• International Journal of Oral Biology
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• v.46 no.4
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• pp.168-175
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• 2021

To investigate the perceptions and attitudes of dental hygienists toward radiation safety management in Korea. A total of 800 dental hygienists were randomly selected for an anonymous survey, and 203 of them participated. The questionnaire items included the following: sex, career period, type of installed radiographic equipment, recognition of the diagnostic reference level (DRL), participation in radiation safety education, and attitudes toward radiation protection for both patients and dental hygienists. The participants were divided into two groups according to their years of experience (< 10 years versus ≥ 10 years). The difference between the groups was investigated according to frequency distribution. Fisher's exact test or Pearson's chi-square (𝛘²) test was used as appropriate. A regression analysis was performed to investigate the impact of wearing a thyroid collar for personnel protection during patient radiation exposure. The types of installed radiographic equipment included panoramic radiography (96.1%), cephalometric radiography (76.9%), intraoral radiography (72.9%), and cone-beam computed tomography (69.5%). Significant differences were observed in the learning pathway for the DRL (Fisher's exact test, p < 0.05), satisfaction with radiation safety education (Pearson's 𝛘² test = 5.3975, Pr = 0.02), and use of personnel radiation monitoring systems (Pearson's 𝛘² test = 18.1233, Pr = 0.000) between the groups. Significant differences were also observed in personnel protection using a thyroid collar and patient protection during panoramic radiography (odds ratio = 14.2). Dental hygienists with more than 10 years of experience were more satisfied with radiation safety education and more interested in radiation monitoring. Considering career experience, customized, continuous, and effective radiation safety management education should be provided.

• Journal of Korean Dental Science
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• v.15 no.1
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• pp.31-50
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• 2022

Purpose: This study was to investigate the types of imaging modalities, analytical methods for age estimation, and the age of the subjects in research on age estimation using dental radiography through a scoping review, and to investigate the overall trends in age estimation studies. Materials and Methods: A scoping review was designed according to the Arksey and O'Malley guidelines and the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) statement. Three electronic databases were used as search sources (Medline, Embase, and Cochrane Library). Studies were classified according to the three main components of the research question. "What are the imaging modalities, analytical methods, and target age in dental imaging-based age estimation studies?" Result: The final 198 studies were selected by two reviewers. The most common imaging modality used in studies was panoramic radiography (69.7%), and studies using cone-beam computed tomography have increased over time. Analytical methods for age estimation were 62.6% in studies based on tooth development and 26.3% in studies using pulp/tooth ratio. The subject age was 27.8% for children and 27.3% for adults. Studies conducted in all age groups comprised the smallest category (5.2%). Conclusion: Panoramic radiography has been the most used types of imaging modalities for age estimation, and the most common analytical method was analysis of tooth development. Most studies targeted specific ages, and very few involved all age groups. Dental age estimation studies should be carried out with appropriate consideration of the imaging modality that is analyzed, the methods that are used, and the age that is targeted.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.48 no.5
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• pp.292-296
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• 2022

Objectives: During Le Fort I osteotomy, the separation of the pterygomaxillary junction (PMJ) is a difficult procedure for most surgeons because it is invisible. In this process, damage to the posterior structures constituting the sinus or those adjacent to it, including the maxillary sinus posterior wall and pterygoid plate, may occur. We would like to investigate the effects of this on the inside of the maxillary sinus after surgery and whether there are complications. Materials and Methods: One-hundred patients who underwent Le Fort I osteotomy from 2013 to 2020 using cone-beam computed tomography images were classified into two groups (clean-cut type and fractured type) according to the PMJ cutting pattern. In addition, the mucosal thickness in the maxillary sinus was divided into preoperative, postoperative three months, one year, and the change over the course of surgery was evaluated retrospectively. Results: Of the total 100 cases, the clean-cut type numbered 28 cases and the fractured type totaled 72 cases. Among the fracture types, part of the sinus wall and the pterygoid plate were broken in 69 cases, and the maxillary sinus posterior wall was detached in three cases. There was no statistically significant difference in sinus mucosal thickening between the clean-cut type and fractured type of the PMJ, three months and one year after surgery between the two groups. However, there was a significant difference in sinus mucosal thickness at postoperative one year in the case where a partial detachment of the maxillary sinus posterior wall occurred compared to not. Conclusion: Even if there is some damage to the structures behind the PMJ, it may not be reasonable to spend some time on the PMJ separation process considering the overall postoperative complications, if there is no significant difference inside the sinus, or increased probability of postoperative complications.

• Progress in Medical Physics
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• v.32 no.4
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• pp.165-171
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• 2021

Purpose: This study aimed to evaluate the effect of collimator width on effective atomic number (EAN), relative electron density (RED), and stopping power ratio (SPR) measured by dual-layer dual-energy computed tomography (DL-DECT). Methods: CIRS electron density calibration phantoms with two different arrangements of material plugs were scanned by DL-DECT with two different collimator widths. The first phantom included two dense bone plugs, while the second excluded dense bone plugs. The collimator widths selected were 64 mm×0.625 mm for wider collimators and 16 mm×0.625 mm for narrow collimators. The scanning parameters were 120 kVp, 0.33 second gantry rotation, 3 mm slice thickness, B reconstruction filter, and spectral level 4. An image analysis portal system provided by a computed tomography (CT) manufacturer was used to derive the EAN and RED of the phantoms from the combination of low energy and high energy CT images. The EAN and RED were compared between the images scanned using the two different collimation widths. Results: The CT images with the wider collimation width generated more severe artifacts, particularly with high-density material (i.e., dense bone). RED and EAN for tissues (excluding lung and bones) with the wider collimation width showed significant relative differences compared to the theoretical value (4.5% for RED and 20.6% for EAN), while those with the narrow collimation width were closer to the theoretical value of each material (2.2% for EAN and 2.3% for RED). Scanning with narrow collimation width increased the accuracy of SPR estimation even with high-density bone plugs in the phantom. Conclusions: The effect of CT collimation width on EAN, RED, and SPR measured by DL-DECT was evaluated. In order to improve the accuracy of the measured EAN, RED, and SPR by DL-DECT, CT scanning should be performed using narrow collimation widths.

• The korean journal of orthodontics
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• v.52 no.6
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• pp.399-411
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• 2022

Objective: The objective of this randomized clinical trial was to study the skeletal and dental effects of low-level laser therapy (LLLT) along with a miniscrew-assisted expander (Hyrax) after six months of retention. Methods: After sequence generation, concealed allocation, and implementation, 24 female patients were randomly divided (1:1) into two-groups: bone-borne rapid palatal expansion (BBE) without LLLT (n = 12) and BBE with LLLT (n = 12). Eligibility criteria included female patients aged 10-13 years old with bilateral posterior crossbites. Intraoral and extraoral photographs, cone-beam computed tomography images, and digital study models were obtained before expansion and six months after retention. The 7 mm Hyrax appliance was anchored to four palatal mini-screws, which were activated twice daily for 15 days, then locked and kept in place as a retainer. LLLT was performed in the laser group during expansion and retention, according to the guidelines provided. Results: The records of 24 patients were analyzed. According to the post-retention measurements, both groups showed a significant increase in nasal and maxillary widths and total facial height. In the laser group, the Sella-Nasion-Point A and Point A-Nasion-Point B angles and the interpremolar apical distance were significantly increased. Conclusions: Within the limitations of this study, the results suggest that the parameters and protocol of LLLT do not clinically affect the efficiency of BBE in prepubertal and pubertal patients.

• Journal of dental hygiene science
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• v.22 no.4
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• pp.249-255
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• 2022

Background: Sexual dimorphism is important for sex determination in the field of forensics. However, sexual dimorphism is commonly assessed using cone beam computed tomography (CBCT) rather than three-dimensional (3D) modeling software; therefore, studies using a more accurate measurement approach are necessary. This study assessed the sexual dimorphism of the MS using a 3D modeling program to obtain information that could contribute to the fields of surgery and forensics. Methods: The CBCT data of 60 patients (age, 20~29 y; 30 males and 30 females) admitted to the Department of Orthodontics at the Dankook University School of Dentistry were provided in Digital Imaging and Communications in Medicine (DICOM) format. The left MS and right MS were modeled based on the DICOM files using the Mimics (version 22; Materialise, Leuven, Belgium) 3D program and converted to stereolithography (STL) files used to measure the width, length, and height of the MS, infraorbital foramen (IOF), right MS, and left MS. The average of three repeated measurements was calculated, and a reliability test was performed to ensure data reliability (Cronbach's α=0.618). A canonical discriminant analysis was performed using a standard approach (left: Box's M=0.096; right: Box's M=0.115). Results: Males had greater values for all parameters (MS width, MS length, MS height, IOF, right MS, left MS) than females. The discriminant analysis identified six independent variables (MS width, MS height, MS length, IOF, right MS, left MS) that could identify sex. The left MS and right MS correctly identified the sex of 81.7% and 71.7% of the patients, respectively, with the left MS having higher accuracy. Conclusion: This study confirmed that, for Korean individuals, the left MS has a better ability to identify sex than the right MS. These results may contribute to sex identification in the fields of surgery and forensics.

• The korean journal of orthodontics
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• v.53 no.1
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• pp.26-34
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• 2023

Objective: The purpose of the present study was to compare the root positions in virtual tooth setups using only crowns in a simulated treatment with those achieved in the actual treatment. Methods: Pre- and post-treatment intraoral and corresponding cone beam computed tomography (CBCT) scans were obtained from 15 patients who underwent orthodontic treatment with premolar extraction. A conventional virtual tooth setup was used for the treatment simulation. Pre- and post-treatment three-dimensional digital tooth models were fabricated by integrating the patients' intraoral and CBCT scans. The simulated root positions in the virtual setup were obtained by merging the crown in the virtual setup and root in the pre-treatment tooth model. The root positions of the simulated and actual post-treatment tooth models were compared. Results: Differences in root positions between the simulated and actual models were > 1 mm in all teeth, and statistically significant differences were observed (p < 0.05), except for the maxillary lateral incisors. The differences in the inter-root angulation were > 1° in all teeth, and statistically significant differences were observed in the maxillary and mandibular canines. Conclusions: The virtual tooth setup using only crown data showed errors over the clinical limits. The clinical application of a virtual setup using crowns and roots is necessary for accurate and precise treatment simulation, particularly in extraction treatment.

• Imaging Science in Dentistry
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• v.53 no.3
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• pp.229-238
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• 2023

Purpose: Ectopic eruption can be defined as the emergence of a tooth in an abnormal location, where the tooth does not follow its typical eruption pathway. While ectopic eruption within the dentate region is well-documented in the literature, ectopic eruption in non-dentate regions is relatively rare. This study aimed to report 6 cases of ectopic teeth and present a systematic review of the English-language literature on ectopic teeth, emphasizing demographic characteristics, radiographic features, potential complications, and treatment options. Materials and Methods: A literature search was conducted using the PubMed, Medline, Web of Science, and Cochrane databases. The demographic data and radiographic findings of patients presenting with ectopic teeth were recorded. Results: The literature review yielded 61 cases of ectopic teeth, with patients ranging in age from 3 to 74 years. The findings from these previously reported cases demonstrated that the most common location for ectopic teeth was the maxillary sinus, which is consistent with this case series. The Pearson chi-square test was performed to evaluate the correlation between age and location of ectopic teeth, and the results were found to be statistically significant (P<0.05). However, no statistically significant relationship was observed between sex and the location of ectopic teeth. Conclusion: The distinct features of these cases warrant reporting. This study presents the first case of supernumerary teeth in the condyle without any associated pathosis. Another notable characteristic is the pre-eruptive resorption of 2 inverted supernumerary teeth ectopically located in the palate, which predisposes to sinus opacification.

• Archives of Plastic Surgery
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• v.50 no.3
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• pp.254-263
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• 2023

Background The three-dimensional (3D) evaluation of skeletal stability after orthognathic surgery is a time-consuming and complex procedure. The complexity increases further when evaluating the surgery-first orthognathic approach (SFOA). Herein, we propose and validate a simple time-saving method of 3D analysis using a single software, demonstrating high accuracy and repeatability. Methods This retrospective cohort study included 12 patients with skeletal class 3 malocclusion who underwent bimaxillary surgery without any presurgical orthodontics. Computed tomography (CT)/cone-beam CT images of each patient were obtained at three different time points (preoperation [T0], immediately postoperation [T1], and 1 year after surgery [T2]) and reconstructed into 3D images. After automatic surface-based alignment of the three models based on the anterior cranial base, five easily located anatomical landmarks were defined to each model. A set of angular and linear measurements were automatically calculated and used to define the amount of movement (T1-T0) and the amount of relapse (T2-T1). To evaluate the reproducibility, two independent observers processed all the cases, One of them repeated the steps after 2 weeks to assess intraobserver variability. Intraclass correlation coefficients (ICCs) were calculated at a 95% confidence interval. Time required for evaluating each case was recorded. Results Both the intra- and interobserver variability showed high ICC values (more than 0.95) with low measurement variations (mean linear variations: 0.18 mm; mean angular variations: 0.25 degree). Time needed for the evaluation process ranged from 3 to 5 minutes. Conclusion This approach is time-saving, semiautomatic, and easy to learn and can be used to effectively evaluate stability after SFOA.

• Journal of Korean Dental Science
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• v.16 no.1
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• pp.63-73
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• 2023

Purpose: Hyperdontia is a developmental disorder of the oral cavity. Mesiodens refers to the hyperdontia located between the maxillary central incisors. During the surgical procedure, the anesthetic method for pain control should be considered along with factors related to the surgery itself. The purpose of this study was to evaluate the effect of the impacted position of the mesiodens on the selection of sedation method and to suggest incisive foramen as a brief reference. Materials and Methods: This study included 126 patients who were scheduled for extraction of mesiodens. The selection criteria included patients with one palatally impacted inverted mesiodens accessible from the palatal gingival margin, and those with good cooperation potential in order to control for clinical information. Using cone beam computed tomography, vertical, horizontal, and palatal positional factors were measured, and the anesthetic method was determined by two examiners. The patients were grouped into vertical and horizontal groups based on the position of the incisive foramen. Data were statistically analyzed using the Mann-Whitney test, the chi-square test, and logistic regression analysis. Result: All positional factors differed between the outpatient and inpatient anesthetic groups. The vertical minimum distance from the alveolar ridge to the mesiodens (Va) and the minimum distance from the palatal surface to the crown tip of the mesiodens (Tc) were factors affecting the choice of anesthetic method. The distribution of the vertical and horizontal positional groups differed between the outpatient and inpatient anesthetic groups. Conclusion: The incisive foramen can be used as a brief reference to determine the appropriate anesthetic method. Referral for inpatient anesthesia may be a priority if they are in the V₂H₂ group with Va ≥5 mm, and Tc ≥6 mm, and outpatient sedation may be considered if they are in the V₁H₁ group with Va ≤1.5 mm, and Tc ≤2.5 mm.