• Imaging Science in Dentistry
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• 제53권2호
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• pp.127-135
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• 2023

Purpose: This study assessed the intensity of artifacts produced by 2 metal posts, 2 cements, and different exposure parameters using 2 cone-beam computed tomography (CBCT) units. Materials and Methods: The sample was composed of 20 single-rooted premolars, divided into 4 groups: Ni-Cr/zinc phosphate, Ni-Cr/resin cement, Ag-Pd/zinc phosphate, and Ag-Pd/resin cement. Samples were scanned before and after post insertion and cementation using a CS9000 3D scanner with 4 exposure parameters (85/90 kV and 6.3/10 mA) and an i-CAT scanner with 120 kV and 5 mA. The presence of artifacts was assessed subjectively by 2 observers and objectively by a trained observer using ImageJ software. The Mann-Whitney, Wilcoxon, weighted kappa, and chi-square tests were used to assess data at a 95% confidence level(α<0.05). Results: In the subjective analyses, AgPd presented more hypodense and hyperdense lines than NiCr (P<0.05), and more hypodense halos were found using i-CAT (P<0.05) than using CS9000 3D. More hypodense halos, hypodense lines, and hyperdense lines were observed at 10 mA than at 6.3 mA (P<0.05). More hypodense halos were observed at 85 kV than at 90 kV (P<0.05). CS9000 3D presented more hypodense and hyperdense lines than i-CAT (P<0.05). In the objective analyses, AgPd presented higher percentages of hyperdense and hypodense artifacts than NiCr (P<0.05). Zinc phosphate cement presented higher hyperdense artifact percentages on CS9000 3D scans(P<0.05). CS9000 3D presented higher artifact percentages than i-CAT(P<0.05). Conclusion: High-atomic-number alloys, higher tube current, and lower tube voltage may increase the artifacts present in CBCT images.

• 대한치과교정학회지
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• 제51권2호
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• pp.86-94
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• 2021

Objective: This study aimed to investigate the effect of micro-osteoperforations (MOPs) on external apical root resorption (EARR) during the initial orthodontic alignment phase of maxillary anterior crowding. Methods: Thirty patients (25 females, 5 males; mean age, 22.66 ± 3.27 years) who presented with moderate crowding of the upper labial segment and underwent extraction-based fixed appliance treatment were recruited. They were randomly allocated to receive adjunctive therapy with MOPs (n = 15) or treatment with fixed appliances only (control group; n = 15). EARR was measured from long-cone periapical radiographs taken at the start and the sixth month of treatment. A correction factor for the enlargement difference was used to calculate EARR. Data were analyzed with descriptive statistics and repeated-measures analysis of variance. Results: The mean root lengths of 168 teeth were measured and showed no statistically significant difference (p > 0.05) after six months of fixed appliance treatment in the MOP (mean difference [MD] = 0.13 mm; 95% confidence interval [CI] = -0.10-0.35) and control group (MD = 0.14 mm; 95% CI = -0.10-0.37). Most of the roots in the MOP and control groups (42.86% and 52.38%, respectively) showed only mild resorption. Less than 8% of the roots in both groups (7.14% in the MOP group and 4.76% in the control group) showed moderate resorption. Conclusions: Acceleration of orthodontic tooth movement with adjunctive MOPs therapy during the alignment phase does not exacerbate EARR in patients with moderate crowding of the upper labial segment in comparison with controls.

• Archives of Plastic Surgery
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• 제50권3호
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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.

• Korean Journal of Radiology
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• 제20권8호
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• pp.1300-1310
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• 2019

Objective: To measure the diagnostic accuracy of percutaneous transthoracic needle lung biopsies (PTNBs) on the basis of the intention-to-diagnose principle and identify risk factors for diagnostic failure of PTNBs in a multi-institutional setting. Materials and Methods: A total of 9384 initial PTNBs performed in 9239 patients (mean patient age, 65 years [range, 20-99 years]) from January 2010 to December 2014 were included. The accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of PTNBs for diagnosis of malignancy were measured. The proportion of diagnostic failures was measured, and their risk factors were identified. Results: The overall accuracy, sensitivity, specificity, PPV, and NPV were 91.1% (95% confidence interval [CI], 90.6-91.7%), 92.5% (95% CI, 91.9-93.1%), 86.5% (95% CI, 85.0-87.9%), 99.2% (95% CI, 99.0-99.4%), and 84.3% (95% CI, 82.7-85.8%), respectively. The proportion of diagnostic failures was 8.9% (831 of 9384; 95% CI, 8.3-9.4%). The independent risk factors for diagnostic failures were lesions ≤ 1 cm in size (adjusted odds ratio [AOR], 1.86; 95% CI, 1.23-2.81), lesion size 1.1-2 cm (1.75; 1.45-2.11), subsolid lesions (1.81; 1.32-2.49), use of fine needle aspiration only (2.43; 1.80-3.28), final diagnosis of benign lesions (2.18; 1.84-2.58), and final diagnosis of lymphomas (10.66; 6.21-18.30). Use of cone-beam CT (AOR, 0.31; 95% CI, 0.13-0.75) and conventional CT-guidance (0.55; 0.32-0.94) reduced diagnostic failures. Conclusion: The accuracy of PTNB for diagnosis of malignancy was fairly high in our large-scale multi-institutional cohort. The identified risk factors for diagnostic failure may help reduce diagnostic failure and interpret the biopsy results.

• Restorative Dentistry and Endodontics
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• 제34권2호
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• pp.130-136
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• 2009

본 연구의 목적은 flowable 복합레진의 조작성과 큰 연관이 있는 slumping 경향을 측정하는 방법을 제시하고 이와 관련이 있는 복합레진의 유변학적 특성을 고찰하였다. 5 종의 flowable 복합레진 (Aelitefil flow:AF, Filtek flow:FF, DenFil flow:DF, Tetric flow:TF and Revolution:RV)이 사용되었다. 주사기에 담긴 일정량의 복합레진을 일정 한 속도로 가압할 수 있는 장치를 이용하여 슬라이드글라스 위에 사출 한 후 $25^{\circ}C$의 실온에서 10 초 동안 slumping이 일어나도록 방치한 후 광중합 하였다. 복합레진의 slumping경향을 평가하기 위해 원뿔 형 혹은 동형으로 경화된 시편의 aspect ratio (밑면의 지름에 대한 높이의 비)를 구하였다. Slumping 경향과 복합레진의 유변학적 성질과의 관련성을 알아보기 위해 Rheometer를 사용하여 각진동수 ${\omega}=0.1-100$ rad/s의 범위에서 동적진동전단시험을 시행하여 복합레진의 복소점도를 구하였다. 복합레진의 slumping경향을 비교하기 위해 일원분산분석 및 Turkey's post test를 시행하였고 (${\alpha}<0.05$), 복소점도와 aspect ratio사이의 관련성을 알아보기 위해 회귀분석을 시행하였다 결과는 다음과 같다. 1. Slumping 후 aspect ratio를 측정하여 비교한 flowable 복합레진의 slumping 경향은 제품에 따라 큰 차이를 보였다(AF