Effect of object position in the field of view and application of a metal artifact reduction algorithm on the detection of vertical root fractures on cone-beam computed tomography scans: An in vitro study

PURPOSE: To assess the effects of object position in the field of view (FOV) and application of a metal artifact reduction (MAR) algorithm on the diagnostic accuracy of cone-beam computed tomography (CBCT) for the detection of vertical root fractures (VRFs). MATERIALS AND METHODS: Sixty human single-canal premolars received root canal treatment. VRFs were induced in 30 endodontically treated teeth. The teeth were then divided into 4 groups, with 2 groups receiving metal posts and the remaining 2 only having an empty post space. The roots from different groups were mounted in a phantom made of cow rib bone, and CBCT scans were obtained for the 4 different groups. Three observers evaluated the images independently. RESULTS: The highest frequency of correct diagnoses of VRFs was obtained with the object positioned centrally in the FOV, using the MAR algorithm. Peripheral positioning of the object without the MAR algorithm yielded the highest sensitivity for the first observer (66.7%). For the second and third observers, a central position improved sensitivity, with or without the MAR algorithm. In the presence of metal posts, central positioning of the object in the FOV significantly increased the diagnostic sensitivity and accuracy compared to peripheral positioning. CONCLUSION: Diagnostic accuracy was higher with central positioning than with peripheral positioning, irrespective of whether the MAR algorithm was applied. However, the effect of the MAR algorithm was more significant with central positioning than with peripheral positioning of the object in the FOV. The clinical experience and expertise of the observers may serve as a confounder in this respect.

Frequency of different maxillary sinus septal patterns found on cone-beam computed tomography and predicting the associated risk of sinus membrane perforation during sinus lifting

PURPOSE: Analyzing different patterns of maxillary sinus septa in cone-beam computed tomography (CBCT) images and predicting maxillary sinus membrane perforations. MATERIALS AND METHODS: In this cross-sectional study, CBCT images of 222 patients ranging from 20 to 81 years old were evaluated. One hundred fifty-two patients (93 females and 59 males) who had maxillary sinus septa in axial views were included in this study. Cross-sectional images were used to determine classifications of sinus septa and the risk of membrane perforation using a method modified from Al-Faraje et al. Variables of sex, age, and dental status were considered. Chi-squared and Kruskal-Wallis tests were used for data analysis (P 0.05). CONCLUSION: A higher prevalence of moderate risk of membrane perforation in the molar region relative to the premolar region was observed. Furthermore, maxillary sinus septa occur most frequently in the molar region, demonstrating the importance of paying attention to this region during sinus lift surgery. This study did not show any relationship between tooth loss and the presence of septa.

analysis of visibility and anatomic variations of mandibular canal in digital panoramic radiographs of dentulous and edentulous patients in northern Iran populations

Statement of the Problem: Insufficient information about the anatomical positions and structure of mandibular canal provokes unwanted damage to this important structure of mandible

Purpose: The aim of this study was to determine the visibility and anatomical variations of mandibular canal in digital panoramic radiographs of dentulous and edentulous patients in a sample of Iranian population

Materials and Method: In this retrospective-analytical research, 249 digital panoramic radiographs in dentulous group and 126 in edentulous group were studied by an expert oral and maxillofacial radiologist. In both groups, the visibility of canal borders in anterior, middle, and posterior areas were examined. In dentulous group, the distance between the canal and apex of the first and second molars were measured. Canal-to-alveolar crest distance and lower mandibular border was measured in three different points for both groups. Finally, the upper-lower positions of canals were determined

Results: In both groups, most visibility occurred in 1/3 of posterior and the least visibility was detected in 1/3 of anterior, with the intermediate being the most visible part [Type 2]. There was no significant difference between the left and right sides in all cases. In dentulous group, no correlation was found between the visibility, age, and gender [p> 0.05]; however, canal position was related to gender [p= 0.03 and p= 0.04 in right and left sides, respectively]. High position was more frequent in females and intermediate position was more common in males. In edentulous group, no correlation was found between age, gender, and canal position [p> 0.05]

Conclusion: The most visibility of mandibular canal was in its third posterior and the least was in its third anterior part. Although the middle position of canal was more frequently visible than the high position in this study, it does not refute the possibility of damaging the mandibular canal in critical surgeries

The effects of noise reduction, sharpening, enhancement, and image magnification on diagnostic accuracy of a photostimulable phosphor system in the detection of non-cavitated approximal dental caries

PURPOSE: Contrast, sharpness, enhancement, and density can be changed in digital systems. The important question is to what extent the changes in these variables affect the accuracy of caries detection. MATERIALS AND METHODS: Forty eight extracted human posterior teeth with healthy or proximal caries surfaces were imaged using a photostimulable phosphor (PSP) sensor. All original images were processed using a six-step method: (1) applying "Sharpening 2" and "Noise Reduction" processing options to the original images; (2) applying the "Magnification 1:3" option to the image obtained in the first step; (3) enhancing the original images by using the "Diagonal/" option; (4) reviewing the changes brought about by the third step of image processing and then, applying "Magnification 1:3"; (5) applying "Sharpening UM" to the original images; and (6) analyzing the changes brought about by the fifth step of image processing, and finally, applying "Magnification 1:3." Three observers evaluated the images. The tooth sections were evaluated histologically as the gold standard. The diagnostic accuracy of the observers was compared using a chi-squared test. RESULTS: The accuracy levels irrespective of the image processing method ranged from weak (18.8%) to intermediate (54.2%), but the highest accuracy was achieved at the sixth image processing step. The overall diagnostic accuracy level showed a statistically significant difference (p=0.0001). CONCLUSION: This study shows that the application of "Sharpening UM" along with the "Magnification 1:3" processing option improved the diagnostic accuracy and the observer agreement more effectively than the other processing procedures.

A comparative study of metal artifacts from common metal orthodontic brackets in magnetic resonance imaging

PURPOSE: This study was performed to compare the metal artifacts from common metal orthodontic brackets in magnetic resonance imaging. MATERIALS AND METHODS: A dry mandible with 12 intact premolars was prepared, and was scanned ten times with various types of brackets: American, 3M, Dentaurum, and Masel orthodontic brackets were used, together with either stainless steel (SS) or nickel titanium (NiTi) wires. Subsequently, three different sequences of coronal and axial images were obtained: spin-echo T1-weighted images, fast spin-echo T2-weighted images, and fluid-attenuated inversion recovery images. In each sequence, the two sequential axial and coronal images with the largest signal-void area were selected. The largest diameters of the signal voids in the direction of the X-, Y-, and Z-axes were then measured twice. Finally, the mean linear values associated with different orthodontic brackets were analyzed using one-way analysis of variation, and the results were compared using the independent t-test to assess whether the use of SS or NiTi wires had a significant effect on the images. RESULTS: Statistically significant differences were only observed along the Z-axis among the four different brands of orthodontic brackets with SS wires. A statistically significant difference was observed along all axes among the brackets with NiTi wires. A statistically significant difference was found only along the Z-axis between nickel-free and nickel-containing brackets. CONCLUSION: With respect to all axes, the 3M bracket was associated with smaller signal-void areas. Overall, the 3M and Dentaurum brackets with NiTi wires induced smaller artifacts along all axes than those with SS wires.

[ comparison between digital panoramic view and cone-beam computed tomography [CBCT] images in diagnosis of apical radiolucent lesions]

Panoramic radiography is used extensively in the field of dentistry as a screening method. In endodontic treatment, the diagnosis and evaluation of periapical area is very important. However, using advanced imaging such as cone beam computed tomography [CBCT] has increased diagnostic ability, but it must be used precisely and in special condition. The aim of this study was to compare diagnostic value of digital panoramic view and CBCT in diagnosis of apical lucent lesion. In this cross-sectional study, digital panoramic view and CBCT of 47 patients [573 apical portions of root] who had referred to maxillofacial radiology clinic for maxillary and or mandibular CBCT procedures were assessed. All of the selected patients needed these images as their treatment protocol. According to order of CBCT [maxilla, mandible and both], the teeth of the same jaw in digital panoramic radiography by a maxillofacial radiologist were evaluated. After data enterance, agreement, Sensitivity, specificity and likelihood ratio [positive and negative] were assessed totally and for each jaw separately with 95 percent confidence interval. 0.05 was established as a level of significant. Periapical radiolucency in 15.9% of apical areas in CBCT and in digital panoramic view in 4.2% of them was detected. Overall, sensitivity and specificity of digital panoramic view were 26.4% and 100% respectively. Sensitivity of panoramic view in diagnosis of periapical lucency in mandible was higher than maxilla. According to kappa analysis, the agreement level between panoramic and CBCT was assigned low [kappa=0.374]. Although panoramic is a routine screening method in field of dentistry, it is not accurate in diagnosis of the presence of periapical lesions. This limitation in maxilla is more than mandible

Comparison of high-resolution and standard zoom imaging modes in cone beam computed tomography for detection of longitudinal root fracture: An in vitro study

PURPOSE: The purpose of this study was to compare the efficacy of two imaging modes in a cone beam computed tomography (CBCT) system in detecting root fracture in endodontically-treated teeth with fiber posts or screw posts by selecting two fields of view. MATERIALS AND METHODS: In this study, 78 endodontically-treated single canal premolars were included. A post space was created in all of them. Then the teeth were randomly set in one of 6 artificial dental arches. In 39 of the 78 teeth set in the 6 dental arches, a root fracture was intentionally created. Next, a fiber post and a screw post were cemented into 26 teeth having equal the root fractures. High resolution (HiRes) and standard zoom images were provided by a CBCT device. Upon considering the reconstructed images, two observers in agreement with each other confirmed the presence or absence of root fracture. A McNemar test was used for comparing the results of the two modes. RESULTS: The frequency of making a correct diagnosis using the HiRes zoom imaging mode was 71.8% and in standard zoom was 59%. The overall sensitivity and specificity in diagnosing root fracture in the HiRes mode were 71.79% and 46.15% and in the standard zoom modes were 58.97% and 33.33%, respectively. CONCLUSION: There were no significant differences between the diagnostic values of the two imaging modes used in the diagnosis of root fracture or in the presence of root canal restorations. In both modes, the most true-positive results were reported in the post space group.

[Agreement of digital intraoral bite-wing and super bite-wing in diagnosis of proximal dental caries]

One of developments in field of radiology is providing the radiographic image based on computed radiography [CR] system. Common usable capabilities of CR system are obtaining super BW [Bite-Wing] images from digital panoramic views. Considering advantages of this system such as edge enhancement, we decided to evaluate the agreement of super BW with digital intraoral BW which is produced with PSP [Phosphor Storage Plate] system in detection of proximal caries. In this study, 40 patients with bilateral BW produced by intraoral PSP sensor [Digora Optime] and digital panoramic radiography which was taken with cassette containing storage plate [Konica Minolta] were selected. First, two super BWs were extracted from digital panoramic images of the patients and then proximal caries in digital intraoral BW and super BW images were evaluated by two different observers separately. In this study, the agreement between two methods was evaluated for each observer with kappa agreement test. After analysis of data, it was revealed that there was a moderate agreement between two methods in detection of caries by first and second observers [0.454, 0.421]. There was a poor agreement for detection of proximal caries of premolar teeth and a moderate agreement about molar teeth between first and second observers. Interobserver agreement for both techniques was good [0.664, 0.626]. According to the findings of this study, it seems that due to a good agreement between two observers and a moderate agreement between two techniques about detection of caries, the use of super BW method instead of intraoral BW technique is not proper and therefore, using digital intraoral BW in detection of dental caries is preffered

Diagnostic value of two modes of cone-beam computed tomography in evaluation of simulated external root resorption: an in vitro study

PURPOSE: Field of view and voxel resolution of cone beam computed tomography (CBCT) might affect the diagnostic capability. This study was performed to compare between the standard and HiRes zoom modes in the diagnosis of external root resorption (ERR) using CBCT. MATERIALS AND METHODS: Sixty three small cavities (0.25 mm depth and 0.5 mm diameter) were simulated on the buccal, lingual, and proximal surfaces at three different levels of 16 roots of teeth. After covering the root with nail varnish, the roots were inserted in the sockets and the model was placed in a water-containing lacuna. CBCT scans were taken in both standard and HiRes zoom modes using NewTom VG (QR srl Company, Verona, Italy). Then, an observer assessed the images to determine the presence or absence of the cavities. This process was repeated by increasing the size and depth of cavities to 0.5 mm depth and 1 mm diameter. Data were analyzed by McNemar test. The sensitivity, specificity, positive predictive value, negative predictive value, and likelihood ratio in evaluation of the simulated cavities were calculated. RESULTS: There was a significant difference between the two imaging modes in diagnosing the shallow cavities (p=0.02).The sensitivity of the standard zoom in detecting the shallow cavities was lower than that of the HiRes zoom. The likelihood ratio of the HiRes zoom was higher in the diagnosis of both cavity types. CONCLUSION: This study suggested that a smaller voxel size in the HiRes zoom mode of CBCT is preferred for diagnosis of ERR.

[Comparison between CMOS digital detector and film in detection of simulated external root resorption: an in vitro study]

Root resorption is one of the most difficult diagnostic problems in endodontic treatments. Since successful treatment depends on early diagnosis of this pathology, using several diagnostic methods such as radiographic Images based on films, digital images and finally advanced diagnostic techniques are important. Therefore, in this study, we compared digital detector [CMOS] and conventional films by changing the different variables in diagnosis of simulated external root resorption [RR]. In this in vitro study, in the first group, twelve intact premolar teeth extracted for orthodontic treatments, were selected. On the root surface of each tooth, we created a 2x2 mm window on buccal, lingual or proxinial surface in cervical or middle levels and covered the remaining parts of the teeth with nail varnish. The root resorption was stimulated using acid in two different steps. The radiographic images were taken by two detectors, conventional film and CMOS sensor in three angulations [ortho, 15 degree mesial shift and 15 degree distal shift] before and after resorption induction. In the second group, on another 12 premolar teeth, mechanical root resorption was created by bur in two different sizes. The above mentioned steps were repeated the same as the first step. The images were observed by an expert endodontist and radiologist to find out whether there was root resorption or not. The data were analysed by Chi square test. Overall, the rate of correct diagnosis of acidic resorption in digital method [CMOS] was significantly higher than that of conventional method; however, in mechanical resorption the difference was not significant. According to our study, digital radiographs are more effective and helpful than conventional images in diagnosis of external resorption. Variables such as size, shape of cavity, location and level of root resorption are effective in observers' ability in detection of root resorption

Direct digital radiography versus conventional radiography for estimation of canal length in curved canals

PURPOSE: The purpose of this study was to compare the conventional and digital radiography in the estimation of working length in mandibular molars. MATERIALS AND METHODS: Sixty molar teeth were selected and divided into three groups in the basis of canal curves (0-15degrees, 15-30degrees, >30degrees). After the placement of a 15 K-file, radiographs were taken with a conventional film (F-speed) and a digital sensor. Canal lengths were measured in these images by two observers. Statistical analysis was performed with repeated measures of ANOVA and paired sample t-test with 95% confidence. RESULTS: There was a high inter-observer agreement on the measurements of working length in conventional and digital radiographs. There was no significant difference between the mean values of measurements in conventional and digital radiography. Moreover, there was no significant difference between conventional and digital radiography with the actual values in the basis of canal curves. CONCLUSION: The accuracy of conventional and digital radiography in the determination of the working length was in an acceptable range.

Effect of topacal C-5 on demineralized enamel adjacent to orthodontic brackets

Enamel white spots are one of the patients' problems after fixed orthodontic treatment. Casein phosphopeptides [CPP] stabilize amorphous calcium phosphate. They may be used to reducing demineralization and enhancing remineralization. Topacal C-5 is one of CPP preparations.The purpose of this study was to evaluate the effect of Topacal C-5 on inhibition of further demineralization of enamel or remineralization of caries producing enamel lesions. In this study, 24 extracted human premolars were divided randomly in control and experimental groups. The samples were immersed in an artificial caries solution for an hour twice daily over a 31-day period. After each caries-producing attack, Topacal C-5 was applied on the exposed enamel window twice daily. Then, teeth were sectioned longitudinally and the depth of enamel lesion was measured under polarized light microscopy. A T-test and a T-paired test were employed to identify significant differences between the given groups [p<0.05]. The depth of the lesion in experimental group, was significantly lower than control group [p<0.05]. Topacal C-5 is a factor in reducing demineralization process or it may be effective in the induction of remineralization