METHODS

Twenty-seven extracted teeth served as proximal caries samples. Three digital radiographic systems; the Compuray, the Dixel, and the Sens-A-Ray without scintillator layer, and Kodak Ekta-speed Plus films were used as recording media. Radiographs of the teeth samples were obtained with each recording medium under seven to eight different exposures including the optimum level. Six oral radiologists evaluated the possibility of proximal caries with the five-grade-confidence-scale. On digital radiographs, image manipulations were allowed after the initial assessment. Receiver operating characteristic (ROC) curves were obtained at each exposure in each recording medium. The area under the ROC curve (Az) was used as the representative value of diagnostic accuracy. Diagnostic accuracy (DA) curves were obtained by plotting averaged Az values from all observers as a function of incident exposure in each system.

RESULTS

The effect of exposure variation on the DA was slight in the film while it was significantly larger in the digital systems without AEC. Among digital systems, the effect of exposure variation was smaller in the system with AEC than those without AEC. There was no significant effect on the diagnostic accuracy even if digital image manipulation was employed.

CONCLUSION

AEC minimizes the decrease of DA due to inadequate exposures. Since it compensates for the narrow exposure range in the digital intraoral sensor systems, the system with AEC may be preferable for the clinical diagnostic tasks.

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

OBJECTIVES

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.

METHOD

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).

RESULTS

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.

CONCLUSION

JPEG compression does not impact detectability of artificial periapical lesions at low and moderate compression ratios up to and including 28:1.

Comparison of the diagnostic potential of direct digital and conventional intraoral radiography in the evaluation of peri-implant conditions

The aims of this study were to examine whether viewers agreed on details seen in direct (real time) digital and conventional film radiographs of implants, and whether there were differences in agreement between the systems. Intra-oral radiographs of implants were exposed both as direct digital and conventional film radiographs. Fifty pairs of radiographs with similar projection and exposure were selected, showing 59 implants. Ten viewers assessed the radiographs separately and noted eight different details. The viewers showed very high agreement in their assessments of radiographs of each technique separately, and there were no statistically significant differences. However, there was a tendency to stronger agreement in the direct digital radiographs in four assessed points out of eight. The patients' experience of having radiographs exposed with the two methods was also studied by questionnaire. The patients' opinions on the two techniques did not differ statistically. This study shows that digital radiography has at least equal diagnostic yield compared to film radiography.

Root fracture detection on digital images: effect of the zoom function

To assess the accuracy of root fracture detection at various levels of image magnification.

METHODS

Extracted single-rooted human teeth (100 non-fractured and 101 fractured) were mounted singly in wax blocks and a charge-coupled device (CCD)-based digital Sidexis imaging system was used to take images using the paralleling technique. Image sizes 1 : 1, 2 : 1, and 1 : 2 were prepared for each tooth. All 603 images were examined randomly and interpreted by an experienced radiologist unaware of which images were of fractured roots. The degree of agreement between image interpretation and the actual condition was estimated using a kappa statistic. A modified goodness-of-fit chi2-test was used to assess the significance of the difference between the three image sizes. The sensitivity, specificity, predictive value, and likelihood ratio were used to evaluate the accuracy of root fracture detection at each level of magnification. The degree of agreement between pairs of viewing conditions was also calculated using a kappa statistic.

RESULTS

There was substantial agreement between image interpretation and the actual condition for both the 1 : 1 and 1 : 2 image sizes but only moderate agreement for the 2 : 1 size. The kappa values (and 95% CIs) were 0.65 (0.51-0.79), 0.63 (0.49-0.77), and 0.58 (0.44-0.72), respectively. The differences were not statistically significant (P-value = 0.79). The sensitivity (95% CI) of the image magnification ranged between 79.0% (70.0-87.5%) and 81.0% (72.2-87.5%). The 1 : 1 image size gave the highest specificity of 86.1% (95% CI: 78.1-91.6%). The positive predictive values (95% CI) of the 1 : 1, 1 : 2, and 2 : 1 images sizes were 84.9% (76.3-90.8%), 81.8% (73.1-88.2%), and 77.9% (69.0-84.8%), respectively. The negative predictive values (95% CI) were 80.6% (72.1-86.9%), 81.4% (73.8-88.9%), and 80.4% (71.4-87.1%) for the 1 : 1, 1 : 2, and 2 : 1 image sizes, respectively. The likelihood ratios of the positive test (95% CI) were 5.70 (3.47-9.36), 4.55 (3.00-6.98), and 3.56 (2.45-5,16) for the 1 : 1, 1 : 2, and 2 : 1 image sizes, respectively. The likelihood ratios of the negative test (95% CI) were 0.24 (0.17-0.36), 0.23 (0.15-0.35), and 0.25 (0.16-0.37) for the 1 : 1, 1 : 2, and 2 : 1 image sizes, respectively. The reliability between pairs of viewing conditions was substantial. The kappa statistics (95% CI) was 0.80 (0.72-0.88), 0.73 (0.64-0.83), and 0.77 (0.68-0.86), respectively.

CONCLUSION

In this in vitro study, the three digital magnifications used did not affect the detection of root fractures.

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.

Estimation of skeletal bone mineral density by means of the trabecular pattern of the alveolar bone, its interdental thickness, and the bone mass of the mandible

OBJECTIVE

We sought to evaluate the use of the alveolar trabecular pattern, the mandibular alveolar bone mass (MABM) measured by photodensitometry, and the interdental alveolar thickness for prediction of the skeletal bone mineral density (BMD).

STUDY DESIGN

MABM and the coarseness of trabeculation were assessed by using periapical radiographs in 80 dentate women. The interdental alveolar thickness was measured on casts, and BMD of the forearm with dual X-ray absorptiometry.

RESULTS

Significant correlations were found between skeletal BMD and MABM (r = 0.46, P <.001) as well as the coarseness of the trabeculation (r = 0.62, P <.001). The interdental alveolar thickness improved the correlation between skeletal BMD and MABM (R2 = 0.44, P <.001). Age, but not interdental thickness, improved the correlation between the coarseness of trabeculation and skeletal BMD (R2 = 0.52, P <.001).

CONCLUSION

Evaluation of the coarseness of trabeculation of the alveolar bone as seen on intraoral radiographs is a helpful clinical indicator of skeletal BMD and better than densitometric measurements of the alveolar bone. Dense trabeculation is a strong indicator of high BMD, whereas sparse trabeculation may be used to predict low BMD.

A comparative evaluation of the diagnostic efficacy of film and digital sensors for detection of simulated periapical lesions

OBJECTIVE

The purpose of this study was to evaluate the diagnostic efficacy of Ektaspeed Plus film (EPF), a charge-coupled device (CCD), and photostimulable phosphor (PSP)-based digital images for detection of simulated periapical lesions.

STUDY DESIGN

Lesions were simulated in the periapical areas of 24 human mandibular sections invested in acrylic using burs of sizes #1, 2, 4, and 6 and imaged using EPF, CCD, and PSP sensors. Percent correct response scores, sensitivity, and specificity values were computed for all variables. Repeated-measures analysis of variance and post hoc testing were performed to determine the effects of imaging modality, observer, and lesion sizes with respect to lesion detection.

RESULTS

EPF displayed the highest sensitivity and specificity, followed by PSP and CCD images (P <.001). Percent correct score was the highest for 3 of 4 observers when EPF was used. Analysis of variance revealed significance (P <.001) with respect to all variables. Observers with experience in digital image-viewing performed better than those without such experience (P <.001). Intraobserver agreement was fair (kappa = 0.5).

CONCLUSIONS

EPF outperformed CCD and PSP images when observers could manipulate image characteristics.

In vivo accuracy and reliability of color-coded image enhancements for the assessment of periradicular lesion dimensions

OBJECTIVE

The purpose of this study was to compare dimensions on charge-coupled device-acquired images under various enhancements with dimensions on film radiographs and in vivo dimensions with respect to the linear measurement of periradicular radiolucent lesions.

STUDY DESIGN

The dimensions of 25 lesions imaged by means of a charge-coupled device-based digital receptor and Ektaspeed Plus radiographic film were measured and compared with dimensions as actually measured on impressions of the lesions taken during surgery. Digital images were displayed in unenhanced, equalized, and equalized/color-coded modes. The color-coding protocol was repeated to determine the method error, and each image treatment was also remeasured to determine intrarater reliability. Differences were compared through use of a Friedman 2-way analysis of variance with a follow-up Wilcoxon signed rank test (alpha = 0.01).

RESULTS

Actual lesion dimensions were larger than dimension estimates obtained with digital images (range, 23% to 35%) and film radiographs (range, 29% to 43%). Color-coded images were significantly less accurate than equalized images and unenhanced images. Images equalized through use of the measurement algorithm of the resident software provided estimates that were more accurate than estimates made with film radiographs and a standard millimeter rule. Intrarater variability was low. The application of color coding was found to be unreliable.

CONCLUSIONS

When applied to intraoral images, color-coded image processing of digital images had limited value in the estimation of periradicular lesional dimensions.

Radiographic study of the maxillary canine tooth of four mesaticephalic cats

The radiopaque and radiolucent anatomical structures that are superimposed over the root of the maxillary canine tooth in mesaticephalic cats were identified on digital radiographs made at various angles. The vomer bone, the nasal bone, the palatine fissure, and the infraorbital foramen were not superimposed over the root of the canine tooth in the range of angles examined. Superimposition with the palatine sulcus (which is rarely visible clinically because of silhouetting of the soft tissues) only occurred at extreme horizontal (cross-sectional arc) angles. The second premolar tooth was superimposed at a cross-sectional angle of 80 degrees and 90 degrees. The structures of concern in the interpretation of radiographs of the maxillary canine tooth in mesaticephalic cats are the conchal crest, the line of conjunction between the vertical body of the maxilla and its palatine process, the incisivomaxillary canal (which is rarely visible on radiographic images), and the lachrymal canal. Because of their anatomical vicinity, the radiographic position of these structures relative to the maxillary canine tooth can only be minimally changed. It was not possible to identify an "ideal" angle to radiograph the maxillary canine tooth in these four mesaticephalic cats. However, an acceptable compromise between minimal distortion of the image and satisfactory visualization of the root was obtained with the radiographic beam (rostro-caudal rotation) angled at 80 degrees and the skull (rotation in cross-sectional arc) angled at 70 degrees.

The role of direct intraoral sensors in the provision of endodontic services

The recent commercial success of intraoral sensor systems largely reflects the quest to improve the quality assurances for endodontic services. The many advantages of these systems include reduced radiation exposures, real-time images, resolution improvements after initial image capture and archival benefits, although their diagnostic benefits over conventional film based radiographs remain a concern. For instance, the images from either charge-coupled device or storage phosphor sensors have yet to exceed the potential 50 microns spatial and 12-bit contrast resolutions obtained from the 1.75-6.40 microns silver grain emulsions of conventional films or the potential improvements derived from smaller (1 micron) grains. Intraoral sensor systems alone are therefore unlikely to improve the quality assurances for endodontic services.