• Restorative Dentistry and Endodontics
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• 제48권2호
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• pp.16.1-16.11
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• 2023

Objectives: The aim of this study was to evaluate the influence of peak kilovoltage (kVp) and a metal artifact reduction (MAR) tool on image quality and the diagnosis of vertical root fracture (VRF) in cone-beam computed tomography (CBCT). Materials and Methods: Twenty single-rooted human teeth filled with an intracanal metal post were divided into 2 groups: control (n = 10) and VRF (n = 10). Each tooth was placed into the socket of a dry mandible, and CBCT scans were acquired using a Picasso Trio varying the kVp (70, 80, 90, or 99), and the use of MAR (with or without). The examinations were assessed by 5 examiners for the diagnosis of VRF using a 5-point scale. A subjective evaluation of the expression of artifacts was done by comparing random axial images of the studied protocols. The results of the diagnoses were analyzed using 2-way analysis of variance and the Tukey post hoc test, the subjective evaluations were compared using the Friedman test, and intra-examiner reproducibility was evaluated using the weighted kappa test (α = 5%). Results: The kVp and MAR did not influence the diagnosis of VRF (p > 0.05). According to the subjective classification, the 99 kVp protocol with MAR demonstrated the least expression of artifacts, while the 70 kVp protocol without MAR led to the most artifacts. Conclusions: Protocols with higher kVp combined with MAR improved the image quality of CBCT examinations. However, those factors did not lead to an improvement in the diagnosis of VRF.

• Imaging Science in Dentistry
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• 제53권4호
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• pp.271-281
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• 2023

Purpose: The objective of this scoping review was to investigate the applicability and performance of various convolutional neural network (CNN) models in tooth numbering on panoramic radiographs, achieved through classification, detection, and segmentation tasks. Materials and Methods: An online search was performed of the PubMed, Science Direct, and Scopus databases. Based on the selection process, 12 studies were included in this review. Results: Eleven studies utilized a CNN model for detection tasks, 5 for classification tasks, and 3 for segmentation tasks in the context of tooth numbering on panoramic radiographs. Most of these studies revealed high performance of various CNN models in automating tooth numbering. However, several studies also highlighted limitations of CNNs, such as the presence of false positives and false negatives in identifying decayed teeth, teeth with crown prosthetics, teeth adjacent to edentulous areas, dental implants, root remnants, wisdom teeth, and root canal-treated teeth. These limitations can be overcome by ensuring both the quality and quantity of datasets, as well as optimizing the CNN architecture. Conclusion: CNNs have demonstrated high performance in automated tooth numbering on panoramic radiographs. Future development of CNN-based models for this purpose should also consider different stages of dentition, such as the primary and mixed dentition stages, as well as the presence of various tooth conditions. Ultimately, an optimized CNN architecture can serve as the foundation for an automated tooth numbering system and for further artificial intelligence research on panoramic radiographs for a variety of purposes.

• 한국치위생학회지
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• 제9권2호
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• pp.111-124
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• 2009

This study analyzes through the review of literature and laws the exposure time, clinical frequency, and radiation exposure of intraoral and extraoral radiography as well as of panoramic radiography performed by dental hygienists in dental clinics, compares the dental radiology curriculums of radiological science and dental hygiene departments, and proposes the expansion of dental hygienists' radiography operations. The radiology curriculums were compared between the radiological science and dental hygiene departments of colleges. For new analysis by radiography for dental diagnosis, the exposure time, radiation absorbed dose, effective dose, and number of days of natural radiation were compared by the type of oral radiation films and radiographical techniques proposed by domestic and international studies. The exposure time of panoramic radiography is 15 seconds and it takes about two minutes for completion, whereas the exposure time of the standard radiography is 0.2~0.8 seconds and it takes 10 times longer for completion of the radiography of full mouth than the panoramic radiography. The standard radiography can cause distortions of radiation at severely curved parts of dental arch and palatopharyngeal reflex. However, panoramic radiography can be performed even for lock jaw patients, causes less inconvenience to patients and is much simpler than the standard radiography. The percentage of dental clinics where radiography is performed by dental hygienists was 92.0%, and the percentage of standard film radiography by dental hygienists was 98% whereas the percentage of panoramic radiography by dental hygienists was 92%. For the absorbed dose which is an indicator of radiation exposure, the When the effective dose which is an indicator of the danger of radiation exposure was converted to the number of days of natural radiation, it was 3.3 days for panoramic radiography, but 13.9 days for the full mouth standard radiography by bisecting angle technique which was 4.2 times longer than the panoramic radiography. There were two colleges that had a dental radiology course with two credits in the departments of radiological science. The credits for dental radiology courses in the department of dental hygiene ranged varied by college, ranging from 3 to 8; on average, the theory course was 2.2 credits and the practice course was 2.02 credits. To summarize the above results, the percentage of dental clinics where panoramic radiography is performed by dental hygienists under the guidance of dentists is high. Panoramic radiography has become an essential facility for dental clinics. It is faster than standard film radiography and less dangerous due to low radiation exposure. Panoramic radiography is a simple mechanical job that does not require training of oral radiography by radiotechnologist. Because panoramic radiography is one of major operations which must be performed at all times in dental clinics, it must be designated as intraoral technique rather than extraoral technique, or legalized for inclusion in the scope of operations of dental hygienists.

• Imaging Science in Dentistry
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• 제30권4호
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• pp.249-254
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• 2000

Purpose: To clarify the clinical and radiologic parameters that can be used to differentiate odontogenic keratocyst and ameloblastoma Materials and Methods: The records of 46 patients of ameloblastoma and 48 patients of odontogenic keratocyst at the Yonsei University Dental Hospital during the period of 1979 to 1995 were retrospectively reviewed. As a possible means for differentiating between the odontogenic keratocyst and ameloblastoma, the clinical parameters and the radiologic parameters were evaluated. Results: In the clinical parameters, there was no significant difference in age, sex, and sign and symptoms (p>0.05). In the radiologic parameters, there was significant difference in site, shape of the lesion, and external root resorption of adjacent teeth (p<0.05). Conclusion: The site, shape of the lesion, and external root resorption of adjacent teeth can be the parameters to differentiate odontogenic keratocyst and ameloblastoma, but a definite differentiation of these two lesions needs a more specialized imaging modality.

• Imaging Science in Dentistry
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• 제30권3호
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• pp.199-205
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• 2000

Purpose: To determine whether the significant relationship exists between radiographic appearance, whether it is unilocular or multilocular, and its corresponding clinical and histologic features by examining the odontogenic keratocyst clinically, radiologically and histologically. Materials and Methods: This study was conducted on 48 cases of odontogenic keratocyst from the files of Dental Hospital, Yonsei University for the years 1982 through 1995. Results and Conclusions : The mean age of patients was 30.5 years in the unilocular group and 35.5 years in the multilocular group. The male to female ratio was 1 : 1.06 in the unilocular group and 1 : 1.75 in the multilocular group. The chief complaint was swelling in both groups(unilocular 35.1 %, multilocular 54.5%). In the occurrence site, the border of the lesion, the displacement and external root resorption of the adjacent teeth, there were no statistically significant difference between the unilocular group and multilocular group, but in the border type, there was statistically significant difference (x²-test, p<0.05)wo recurred cases were observed among 11 cases of odontogenic keratocyst. One was unilocular case and the other was multilocular case.

• Imaging Science in Dentistry
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• 제44권1호
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• pp.67-73
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• 2014

Intraosseous vascular lesions of the maxillofacial region are rare, and the differential diagnosis of intraosseous vascular malformations from other jaw lesions can be challenging. In the present case, magnetic resonance imaging and three-dimensional computed tomographic angiography (CTA) was used for diagnosis, and the lesion was treated wih surgical excision. Diverse characteristics such as the "honeycomb" and "sunburst" radiographic appearances and the absence of major peripheral feeder vessels in the CTA were noted. Intraosseous vascular malformations have a varied radiographic appearance, and the nomenclature of these lesions is equally diverse, with several overlapping terms. Pathologists do not generally differentiate among intraosseous vascular lesions on the basis of histopathology, although these lesions may present with contrasting immunohistochemical and clinical behaviors requiring varied treatment strategies. This case report highlights the need for multiple imaging modalities to differentiate among vascular lesions, as well as to better understand the behaviors of these unique lesions.

• Imaging Science in Dentistry
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• 제41권4호
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• pp.177-181
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• 2011

Pyknodysostosis is a rare autosomal recessive disorder characterized by the post natal onset of short limbs, short stature, and generalized hyperostosis along with acro-osteolysis with sclerosis of the terminal phalanges, a feature that is considered essentially pathognomonic. Other features include persistence of fontanelles, delayed closure of sutures, wormian bones, absence of frontal sinuses, and obtuse mandibular gonial angle with relative mandibular prognathism. We report a case of 17-year-old girl who presented with a chief complaint of retention of deciduous teeth. General physical examination demonstrated short stature, frontal and parietal bossing, depressed nasal bridge, beaked nose, hypoplastic midface, wrinkled skin over the finger tips, and nail abnormalities. Radiographs showed multiple impacted permanent and supernumerary teeth, hypoplastic paranasal sinuses with acro-osteolysis of terminal phalanges, and open fontanelles, and sutures along with wormian bones in the lambdoidal region.

• Imaging Science in Dentistry
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• 제42권4호
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• pp.255-260
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• 2012

Dentigerous cysts are the most common developmental cysts of the jaws, most frequently associated with impacted mandibular third molar teeth. Dentigerous cysts around supernumerary teeth, however, account for 5% of all dentigerous cysts, with most developing around a mesiodens in the anterior maxilla. This report describes two cases of a dentigerous cyst associated with an impacted mesiodens. Both of the patients complained of swelling in the maxillary anterior region. Radiographic examination revealed an impacted mesiodens surrounded by a large corticated radiolucency in both cases. A provisional diagnosis of infected odontogenic cyst was made. The cysts were enucleated with the removal of the mesiodens in the two cases. Histopathological examination confirmed the diagnosis of infected dentigerous cyst associated with an impacted mesiodens in both cases. The patients remained asymptomatic, and no complications were noted.

• Imaging Science in Dentistry
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• 제54권1호
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• pp.115-120
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• 2024

Components derived from an infected lesion within the bone can spread through various passages in the mandible, particularly via the mental foramen. Radiologically, the spread of infection is typically nonspecific and challenging to characterize; however, multislice computed tomography (MSCT) can effectively detect pathological changes in soft tissues and the bone marrow space. This report describes the case of a 55-year-old woman who experienced mental nerve paresthesia due to a periapical infection of the right mandibular second premolar. MSCT imaging revealed increased attenuation around the periapical lesion extending into the mandibular canal and loss of the juxta-mental foraminal fat pad. Following endodontic treatment of the tooth suspected to be the source of the infection, the patient's symptoms resolved, and the previous MSCT imaging findings were no longer present. Increased bone marrow attenuation and obliteration of the fat plane in the buccal aspect of the mental foramen may serve as radiologic indicators of inflammation spreading from the bone marrow space.

• Imaging Science in Dentistry
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• 제35권4호
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• pp.231-234
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• 2005

Coronoid impingement can cause limitation of mouth opening. In many cases, it appears to be related to the coronoid hyperplasia. We present a case of mouth opening limitation caused by coronoid impingement on the posterior surface of the zygomatic bone without coronoid hyperplasia. The bony changes in coronoid and zygoma including surface irregularity and discontinuity of the cortex and sclerotic change of inner medullary space were noted on computed tomography (CT) scans in different level of axial planes. Through another CT scans in open mouth position could demonstrate that those bony changes were caused by the contact of both surfaces against each other. In case coronoid impingement is suspected of the many possible causes, the open mouth CT scans will be needed to reveal the direct impingement of coronoid on zygoma even without coronoid hyperplasia.