Head and neck manifestations of fibrodysplasia ossificans progressiva: Clinical and imaging findings in 2 cases

Fibrodysplasia ossificans progressiva is a rare hereditary disorder characterized by progressive heterotopic ossifica-tion in muscle and connective tissue, with few reported cases affecting the head and neck region. Although plain radiographic findings and computed tomography features have been well documented, limited reports exist onmagnetic resonance findings. This report presents 2 cases of fibrodysplasia ossificans progressiva, one with limited mouth opening due to heterotopic ossification of the lateral pterygoid muscle and the other with restricted neck movement due to heterotopic ossification of the platysma muscle. Clinical findings of restricted mouth opening or limited neck movement, along with radiological findings of associated heterotopic ossification, should prompt consideration of fibrodysplasia ossificans progressiva in the differential diagnosis. Dentists should be particularly vigilant with patients diagnosed with fibrodysplasia ossificans progressiva to avoid exposure to diagnostic biopsy andinvasive dental procedures.

A case report of an unusual temporomandibular joint mass: Nodular fasciitis

Nodular fasciitis (NF) is a benign myofibroblastic proliferation that grows very rapidly, mimicking a sarcoma on imaging. It is treated by local excision, and recurrence has been reported in only a few cases, even when excised incompletely. The most prevalent diagnoses of temporomandibular joint (TMJ) masses include synovial chondromatosis, pigmented villonodular synovitis, and sarcomas. Cases of NF in the TMJ are extremely rare, and only 3 cases have been reported to date. Due to its destructive features and rarity, NF has often been misdiagnosed as a more aggressive lesion, which could expose patients to unnecessary and invasive treatment approaches beyond repair. This report presents a case of NF in the TMJ, focusing on various imaging features, along with a literature review aiming to determine the hallmark features of NF in the TMJ and highlight the diagnostic challenges.

Deep learning-based apical lesion segmentation from panoramic radiographs

Purpose@#Convolutional neural networks (CNNs) have rapidly emerged as one of the most promising artificial intelligence methods in the field of medical and dental research. CNNs can provide an effective diagnostic methodology allowing for the detection of early-staged diseases. Therefore, this study aimed to evaluate the performance of a deep CNN algorithm for apical lesion segmentation from panoramic radiographs. @*Materials and Methods@#A total of 1000 panoramic images showing apical lesions were separated into training (n=800, 80%), validation (n=100, 10%), and test (n=100, 10%) datasets. The performance of identifying apical lesions was evaluated by calculating the precision, recall, and F1-score. @*Results@#In the test group of 180 apical lesions, 147 lesions were segmented from panoramic radiographs with an intersection over union (IoU) threshold of 0.3. The F1-score values, as a measure of performance, were 0.828, 0.815, and 0.742, respectively, with IoU thresholds of 0.3, 0.4, and 0.5. @*Conclusion@#This study showed the potential utility of a deep learning-guided approach for the segmentation of apical lesions. The deep CNN algorithm using U-Net demonstrated considerably high performance in detecting apical lesions.

Mucormycosis-related osteomyelitis of the maxilla in a post-COVID-19 patient

Mucormycosis is a rare, invasive fungal infection that progresses aggressively and requires prompt surgery and appropriate treatment. The number of cases of mucormycosis in coronavirus disease 2019 (COVID-19) patients has recently increased, and patients with uncontrolled diabetes mellitus are particularly at an elevated risk of infection. This report presents a case of mucormycosis-related osteomyelitis of the maxilla in a 37-year-old man with diabetes mellitus. The patient complained of severe and persistent pain in the right maxilla, accompanied by increased tooth mobility and headache. On contrast-enhanced computed tomographic images, gas-forming osteomyelitis of the right maxilla was observed. Destruction of the maxilla and palatine bone then proceeded aggressively. Sequestrectomy was performed on the right maxilla, and the histopathological diagnosis was mucormycosis. Further investigation after the first operation revealed the patient's history of COVID-19 infection.

Evaluation of the clinical efficacy of a TW3-based fully automated bone age assessment system using deep neural networks

Purpose@#The aim of this study was to evaluate the clinical efficacy of a Tanner-Whitehouse 3 (TW3)-based fully automated bone age assessment system on hand-wrist radiographs of Korean children and adolescents. @*Materials and Methods@#Hand-wrist radiographs of 80 subjects (40 boys and 40 girls, 7-15 years of age) were collected. The clinical efficacy was evaluated by comparing the bone ages that were determined using the system with those from the reference standard produced by 2 oral and maxillofacial radiologists. Comparisons were conducted using the paired t-test and simple regression analysis. @*Results@#The bone ages estimated with this bone age assessment system were not significantly different from those obtained with the reference standard (p>0.05) and satisfied the equivalence criterion of 0.6 years within the 95% confidence interval ( - 0.07 to 0.22), demonstrating excellent performance of the system. Similarly, in the comparisons of gender subgroups, no significant difference in bone age between the values produced by the system and the reference standard was observed (p>0.05 for both boys and girls). The determination coefficients obtained via regression analysis were 0.962, 0.945, and 0.952 for boys, girls, and overall, respectively (p=0.000); hence, the radiologist-determined bone ages and the system-determined bone ages were strongly correlated. @*Conclusion@#This TW3-based system can be effectively used for bone age assessment based on hand-wrist radiographs of Korean children and adolescents.

Acquired facial lipoatrophy: A report of 3 cases with imaging features

Acquired facial lipoatrophy is a rare disease with an unclear etiology and pathological pathway. The distinct causative factors of this disease have been not elucidated, but it is suspected to be associated with immune systemrelated diseases, most notably AIDS. Although the management of facial lipoatrophy is very important for patients’ social life and mental health, no treatment framework has been developed due to the unknown nature of the disease manifestation. The present case report was designed to provide sequential imaging to visualize the disease progression. The clinical backgrounds of the patients are also introduced, helping characterize this disease entity more clearly for maxillofacial specialists.

Development of an evidence-based clinical imaging diagnostic guideline for implant planning: Joint recommendations of the Korean Academy of Oral and Maxillofacial Radiology and National Evidence-based Healthcare Collaborating Agency

PURPOSE: This study was conducted to develop an evidence-based clinical imaging diagnostic guideline for implant planning, taking into account efficacy, benefits, and risks.MATERIALS AND METHODS: The guideline development process employed the adaptation methodology used for Korean clinical imaging guidelines(K-CIG). Core databases(Ovid-Medline, Ovid-Embase, National Guideline Clearinghouse, Guideline International Network) and domestic databases (KoreaMed, KMbase, and KoMGI) were searched for guidelines. The retrieved articles were analyzed by 2 reviewers, and articles were selected using well-established inclusion criteria.RESULTS: The search identified 294 articles, of which 3 were selected as relevant guidelines. Based on those 3 guidelines, 3 recommendations for implant planning were derived.CONCLUSION: We recommend radiography or cone-beam computed tomography (CBCT) scanning for individual patients judged to require a cross-sectional image after reading of a panoramic X-ray image and a conventional intraoral radiological image. Various steps should be taken to raise awareness of these recommendations among clinicians and the public, and K-CIG should be regularly reviewed and revised.

Very deep super-resolution for efficient cone-beam computed tomographic image restoration

Purpose@#As cone-beam computed tomography (CBCT) has become the most widely used 3-dimensional (3D) imaging modality in the dental field, storage space and costs for large-capacity data have become an important issue. Therefore, if 3D data can be stored at a clinically acceptable compression rate, the burden in terms of storage space and cost can be reduced and data can be managed more efficiently. In this study, a deep learning network for super-resolution was tested to restore compressed virtual CBCT images. @*Materials and Methods@#Virtual CBCT image data were created with a publicly available online dataset (CQ500) of multidetector computed tomography images using CBCT reconstruction software (TIGRE). A very deep superresolution (VDSR) network was trained to restore high-resolution virtual CBCT images from the low-resolution virtual CBCT images. @*Results@#The images reconstructed by VDSR showed better image quality than bicubic interpolation in restored images at various scale ratios. The highest scale ratio with clinically acceptable reconstruction accuracy using VDSR was 2.1. @*Conclusion@#VDSR showed promising restoration accuracy in this study. In the future, it will be necessary to experiment with new deep learning algorithms and large-scale data for clinical application of this technology.

Effects of energy level, reconstruction kernel, and tube rotation time on Hounsfield units of hydroxyapatite in virtual monochromatic images obtained with dual-energy CT

PURPOSE: This study was performed to investigate the effects of energy level, reconstruction kernel, and tube rotation time on Hounsfield unit (HU) values of hydroxyapatite (HA) in virtual monochromatic images (VMIs) obtained with dual-energy computed tomography (DECT) (Siemens Healthineers, Erlangen, Germany).MATERIALS AND METHODS: A bone density calibration phantom with 3 HA inserts of different densities (CTWATER®; 0, 100, and 200 mg of HA/cm³) was scanned using a twin-beam DECT scanner at 120 kVp with tube rotation times of 0.5 and 1.0 seconds. The VMIs were reconstructed by changing the energy level (with options of 40 keV, 70 keV, and 140 keV). In order to investigate the impact of the reconstruction kernel, virtual monochromatic images were reconstructed after changing the kernel from body regular 40 (Br40) to head regular 40 (Hr40) in the reconstruction phase. The mean HU value was measured by placing a circular region of interests (ROIs) in the middle of each insert obtained from the VMIs. The HU values were compared with regard to energy level, reconstruction kernel, and tube rotation time.RESULTS: Hydroxyapatite density was strongly correlated with HU values (correlation coefficient=0.678, P<0.05). For the HA 100 and 200 inserts, HU decreased significantly at increased energy levels (correlation coefficient= −0.538, P<0.05) but increased by 70 HU when using Hr40 rather than Br40 (correlation coefficient=0.158, P<0.05). The tube rotation time did not significantly affect the HU (P>0.05).CONCLUSION: The HU values of hydroxyapatite were strongly correlated with hydroxyapatite density and energy level in VMIs obtained with DECT.

Clinical and panoramic radiographic features of osteomyelitis of the jaw: A comparison between antiresorptive medication-related and medication-unrelated conditions

PURPOSE: This study was performed to analyze the clinical and imaging features of contemporary osteomyelitis (OM) and to investigate differences in these features on panoramic radiography according to patients' history of use of medication affecting bone metabolism.MATERIALS AND METHODS: The records of 364 patients (241 female and 123 male, average age 66.8±14.9 years) with OM were retrospectively reviewed. Panoramic imaging features were analyzed and compared between patients with medication-related OM (m-OM) and those with conventional, medication-unrelated OM (c-OM).RESULTS: The age of onset of OM tended to be high, with the largest number of patients experiencing onset in their 70s. The 2 most frequent presumed causes were antiresorptive medication use (44.2%) and odontogenic origin (34.6%). On panoramic radiographs, a mix of osteolysis and sclerosis was the most common lesion pattern observed (68.6%). Sequestrum, extraction socket, and periosteal new bone formation were found in 143 (42.1%), 79 (23.2%), and 24 (7.1%) cases, respectively. The m-OM group exhibited sequestrum and extraction socket more frequently and displayed significantly higher mandibular cortical index values than the c-OM group.CONCLUSION: We observed some differences in imaging features as shown on panoramic radiography according to the history of antiresorptive medication use. This study may help elucidate the predictive imaging features of medication-related osteonecrosis of the jaw.

A clinical pilot study of jawbone mineral density measured by the newly developed dual-energy cone-beam computed tomography method compared to calibrated multislice computed tomography

PURPOSE: This clinical pilot study was performed to determine the effectiveness of dual-energy cone-beam computed tomography (DE-CBCT) in measuring bone mineral density (BMD).MATERIALS AND METHODS: The BMD values obtained using DE-CBCT were compared to those obtained using calibrated multislice computed tomography (MSCT). After BMD calibration with specially designed phantoms, both DE-CBCT and MSCT scanning were performed in 15 adult dental patients. Three-dimensional (3D) Digital Imaging and Communications in Medicine data were imported into a dental software program, and the defined regions of interest (ROIs) on the 3-dimensional surface-rendered images were identified. The automatically-measured BMD values of the ROIs (g/cm³), the differences in the measured BMD values of the matched ROIs obtained by DE-CBCT and MSCT 3D images, and the correlation between the BMD values obtained by the 2 devices were statistically analyzed.RESULTS: The mean BMD values of the ROIs for the 15 patients as assessed using DE-CBCT and MSCT were 1.09±0.07 g/cm³ and 1.13±0.08 g/cm³, respectively. The mean of the differences between the BMD values of the matched ROIs as assessed using DE-CBCT and calibrated MSCT images was 0.04±0.02 g/cm³. The Pearson correlation coefficient between the BMD values of DE-CBCT and MSCT images was 0.982 (r=0.982, P<0.001).CONCLUSION: The newly developed DE-CBCT technique could be used to measure jaw BMD in dentistry and may soon replace MSCT, which is expensive and requires special facilities.

Steatocystoma multiplex: A case report of a rare entity

Steatocystoma multiplex is an uncommon benign skin disease, which typically manifests as numerous intradermal cysts that can be scattered anywhere on the body. Although usually asymptomatic, it can be significantly disfiguring. One type of steatocystoma multiplex is known to be associated with the autosomal dominant inheritance of a mutation in the gene coding for keratin 17 (KRT17). In such cases, it is often concurrent with other developmental abnormalities of the ectoderm-derived tissues, such as the nails, hair, and teeth. To the best of our knowledge, few cases have been reported of steatocystoma multiplex of the oral and maxillofacial region. This report describes a case of steatocystoma multiplex of both sides of the neck and multiple dental anomalies, with a focus on its clinical, radiological, and histopathological characteristics, as well as the possibility that the patient exhibited the familial type of this condition.

Erratum to: Development of a new ball-type phantom for evaluation of the image layer of panoramic radiography

The authors would like to correct an error in the publication of the original article. The number in the formula on page 256, right column, line 5 should be ‘346.0121’ instead of ‘3446.0121.’

An overview of deep learning in the field of dentistry

PURPOSE: Artificial intelligence (AI), represented by deep learning, can be used for real-life problems and is applied across all sectors of society including medical and dental field. The purpose of this study is to review articles about deep learning that were applied to the field of oral and maxillofacial radiology. MATERIALS AND METHODS: A systematic review was performed using Pubmed, Scopus, and IEEE explore databases to identify articles using deep learning in English literature. The variables from 25 articles included network architecture, number of training data, evaluation result, pros and cons, study object and imaging modality. RESULTS: Convolutional Neural network (CNN) was used as a main network component. The number of published paper and training datasets tended to increase, dealing with various field of dentistry. CONCLUSION: Dental public datasets need to be constructed and data standardization is necessary for clinical application of deep learning in dental field.

Development of a new ball-type phantom for evaluation of the image layer of panoramic radiography

PURPOSE: This study proposes a new ball-type phantom for evaluation of the image layer of panoramic radiography. MATERIALS AND METHODS: The arch shape of an acrylic resin phantom was derived from average data on the lower dental arch in Korean adult males. Metal balls with a 2-mm diameter were placed along the center line of the phantom at a 4-mm mesiodistal interval. Additional metal balls were placed along the 22 arch-shaped lines that ran parallel to the center line at 2-mm buccolingual intervals. The height of each ball in the horizontal plane was spaced by 2.5 mm, and consequently, the balls appeared oblique when viewed from the side. The resulting phantom was named the Panorama phantom. The distortion rate of the balls in the acquired image was measured by automatically calculating the difference between the vertical and horizontal length using MATLAB®. Image layer boundaries were obtained by applying various distortion rate thresholds. RESULTS: Most areas containing metal balls (91.5%) were included in the image layer with a 50% distortion rate threshold. When a 5% distortion rate threshold was applied, the image layer was formed with a small buccolingual width along the arch-shaped center line. However, it was medially located in the temporomandibular joint region. CONCLUSION: The Panorama phantom could be used to evaluate the image layer of panoramic radiography, including all mesiodistal areas with large buccolingual width.

Radiopacity of contemporary luting cements using conventional and digital radiography

PURPOSE: This study evaluated the radiopacity of contemporary luting cements using conventional and digital radiography. MATERIALS AND METHODS: Disc specimens (N=24, n=6 per group, ø7 mm×1 mm) were prepared using 4 resin-based luting cements (Duolink, Multilink N, Panavia F 2.0, and U-cem). The specimens were radiographed using films, a complementary metal oxide semiconductor (CMOS) sensor, and a photostimulable phosphor plate (PSP) with a 10-step aluminum step wedge (1 mm incremental steps) and a 1-mm-thick tooth cut. The settings were 70 kVp, 4 mA, and 30 cm, with an exposure time of 0.2 s for the films and 0.1 s for the CMOS sensor and PSP. The films were scanned using a scanner. The radiopacity of the luting cements and tooth was measured using a densitometer for the film and NIH ImageJ software for the images obtained from the CMOS sensor, PSP, and scanned films. The data were analyzed using the Kruskal-Wallis and Mann-Whitney U tests. RESULTS: Multilink (3.44–4.33) showed the highest radiopacity, followed by U-cem (1.81–2.88), Panavia F 2.0 (1.51–2.69), and Duolink (1.48–2.59). The R² values of the optical density of the aluminum step wedge were 0.9923 for the films, 0.9989 for the PSP, 0.9986 for the scanned films, and 0.9266 for the CMOS sensor in the linear regression models. CONCLUSION: The radiopacities of the luting materials were greater than those of aluminum or dentin at the same thickness. PSP is recommended as a detector for radiopacity measurements because of its accuracy and convenience.

Is the panoramic mandibular index useful for bone quality evaluation?

PURPOSE: The aim of this study was to determine whether the panoramic mandibular index (PMI) is useful for assessing bone mineral density. We also analyzed the potential correlations between PMI parameters and patient age. MATERIALS AND METHODS: Four observers measured the PMI of both sides of the mental foramen using a picture archiving and communication system and images in the Digital Imaging and Communications in Medicine format. They studied 300 panoramic radiographic images of patients belonging to the following age groups: 40–49 years, 50–59 years, 60–69 years, 70–79 years, and 80–89 years. The observers were allowed to zoom in or out and to adjust the contrast of the images. Further, they were instructed to record the reasons for any measurements that could not be made. Then, we conducted a reliability analysis of the measured PMI and assessed the correlations between different patient age groups and the 3 parameters used for determining the PMI from the available data. RESULTS: Among the 600 data items collected, 23 items were considered unmeasurable by at least 1 observer for the following 4 reasons: postoperative state, lesion, unidentified mental foramen, and alveolar bone loss. The intraobserver reproducibility of the measurable data was 0.611-0.752. The mandibular cortical width (MCW) decreased significantly as patient age increased. CONCLUSION: PMI had limited usability when the margin of the mental foramen was not clear. In contrast, MCW, a parameter used for determining the PMI, had fewer drawbacks than the PMI with respect to bone mineral density measurements and exhibited a significant correlation with patient age.

Therapeutic effect of intraductal irrigation of the salivary gland: A technical report

PURPOSE: Obstructive and inflammatory disease often occurs in the major salivary glands, and no predictive treatment has yet been developed for this condition. The aim of this report was to introduce an intraductal irrigation procedure and to illustrate its application to practical patient cases. MATERIALS AND METHODS: Two patients complaining of pain and swelling in the parotid gland during meals who underwent sialography were diagnosed as having sialodochitis with sialadenitis. Intraductal irrigation was then performed on the parotid gland on the side of the complaint. The irrigation procedure was conducted in the same manner as the sialography procedure, except that saline was used as the filling solution. Symptom severity was evaluated with a numerical rating scale (NRS) at the initial visit and a month after the irrigation. RESULTS: The initial NRS value of patient 1 was 10. The value decreased to 6 and then to 0 after 2 irrigation procedures. The NRS value of patient 2 regarding the symptoms involving the left parotid gland decreased from 4-5 to 1 after 4 irrigation procedures performed at 1-month intervals. CONCLUSION: Intraductal irrigation of the salivary gland may be a simple, safe, and effective treatment option for patients with obstructive and inflammatory disease of the salivary gland that is capable of resolving their symptoms.

The development of a learning management system for dental radiology education: A technical report

PURPOSE: This study was conducted to suggest the development of a learning management system for dental radiology education using the Modular Object-Oriented Dynamic Learning Environment (Moodle). MATERIALS AND METHODS: Moodle is a well-known and verified open-source software-learning management system (OSS-LMS). The Moodle software was installed on a server computer and customized for dental radiology education. The system was implemented for teaching undergraduate students to diagnose dental caries in panoramic images. Questions were chosen that could assess students' diagnosis ability. Students were given several questions corre-sponding to each of 100 panoramic images. RESULTS: The installation and customization of Moodle was feasible, cost-effective, and time-saving. By having students answer questions repeatedly, it was possible to train them to examine panoramic images sequentially and thoroughly. CONCLUSION: Based on its educational efficiency and efficacy, the adaptation of an OSS-LMS in dental school may be highly recommended. The system could be extended to continuing education for dentists. Further studies on the objective evaluation of knowledge acquisition and retention are needed.

CT evaluation of underlying bone sclerosis in patients with oral squamous cell carcinoma: A preliminary retrospective study

PURPOSE: Underlying bone sclerosis is frequently observed in clinical settings when oral squamous cell carcinoma (OSCC) invades the jaw bone. The aim of this study was to assess the prevalence and characteristics of underlying bone sclerosis in patients with OSCC. MATERIALS AND METHODS: We retrospectively reviewed the computed tomographic (CT) images of 131 patients who underwent mandibulectomy between January 2012 and December 2015 to treat OSCC. The presence, degree, and extent of underlying bone sclerosis were assessed on CT images and correlated with the following imaging patterns of bone invasion: cortical invasion, medullary invasion with a smooth margin, and medullary invasion with an irregular margin. The chi-square test was used to determine the relationships between the variables. RESULTS: The prevalence of underlying bone sclerosis on CT images was 70.1% (47 of 67). The prevalence was 85.7% (42 of 49) in patients with medullary invasion, but it was 27.8% (5 of 18) in patients with only cortical invasion, indicating a significant increase in the prevalence of underlying bone sclerosis in patients with medullary invasion (P < .05). Aggressive patterns of bone invasion were associated with increases in the degree and extent of the underlying bone sclerosis (P < .05). CONCLUSION: More than two-thirds of OSCC cases with bone invasion showed underlying bone sclerosis. On CT images, reactive sclerosis in the remaining margin of the alveolar bone should not be used as the primary means to differentiate periodontal inflammatory lesions from those resulting from OSCC.