Cervical resorption is a serious threat to the longevity of the teeth. In this study, the Canny edge-detection algorithm was applied on CBCT images to compare the accuracy of original and Canny views ...for diagnosing cervical resorption in endodontically treated teeth. Intracanal metallic posts were inserted in 60 extracted teeth being randomly divided into three groups: control, 0.5 mm, and 1 mm cervical resorption. CBCT scans of the teeth were presented to three observers in both original and Canny formats with the accuracy being determined by receiver operating characteristic (ROC) analysis. The DeLong test was used for paired comparisons with the significance level set at 0.05. The highest accuracy belonged to Canny images in 1 mm resorption, followed by Canny images in 0.5 mm resorption, original images in 1 mm resorption, and original images in 0.5 mm resorption, respectively. The Canny images were significantly more accurate in the diagnosis of 0.5 mm (p < 0.001) and 1 mm (p = 0.009) resorption. Application of the Canny edge-detection algorithm could be suggested as a new technique for facilitating the diagnosis of cervical resorption in teeth that are negatively affected by metallic artifacts.
To compare the diagnostic accuracy of cone-beam computed tomography (CBCT) with that of parallel (PPA) and oblique projected periapical (OPA) radiography for the detection of different types of ...peri-implant bone defects.
Forty implants inserted into bovine rib blocks were used. Thirty had standardized bone defects (10 each of angular, fenestration, and dehiscence defects), and 10 were defect-free controls. CBCT, PPA, and OPA images of the samples were acquired. The images were evaluated twice by each of 2 blinded observers regarding the presence or absence and the type of the defects. The area under the receiver operating characteristic curve (AUC), sensitivity, and specificity were determined for each radiographic technique. The 3 modalities were compared using the Fisher exact and chi-square tests, with
<0.05 considered as statistical significance.
High inter-examiner reliability was observed for the 3 techniques. Angular defects were detected with high sensitivity and specificity by all 3 modalities. CBCT and OPA showed similar AUC and sensitivity in the detection of fenestration defects. In the identification of dehiscence defects, CBCT showed the highest sensitivity, followed by OPA and PPA, respectively. CBCT and OPA had a significantly greater ability than PPA to detect fenestration and dehiscence defects (
<0.05).
The application of OPA radiography in addition to routine PPA imaging as a radiographic follow-up method for dental implantation greatly enhances the visualization of fenestration and dehiscence defects. CBCT properly depicted all defect types studied, but it involves a relatively high dose of radiation and cost.
The purpose of this study was to evaluate the accuracy of linear measurements in the horizontal and vertical dimensions based on object position and slice inclination in cone-beam computed tomography ...(CBCT) images.
Ten dry sheep hemi-mandibles, each with 4 sites (incisor, canine, premolar, and molar), were evaluated when either centrally or peripherally positioned within the field of view (FOV) with the image slices subjected to either oblique or orthogonal inclinations. Four types of images were created of each region: central/cross-sectional, central/coronal, peripheral/cross-sectional, and peripheral/coronal. The horizontal and vertical dimensions were measured for each region of each image type. Direct measurements of each region were obtained using a digital caliper in both horizontal and vertical dimensions. CBCT and direct measurements were compared using the Bland-Altman plot method.
values <0.05 were considered to indicate statistical significance.
The buccolingual dimension of the incisor and premolar areas and the height of the incisor, canine, and molar areas showed statistically significant differences on the peripheral/coronal images compared to the direct measurements (
<0.05). Molar area height in the central/coronal slices also differed significantly from the direct measurements (
<0.05). Cross-sectional images of either the central or peripheral position had no marked difference from the gold-standard values, indicating sufficient accuracy.
Peripheral object positioning within the FOV in combination with applying an orthogonal inclination to the slices resulted in significant inaccuracies in the horizontal and vertical measurements. The most undesirable effect was observed in the molar area and the vertical dimension.
Background
Chronic periodontitis is the most common form of periodontitis. Several immune and inflammatory factors responsible for periodontal destruction have been found in gingival crevicular fluid ...(GCF). The current study was conducted to determine the correlation between mucin and alpha‐amylase protein values in GCF with chronic periodontitis.
Method
Forty‐five patients with moderate‐to‐severe chronic periodontitis were selected. Samples of GCF were taken from a specific part of a single root tooth and placed in a closed test tube containing phosphate‐buffered saline (PBS) (pH = 7). Sampling was done again after one month. Pre‐ and post‐treatment samples were analyzed for measuring the levels of mucin and alpha‐amylase proteins.
Results
Paired t test results for these two variables showed that the difference between mucin and alpha‐amylase levels before and after treatment is significant.
Conclusion
The level of both mucin and alpha‐amylase in GCF in patients with chronic periodontitis was higher than that of patients who have recovered successfully; and evaluating the values of these two markers could be used to determine the activity of the periodontal disease.
Implant fracture is a rare but devastating complication of treatment in partially or fully edentulous patients which requires prompt diagnosis. Nevertheless, studies on defining the most accurate ...technique for the detection of implant fractures are lacking. In the present study, the Canny edge detection algorithm was applied on multiple radiographic modalities including parallel periapical (PPA), oblique periapical (OPA), and cone beam CT (CBCT) with and without metal artifact reduction (MAR) to examine its accuracy for diagnosis of simulated implant fractures. Radiographs were taken from 24 intact implants and 24 implants with artificially created fractures. Images were evaluated in their original and Canny formats. The accuracy of each radiograph was assessed by comparison with a reference standard of direct observation of the implant. The greatest area under the receiver operating characteristic curve belonged to Canny CBCT with MAR (0.958), followed by original CBCT with MAR (0.917), original CBCT without MAR = Canny CBCT without MAR = Canny OPA (0.875), Canny PPA (0.833), original PPA = original OPA (0.792), respectively. The Canny edge detection algorithm is suggested as an innovative method for accurate diagnosis of clinically suspected implant fractures on CBCT and periapical radiographies.
The effect of metallic objects on the fractal dimension (FD), bone area fraction (BAF) and gray scale values (GSVs) of cone-beam CT (CBCT) images was assessed. Also, FD, BAF and GSV were compared ...among CBCT, digital periapical and panoramic radiographies.
Digital periapical and panoramic radiographs were acquired from six blocks of bovine rib. Additionally, different arrangements of titanium implants and intracanal metallic posts were created in the bone blocks and CBCT scans were taken from the different implant-root arrangements. The three radiographical modalities were compared by analysis of variance. Pairwise comparisons between the modalities were performed by the Tukey test (significance level set at 0.05).
Different root-implant arrangements in the CBCT images revealed no significant differences in the FD (
= 0.920), BAF and GSV values (
= 0.623). FD differed significantly among the three modalities (
< 0.001). Significant differences were found between CBCT and each of the periapical and panoramic techniques (
< 0.001), while no remarkable differences were observed in the FD of the periapical and panoramic images (
= 0.294). BAF and GSV showed significantly different results among the three radiographical techniques (
< 0.001). The difference was remarkable between CBCT and periapical (
< 0.001), CBCT and panoramic (
< 0.001) and periapical and panoramic (
= 0.008).
Presence of titanium implants and intracanal posts does not produce different results in the fractal analysis (FA) of the CBCT images. The trabecular bone pattern is best assessed by FA of the periapical radiographs followed by the panoramic and CBCT techniques, respectively.
Assessment of alveolar bone level in periodontitis is very important in determining prognosis and treatment plan. Panoramic radiography is a diagnostic tool used to screen patients. The aim of the ...present study was to assess the diagnostic value of digital panoramic radiography in angular bony defects with 5 mm or deeper pocket depth in mandibular molars.
In this cross-sectional study, ninety angular bony defects in mandibular molars teeth with 5 mm or deeper pocket depth were selected in sixty patients with the diagnosis of chronic periodontitis. Before surgery, bone probing was performed. During the surgery, the vertical distance from cementoenamel junction to the most apical part of bony defect was measured using a Williams probe and this measurements were employed as gold standard. This distance was measured on the panoramic radiographs by a Digital Calliper and Digital Ruler. All data were compare dusing independent samples
-test and Pearson's correlation coefficient.
No significant difference was found between the results of bone probing and intra-surgical measurements (
= 0.377). The mean defect depth determined by Digital Caliper and Digital Ruler on panoramic radiographs was significantly less than surgical measurements (
< 0.001). The correlation between bone probing and surgical measurements in determining the defect depth was strong (
= 0.98,
< 0.001). Radiographic measurements made by Digital Ruler (
= 0.86), comparing to Digital Caliper (
= 0.79), showed a higher degree of correlation with surgical measurements.
Based on this study, bone probing is a reliable method in vertical alveolar bone defect measurements. While the information obtained from digital panoramic radiographs should be used with caution and the ability of digital panoramic radiography in the determination of defect depth is limited.
Purpose: Use of chlorhexidine (CHX) gel to eliminate the malodor of implant cavity may decrease the friction coefficient and effective preload and result in abutment screw loosening. This study aimed ...to assess the effect of CHX gel on the preload, torque, and detorque values. Materials and Methods: This in vitro experimental study was conducted on three groups of five implants. Group A (G1) was the control group and no material was applied to the implant cavity. In Group B (G2), implant cavity was filled with saliva before abutment screw tightening. In Group C (G3), implant cavity was first filled with saliva and then with CHX gel. The abutments were torqued to 24 N/cm2 according to the manufacturer's instructions and were then loosened. These processes were repeated five times. The ratio of the mean percentage of detorque to torque values was measured in all groups. The collected data were analyzed using ANOVA and post hoc Tukey's test. Results: No significant difference was noted between G1 and G2. Group G2 had significantly higher detorque value (p < 0.05). ANOVA detected a significant difference in the mean torque (p < 0.05) and detorque (p < 0.001) values among the three groups. G3 showed maximum difference between torque and detorque values; the minimum difference was noted in G2. Conclusion: Application of CHX gel (to decrease the malodor of the implant cavity) decreases the detorque and preload values and increases the risk of screw loosening.
Background and aim: This study aimed to assess dentistry students' understanding of the educational environment of Guilan University of Medical Sciences in two Basic and clinical fields. Materials ...and methods: This cross-sectional descriptive study was conducted in the academic year of 2016-17 at the Faculty of Dentistry, Guilan University of Medical Sciences. For this purpose, a sample of 190 students was selected in both the primary and clinical fields. Assess the learning environment, DREEM's Assessment Questionnaire (DREEM) questionnaire consisted of 50 questions in 5 areas of learning, professors, student perception of their ability, educational background, and student perception of their social status. Data were analyzed using descriptive statistics and the Mann-Whitney test in SPSS Ver 16 software. Results: The findings showed that the average total score of educational and learning environments in the Basic Section was 108.22 in the maximum of 200, and the Clinical Section was 111.03, which means a favorable threshold. In Basic Section, the lowest average score was 15.28 for self-social understanding, and the highest score was 26.09 for the educational atmosphere, while in the Clinical Section, the lowest and the highest mean scores were 15.81and 26.56 related to the same field of Basic Section. Conclusion: The results showed that the perception of students at two different levels of Basic Science and Clinical Section from the educational environment is favorable, but more attention of the faculty members to reducing the stress of the environment and creating an appropriate environment is essential.
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