OBJECTIVE: The purpose of this study was to evaluate the effects of three different surface conditioning methods on the shear bond strength (SBS) of metal brackets bonded directly to gold alloy with chemically cured resin. METHODS: Two hundred ten type III gold alloy specimens were randomly divided into six groups according to the combination of three different surface conditioning methods (aluminum oxide sandblasting only, application of a metal primer after aluminum oxide sandblasting, silica coating and silanation) and thermocycling (with thermocycling, without thermocycling). After performing surface conditioning of specimens in accordance with each experimental condition, metal brackets were bonded to all specimens using a chemically cured resin. The SBS was measured at the moment of bracket debonding, and the resin remnants on the specimen surface were evaluated using the adhesive remnant index. RESULTS: Application of metal primer after aluminum oxide sandblasting yielded a higher bond strength than that with aluminum oxide sandblasting alone (p < 0.001), and silica coating and silanation yielded a higher bond strength than that with metal primer after aluminum oxide sandblasting (p < 0.001). There was no significant change in SBS after thermocycling in all groups. CONCLUSIONS: With silica coating and silanation, clinically satisfactory bond strength can be attained when metal brackets are directly bonded to gold alloys using a chemically cured resin.
Adhesives ; Alloys* ; Aluminum Oxide ; Gold Alloys ; Silicon Dioxide*

Objective: To evaluate the impact of surgical simulation training using a three-dimensional (3D)-printed model of tetralogy of Fallot (TOF) on surgical skill development. Materials and Methods: A life-size congenital heart disease model was printed using a Stratasys Object500 Connex2 printer from preoperative electrocardiography-gated CT scans of a 6-month-old patient with TOF with complex pulmonary stenosis.Eleven cardiothoracic surgeons independently evaluated the suitability of four 3D-printed models using composite Tango 27, 40, 50, and 60 in terms of palpation, resistance, extensibility, gap, cut-through ability, and reusability of. Among these, Tango 27 was selected as the final model. Six attendees (two junior cardiothoracic surgery residents, two senior residents, and two clinical fellows) independently performed simulation surgeries three times each. Surgical proficiency was evaluated by an experienced cardiothoracic surgeon on a 1–10 scale for each of the 10 surgical procedures. The times required for each surgical procedure were also measured. Results: In the simulation surgeries, six surgeons required a median of 34.4 (range 32.5–43.5) and 21.4 (17.9–192.7) minutes to apply the ventricular septal defect (VSD) and right ventricular outflow tract (RVOT) patches, respectively, on their first simulation surgery. These times had significantly reduced to 17.3 (16.2–29.5) and 13.6 (10.3–30.0) minutes, respectively, in the third simulation surgery (p = 0.03 and p = 0.01, respectively). The decreases in the median patch appliance time among the six surgeons were 16.2 (range 13.6–17.7) and 8.0 (1.8–170.3) minutes for the VSD and RVOT patches, respectively. Summing the scores for the 10 procedures showed that the attendees scored an average of 28.58 ± 7.89 points on the first simulation surgery and improved their average score to 67.33 ± 15.10 on the third simulation surgery (p = 0.008). Conclusion Inexperienced cardiothoracic surgeons improved their performance in terms of surgical proficiency and operation time during the experience of three simulation surgeries using a 3D-printed TOF model using Tango 27 composite.

Objective: To evaluate the impact of surgical simulation training using a three-dimensional (3D)-printed model of tetralogy of Fallot (TOF) on surgical skill development. Materials and Methods: A life-size congenital heart disease model was printed using a Stratasys Object500 Connex2 printer from preoperative electrocardiography-gated CT scans of a 6-month-old patient with TOF with complex pulmonary stenosis.Eleven cardiothoracic surgeons independently evaluated the suitability of four 3D-printed models using composite Tango 27, 40, 50, and 60 in terms of palpation, resistance, extensibility, gap, cut-through ability, and reusability of. Among these, Tango 27 was selected as the final model. Six attendees (two junior cardiothoracic surgery residents, two senior residents, and two clinical fellows) independently performed simulation surgeries three times each. Surgical proficiency was evaluated by an experienced cardiothoracic surgeon on a 1–10 scale for each of the 10 surgical procedures. The times required for each surgical procedure were also measured. Results: In the simulation surgeries, six surgeons required a median of 34.4 (range 32.5–43.5) and 21.4 (17.9–192.7) minutes to apply the ventricular septal defect (VSD) and right ventricular outflow tract (RVOT) patches, respectively, on their first simulation surgery. These times had significantly reduced to 17.3 (16.2–29.5) and 13.6 (10.3–30.0) minutes, respectively, in the third simulation surgery (p = 0.03 and p = 0.01, respectively). The decreases in the median patch appliance time among the six surgeons were 16.2 (range 13.6–17.7) and 8.0 (1.8–170.3) minutes for the VSD and RVOT patches, respectively. Summing the scores for the 10 procedures showed that the attendees scored an average of 28.58 ± 7.89 points on the first simulation surgery and improved their average score to 67.33 ± 15.10 on the third simulation surgery (p = 0.008). Conclusion Inexperienced cardiothoracic surgeons improved their performance in terms of surgical proficiency and operation time during the experience of three simulation surgeries using a 3D-printed TOF model using Tango 27 composite.

Basal Cell Nevus Syndrome ; Carcinoma, Basal Cell ; Child ; Early Diagnosis ; Humans ; Hypertelorism ; Incisor ; Jaw ; Macrocephaly ; Odontogenic Cysts ; Orthodontic Extrusion ; Ribs

OBJECTIVES: To provide reference data for the study and treatment of thoracic scoliosis.SUMMARY OF LITERATURE REVIEW: There have been no reports on the prevalence of thoracic scoliosis in Korea. MATERIALS AND METHODS: From August 2011 to October 2012, radiographs of patients under 80 years of age who underwent routine chest radiographs were retrospectively reviewed. Based on their age when the chest radiographs were obtained, the patients were divided into 8 groups. The prevalence and angle of the curve of thoracic scoliosis were investigated in each age group, and the prevalence of thoracic scoliosis according to sex, the direction of the curve, number of vertebrae in the major curve, the location and rotation of the apical vertebrae, and osteophyte location were examined. RESULTS: The prevalence of thoracic scoliosis was 2.4% (621 patients), and female patients (3.0%, 375 of 12471) showed a higher prevalence than male patients (1.8%, 246 of 13654) (p<0.001). Right curvature was present in 445 patients and left curvature in 176 patients. In each age group, the prevalence and degree of thoracic scoliosis were 1.1% (14.2°±3.2°), 2.3% (17.4°±7.7°), 2.5% (17.0°±8.9°), 1.9% (15.8°±5.9°), 1.3% (15.5°±6.6°), 2.1% (18.0°±13.6°), 2.9% (14.3°±3.6°), and 6.1% (16.2°±4.8°), respectively. The mean curvature in all scoliosis patients was 16.0°±7.0°. The angle of the curve was significantly different by sex (15.4°±7.1° for males, 16.8°±7.6° for females). The average curve angle of patients with thoracic scoliosis was 16.0°±7.0°, among whom it was 10°–20° in 533 patients, 20°–30° in 64, 30°–40° in 11, and over 40° in 13. CONCLUSIONS This study could be used as a reference point for the study and treatment of thoracic scoliosis.

Objective: It is unknown whether artificial intelligence-based computer-aided detection (AI-CAD) can enhance the accuracy of chest radiograph (CR) interpretation in real-world clinical practice. We aimed to compare the accuracy of CR interpretation assisted by AI-CAD to that of conventional interpretation in patients who presented to the emergency department (ED) with acute respiratory symptoms using a pragmatic randomized controlled trial. Materials and Methods: Patients who underwent CRs for acute respiratory symptoms at the ED of a tertiary referral institution were randomly assigned to intervention group (with assistance from an AI-CAD for CR interpretation) or control group (without AI assistance). Using a commercial AI-CAD system (Lunit INSIGHT CXR, version 2.0.2.0; Lunit Inc.). Other clinical practices were consistent with standard procedures. Sensitivity and false-positive rates of CR interpretation by duty trainee radiologists for identifying acute thoracic diseases were the primary and secondary outcomes, respectively. The reference standards for acute thoracic disease were established based on a review of the patient’s medical record at least 30 days after the ED visit. Results: We randomly assigned 3576 participants to either the intervention group (1761 participants; mean age ± standard deviation, 65 ± 17 years; 978 males; acute thoracic disease in 472 participants) or the control group (1815 participants; 64 ± 17 years; 988 males; acute thoracic disease in 491 participants). The sensitivity (67.2% [317/472] in the intervention group vs. 66.0% [324/491] in the control group; odds ratio, 1.02 [95% confidence interval, 0.70–1.49]; P = 0.917) and false-positive rate (19.3% [249/1289] vs. 18.5% [245/1324]; odds ratio, 1.00 [95% confidence interval, 0.79–1.26]; P = 0.985) of CR interpretation by duty radiologists were not associated with the use of AI-CAD. Conclusion AI-CAD did not improve the sensitivity and false-positive rate of CR interpretation for diagnosing acute thoracic disease in patients with acute respiratory symptoms who presented to the ED.

Bone Marrow Cells ; Dexamethasone ; Mandible ; Osteoblasts ; Osteogenesis ; Platelet-Rich Plasma ; Rabbits ; Silver Nitrate

STUDY DESIGN: A cross-sectional study. OBJECTIVES: To provide reference data for the study and treatment of thoracic scoliosis. SUMMARY OF LITERATURE REVIEW: There have been no reports on the prevalence of thoracic scoliosis in Korea. MATERIALS AND METHODS: From August 2011 to October 2012, radiographs of patients under 80 years of age who underwent routine chest radiographs were retrospectively reviewed. Based on their age when the chest radiographs were obtained, the patients were divided into 8 groups. The prevalence and angle of the curve of thoracic scoliosis were investigated in each age group, and the prevalence of thoracic scoliosis according to sex, the direction of the curve, number of vertebrae in the major curve, the location and rotation of the apical vertebrae, and osteophyte location were examined. RESULTS: The prevalence of thoracic scoliosis was 2.4% (621 patients), and female patients (3.0%, 375 of 12471) showed a higher prevalence than male patients (1.8%, 246 of 13654) (p<0.001). Right curvature was present in 445 patients and left curvature in 176 patients. In each age group, the prevalence and degree of thoracic scoliosis were 1.1% (14.2°±3.2°), 2.3% (17.4°±7.7°), 2.5% (17.0°±8.9°), 1.9% (15.8°±5.9°), 1.3% (15.5°±6.6°), 2.1% (18.0°±13.6°), 2.9% (14.3°±3.6°), and 6.1% (16.2°±4.8°), respectively. The mean curvature in all scoliosis patients was 16.0°±7.0°. The angle of the curve was significantly different by sex (15.4°±7.1° for males, 16.8°±7.6° for females). The average curve angle of patients with thoracic scoliosis was 16.0°±7.0°, among whom it was 10°–20° in 533 patients, 20°–30° in 64, 30°–40° in 11, and over 40° in 13. CONCLUSIONS: This study could be used as a reference point for the study and treatment of thoracic scoliosis.
Cross-Sectional Studies ; Female ; Humans ; Korea ; Male ; Osteophyte ; Prevalence ; Radiography ; Radiography, Thoracic ; Retrospective Studies ; Scoliosis ; Spine ; Thoracic Vertebrae ; Thorax

OBJECTIVE: To compare a high acceleration three-dimensional (3D) T1-weighted gradient-recalled-echo (GRE) sequence using the combined compressed sensing (CS)-sensitivity encoding (SENSE) method with a conventional 3D GRE sequence using SENSE, with respect to image quality and detectability of solid focal liver lesions (FLLs) in the hepatobiliary phase (HBP) of gadoxetic acid-enhanced liver MRI. MATERIALS AND METHODS: A total of 217 patients with gadoxetic acid-enhanced liver MRI at 3T (54 in the preliminary study and 163 in the main study) were retrospectively included. In the main study, HBP imaging was done twice using the standard mDixon-3D-GRE technique with SENSE (acceleration factor [AF]: 2.8, standard mDixon-GRE) and the high acceleration mDixon-3D GRE technique using the combined CS-SENSE technique (CS-SENSE mDixon-GRE). Two abdominal radiologists assessed the two MRI data sets for image quality in consensus. Three other abdominal radiologists independently assessed the diagnostic performance of each data set and its ability to detect solid FLLs in 117 patients with 193 solid nodules and compared them using jackknife alternative free-response receiver operating characteristics (JAFROC). RESULTS: There was no significant difference in the overall image quality. CS-SENSE mDixon-GRE showed higher image noise, but lesser motion artifact levels compared with the standard mDixon-GRE (all p < 0.05). In terms of lesion detection, reader-averaged figures-of-merit estimated with JAFROC was 0.918 for standard mDixon-GRE, and 0.953 for CS-SENSE mDixon-GRE (p = 0.142). The non-inferiority of CS-SENSE mDixon-GRE over standard mDixon-GRE was confirmed (difference: 0.064 [−0.012, 0.081]). CONCLUSION: The CS-SENSE mDixon-GRE HBP sequence provided comparable overall image quality and non-inferior solid FFL detectability compared with the standard mDixon-GRE sequence, with reduced acquisition time.
Acceleration ; Artifacts ; Consensus ; Dataset ; Humans ; Liver ; Magnetic Resonance Imaging ; Methods ; Noise ; Retrospective Studies ; ROC Curve

OBJECTIVE: To investigate whether computed tomography (CT) and fluorine-18-labeled fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) may be applied to distinguish thymic epithelial tumors (TETs) from benign cysts in the anterior mediastinum. MATERIALS AND METHODS: We included 262 consecutive patients with pathologically proven TETs and benign cysts 5 cm or smaller who underwent preoperative CT scans. In addition to conventional morphological and ancillary CT findings, the relationship between the lesion and the adjacent mediastinal pleura was evaluated qualitatively and quantitatively. Mean lesion attenuation was measured on CT images. The maximum standardized uptake value (SUVmax) was obtained with FDG-PET scans in 40 patients. CT predictors for TETs were identified with multivariate logistic regression analysis. For validation, we assessed the diagnostic accuracy and inter-observer agreement between four radiologists in a size-matched set of 24 cysts and 24 TETs using a receiver operating characteristic curve before and after being informed of the study findings. RESULTS: The multivariate analysis showed that post-contrast attenuation of 60 Hounsfield unit or higher (odds ratio [OR], 12.734; 95% confidence interval [CI], 2.506–64.705; p = 0.002) and the presence of protrusion from the mediastinal pleura (OR, 9.855; 95% CI, 1.749–55.535; p = 0.009) were the strongest CT predictors for TETs. SUVmax was significantly higher in TETs than in cysts (5.3 ± 2.4 vs. 1.1 ± 0.3; p < 0.001). After being informed of the study findings, the readers' area under the curve improved from 0.872–0.955 to 0.949–0.999 (p = 0.066–0.149). Inter-observer kappa values for protrusion were 0.630–0.941. CONCLUSION: Post-contrast CT attenuation, protrusion from the mediastinal pleura, and SUVmax were useful imaging features for distinguishing TETs from cysts in the anterior mediastinum.
Humans ; Logistic Models ; Mediastinum ; Multivariate Analysis ; Pleura ; Positron-Emission Tomography ; ROC Curve ; Thymus Neoplasms ; Tomography, X-Ray Computed