Diagnostic and prognostic impact of fluorodeoxyglucosepositron emission tomography in diagnosing intraductal papillary neoplasms of the bile duct of the liver

Purpose@#Malignant intraductal papillary neoplasm of the bile duct of the liver (IPNB-L) cannot readily be diagnosed through preoperative CT or MRI, but fluorodeoxyglucose (FDG)-PET is a viable alternative. This study evaluated the diagnostic and prognostic impacts of FDG-PET in patients with IPNB-L. @*Methods@#This was a retrospective single-center study of 101 IPNB-L patients who underwent hepatectomy between 2010 and 2019. @*Results@#Mean age was 64.4 ± 8.3 years and 76 (75.2%) were male. Anatomical hepatic resection was performed in 99 (98.0%). Concurrent bile duct resection and pancreaticoduodenectomy were performed in 41 (40.6%) and 1 (1.0%), respectively. R0 and R1 resections were performed in 88 (87.1%) and 13 (12.9%), respectively. Low-grade intraepithelial neoplasia and high-grade neoplasia/invasive carcinoma were diagnosed in 19 (18.8%) and 82 (81.2%), respectively. Median FDG-PET maximal standardized uptake values (SUVmax) in low-grade neoplasia and high-grade neoplasia/carcinoma were 3.6 (range, 1.7–7.6) and 5.2 (range, 1.5–18.7) (P = 0.019), respectively. Receiver operating characteristic curve analysis of SUVmax showed area under the curve of 0.674, with sensitivity of 84.2% and specificity of 47.4% at SUVmax cutoff of 3.0. This cutoff had no significant influence on tumor recurrence (P = 0.832) or patient survival (P = 0.996) in patients with IPNB-L of high-grade neoplasia or invasive carcinoma. @*Conclusion@#IPNB-L is a rare type of biliary neoplasm and encompasses a histological spectrum ranging from benign disease to invasive carcinoma. An FDG-PET SUVmax cutoff of 3.0 appears to effectively discern high-grade neoplasia/ carcinoma from low-grade neoplasia, which will assist with the surgical strategy for these cases.

Fates of retained hepatic segment IV and its prognostic impact in adult split liver transplantation using an extended right liver graft

Purpose@#When splitting a liver for adult and pediatric graft recipients, the retained left medial section (S4) will undergo ischemic necrosis and the right trisection graft becomes an extended right liver (ERL) graft. We investigated the fates of the retained S4 and its prognostic impact in adult split liver transplantation (SLT) using an ERL graft. @*Methods@#This was a retrospective analysis of 25 adult SLT recipients who received split ERL grafts. @*Results@#The mean model for end-stage liver disease (MELD) score was 27.3 ± 10.9 and graft-recipient weight ratio (GRWR) was 1.98 ± 0.44. The mean donor age was 26.5 ± 7.7 years. The split ERL graft weight was 1,181.5 ± 252.8 g, which resulted in a mean GRWR of 1.98 ± 0.44. Computed tomography of the retained S4 parenchyma revealed small ischemic necrosis in 16 patients (64.0%) and large ischemic necrosis in the remaining 9 patients (36.0%). No S4-associated biliary complications were developed. The mean GRWR was 1.87 ± 0.43 in the 9 patients with large ischemic necrosis and 2.10 ± 0.44 in the 15 cases with small ischemic necrosis (P = 0.283). The retained S4 parenchyma showed gradual atrophy on follow-up imaging studies. The amount of S4 ischemic necrosis was not associated with graft (P = 0.592) or patient (P = 0.243) survival. A MELD score of >30 and pretransplant ventilator support were associated with inferior outcomes. @*Conclusion@#The amount of S4 ischemic necrosis is not a prognostic factor in adult SLT recipients, probably due to a sufficiently large GRWR.

Fates of retained hepatic segment IV and its prognostic impact in adult split liver transplantation using an extended right liver graft

Purpose@#When splitting a liver for adult and pediatric graft recipients, the retained left medial section (S4) will undergo ischemic necrosis and the right trisection graft becomes an extended right liver (ERL) graft. We investigated the fates of the retained S4 and its prognostic impact in adult split liver transplantation (SLT) using an ERL graft. @*Methods@#This was a retrospective analysis of 25 adult SLT recipients who received split ERL grafts. @*Results@#The mean model for end-stage liver disease (MELD) score was 27.3 ± 10.9 and graft-recipient weight ratio (GRWR) was 1.98 ± 0.44. The mean donor age was 26.5 ± 7.7 years. The split ERL graft weight was 1,181.5 ± 252.8 g, which resulted in a mean GRWR of 1.98 ± 0.44. Computed tomography of the retained S4 parenchyma revealed small ischemic necrosis in 16 patients (64.0%) and large ischemic necrosis in the remaining 9 patients (36.0%). No S4-associated biliary complications were developed. The mean GRWR was 1.87 ± 0.43 in the 9 patients with large ischemic necrosis and 2.10 ± 0.44 in the 15 cases with small ischemic necrosis (P = 0.283). The retained S4 parenchyma showed gradual atrophy on follow-up imaging studies. The amount of S4 ischemic necrosis was not associated with graft (P = 0.592) or patient (P = 0.243) survival. A MELD score of >30 and pretransplant ventilator support were associated with inferior outcomes. @*Conclusion@#The amount of S4 ischemic necrosis is not a prognostic factor in adult SLT recipients, probably due to a sufficiently large GRWR.

Pretransplant Hepatic Malignancy Increases Risk of De Novo Malignancy after Liver Transplantation

BACKGROUND: Hepatocellular carcinoma (HCC) recurrence and development of de novo malignancy (DNM) after liver transplantation (LT) are the major causes of late recipient death.METHODS: We analyzed the incidence of extrahepatic DNM following living donor LT according to the status of pretransplant hepatic malignancy. We selected 2,076 adult patients who underwent primary LDLT during 7 years from January 2010 to December 2016.RESULTS: The pretransplant hepatic malignancy group (n = 1,012) showed 45 cases (4.4%) of the following extrahepatic DNMs: posttransplant lymphoproliferative disease (PTLD) in 10; lung cancer in 10; stomach cancer in 6; colorectal cancer in 5; urinary bladder cancer in 3; and other cancers in 11. The pretransplant no hepatic malignancy group (n = 1,064) showed 25 cases (2.3%) of the following extrahepatic DNMs: colorectal cancer in 3; stomach cancer in 3; leukemia in 3; lung cancer in 3; PTLD in 2; prostate cancer in 2; and other cancers in 9. Incidences of extrahepatic DNM in the pretransplant hepatic malignancy and no hepatic malignancy groups were as follows: 1.1% and 0.5% at 1 year, 3.2% and 2.0% at 3 years, 4.6% and 2.5% at 5 years, and 5.4% and 2.8% at 8 years, respectively (P = 0.006). Their overall patient survival rates were as follows: 97.3% and 97.2% at 1 year, 91.6% and 95.9% at 3 years, 89.8% and 95.4% at 5 years, and 89.2% and 95.4% at 8 years, respectively (P < 0.001). Pretransplant hepatic malignancy was the only significant risk factor for posttransplant extrahepatic DNM.CONCLUSION: Our results suggest that patients who had pretransplant hepatic malignancy be followed up more strictly because they have a potential risk of primary hepatic malignancy recurrence as well as a higher risk of extrahepatic DNM than patients without pretransplant hepatic malignancy.

Prognosis of Split Liver Transplantation Compared with Whole Liver Transplantation in Adult Patients:Single-center Results under the Korean MELD Score-based Allocation Policy

Background@#Split liver transplantation (SLT) has been occasionally performed in Korea. This study compared the incidence and prognosis of SLT with whole liver transplantation (WLT) in adult patients. @*Methods@#Between June 2016 and November 2019, 242 adult patients underwent a total of 256 deceased donor liver transplantation operations. SLT was performed in 7 patients (2.9%). @*Results@#The mean age of SLT donors was 29.7 ± 7.4 years, and the mean age of recipients was 55.7 ± 10.6 years, with the latter having a mean model for end-stage liver disease score of 34.6 ± 3.1. Mean split right liver graft weight was 1,228.6 ± 149.7 g and mean graft-recipient weight ratio was 1.97 ± 0.39. Of the seven SLT recipients, Korean Network for Organ Sharing (KONOS) status was one in status 1, one in status 2 and five in status 3. The graft (p = 0.72) and patient (p = 0.84) survival rates were comparable in the SLT and WLT groups. Following propensity score matching, graft (p = 0.61) and patient (p = 0.91) survival rates remained comparable in the two groups. Univariate analysis showed that pretransplant ventilator support and renal replacement therapy were significantly associated with patient survival, whereas KONOS status category and primary liver diseases were not. Multivariate analysis showed that pretransplant ventilator support was an independent risk factor for patient survival. @*Conclusion@#Survival outcomes were similar in adult SLT and WLT recipients, probably due to selection of high-quality grafts and low-risk recipients. Prudent selection of donors and adult recipients for SLT may expand the liver graft pool for pediatric patients without affecting outcomes in adults undergoing SLT.

Refined surgical techniques to improve the patency of cryopreserved iliac artery homografts for middle hepatic vein reconstruction during living donor liver transplantation

Purpose@#A cryopreserved iliac artery homograft (IAH) has not been considered suitable for middle hepatic vein (MHV) reconstruction during living donor liver transplantation (LDLT), primarily due to the low patency from its small diameter. We revised our surgical techniques for MHV reconstruction using an IAH to improve its patency. @*Methods@#This study analyzed the causes of early conduit occlusion and developed revised techniques to address this that had clinical application. @*Results@#The potential risk factors for early conduit occlusion were the small IAH size, small graft in the segment V vein (V5) and segment VIII vein (V8) opening, and small recipient MHV-left hepatic vein stump. These factors were reflected to our revised surgical methods which included endarterectomy of the atherosclerotic plaque, unification of the internal and external iliac artery branches for large V5, and branch-patch arterioplasty for large V8. IAH endarterectomy, branch unification technique, and branch-patch arterioplasty were applied to 8, 5, and 5 patients, respectively and resulted in 1-month occlusion rates of 37.5%, 20.0%, and 40.0%, respectively. The overall patency rates of the IAH-MHV conduits in our 18 patients were 66.7% at 1 month, 38.9% at 3 months, and 33.3% at 1 year. @*Conclusion@#Our refined MHV reconstruction using an IAH improved short-term MHV conduit patency, but did not effectively prevent early conduit occlusion, particularly with a small- or medium-sized IAH. Individualized reconstruction designs during LDLT operation are needed when an IAH is used for a modified right liver graft.

Is renal replacement therapy necessary in deceased donor liver transplantation candidates with hepatorenal syndrome?: a 2-year experience at a high-volume center

PURPOSE: Hepatorenal syndrome (HRS) is a fatal complication in patients with end-stage liver disease awaiting liver transplantation (LT). HRS often develops in patients with high model for end-stage liver disease (MELD) score. This study investigated the outcomes of peritransplant management of HRS in a high-volume LT center in Korea for 2 years.METHODS: A total of 157 recipients that deceased donor liver transplantation (DDLT) from January 2017 to December 2018 were included. In-hospital mortality (IHM) was analyzed in relation to pre- and posttransplant application of renal replacement therapy (RRT).RESULTS: Primary diagnoses for DDLT were alcoholic liver disease (n = 61), HBV-associated liver cirrhosis (n = 48), retransplantation for chronic graft failure (n = 24), and others (n = 24). Mean MELD score was 34.6 ± 6.2 with 72 patients at Korean Network for Organ Sharing MELD status 2 (45.9%), 43 at status 3 (27.4%), 36 at status 4 (22.9%), and 6 at status 5 (3.8%). Pretransplant RRT was performed in 16 patients (10.2%) that did not show IHM. Posttransplant RRT was performed in 69 patients (44.0%), for whom IHM incidence was 15.9%. In 53 patients that had undergone de novo posttransplant RRT, IHM incidence increased to 20.8%. IHM in the 88 patients not requiring RRT was 2.3%.CONCLUSION: The majority of adult DDLT recipients in Korean MELD score-based allocation system have very high MELD scores, which is often associated with HRS. Pretransplant RRT appears to improve posttransplant survival outcomes. We thereby recommend that, if indicated, pretransplant RRT be performed while awaiting DDLT.

Pretransplant Hepatic Malignancy Increases Risk of De Novo Malignancy after Liver Transplantation

BACKGROUND@#Hepatocellular carcinoma (HCC) recurrence and development of de novo malignancy (DNM) after liver transplantation (LT) are the major causes of late recipient death.@*METHODS@#We analyzed the incidence of extrahepatic DNM following living donor LT according to the status of pretransplant hepatic malignancy. We selected 2,076 adult patients who underwent primary LDLT during 7 years from January 2010 to December 2016.@*RESULTS@#The pretransplant hepatic malignancy group (n = 1,012) showed 45 cases (4.4%) of the following extrahepatic DNMs: posttransplant lymphoproliferative disease (PTLD) in 10; lung cancer in 10; stomach cancer in 6; colorectal cancer in 5; urinary bladder cancer in 3; and other cancers in 11. The pretransplant no hepatic malignancy group (n = 1,064) showed 25 cases (2.3%) of the following extrahepatic DNMs: colorectal cancer in 3; stomach cancer in 3; leukemia in 3; lung cancer in 3; PTLD in 2; prostate cancer in 2; and other cancers in 9. Incidences of extrahepatic DNM in the pretransplant hepatic malignancy and no hepatic malignancy groups were as follows: 1.1% and 0.5% at 1 year, 3.2% and 2.0% at 3 years, 4.6% and 2.5% at 5 years, and 5.4% and 2.8% at 8 years, respectively (P = 0.006). Their overall patient survival rates were as follows: 97.3% and 97.2% at 1 year, 91.6% and 95.9% at 3 years, 89.8% and 95.4% at 5 years, and 89.2% and 95.4% at 8 years, respectively (P < 0.001). Pretransplant hepatic malignancy was the only significant risk factor for posttransplant extrahepatic DNM.@*CONCLUSION@#Our results suggest that patients who had pretransplant hepatic malignancy be followed up more strictly because they have a potential risk of primary hepatic malignancy recurrence as well as a higher risk of extrahepatic DNM than patients without pretransplant hepatic malignancy.

Validation of prognostic impact of ADV score for resection of hepatocellular carcinoma: analysis using Korea Liver Cancer Registry Database

Purpose@#We aimed to validate the prognostic predictive power of ADV score (α-FP-des-γ-carboxyprothrombin [DCP]-tumor volume [TV] score, calculated as α-FP [ng/mL] × DCP [mAU/mL] × TV [mL] and expressed in log10) for predicting patient survival after resection of hepatocellular carcinoma (HCC). @*Methods@#This study included 1,390 patients with HCC registered in the Korea Liver Cancer Registry. Patients underwent hepatic resection between 2008 and 2012 and were followed up until December 2016. They were divided into 4 groups according to the number of tumors and preoperative treatment. @*Results@#There was no significant correlation among α-FP, DCP, and TV values (r2 ≤ 0.04, P < 0.001). In group 1 with single treatment-naive tumor (n = 1,154), patient stratification with postoperative ADV 1log-interval and cutoffs of 5log, 7log, and 10log showed great prognostic contrast (P < 0.001). In group 2 with multiple treatment-naive tumors (n = 170), patient stratification with postoperative ADV 1log-interval and above-mentioned 3 cutoffs also showed great prognostic contrast (P < 0.001). In group 3 (n = 50) and group 4 (n = 16) with preoperative-treated tumors, patient stratification with postoperative ADV 1log-interval and above-mentioned 3 cutoffs showed noticeable prognostic contrast (P ≤ 0.031). Preoperative ADV score based on preoperative findings also showed great prognostic contrast in 1,106 patients preoperatively diagnosed as having single treatment-naive tumor (P < 0.001). Confining patients to tumor-node-metastasis stages I and II (n = 1,072) as well as Barcelona Clinic Liver Cancer stage 0 and A (n = 862), postoperative ADV cutoffs showed further prognostic stratification. @*Conclusion@#This validation study strongly suggests that ADV score is an integrated surrogate marker for postresection prognosis in patients with HCC.

Pretransplant Hepatic Malignancy Increases Risk of De Novo Malignancy after Liver Transplantation

BACKGROUND@#Hepatocellular carcinoma (HCC) recurrence and development of de novo malignancy (DNM) after liver transplantation (LT) are the major causes of late recipient death.@*METHODS@#We analyzed the incidence of extrahepatic DNM following living donor LT according to the status of pretransplant hepatic malignancy. We selected 2,076 adult patients who underwent primary LDLT during 7 years from January 2010 to December 2016.@*RESULTS@#The pretransplant hepatic malignancy group (n = 1,012) showed 45 cases (4.4%) of the following extrahepatic DNMs: posttransplant lymphoproliferative disease (PTLD) in 10; lung cancer in 10; stomach cancer in 6; colorectal cancer in 5; urinary bladder cancer in 3; and other cancers in 11. The pretransplant no hepatic malignancy group (n = 1,064) showed 25 cases (2.3%) of the following extrahepatic DNMs: colorectal cancer in 3; stomach cancer in 3; leukemia in 3; lung cancer in 3; PTLD in 2; prostate cancer in 2; and other cancers in 9. Incidences of extrahepatic DNM in the pretransplant hepatic malignancy and no hepatic malignancy groups were as follows: 1.1% and 0.5% at 1 year, 3.2% and 2.0% at 3 years, 4.6% and 2.5% at 5 years, and 5.4% and 2.8% at 8 years, respectively (P = 0.006). Their overall patient survival rates were as follows: 97.3% and 97.2% at 1 year, 91.6% and 95.9% at 3 years, 89.8% and 95.4% at 5 years, and 89.2% and 95.4% at 8 years, respectively (P < 0.001). Pretransplant hepatic malignancy was the only significant risk factor for posttransplant extrahepatic DNM.@*CONCLUSION@#Our results suggest that patients who had pretransplant hepatic malignancy be followed up more strictly because they have a potential risk of primary hepatic malignancy recurrence as well as a higher risk of extrahepatic DNM than patients without pretransplant hepatic malignancy.

Validation of prognostic impact of ADV score for resection of hepatocellular carcinoma: analysis using Korea Liver Cancer Registry Database

Purpose@#We aimed to validate the prognostic predictive power of ADV score (α-FP-des-γ-carboxyprothrombin [DCP]-tumor volume [TV] score, calculated as α-FP [ng/mL] × DCP [mAU/mL] × TV [mL] and expressed in log10) for predicting patient survival after resection of hepatocellular carcinoma (HCC). @*Methods@#This study included 1,390 patients with HCC registered in the Korea Liver Cancer Registry. Patients underwent hepatic resection between 2008 and 2012 and were followed up until December 2016. They were divided into 4 groups according to the number of tumors and preoperative treatment. @*Results@#There was no significant correlation among α-FP, DCP, and TV values (r2 ≤ 0.04, P < 0.001). In group 1 with single treatment-naive tumor (n = 1,154), patient stratification with postoperative ADV 1log-interval and cutoffs of 5log, 7log, and 10log showed great prognostic contrast (P < 0.001). In group 2 with multiple treatment-naive tumors (n = 170), patient stratification with postoperative ADV 1log-interval and above-mentioned 3 cutoffs also showed great prognostic contrast (P < 0.001). In group 3 (n = 50) and group 4 (n = 16) with preoperative-treated tumors, patient stratification with postoperative ADV 1log-interval and above-mentioned 3 cutoffs showed noticeable prognostic contrast (P ≤ 0.031). Preoperative ADV score based on preoperative findings also showed great prognostic contrast in 1,106 patients preoperatively diagnosed as having single treatment-naive tumor (P < 0.001). Confining patients to tumor-node-metastasis stages I and II (n = 1,072) as well as Barcelona Clinic Liver Cancer stage 0 and A (n = 862), postoperative ADV cutoffs showed further prognostic stratification. @*Conclusion@#This validation study strongly suggests that ADV score is an integrated surrogate marker for postresection prognosis in patients with HCC.

Determination of Hepatitis B Immunoglobulin Infusion Interval Using Pharmacokinetic Half-life Simulation for Posttransplant Hepatitis B Prophylaxis

BACKGROUND: Prophylaxis for hepatitis B virus (HBV) recurrence is essential after liver transplantation (LT) in HBV-associated recipients. This study established an individualized HBV prophylaxis protocol, through optimization of hepatitis B immunoglobulin (HBIG) administration, with application of simulative half-life (SHL). METHODS: This study involved five parts: Part 1 developed the SHL estimation method with 20 patients; Parts 2 and 3 assessed the SHL variability and developed a simulation model to apply SHL in 100 patients; Part 4 validated the simulation model in 114 patients, and Part 5 was a cross-sectional study on the current status of HBIG infusion intervals in 660 patients. RESULTS: In Part 1, infusion of 10,000 IU HBIG induced add-on rise hepatitis B surface antibody (anti-HBs) titer of 5,252.5 ± 873.7 IU/L, which was 4.4% lower than actual measurement. Mean SHL of 20.0 ± 3.7 days was 2.2% longer than actual measurement. In Part 2, the medians of the intra- and inter-individual coefficient of variation in SHL were 13.5% and 18.5%, respectively. Pretransplant HBV DNA load and posttransplant antiviral therapy did not affect SHL. In Part 3, a simulation model was developed to determine the interval of HBIG infusion, by using SHL. In Part 4, all 114 patients were successfully managed with regular HBIG infusion intervals of ≥ 8 weeks, and the interval was prolonged to ≥ 12 weeks in 89.4%, with a target trough anti-HBs titer ≥ 200 IU/L. In Part 5, 47.4% of our patients received HBIG excessively, at a target trough titer of 500 IU/L. CONCLUSION: SHL estimation using only clinically available parameters seems to be reliably accurate when compared with actual measurements. We believe that SHL estimation is helpful to establish a personalized HBV prophylaxis protocol for optimizing HBIG administration.

Central Line-Associated Bloodstream Infection Prevention by Central Venous Catheter Management Staff in the Surgical Intensive Care Unit

PURPOSE: Patients in the intensive care unit (ICU) are more susceptible to nosocomial infections, including central line-associated bloodstream infection (CLABSI), surgical site infection, urinary tract infection or ventilator-associated pneumonia. This study is a comparative analysis of how central venous catheter (CVC) management staff affects CLABSI. METHODS: We performed a two-phase review of all patients transferred to the surgical ICU (SICU) from January 2013 to June 2014. CVC management staff was introduced in October 2013. Electronic medical records provided the data for a comparative analysis of incidence rates and risks of CLABSI, as well as the subjects' general characteristics. RESULTS: This study included 248 patients before the introduction of a CVC management staff member and 196 patients after the introduction. General patient characteristics before and after the CVC management staff was in place did not differ significantly. The CLABSI rate decreased by 4.61 cases/1,000 device days after the introduction (6.26 vs. 1.65; odds ratio, 4.47; 95% confidence interval, 1.39~14.37; p=0.009). However, the mortality rate and length of ICU stay did not change after CVC management staff was in place (12.9% vs. 10.7%, p=0.480; 16.00±24.89 vs. 15.87±18.80, p=0.954; respectively). CONCLUSION: In this study, the introduction of CVC management staff effectively reduced CLABSI rates in current ICU system.

A Case of Sarcomatoid Hepatocellular Carcinoma in a Young Female without Risk Factor / 대한소화기학회지

A previously healthy 22-year-old woman was admitted with a complaint of right upper quadrant abdominal pain for 2 weeks. Her past history was not remarkable. On admission, HBsAg and anti-HCV were negative and alpha-FP was within normal range. Abdominal sonography and CT showed a mass in liver measuring 10 11 cm with features of central necrosis and hemorrhage. On 6th hospital day, hemoperitoneum developed suddenly. She underwent emergency laparotomy and trisegmentectomy. Intraoperative finding revealed a hemoperitoneum with a tumor filled with liquefied necrotic tissues. Microscopically, the tumor was mostly composed of pleomorphic spindle cells with abundant anastomosing vascular channels and partly composed of tumor cells with trabecular arrangement. On immunohistochemical staining, tumor cells reacted with cytokeratin and vimentin, while CD34 and hepatocyte staining revealed negative. She died 2 months after the operation. We report a case of rapidly deteriorated primary sarcomatoid hepatocellular carcinoma in a young female without any risk factor.

Influence of tungsten carbide/carbon coating on the preload of implant abutment screws / 대한치과보철학회지

STATEMENT OF PROBLEM: In order to increase preload with reducing the friction coefficient, abutment screws coated with pure gold and Teflon as dry lubricant coatings have been introduced. But the reported data indicate that if screw repeated tightening and loosening cycle, an efficiency of increasing preload was decreased by screw surface wearing off. PURPOSE: This study was to evaluate the influence of tungsten carbide/carbon coating, which has superior hardness and frictional wear resistance, on the preload of abutment screws and the stability of coating surface after repeated closures. MATERIAL AND METHOD: The rotational values of abutment screws and the compressive forces between abutment and fixture were measured in implant systems with three different joint connections, one external butt joint and two internal cones. Moreover, the stability and the alteration of coating surface were examined by comparison of the compressive force and the removable torque values during 10 consecutive trials, observation with scanning electron microscope and analyzed the elemental composition with energy dispersive x-ray spectroscopy. RESULTS AND CONCLUSION: 1. Application of coating resulted in significant increase of compressive force in all implant systems(P.05). 3. Removable torque values were greater with non-coated screw than that with coated screw (P.05). 5. After repeated trials, the surface layer of coated screw was maintained relatively well. However, surface wearing and irregular titanium fragments were found in non-coated screw.