Evaluation of the marginal and internal fit of a single crown fabricated based on a three-dimensional printed model

PURPOSE: To evaluate the fit of a crown produced based on a 3D printed model and to investigate its clinical applicability. MATERIALS AND METHODS: A master die was fabricated with epoxy. Stone dies were fabricated from conventional impressions (Conventional stone die group: CS, n=10). Digital virtual dies were fabricated by making digital impressions (Digital Virtual die group: VD, n=10). 3D data obtained from the digital impression was used to fabricate 3D printed models (DLP die group: DD, n=10, PolyJet die group: PD, n=10). A total of 40 crowns were fabricated with a milling machine, based on CS, VD, DD and PD. The inner surface of all crowns was superimposed with the master die files by the “Best-fit alignment” method using the analysis software. One-way and 2-way ANOVA were performed to identify significant differences among the groups and areas and their interactive effects (α=.05). Tukey's HSD was used for post-hoc analysis. RESULTS: One-way ANOVA results revealed a significantly higher RMS value in the 3D printed models (DD and PD) than in the CS and DV. The RMS values of PD were the largest among the four groups. Statistically significant differences among groups (P < .001) and between areas (P < .001) were further revealed by 2-way ANOVA. CONCLUSION: Although the fit of crowns fabricated based on the 3D printed models (DD and PD) was inferior to that of crowns prepared with CS and DV, the values of all four groups were within the clinically acceptable range ( < 120 µm).

Accuracy evaluation of metal copings fabricated by computer-aided milling and direct metal laser sintering systems

PURPOSE: To assess the marginal and internal gaps of the copings fabricated by computer-aided milling and direct metal laser sintering (DMLS) systems in comparison to casting method. MATERIALS AND METHODS: Ten metal copings were fabricated by casting, computer-aided milling, and DMLS. Seven mesiodistal and labiolingual positions were then measured, and each of these were divided into the categories; marginal gap (MG), cervical gap (CG), axial wall at internal gap (AG), and incisal edge at internal gap (IG). Evaluation was performed by a silicone replica technique. A digital microscope was used for measurement of silicone layer. Statistical analyses included one-way and repeated measure ANOVA to test the difference between the fabrication methods and categories of measured points (alpha=.05), respectively. RESULTS: The mean gap differed significantly with fabrication methods (P<.001). Casting produced the narrowest gap in each of the four measured positions, whereas CG, AG, and IG proved narrower in computer-aided milling than in DMLS. Thus, with the exception of MG, all positions exhibited a significant difference between computer-aided milling and DMLS (P<.05). CONCLUSION: Although the gap was found to vary with fabrication methods, the marginal and internal gaps of the copings fabricated by computer-aided milling and DMLS fell within the range of clinical acceptance (<120 microm). However, the statistically significant difference to conventional casting indicates that the gaps in computer-aided milling and DMLS fabricated restorations still need to be further reduced.

Accuracy evaluation of metal copings fabricated by computer-aided milling and direct metal laser sintering systems

PURPOSE: To assess the marginal and internal gaps of the copings fabricated by computer-aided milling and direct metal laser sintering (DMLS) systems in comparison to casting method. MATERIALS AND METHODS: Ten metal copings were fabricated by casting, computer-aided milling, and DMLS. Seven mesiodistal and labiolingual positions were then measured, and each of these were divided into the categories; marginal gap (MG), cervical gap (CG), axial wall at internal gap (AG), and incisal edge at internal gap (IG). Evaluation was performed by a silicone replica technique. A digital microscope was used for measurement of silicone layer. Statistical analyses included one-way and repeated measure ANOVA to test the difference between the fabrication methods and categories of measured points (alpha=.05), respectively. RESULTS: The mean gap differed significantly with fabrication methods (P<.001). Casting produced the narrowest gap in each of the four measured positions, whereas CG, AG, and IG proved narrower in computer-aided milling than in DMLS. Thus, with the exception of MG, all positions exhibited a significant difference between computer-aided milling and DMLS (P<.05). CONCLUSION: Although the gap was found to vary with fabrication methods, the marginal and internal gaps of the copings fabricated by computer-aided milling and DMLS fell within the range of clinical acceptance (<120 microm). However, the statistically significant difference to conventional casting indicates that the gaps in computer-aided milling and DMLS fabricated restorations still need to be further reduced.

Adult Intussusception Caused by an Appendiceal Mucocele and Reduced by Colonoscopy

Appendiceal intussusception is a very rare disease that is found in only 0.01% of patients who have undergone an appendectomy. Clinical symptoms vary but include acute appendicitis symptoms such as right lower quadrant abdominal pain or repetitive right lower quadrant crampy pain. Some patients are asymptomatic. Operative treatment is necessary to reduce an appendiceal intussusception in adults, but there is a debate about how to perform the reduction. Successful colonoscopic reductions have been recently reported for some cases. We report a case of appendiceal intussusception that was diagnosed, reduced by colonoscopy, and histologically confirmed as a mucinous cystadenoma after the operation.

The Meaning of Open Cholecystectomy for Acute Cholecystitis

PURPOSE: Laparoscopic cholecystectomy has been used widely for effective management of acute cholecystitis. However, it has limitations. In this study, we compared laparoscopic approaches and an open method. The meaning of the open method was assessed again. METHODS: A retrospective review of 60 patients undergoing cholecystectomy for acute cholecystitis was done. Thirty patients were part of a laparoscopic cholecystectomy group; the other 30 patients were part of an open cholecystectomy group. Laparoscopic cholecystectomy was done using a 4-trochar method. We reviewed geographic characteristics, body mass index, white blood cell count, and clinical outcomes. RESULTS: Age, gallbladder wall thickness and white blood cell counts were significantly different between the 2 groups; operation time was not. The length of the postoperative hospital stay in the laparoscopic group was significantly shorter than that in the open group. There was one case of bile leakage in the laparoscopic group which was treated by endoscopic nasal bile drainage. CONCLUSION: Open cholecystectomy is still a valid choice for acute cholecystitis in the modern era of laparoscopic surgery. In severe cases, conversion is not a failure and should be done immediately if necessary.

Laparoscopic Colorectal Resection after Endoscopic Stent Insertion in Cases of Malignant Colorectal Obstruction: the Experience of a Single Center

PURPOSE: Laparoscopic surgery has been considered to be contraindicated for obstructive colorectal cancer. However, endoscopic stent insertion for obstructive colorectal cancer has recently allowed elective laparoscopic surgery. The aim of this study is to evaluate the feasibility and the short-term clinical outcomes of laparoscopic surgery following endoscopic stent insertion for management of malignant colorectal obstruction at a single center. METHODS: The medical records of patients who had undergone endoscopic stent insertion for colorectal cancer obstruction, followed by laparoscopic colorectal resections, from August 2004 to August 2008 were reviewed. To evaluate the surgical and clinical outcomes, we analyzed the clinical and pathologic data. RESULTS: Thirty-six endoscopic stent insertions were successfully performed during the study period. Of those 36, the 28 treated by laparoscopic surgery were enrolled in this study. The mean interval between stent insertion and surgery was 7.4+/-2.3 days. Two cases were converted to open surgery. The mean operative time was 185.5+/-53.1 min, and the mean blood loss was 77.0+/-72.9 mL. Flatus was passed on the mean 2nd postoperative day, and patients started to eat on the mean 4th postoperative day. The mean postoperative hospital stay was 11.2+/-4.4 days. Anastomosis leakages occurred in two cases and were treated by a secondary operation with a transient ileostomy. There were morbidities in five cases, but no mortalities. CONCLUSION: A combined endoscopic stent insertion and laparoscopic surgery is an effective and safe, minimally invasive operation for malignant colorectal obstruction.