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    Cone beam computed tomography evaluation of c-shaped canal morphology in mandibular premolar teeth
    (Istanbul Univ Press, Istanbul Univ Rectorate, 2024) Aslan, Elif; Ulusoy, A. Canberk; Baksi, B. Guniz; Mert, Ali; Sen, B. Hakan
    Purpose The aim of this study was to evaluate the prevalence and the morphology of c -shaped root canal(s) in mandibular premolars using cone beam computed tomography (CBCT) images. Materials and Methods CBCT images of 1095 mandibular premolars were examined at coronal, middle, and apical levels of the root canals. The type, the level, and the position (buccal or lingual) of the c -shaped anatomy were recorded. Absolute counts and percentages of different groups and subgroups of C -shape morphologies were calculated. The Chi-square test was used to compare the prevalence of C -shaped morphology between mandibular first and second premolars. The Z -test for proportions in independent groups was used to analyze the differences in mandibular C -shaped premolar proportions between location (left and right side) and tooth (first or second premolars) (p=0.05). Results C -shaped root canal morphology was present in 44 teeth. The percentage of c -shaped morphologies was 6.9% and 1.6% in mandibular first and second premolars, respectively. Comparison of the first and the second premolars showed that C1 type (p=0.008) and C4b type (p=0.013) configurations are more common in the first premolars at the coronal level. In contrast, the C2 type configuration showed significantly higher prevalence in the second premolars (p=0.009). Additionally, the C4c type configuration was significantly frequent on the right premolars at the coronal level (p=0.038). Conclusion C -shape canal morphology is a rare but complex anatomic feature in mandibular premolars. Therefore, clinicians should be aware of this complex root canal anatomy for the success of endodontic treatment in mandibular premolar teeth.
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    Effect of Mandibular Angulation on Pre-Implant Site Measurement Accuracy Using CBCT
    (Quintessence Publishing Co Inc, 2021) Onem, Erinc; Baksi, B. Guniz; Turhal, R. Irmak; Sen, B. Hakan
    Purpose: To evaluate the accuracy of available bone width, height, and length measurements on preplanned implant sites using cone beam computed tomography (CBCT) images scanned at different angulations of the mandible. Materials and Methods: Standard cylindrical holes were prepared on six dry human mandibles and filled with warm gutta-percha to create spherical markers for measurements of available bone width, height, and length. Mandibles were first scanned with a CBCT device in the ideal position with the occlusal plane parallel to the horizontal plane. Then, images of the mandibles were obtained in rotation, tilt, flexion, and extension positions using 5-and 10-degree angulations. Measurements were done on a total of 54 images. Original dimensions of the available bone for planned implant sites were measured with a digital caliper on dry mandibles as the gold standard. The absolute values of the differences between each measurement and the gold standard were obtained for measurement errors. Repeated-measures analysis of variance and Dunnett's multiple comparisons test were used for comparisons (P=.05). Intraobserver and interobserver agreement was calculated using intraclass correlation coefficient (ICC). Results: ICC was excellent for both intraobserver and interobserver reproducibility. No significant difference was found between length and height measurements in the ideal position and in rotation, tilt, flexion, and extension movements of mandibles at two different angulations (P > .05). Width measurements revealed a significant difference among the ideal position and measurements at the 10-degree flexion, 10-degree extension, 10-degree rotation, and 10-degree tilted mandibular positions (P < .05). Conclusion: The position of the occlusal plane with respect to the floor during the CBCT scan may have a clinically significant effect on dental implant site dimensions.
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    Pixel Intensity and Fractal Dimension of Periapical Lesions Visually Indiscernible in Radiographs
    (Elsevier Science Inc, 2013) Sogur, Elif; Bakst, B. Guniz; Grondahl, Hans-Goran; Sen, B. Hakan
    Introduction:The purpose of the study was to analyze pixel intensity (PI) and fractal dimension (FD) values in radiographs of chemically created but visually undetectable periapical lesions. Method:Artificial lesions were created by applying 70% perchloric acid to the sockets of left and right first premolars in 12 cadaver mandibles. For preparation of relatively small lesions, the acid was applied for 30 and 60 minutes. Before and after each acid application, radiographs were taken (60 kVp, 7 mA, and 1.5 mm Al equivalent filtration for 0.12 second) with storage phosphor plates. An optical bench was used to standardize projection geometry. Image plates were scanned immediately after exposure, and the acquired images were saved uncompressed in TIF format. Six observers evaluated the images by using a 5-grade scale, and the images scored as "definitely absent" by all observers were used for the calculations of PI and FD. Box-counting FDs and differences in mean PI were computed for regions of interest at the apical areas of each premolar. Repeated-measures analysis of variance, Tukey test, and Pearson correlation coefficient test were used for statistical analysis. Results:A significant difference was found in FD values after both acid application periods (P < .05), whereas a difference in PI was detected only in images obtained after 60-minute acid application (P < .05). There was a negative correlation between FD and PI values (-0.754, P < .05). Conclusions:Calculation of FD can be a tool for the early detection of periapical lesions given the presence of baseline radiographs. (J Endod 2013;39:16,19)