Evaluating the accuracy (trueness and precision) of interim crowns manufactured using digital light processing according to post-curing time: An in vitro study

PURPOSE@#This study aimed to compare the accuracy (trueness and precision) of interim crowns fabricated using DLP (digital light processing) according to postcuring time. MATERIALS AND METHODS: A virtual stone study die of the upper right first molar was created using a dental laboratory scanner. After designing interim crowns on the virtual study die and saving them as Standard Triangulated Language files, 30 interim crowns were fabricated using a DLP-type 3D printer. Additively manufactured interim crowns were post-cured using three different time conditions-10-minute post-curing interim crown (10-MPCI), 20-minute postcuring interim crown (20-MPCI), and 30-minute post-curing interim crown (30-MPCI) (n = 10 per group). The scan data of the external and intaglio surfaces were overlapped with reference crown data, and trueness was measured using the best-fit alignment method. In the external and intaglio surface groups (n = 45 per group), precision was measured using a combination formula exclusive to scan data (10 C2). Significant differences in accuracy (trueness and precision) data were analyzed using the Kruskal-Wallis H test, and post hoc analysis was performed using the Mann-Whitney U test with Bonferroni correction (α=.05). @*RESULTS@#In the 10-MPCI, 20-MPCI, and 30-MPCI groups, there was a statistically significant difference in the accuracy of the external and intaglio surfaces (P <.05). On the external and intaglio surfaces, the root mean square (RMS) values of trueness and precision were the lowest in the 10-MPCI group. @*CONCLUSION@#Interim crowns with 10-minute post-curing showed high accuracy.

Effect of rinsing time on the accuracy of interim crowns fabricated by digital light processing: An in vitro study

PURPOSE@#This study was to evaluate the effect of rinsing time on the accuracy of interim crowns fabricated by digital light processing. @*MATERIALS AND METHODS@#The maxillary right first molar master die was duplicated using a silicone material, while a study die was produced using epoxy resin. Scans of the epoxy resin die were used in combination with CAD software to design a maxillary right first molar interim crown. Based on this design, 24 interim crowns were fabricated with digital light processing. This study examined the trueness and precision of products that were processed with one of the three different postprocessing rinsing times (1 min, 5 min, and 10 min). Trueness was measured by superimposing reference data with scanned data from external, intaglio, and marginal surfaces. Precision was measured by superimposing the scan data within the group. The trueness and precision data were analyzed using KruskalWallis, nonparametric, and post-hoc tests, and were compared using a MannWhitney U test with Bonferroni correction (α=.05). @*RESULTS@#The trueness of the external and intaglio surfaces of crowns varied significantly among the different rinsing times (P=.004, P=.003), but there was no statistically significant difference in terms of trueness measurements of the marginal surfaces (P=.605). In terms of precision, statistically significant differences were found among the external, intaglio, and marginal surfaces (P=.001). @*CONCLUSION@# Interim crowns rinsed for 10 minutes showed high accuracy.

Evaluating the accuracy (trueness and precision) of interim crowns manufactured using digital light processing according to post-curing time: An in vitro study

PURPOSE@#This study aimed to compare the accuracy (trueness and precision) of interim crowns fabricated using DLP (digital light processing) according to postcuring time. MATERIALS AND METHODS: A virtual stone study die of the upper right first molar was created using a dental laboratory scanner. After designing interim crowns on the virtual study die and saving them as Standard Triangulated Language files, 30 interim crowns were fabricated using a DLP-type 3D printer. Additively manufactured interim crowns were post-cured using three different time conditions-10-minute post-curing interim crown (10-MPCI), 20-minute postcuring interim crown (20-MPCI), and 30-minute post-curing interim crown (30-MPCI) (n = 10 per group). The scan data of the external and intaglio surfaces were overlapped with reference crown data, and trueness was measured using the best-fit alignment method. In the external and intaglio surface groups (n = 45 per group), precision was measured using a combination formula exclusive to scan data (10 C2). Significant differences in accuracy (trueness and precision) data were analyzed using the Kruskal-Wallis H test, and post hoc analysis was performed using the Mann-Whitney U test with Bonferroni correction (α=.05). @*RESULTS@#In the 10-MPCI, 20-MPCI, and 30-MPCI groups, there was a statistically significant difference in the accuracy of the external and intaglio surfaces (P <.05). On the external and intaglio surfaces, the root mean square (RMS) values of trueness and precision were the lowest in the 10-MPCI group. @*CONCLUSION@#Interim crowns with 10-minute post-curing showed high accuracy.

Risk of Vertebral Artery Injury: A Comparison between C2 Subarticular Segmental and C1-2 Transarticular Screws / 대한정형외과학회잡지

PURPOSE: We compared the risk of vertebral artery injury associated with the insertion of C1-2 transarticular screws and C2 subarticular segmental screws using a computer simulation of computed tomography (CT) scans. MATERIALS AND METHODS: We simulated the placement of C1-2 transarticular screws and C2 subarticular segmental screws using 1-mm interval CT scan images in 166 patients, along with simulation software. We then determined the incidence of violation of the C2 vertebral artery groove. The same determination was performed for high-riding vertebral arteries found among those patients. RESULTS: Among the 332 C2 vertebral artery grooves (166 patients), C1-2 transarticular screws violated the groove in 33 (9.9%) instances, while C2 subarticular segmental screws violated the groove in 19 (5.7%) instances. The difference in incidence between the two screw types was statistically significant (p=0.001, McNemar test). In the 48 high-riding vertebral arteries, C1-2 transarticular screws led to violation of the C2 vertebral artery groove in 30 (62.5%) instances, while C2 subarticular segmental screws led to violation of the groove in 18 (37.5%) instances. The difference in incidence between the two screw types was statistically significant (p=0.002, McNemar test). CONCLUSION: Use of C2 subarticular segmental screws is associated with a lower risk of vertebral artery injury than is the use of C1-2 transarticular screws, even for high-riding vertebral arteries.

Efficacy of Pigtail Catheter Drainage in Patients with Thoracic Empyema or Complicated Parapneumonic Effusion / 결핵

BACKGROUND: The management of thoracic empyema and complicated parapneumonic effusion requires adequate antibiotics use and prompt drainage of infected pleural space. Tube thoracostomy for loculated empyema has low success rate and is also an invasive procedure with potential morbidity. Complications include hemothorax, perforation of intra-abdominal or intra-thoracic organs, diaphragmatic laceration, empyema, pulmonary edema, and Horner's syndrome. Given the potential morbidity of traditional chest tube insertion, use of the image-guided pigtail catheter drainage(PCD) of empyema has been employed. We retrospectively analyzed the medical records of patients with empyema or complicated parapneumonic effusion to determine the efficacy of percutaneous pigtail catheter drainage. MATERIALS AND METHODS: 45 patients with complicated parapneumonic effusions or empyema were treated at Gil medical center from January 1998 to June, 1999. All were initially given PCD procedure and the following data were collected: clinical symptoms at the time of diagnosis, alcohol and smoking history, the characteristics of pleural effusion, radiologic findings (at the time of catheter insertion, removal and 1 month after catheter removal), the amount of effusion drained for initial 24 hours, the time from catheter insertion to removal and the use of surgical approach. RESULTS: Male gender was more frequent (42 men vs. 3 women), the mean age of the study population was 52(range: 21~74) years. Empyema was found in 23 patients, complicated parapneumonic effusion in 22 patients. Four patients(three, parapneumonic effusion and one, with empyema) with PCD only treated were cast off. Among the available patients, 36(80%) patients were treated with PCD only or PCD with urokinase. Among the 23 patients with empyema, surgical approach was required in five patients(27.1%, one required decortication, four open thoracostomy), one patient, treated with surgical procedure, died of sepsis. There was no significant difference of the duration of catheter insertion, the duration of hospital admission after catheter insertion and the mean amount of effusion drained for initial 24 hours between the patients with only PCD treated and the patients treated with PCD and urokinase. The duration of catheter insertion(9.4+/-5.25 days vs. 19.2+/-9.42 days, p<0.05) and the duration of hospital admission after catheter insertion(15.9+/-10.45 days vs. 38.6+/-11.46 days, p<0.01) of the patients with only PCD treated were more longer than those of the patients treated with surgical procedure after PCD. They were same between the patients treated with urokinase after PCD and the patients treated with surgical procedure after PCD(11.1+/-7.35 days vs. 19.2+/-9.42 days, p<0.05, 17.5+/-9.17 days vs. 38.6+/-11.46 days, p<0.01). In 16 patients(44.4%) with only PCD treated or PCD and urokinase treated, the amount of effusion at the time of catheter removal was decreased more than 75% and in 17 patients(47.2%) effusion decreased 50~75%. .In one patient effusion decreased 25~50%, in two patients effusion decreased less than 25%. One month after catheter removal, in 35 patients(97.2%, four patients were cast off), the amount of pleural effusion was successfully decreased more than 50%. There were no complications related to pigtail catheter insertion. CONCLUSION: In this study, PCD seemed to be an early efficacious procedure in treating the patients with complicated parapneumonic effusion or empyema without any serious procedure related complication.

Effects of Simvastatin Alone or Combined With Ramipril on Nitric Oxide Bioactivity and Inflammation Markers in Hypercholesterolemic Patients

BACKGROUND AND OBJECTIVES: Because the mechanisms of the biological effects of statin and antiotensin converting enzyme inhibitor therapies differ, the vascular responses to these therapies were studied in hypercholesterolemic patients. MATERIALS AND METHODS: Simvastatin, 20 mg, placebo or ramipril, 10 mg, were administered daily for 2 months, with a 2 month washout, to 32 hypercholesterolemic patients. This was a randomized, double-blind, placebo-controlled, crossover in design study. RESULTS: Simvastatin alone, or in combination with ramipril, significantly changed the lipoproteins, and improved the percentage of the flow-mediated dilator response to hyperemia by 46+/-48% and by 59+/-66%, respectively, relative to the baseline measurements (both p<0.001). The plasma malondialdehyde levels were reduced, relative to baseline measurements, by 6+/-57% (p=0.045) and 13+/-47% (p=0.045 and p<0.001, respectively) and plasma levels of monocyte chemoattractant protein-1 by 3+/-27% and by 9+/-16%, respectively (p=0.113 and p=0.001, respectively). The C-reactive protein were also reduced, relative to baseline measurements, by 17+/-75% and by 17+/-37%, respectively (p=0.003 and p=0.001, respectively). However, simvastatin combined with ramipril changed, to a greater extent, but was statistically insignificant, the percentage of the flow-mediated dilator response to hyperemia, and the plasma monocyte chemoattractant protein-1 levels, than simvastatin alone. CONCLUSION: Compared with simvastatin alone, the addition of ramipril improved the endothelial function to greater extent, but was statistically insignificant, in hypercholes-terolemic patients.