• Imaging Science in Dentistry
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• v.50 no.1
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• pp.31-36
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• 2020

Purpose: The purpose of this study was to investigate the impact of radiotherapy on mandibular bone tissue in head and neck cancer patients through an analysis of pixel intensity and fractal dimension values on digital panoramic radiographs. Materials and Methods: Thirty patients with radiographic records from before and after 3-dimensional (3D) conformational radiotherapy were selected. A single examiner carried out digital analyses of pixel intensity values and fractal dimensions, with the areas of interest unilaterally located in the right angle medullary region of the mandible below the mandibular canal and posterior to the molar region. Results: Statistically significant decreases were observed in the mean pixel intensity (P=0.0368) and fractal dimension (P=0.0495) values after radiotherapy. Conclusion: The results suggest that 3D conformational radiotherapy for head and neck cancer negatively affected the trabecular microarchitecture and mandibular bone mass.

• Imaging Science in Dentistry
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• v.50 no.1
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• pp.53-64
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• 2020

Purpose: The aim of this study was to determine the prevalence of incidental findings(IFs) on digital dental panoramic radiographs(DPRs) of asymptomatic patients attending a general dental practice. Materials and Methods: This was a retrospective study of 6,252 consecutive digital (photostimulatable phosphor) DPRs of patients who visited a Canadian general dental practice for a complete new patient examination. The IFs were grouped into dental-related anomalies, radiopacities and radiopacities in the jaws, changes in the shape of the condyles, and other findings in the jaws, such as tonsilloliths and mucosal antral pseudocysts. Their prevalence was determined. Results: Thirty-two percent of the DPRs showed at least 1 IF. The highest prevalence was found for dental-related anomalies(29% of all DPRs), of which impacted teeth were the most prevalent finding (24% of all DPRs), followed by idiopathic osteosclerosis(6% of all DPRs). A lower prevalence was noted for tonsilloliths(3%), and the prevalence of root tips, mucosal antral pseudocysts, and anomalies in condylar shape was approximately 1% each. Conclusion: The observed prevalence of 32.1% for IFs of any type underscores the need for a dental practitioner to review the entire DPR when a patient presents for an initial dental examination (or check-up) or for dental hygiene. Only a single IF (a central giant cell granuloma) provoked alarm, as it was initially considered malignant. Similarly, impacted teeth and suspected cysts need careful evaluation upon discovery to determine how they may be optimally managed.

• Imaging Science in Dentistry
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• v.41 no.1
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• pp.17-21
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• 2011

Purpose : The purpose of this study was to examine the patient- and treatment-related etiologic factors of external root resorption. Materials and Methods : This study consisted of 163 patients who had completed orthodontic treatments and taken the pre- and post-treatment panoramic and lateral cephalometric radiographs. The length of tooth was measured from the tooth apex to the incisal edge or cusp tip on the panoramic radiograph. Overbite and overjet were measured from the pre- and post-treatment lateral cephalometric radiographs. The root resorption of each tooth and the factors of malocclusion were analyzed with an analysis of variance. A paired t test was performed to compare the mean amount of root resorption between male and female, between extraction and non-extraction cases, and between surgery and non-surgery groups. Correlation coefficients were measured to assess the relationship between the amount of root resorption and the age in which the orthodontic treatment started, the degree of changes in overbite and overjet, and the duration of treatment. Results : Maxillary central incisor was the most resorbed tooth, followed by the maxillary lateral incisor, the mandibular central incisor, and the mandibular lateral incisor. The history of tooth extraction was significantly associated with the root resorption. The duration of orthodontic treatment was positively correlated with the amount of root resorption. Conclusion : These findings show that orthodontic treatment should be carefully performed in patients who need the treatment for a long period and with a pre-treatment extraction of teeth.

• Imaging Science in Dentistry
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• v.49 no.3
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• pp.213-218
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• 2019

Purpose: The aim of this study was to evaluate the relationship between the mandibular canal and impacted mandibular third molars using cone-beam computed tomography (CBCT) and to compare the CBCT findings with signs on panoramic radiographs(PRs). Materials and Methods: This retrospective study consisted of 200 mandibular third molars from 200 patients who showed a close relationship between the mandibular canal and impacted third molars on PRs and were referred for a CBCT examination of the position of the mandibular canal. The sample consisted of 124 females and 76 males, with ages ranging from 18 to 47 years (mean, $25.75{\pm}6.15$ years). PRs were evaluated for interruption of the mandibular canal wall, darkening of the roots, diversion of the mandibular canal, and narrowing of the mandibular canal. Correlations between the PR and CBCT findings were statistically analyzed. Results: In total, 146 cases(73%) showed an absence of canal cortication between the mandibular canal and impacted third molar on CBCT images. A statistically significant relationship was found between CBCT and PR findings (P<0.05). The absence of canal cortication on CBCT images was most frequently accompanied by the PR sign of diversion of the mandibular canal(96%) and least frequently by interruption of the mandibular canal wall(65%). Conclusion: CBCT examinations are highly recommended when diversion of the mandibular canal is observed on PR images to reduce the risk of mandibular nerve injury, and this sign appears to be more relevant than other PR signs.

• Imaging Science in Dentistry
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• v.52 no.2
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• pp.187-195
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• 2022

Purpose: This study developed a convolutional neural network (CNN) model to diagnose maxillary sinusitis on panoramic radiographs(PRs) and cone-beam computed tomographic (CBCT) images and evaluated its performance. Materials and Methods: A CNN model, which is an artificial intelligence method, was utilized. The model was trained and tested by applying 5-fold cross-validation to a dataset of 148 healthy and 148 inflamed sinus images. The CNN model was implemented using the PyTorch library of the Python programming language. A receiver operating characteristic curve was plotted, and the area under the curve, accuracy, sensitivity, specificity, positive predictive value, and negative predictive values for both imaging techniques were calculated to evaluate the model. Results: The average accuracy, sensitivity, and specificity of the model in diagnosing sinusitis from PRs were 75.7%, 75.7%, and 75.7%, respectively. The accuracy, sensitivity, and specificity of the deep-learning system in diagnosing sinusitis from CBCT images were 99.7%, 100%, and 99.3%, respectively. Conclusion: The diagnostic performance of the CNN for maxillary sinusitis from PRs was moderately high, whereas it was clearly higher with CBCT images. Three-dimensional images are accepted as the "gold standard" for diagnosis; therefore, this was not an unexpected result. Based on these results, deep-learning systems could be used as an effective guide in assisting with diagnoses, especially for less experienced practitioners.

• Imaging Science in Dentistry
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• v.46 no.3
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• pp.159-165
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• 2016

Purpose: The purpose of this study was to detect the anterior loop of the mental nerve and the mandibular incisive canal in panoramic radiographs (PAN) and cone-beam computed tomography (CBCT) images, as well as to determine the anterior/mesial extension of these structures in panoramic and cross-sectional reconstructions using PAN and CBCT images. Materials and Methods: Images (both PAN and CBCT) from 90 patients were evaluated by 2 independent observers. Detection of the anterior loop and the incisive canal were compared between PAN and CBCT. The anterior/mesial extension of these structures was compared between PAN and both cross-sectional and panoramic CBCT reconstructions. Results: In CBCT, the anterior loop and the incisive canal were observed in 7.7% and 24.4% of the hemimandibles, respectively. In PAN, the anterior loop and the incisive canal were detected in 15% and 5.5% of cases, respectively. PAN presented more difficulties in the visualization of structures. The anterior/mesial extensions ranged from 0.0 mm to 19.0 mm on CBCT. PAN underestimated the measurements by approximately 2.0 mm. Conclusion: CBCT appears to be a more reliable imaging modality than PAN for preoperative workups of the anterior mandible. Individual variations in the anterior/mesial extensions of the anterior loop of the mental nerve and the mandibular incisive canal mean that is not prudent to rely on a general safe zone for implant placement or bone surgery in the interforaminal region.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.29 no.1
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• pp.35-42
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• 2003

Purpose: This study was aimed to investigate the relationship between the mandibular asymmetry and the internal derangement of temporomandibular joint. Materials and methods: One hundred and sixty eight patients had been assessed through clinical examinations, panoramic radiographs and magnetic resonance imagings (MRIs), were selected. The samples were classified into three subgroups according to the severity of the mandibular asymmetries in the panoramic radiographs and the status of TMJ discs on the MRI were compared among each groups. Results: In an apparent asymmetry group, there was a significant difference in the number of temporomandibular disk displacement without reduction between the long and short side (66.7%, 18/27 joints on the short side) when the ratio of condylar process and coronoid process was used (p<0.05), but there was no statistically significant difference when the ratio of condyle and ramus was used. Conclusion: The probability of the disc displacement without reduction was higher at the side with relatively shorter condylar process on the panoramic radiograph, and also it might be more effective to use ratio of condylar process and coronoid process in the assessment of mandibular asymmetry. Therefore, a careful assessment on the temporomandibular disorders is necessary to diagnose and establish the treatment plans for the patients with a mandibular asymmetry and the panoramic radiograph can be used effectively on that way.

• Imaging Science in Dentistry
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• v.37 no.1
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• pp.9-14
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• 2007

Purpose : To determine the more valuable information to detect the mandibular canal and the mental foramen in panoramic radiographs of a selected Korean population for the implant. Materials and Methods : This study analysed 288 panoramic radiographic images of patients taken at the Dental hospital of Chosun University retrospectively. Indirect digital panoramic X-ray machine (ProlineXC, PLANMECA, Finland) with processing by using Directview $CR950^@$ (Kodak, U.S.A.) and Direct digital panoramic X-ray machine (Promax, PLANMECA, Finland) were used for all exposures. All images were converted into Dicom format. Results : The common position of the mental foramen was in line with the longitudinal axis of the second premolar (68.1%). The mental foramen was symmetrical in 81.8% of cases. The mandibular canal was not identified at anterior portion and discontinued with the mental foramen in 27.8% of all cases, in 42.4% identified with lower border line continued with the mental foramen, in 14.6% with both upper and lower border lines, and in 15.3% unilaterally identified with lower border line. Conclusion : Clinicians can estimate the upper border line of the mandibular canal from the confirmation of the mental foramen and the lower border line of the mandibular canal symmetrically on the panoramic radiography taken in adjusted midsaggital plane of patient's head.

• The Journal of the Korean dental association
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• v.56 no.10
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• pp.548-554
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• 2018

Choristoma is a growth of normal tissue that occurs at an abnormal region. In the oral cavity, osseous choristoma that has a normal bone feature mainly has been appeared. It is mainly occurred on the tongue. So, It can be found in dental practice or in discomfort in the mouth. Osseous choristoma in the oral cavity is extremely rare. But It can be treated excisional biopsy under local anesthesia. The prognosis is very good. This case is a report of osseous choristoma on the dorsal surface of the tongue. A 17-year-old female patient presented with a foreign body sensation of the tongue. A diameter of the mass is 0.7cm, and there is no pain. Panoramic radiographs showed a radiopaque image in the form of a double image. An excisional biopsy was performed and diagnosed as an osseous choristoma. 12 months after the resection, there were no signs of recurrence. Intraoral osseous choristoma is very rare, but it is clinically very simple and can be found in dental radiographs. We present this case because of Dentists who examine the oral cavity of the patient can easily diagnose the lesion and treat it by simple resection.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.33 no.4
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• pp.323-330
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• 2011

Purpose: The present study examined the reproducibility of an operation plan by comparing the jaw position of STO with the postoperative mandibular set back measurement in sagittal split ramus osteotomy. Methods: Thirty patients with class III dental and skeletal malocclusion and who were treated with BSSRO were reviewed. Three plain radiographs such as the panoramic view, the lateral cephalogram and the submentovertex view were taken before and after operation. Also, paper surgery for STO and model surgery were used to evaluate the amount of mandibular set back. Results: On the panoramic view, the amount of mandibular set back in STO was similar to the postoperative results of model surgery, but the amount of mandibular set back on the lateral cephalogram was smaller than the postoperative result of model surgery and then the amount of set back on submentovertex view was similar to the postoperative result of model surgery. Conclusion: Precise tracing and paper surgery should be performed for a combined expected STO in order to predict the exact amount of preoperative mandibular set back.