The Perceptibility Ccurve Test Applied to CCD and Two Methods of Digitization of Dental Film-based Radiographs

Objectives: Several methods of image acquisition are accessible in dentistry. There is no overall acceptable method for image digitization so all different types of images can be comparable. The objective of this study was to compare the diagnostic accuracy of different methods of image digitization.Methods: This accuracy diagnostic test study used perceptibility curve test which first introduced by de Balder was applied. In this test a test object is used which is usually made by aluminum. Different levels of thickness and number of holes in the test object were necessary to have different levels of contrast. Images from film and CCD and digitized images by means of CCD scanners and digital camera were prepared. Nine observers assessed the images. Data collected was delivered to SPSS 13 software and for each image acquisition method, interclass correlation coefficience was computed and compared to the gold standard.Results: Mean sensitivity, specifity, positive and negative like hood ratios in dependence on material thickness and the background gray value were calculated. In regions of high optical density the sensitivity for the film images was highest (0.994) following by CCD (0.905), scanner (0.889) and camera (0.821). Difference between CCD images and scanner images was not significant. In dark regions of no dark holes the sensitivity was highest for film images (0.832) following by CCD (0.798), camera (0.714) and scanner (0.615) Difference between film and CCD images was not significant.Conclusion: The diagnostic quality of radiographic films was better than digital CCD sensors. For digitizing analog images scanners were better than digital cameras

Localization of impacted maxillary canine teeth: a comparison between panoramic and buccal object rule in intraoral radiography

Objectives This study aimed to compare the efficacy of panoramic radiography and the buccal object rule in intraoral periapical radiography for localization of impacted maxillary canine teeth.Methods A total of 20 panoramic radiographs depicting 28 displaced maxillary canines were evaluated. The ratio of the mesiodistal width of the impacted canine to the mesiodistal width of the ipsilateral central incisor was calculated and referred to as the canine-incisor index (CII). The height of the crown of each displaced canine was classified in vertical plane relative to the adjacent incisor as apical, middle or coronal. Position of impacted maxillary canines was also determined on two periapical radiographs using the buccal object rule. Surgical exposure and direct observation of impacted teeth were later performed and served as the gold standard. The data were analyzed using SPSS and t-test.Results There was an overlap in the CII range of the buccally (0.78–1.48) and palatally (1.15–1.75) positioned impacted canines. When considering the height factor in the middle and coronal zones, a significant difference was noted between the CII of buccally (0.78–1.1) and palatally (1.15–1.75) positioned teeth enabling determination of their buccolingual orientation (P < 0.05).Conclusion For the impacted maxillary canines located in the middle and coronal zones (90% of cases), the CII of 1.15 and higher represents palatal impaction while the CII smaller than 1.15 represents buccal impaction

Evaluation of diagnostic accuracy and dimensional measurements by using CBCT in mandibular first molars

Background: This study aimed to assess the diagnostic accuracy of cone beam computed tomography (CBCT) and quantitatively evaluate the morphology of mandibular first molars using CBCT. Material and Methods: Twenty-four double-rooted mandibular first molars were evaluated by NewTom VGi CBCT. The distance from the furcation and apex to the cementoenamel junction (CEJ), diameter and thickness of canal walls, the buccolingual (BL) to mesiodistal (MD) ratio (ΔD), prevalence of oval canals at different sections and taper of the canals were all determined. In order to assess the diagnostic accuracy of CBCT, distance from the furcation and apex to the CEJ and thickness of canal walls at the CEJ and apex were compared with the gold standard values (caliper and stereomicroscope). Statistical analyses were carried out using intraclass correlation coefficient (ICC), paired t-test and repeated measures ANOVA. Results: A high correlation existed between the CBCT and gold standard measurements ( P <0.001). In dimensional measurements, length of mesial root was higher than the distal root and lingual furcation was farther from the CEJ than the buccal furcation ( P <0.001). An important finding of this study was the mesiodistal taper of the mesiobuccal (MB) and mesiolingual (ML) canals; which was equal to 0.02. Conclusions: CBCT has acceptable diagnostic accuracy for measurement of canal wall thickness. Cleaning and shaping of the canals should be performed based on the unique anatomy of the respective canal; which necessitates the use of advanced imaging techniques for thorough assessment of root canal anatomy in a clinical settin

The Consistency of Panoramic Radiography Selection Criteria by Dentists in Tehran with the FDA Guidelines

Background and Aim: Use of panoramic radiography in some cases is easier and more cost-effective than other radiographies. However, it has some limitations as well. Considering the importance of radiography in dentistry, the present study sought to assess the consistency of selection of panoramic radiography by general dentists in Tehranwith FDA guidelines during 2010-2011 .   Materials and Methods : In this descriptive cross-sectional study, 500 general dentists were selected using randomized cluster sampling and evaluated by a questionnaire. The questionnaire asked for demographic data and had 27 questions regarding the selection criteria for panoramic radiography. Dentists had the following answer choices for each criterion: “Strongly leads to prescription”, “probably leads to prescription”, “has no effect on prescription”, “probably prevents prescription” and “strongly prevents prescription”. The answers were collected and descriptively analyzed. To evaluate the effect of different factors on dentists’ answers, binary logistic regression with enter method was used .   Results: Of the understudy dentists, 44% were females and 56% were males with a mean age of 36.84 yrs. Based on the results of regression analysis, panoramic radiography was prescribed by dentists in case of concerns regarding the carcinogenicity of radiation, good oral hygiene and for evaluation of growth and development before the age of 6 which are not in accord with the FDA guidelines. Also, for primary assessment of periodontal status, poor oral hygiene, disseminated pain, determination of alveolar crest height in the anterior region and pregnancy, panoramic radiography was prescribed by dentists which is completely in agreement with the FDA guidelines (P<0.05) .   Conclusion: Easy application of panoramic radiography and its accessibility were the reasons for its prescription in 55.5% and 47.6% of cases, respectively. Some reasons of prescription were in accord with the FDA guidelines while some others were in contrast to them

Effect of Developer Age and Film Speed on Diagnostic Accuracy of Endodontic File Length Measurement on Radiographs

Background and Aim: Radiography has extensive applications in root canal treatment and the developer age plays an important role in making a definite diagnosis. The present study examined the effect of developer age on the diagnostic accuracy of endodontic file length measurement using D-speed, E-speed and E/F-speed films. Materials and Methods: In this diagnostic study, radiographs were processed weekly by a developer aged for up to 6 weeks. Radiographs were viewed by 5 postgraduate students of endodontics and oral radiology. They determined the file tip position using a 3-point confidence scale. The area under the curve (Az) was calculated and used as a diagnostic accuracy scale. The effects of film type and endodontic file size were analyzed by one-way ANOVA, Tukey’s post hoc test and Student’s t test. Results: E-speed and D-speed films had similar diagnostic accuracy higher than that of E/F speed film (p<0.0001). The Az values of D, E and E/F speed films were 0.5882, 0.5538 and 0.3578, in fresh developer, 0.5782, 0.5718 and 0.3498 in 2-week old develop-er and 0.6196, 0.6724 and 0.2080, in 4-week old developer solution, respectively. Devel-oper age did not decrease the diagnostic accuracy of D and E-speed films but decreased that of E/F films at 4 weeks. Radiographs processed with 6 weeks old developer were not readable. All observers showed higher diagnostic accuracy determining the size of file # 15 than 10 (p<0.0001). The mean Az values for endodontic file sizes 10 and 15 using fresh, 2-week and 4-week old developers were 0.3984 and 0.6016, 0.3732, and 0.6268 and 0.2774 and 0.7226, respectively. Conclusion: The developer aged for up to 4 weeks did not significantly affect the diag-nostic accuracy of D-speed and E-speed films. E/F speed films cannot be used with de-velopers older than 2 weeks and their usage was associated with lower accuracy compared to E and D-speed films

Experimental Comparison of the Diagnostic Accuracy of Conventional and Digital Radiography in Detection of External Root Resorption

Background and Aim: External root resorption is not detectable clinically and radiography plays a key role in its diagnosis.The present study aimed at comparing the diagnostic efficacy of conventional anddigital radiography in detection of simulated root resorption cavities (In-vitro ).   Materials and Methods : This experimental observational study evaluated 39 extracted teeth. All roots, except for the palatal root of upper molars,were hypotheticallydividedinto apical and coronal sections.Half these sites were considered as the control group .Buccal cavities were randomly made in the remaining sectionsusing # 1/2,2 and 4 round burrs.Each tooth was imaged using a CCD-based digital system and E-speed film. Radiographs were taken at 0 and 20˚ mesial angulation .Six image groups were interpreted by two experienced oral and maxillofacial radiologists and one endodontist.Conventional and enhanced digital radiographs were also takenat 0 and 20˚ mesial angulation. Conventional radiographs were viewedat 2X magnification by a magnifying glass. Sensitivity, specificity,false positive and false negative percentages and accuracyof each method were compared with the gold standard. The degree of agreement among these techniques was measuredbykappa coefficient .   Results: Conventional radiography at 2X magnification had the highest sensitivity and specificity. No significant difference was found in sensitivity of digital radiography and enhanced digital radiography. Enhanced digital radiography ranked second in terms of specificity. Conventional radiography at 2X magnification followed by enhanced digital radiography had the highest diagnostic accuracy. Mesial angulation of the cone increasedsensitivity and decreased specificity in all three techniques and thus, it only improved the diagnostic accuracy of digital radiography with no significant effect on the other two techniques.The degree of agreement between the two digital techniques was higher (k=0.68) .   Conclusion: Diagnostic efficacy of conventional radiography at 2X magnification is more than digital radiographs for detection of external root resorption

The Ability of Panoramic Radiography in Determining the Relationship of Mandibular Third Molar Roots with the Inferior Alveolar Canal

Background and Aim: Panoramic radiography is the preoperative imaging technique of choice for impacted mandibular third molar surgery. However, controversy exists regarding the ability of panoramic radiography in determining the relationship of the mandibular third molar roots with the inferior alveolar canal. This study aimed to assess the ability of panoramic radiography in determining the relationship of mandibular third molar roots with the inferior alveolar nerve (IAN) canal .   Materials and Methods : This diagnostic accuracy study was conducted on 100 panoramic radiographs that were evaluated by 5 oral and maxillofacial surgery residents. They offered their expert opinion on the relationship of third molars with the IAN canal based on panoramic radiographs. These perspectives were compared with the actual post-surgical findings. Kappa and weighted Kappa reproducibility tests were used for data analysis .   Results: Among 100 understudy cases, physical contact between the mandibular third molar roots and the canal was not observed in 88 cases intra-operatively while this relationship existed in 12 cases. The panoramic radiography had a diagnostic sensitivity of 83.3%, specificity of 83%, positive predictive value of 40% and negative predictive value of 97.3%. The overall accuracy was 85%. Kappa and weighted Kappa coefficients of reproducibility were 61% and 79%, respectively .   Conclusion: Panoramic radiography can be confidently used as the most reliable and commonly accessible imaging technique. Considering the obtained negative predictive value, panoramic radiography is capable of revealing the involvement of third molar roots with the IAN canal with 97.3% accuracy. Panoramic radiography had a low diagnostic value in determining the morphology of roots

The Effect of Different Image Processing Techniques on the Measurement Accuracy of Endodontics File Length

Statement of the Problem: Different software capabilities have been used in digital systems to increase the diagnostic quality of radiographic projections. Considering the availability of different enhancement techniques, it is necessary to determine the suitability of each technique for various diagnostic cases. There is controversy between studies over the effect of different digital enhancement techniques on the accuracy of file length measurements in endodontics. Purpose: The present in vitro study aimed to determine the effect of the software capabilities on the diagnostic accuracy to determine endodontic file lengths in photostimulable phosphor (PSP) radiographs. Materials and Method: In the present in vitro study, standard access cavities were prepared in 44 extracted human single-rooted permanent teeth. An endodontic file was placed in each root canal. PSP sensors were used for digital imaging using the parallel technique. All the images were reviewed on a same monitor; once normally with no software enhancement and once using software manipulations including pseudo-color, sharpness, emboss, and edge enhancement. The distance from the file tip to the rubber stop was measured on the images by an electronic ruler. Results: Significantly, all of the image enhancement techniques presented shorter measurements comparing to the actual length. The results revealed the significant accuracy of the measured error in the pseudo-color enhancement technique compared to other techniques. Conclusion: The results revealed significant differences between the initial measurements (the gold standard) and those made on the manipulated radiographs. In all cases, the measurements were significantly lower than the real values. Therefore, none of these digital enhancement techniques can increase the accuracy of file length measurements significantly. However, manipulation with the pseudo-color option resulted in fewer errors compared to other options and the normal images. Hence, for precise measurements of the endodontic file lengths, pseudo-color processing algorithm can be suggested when using PSP sensors

Age Estimation by Kvaal’s Method Using CBCT Scans of Mandibular Canine Teeth in an Iranian Population

Introduction: Age estimation of individuals older than 21 years remains a challenge in forensic medicine. This study sought to assess the accuracy of age estimation by Kvaal’s method using cone beam computed tomography (CBCT) scans of mandibular canine teeth in an Iranian population. Materials and Methods: In this cross-validation study, information of 150 test subjects and 30 controls was collected from the files of patients presenting to Shahid Beheshti University of Medical Sciences, School of Dentistry from 2014 to 2015. The parameters used in the Kvaal’s method were measured in mandibular canine teeth on CBCT scans of patients. First, the regression formula suggested by Kvaal et al, was used for age estimation. Then we designed our own formula for age estimation according to Kvaal’s method in our Iranian population and the fitness of statistical model was assessed. Results: Use of multiple linear regression model for assessment of the correlation of parameters in Kvaal’s method according to CBCT images of mandibular canines and age in a step by step fashion showed that all variables namely pulp length/root length, pulp length/tooth length, pulp width/root width at the cementoenamel junction (CEJ) and pulp width/root width at the mid-point of CEJ and mid-root were significant in age estimation (P&lt;0.005 for all four). In this model, R2 was found to be 0.567, which indicated appropriate fitness of the regression model this should be revised "optimal". In this model, no significant linear correlation was noted between independent variables such that the variance inflation factor was maximally 1.4. Conclusions: Although most of the variables mentioned by Kvaal were effective in age estimation, some errors were seen in age estimation in the modeling and cross-validation phase. Thus, some other variables need to be included in the model to increase the accuracy of Kvaal’s formula in the Iranian population