Initial Experience with Left Bundle Branch Area Pacing in Patients with Atrioventricular Block and Impaired LV Function / 전남의대학술지

Chronic right ventricular (RV) pacing can exacerbate heart failure in patients with a low left ventricular ejection fraction (LVEF). Left bundle branch area pacing (LBBAP) has emerged as a novel physiological pacing technique; however, information remains limited on its use among patients with a low EF. This study investigated the safety and short-term clinical outcomes of LBBAP among patients with impaired left ventricular (LV) function. This retrospective analysis of pacemakers at Chosun University Hospital, South Korea, included all patients with impaired LV function (EF＜50%) who underwent pacemaker implantation for atrioventricular blockage from 2019-2022. Clinical characteristics, 12-lead electrocardiography findings, echocardiography findings, and laboratory parameters were evaluated. Composite outcomes were defined as all-cause mortality, cardiac death, and hospitalization due to heart failure during the 6-month follow-up. Altogether 57 patients (25 men; mean age, 77.4±10.8 y; LVEF, 41.5±3.8%) were divided into LBBAP (n=16), biventricular pacing (BVP; n=16), and conventional RV pacing (RVP; n=25) groups. In the LBBAP group, the mean paced QRS duration (pQRSd) was narrower (119.5±14.7 vs. 140.2±14.3 vs. 163.2±13.9; p＜0.001) and cardiac troponin I level was elevated post-pacing (1.14±1.29 vs. 0.20±0.29 vs.0.24±0.51, p=0.001). Lead parameters were stable. One patient was hospitalized, and four died (one patient each from heart failure admission, myocardial infarction, unexplained death, and pneumonia in RVP vs. one from intracerebral hemorrhage in BVP) during the follow-up period. In conclusion, LBBAP is feasible in patients with impaired LV function without acute or significant complications and provides a remarkably narrower pQRSd with a stable pacing threshold.

A case of sinus arrest in atrial fibrillation with pulmonary embolism after flecainide ingestion

A 76-year-old female visited the emergency department with complaining of dizziness and syncope. She had a history of paroxysmal atrial fibrillation (AF) and had been prescribed flecainide 50 mg and apixaban 5 mg 12-hourly in another hospital 1 day before the presentation. Upon admission, her electrocardiogram showed profound bradycardia and extremely long sinus arrest, which required temporary cardiac pacing. Within 24 hours, her intrinsic rhythm was restored, and the temporary pacemaker was removed. Transthoracic and transesophageal echocardiography revealed no structural heart disease or thrombus in the left atrial appendage. Cardiac computed tomography showed no coronary artery stenosis, but a pulmonary thrombus in the right pulmonary artery. She underwent an electrophysiology study, and four pulmonary vein (PV) isolations were attempted to treat the paroxysmal AF. A bidirectional PV conduction block was acquired in all PVs despite spontaneous dissociation of PV potential in the right PV. Programmed stimulation following ablation resulted in sinus node dysfunction. After the procedure, the patient did not complain of dizziness and syncope for 72 hours of telemetry monitoring. She was discharged with anticoagulant and did not show any further symptoms for 6 months. Flecainide acetate is a class Ic antiarrhythmics, and its clinical efficacy has been confirmed in several clinical trials. However, it can unmask sinus node dysfunction in asymptomatic patients with paroxysmal AF. Clinicians should screen candidates for sinus nodal diseases when prescribing flecainide.

Impact of diastolic dysfunction in patients with preserved ejection fraction undergoing permanent cardiac pacemaker placement

Background@#Chronic right-ventricular (RV) pacing can exacerbate heart failure in patients with a low ejection fraction (EF). There is little information on the effects of diastolic dysfunction (DD) in patients with preserved EF undergoing permanent pacemaker (PPM) placement. We aimed to investigate the clinical outcomes in these patients. @*Methods@#This multicenter, retrospective analysis of PPM use in Chonnam, South Korea, included all patients with preserved EF undergoing transvenous PPM implantation for atrioventricular blockage from 2017 to 2019. Patients were divided into two groups according to DD, which were assessed by including mitral flow velocities (E′ velocity, E/E′ ratio), peak velocity of the tricuspid regurgitant, and left atrial maximum volume index. Composite outcomes were defined as (1) cardiovascular death, and (2) hospitalization by heart failure during the follow-up period. @*Results@#One hundred sixty-seven patients (66 men; overall mean age, 75.3 ± 11.9 years) were divided into two groups: 125 normal versus 42 DD. Compared with normal subjects, the DD group included older patients (mean age, 79.1 ± 9.9 vs. 74.0 ± 12.3; p = 0.016), and had longer paced QTc interval (pQTc, 168.5 ± 20.1 vs. 159.1 ± 16.3  ms; p < 0.001). Fifteen patients were hospitalized and two died. In a Cox proportional regression analysis, DD (hazard ratio [HR], 7.343; 95% confidence interval [CI], 2.035–26.494; p = 0.002) and pQRSd (HR, 1.046; 95% CI, 1.004–1.091; p = 0.033) were independent predictors of composite outcomes. @*Conclusion@#In patients with DD, RV pacing raised the risk of pacing-induced heart failure despite preserved leftventricular function. Thus, patients with DD should be monitored intensively.

The current status and outcomes of in-hospital P2Y12 receptor inhibitor switching in Korean patients with acute myocardial infarction

Background/Aims@#While switching strategies of P2Y12 receptor inhibitors (RIs) have sometimes been used in acute myocardial infarction (AMI) patients, the current status of in-hospital P2Y12RI switching remains unknown. @*Methods@#Overall, 8,476 AMI patients who underwent successful revascularization from Korea Acute Myocardial Infarction Registry-National Institute of Health (KAMIR-NIH) were divided according to in-hospital P2Y12RI strategies, and net adverse cardiovascular events (NACEs), defined as a composite of cardiac death, non-fatal myocardial infarction (MI), stroke, or thrombolysis in myocardial infarction (TIMI) major bleeding during hospitalization were compared. @*Results@#Patients with in-hospital P2Y12RI switching accounted for 16.5%, of which 867 patients were switched from clopidogrel to potent P2Y12RI (C-P) and 532 patients from potent P2Y12RI to clopidogrel (P-C). There were no differences in NACEs among the unchanged clopidogrel, the unchanged potent P2Y12RIs, and the P2Y12RI switching groups. However, compared to the unchanged clopidogrel group, the C-P group had a higher incidence of non-fatal MI, and the P-C group had a higher incidence of TIMI major bleeding. In clinical events of in-hospital P2Y12RI switching, 90.9% of non-fatal MI occurred during pre-switching clopidogrel administration, 60.7% of TIMI major bleeding was related to pre-switching P2Y12RIs, and 71.4% of TIMI major bleeding was related to potent P2Y12RIs. Only 21.6% of the P2Y12RI switching group switched to P2Y12RIs after a loading dose (LD); however, there were no differences in clinical events between patients with and without LD. @*Conclusions@#In-hospital P2Y12RI switching occurred occasionally, but had relatively similar clinical outcomes compared to unchanged P2Y12RIs in Korean AMI patients. Non-fatal MI and bleeding appeared to be mainly related to pre-switching P2Y12RIs.

Suppressive Impact of Ginsenoside-Rg2 on Catecholamine Secretion from the Rat Adrenal Medulla

This study was designed to characterize the effect of ginsenoside-Rg2 (Rg2), one of panaxatriol saponins isolated from Korean ginseng root, on the release of catecholamines (CA) in the perfused model of the rat adrenal medulla, and also to establish its mechanism of action. Rg2 (3~30 µM), administered into an adrenal vein for 90 min, depressed acetylcholine (ACh)-induced CA secretion in a dose- and time-dependent manner.Rg2 also time-dependently inhibited the CA secretion induced by 3-(m-chloro-phenyl-carbamoyl-oxy)-2-butynyltrimethyl ammonium chloride (McN-A-343), 1.1-dimethyl-4-phenyl piperazinium iodide (DMPP), and angiotensin II (Ang II). Also, during perfusion of Rg2, the CA secretion induced by high K+ , veratridine, cyclopiazonic acid, methyl-1,4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluoro-methyl-phenyl)-pyridine-5-carboxylate (Bay-K-8644) depressed, respectively. In the simultaneous presence of Rg2 and Nω -nitro-L-arginine methyl ester hydrochloride (L-NAME), the CA secretion induced by ACh, Ang II, Bay-K-8644 and veratridine was restored nearly to the extent of their corresponding control level, respectively, compared to those of inhibitory effects of Rg2-treatment alone. Virtually, NO release in adrenal medulla following perfusion of Rg2 was significantly enhanced in comparison to the corresponding spontaneous release. Also, in the coexistence of Rg2 and fimasartan, ACh-induced CA secretion was markedly diminished compared to the inhibitory effect of fimasartantreated alone. Collectively, these results demonstrated that Rg2 suppressed the CA secretion induced by activation of cholinergic as well as angiotensinergic receptors from the perfused model of the rat adrenal gland.This Rg2-induced inhibitory effect seems to be exerted by reducing both influx of Na + and Ca 2+ through their ionic channels into the adrenomedullary cells as well as by suppressing Ca 2+ release from the cytoplasmic calcium store, at least through the elevated NO release by activation of NO synthase, which is associated to the blockade of neuronal cholinergic and AT 1 -receptors. Based on these results, the ingestion of Rg2 may be helpful to alleviate or prevent the cardiovascular diseases, via reduction of CA release in adrenal medulla and consequent decreased CA level in circulation.

Suppressive Impact of Ginsenoside-Rg2 on Catecholamine Secretion from the Rat Adrenal Medulla

This study was designed to characterize the effect of ginsenoside-Rg2 (Rg2), one of panaxatriol saponins isolated from Korean ginseng root, on the release of catecholamines (CA) in the perfused model of the rat adrenal medulla, and also to establish its mechanism of action. Rg2 (3~30 µM), administered into an adrenal vein for 90 min, depressed acetylcholine (ACh)-induced CA secretion in a dose- and time-dependent manner.Rg2 also time-dependently inhibited the CA secretion induced by 3-(m-chloro-phenyl-carbamoyl-oxy)-2-butynyltrimethyl ammonium chloride (McN-A-343), 1.1-dimethyl-4-phenyl piperazinium iodide (DMPP), and angiotensin II (Ang II). Also, during perfusion of Rg2, the CA secretion induced by high K+ , veratridine, cyclopiazonic acid, methyl-1,4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluoro-methyl-phenyl)-pyridine-5-carboxylate (Bay-K-8644) depressed, respectively. In the simultaneous presence of Rg2 and Nω -nitro-L-arginine methyl ester hydrochloride (L-NAME), the CA secretion induced by ACh, Ang II, Bay-K-8644 and veratridine was restored nearly to the extent of their corresponding control level, respectively, compared to those of inhibitory effects of Rg2-treatment alone. Virtually, NO release in adrenal medulla following perfusion of Rg2 was significantly enhanced in comparison to the corresponding spontaneous release. Also, in the coexistence of Rg2 and fimasartan, ACh-induced CA secretion was markedly diminished compared to the inhibitory effect of fimasartantreated alone. Collectively, these results demonstrated that Rg2 suppressed the CA secretion induced by activation of cholinergic as well as angiotensinergic receptors from the perfused model of the rat adrenal gland.This Rg2-induced inhibitory effect seems to be exerted by reducing both influx of Na + and Ca 2+ through their ionic channels into the adrenomedullary cells as well as by suppressing Ca 2+ release from the cytoplasmic calcium store, at least through the elevated NO release by activation of NO synthase, which is associated to the blockade of neuronal cholinergic and AT 1 -receptors. Based on these results, the ingestion of Rg2 may be helpful to alleviate or prevent the cardiovascular diseases, via reduction of CA release in adrenal medulla and consequent decreased CA level in circulation.

Clinical Outcomes of Ticagrelor in Korean Patients with Acute Myocardial Infarction without High Bleeding Risk

Background@#Although ticagrelor is known to increase the bleeding risk compared to clopidogrel in East Asian patients, its clinical benefits in patients with acute myocardial infarction (AMI) without high bleeding risk (HBR) remains unknown. @*Methods@#A total of 7,348 patients who underwent successful percutaneous coronary intervention (PCI) from the Korea Acute Myocardial Infarction Registry-National Institute of Health (KAMIR-NIH), between November 2011 and December 2015, were divided into two groups according to the Academic Research Consortium for HBR criteria (KAMIR-HBR, 2,469 patients; KAMIR-non HBR, 4,879 patients). We compared in-hospital major adverse cardiovascular events (MACEs, defined as a composite of cardiac death, non-fatal myocardial infarction, or stroke), and the thrombolysis in myocardial infarction (TIMI) major bleeding between ticagrelor and clopidogrel in the KAMIR-HBR and the KAMIR-non HBR groups, respectively. @*Results@#After propensity score matching, ticagrelor had a higher incidence of in-hospital TIMI major bleeding than clopidogrel in all patients (odds ratio [OR], 1.683; 95% confidence interval [CI], 1.010–2.805; P = 0.046) and the KAMIR-HBR group (OR, 3.460; 95% CI, 1.374–8.714; P = 0.008). However, there was no significant difference in in-hospital TIMI major bleeding between ticagrelor and clopidogrel in the KAMIR-non HBR group (OR, 1.436; 95% CI, 0.722–2.855; P = 0.303). No differences were observed in the cumulative incidences of in-hospital and 6-month MACEs between ticagrelor and clopidogrel in both groups. @*Conclusions@#The bleeding risk of ticagrelor was attenuated in Korean patients with AMI without HBR. Appropriate patient selection could reduce in-hospital bleeding complications associated with ticagrelor in Korean patients with AMI who underwent successful PCI.

Effect of Renal Denervation on Suppression of PVC and QT Prolongation in a Porcine Model of Acute Myocardial Infarction

BACKGROUND AND OBJECTIVES@#Antiarrhythmic effect of renal denervation (RDN) after acute myocardial infarction (AMI) remains unclear. The goal of this study was to evaluate the effect of RDN on ventricular arrhythmia (VA) after AMI in a porcine model.@*METHODS@#Twenty pigs were randomly divided into 2 groups based on RDN (RDN, n=10; Sham, n=10). After implanting a loop recorder, AMI was induced by occlusion of the middle left anterior descending coronary artery. Catheter-based RDN was performed for each renal artery immediately after creating AMI. Sham procedure used the same method, but a radiofrequency current was not delivered. Electrocardiography was monitored for 1 hour to observe VA. One week later, the animals were euthanized and the loop recorder data were analyzed.@*RESULTS@#Ventricular fibrillation event rate and the interval from AMI creation to first VA in acute phase were not different between the 2 groups. However, the incidence of premature ventricular complex (PVC) was lower in the RDN than in the Sham. Additionally, RDN inhibited prolongation of the corrected QT (QTc) interval after AMI. The frequency of non-sustained or sustained ventricular tachycardia, arrhythmic death was lower in the RDN group in the early period.@*CONCLUSIONS@#RDN reduced the incidence of PVC, inhibited prolongation of the QTc interval, and reduced VA in the early period following an AMI. These results suggest that RDN might be a therapeutic option in patients with electrical instability after AMI.

Effect of Renal Denervation on Suppression of PVC and QT Prolongation in a Porcine Model of Acute Myocardial Infarction

BACKGROUND AND OBJECTIVES: Antiarrhythmic effect of renal denervation (RDN) after acute myocardial infarction (AMI) remains unclear. The goal of this study was to evaluate the effect of RDN on ventricular arrhythmia (VA) after AMI in a porcine model.METHODS: Twenty pigs were randomly divided into 2 groups based on RDN (RDN, n=10; Sham, n=10). After implanting a loop recorder, AMI was induced by occlusion of the middle left anterior descending coronary artery. Catheter-based RDN was performed for each renal artery immediately after creating AMI. Sham procedure used the same method, but a radiofrequency current was not delivered. Electrocardiography was monitored for 1 hour to observe VA. One week later, the animals were euthanized and the loop recorder data were analyzed.RESULTS: Ventricular fibrillation event rate and the interval from AMI creation to first VA in acute phase were not different between the 2 groups. However, the incidence of premature ventricular complex (PVC) was lower in the RDN than in the Sham. Additionally, RDN inhibited prolongation of the corrected QT (QTc) interval after AMI. The frequency of non-sustained or sustained ventricular tachycardia, arrhythmic death was lower in the RDN group in the early period.CONCLUSIONS: RDN reduced the incidence of PVC, inhibited prolongation of the QTc interval, and reduced VA in the early period following an AMI. These results suggest that RDN might be a therapeutic option in patients with electrical instability after AMI.

Dendropanax morbifera Extract Inhibits Intimal Hyperplasia in Balloon-Injured Rat Carotid Arteries by Modulating Phenotypic Changes in Vascular Smooth Muscle Cells

The plant Dendropanax morbifera Léveille is effective folk medicines for the treatment of several conditions, such as infectious diseases, skin diseases, and other illnesses. Although the inhibitory effects of D. morbifera on the proliferation and migration of vascular smooth muscle cells (VSMCs) have been shown in our previous study, its effects in vivo remain to be elucidated. In this study, we aimed to investigate the protective effects of the extracts from D. morbifera (EDM) on neointimal hyperplasia of rat carotid artery and explore the underlying mechanisms. We observed that the ratio of intima to media thickness (I/M) was significantly decreased in the EDM-treated groups by ~80% compared to that of the control. The expression of Ki-67 and proliferating cell nuclear antigen was decreased by ~70% in the EDM-treated groups compared to that of the control. In addition, matrix metalloproteinase (MMP)2 and MMP9 significantly reduced in the neointimal layer of the EDM-treated groups. Moreover, the decreased levels of contractile phenotypic markers of VSMCs, such as α-smooth muscle actin, myocardin, and smooth muscle-myosin heavy chain, were successfully restored by EDM treatment. Furthermore, the levels of synthetic phenotypic markers, cellular retinal binding protein 1 and connexin 43 were also restored to normal levels. These results suggest that EDM inhibits vascular neointimal hyperplasia induced by balloon injury in rats via phenotypic modulation of VSMCs. Therefore, EDM may be a potential drug candidate for the prevention of restenosis.

Effectiveness and Safety of Zotarolimus-Eluting Stent (Resolute™ Integrity) in Patients with Diffuse Long Coronary Artery Disease

BACKGROUND AND OBJECTIVES: Diffuse long coronary artery disease (DLCAD) still has unfavorable clinical outcomes after successful percutaneous coronary intervention (PCI). Therefore, we aimed to evaluate the effectiveness and safety of Resolute™ zotarolimus-eluting stent (R-ZES; Resolute™ Integrity) for patients with DLCAD. METHODS: From December 2011 to December 2014, 1,011 patients who underwent PCI using R-ZES for CAD with longer than 25 mm lesion were prospectively enrolled from 21 hospitals in Korea. We assessed the clinical outcome of major adverse cardiac events (MACE) defined as the composite of cardiac death, non-fatal myocardial infarction (MI), and clinically-driven target vessel revascularization at 12 months. RESULTS: Mean age was 63.8±10.8 years, 701 (69.3%) patients were male, 572 (87.0%) patients had hypertension, 339 (33.8%) patients had diabetes, 549 (54.3%) patients diagnosed with acute MI and 545 (53.9%) patients had multi-vessel disease (MVD). A total of 1,697 stents were implanted into a total of 1,472 lesions. The mean diameter was 3.07±0.38 mm and the length was 28.27±6.97 mm. Multiple overlapping stents were performed in 205 (13.8%) lesions. A 12-month clinical follow-up was available in 1,004 patients (99.3%). The incidences of MACE and definite stent thrombosis at 12-month were 3.0% and 0.3% respectively. On multivariate Cox-regression analysis, multiple overlapping stents implantation, previous congestive heart failure, MVD, and age ≥75 years were independent predictors of one-year MACE. CONCLUSIONS: Our study shows that R-ZES has an excellent 1-year clinical outcome in Korean patients with DLCAD.

Effectiveness and Safety of Zotarolimus-Eluting Stent (Resoluteâ„¢ Integrity) in Patients with Diffuse Long Coronary Artery Disease

BACKGROUND AND OBJECTIVES@#Diffuse long coronary artery disease (DLCAD) still has unfavorable clinical outcomes after successful percutaneous coronary intervention (PCI). Therefore, we aimed to evaluate the effectiveness and safety of Resolute™ zotarolimus-eluting stent (R-ZES; Resolute™ Integrity) for patients with DLCAD.@*METHODS@#From December 2011 to December 2014, 1,011 patients who underwent PCI using R-ZES for CAD with longer than 25 mm lesion were prospectively enrolled from 21 hospitals in Korea. We assessed the clinical outcome of major adverse cardiac events (MACE) defined as the composite of cardiac death, non-fatal myocardial infarction (MI), and clinically-driven target vessel revascularization at 12 months.@*RESULTS@#Mean age was 63.8±10.8 years, 701 (69.3%) patients were male, 572 (87.0%) patients had hypertension, 339 (33.8%) patients had diabetes, 549 (54.3%) patients diagnosed with acute MI and 545 (53.9%) patients had multi-vessel disease (MVD). A total of 1,697 stents were implanted into a total of 1,472 lesions. The mean diameter was 3.07±0.38 mm and the length was 28.27±6.97 mm. Multiple overlapping stents were performed in 205 (13.8%) lesions. A 12-month clinical follow-up was available in 1,004 patients (99.3%). The incidences of MACE and definite stent thrombosis at 12-month were 3.0% and 0.3% respectively. On multivariate Cox-regression analysis, multiple overlapping stents implantation, previous congestive heart failure, MVD, and age ≥75 years were independent predictors of one-year MACE.@*CONCLUSIONS@#Our study shows that R-ZES has an excellent 1-year clinical outcome in Korean patients with DLCAD.

Massive Thoracoabdominal Aortic Thrombosis in a Patient with Iatrogenic Cushing Syndrome

Massive thoracoabdominal aortic thrombosis is a rare finding in patients with iatrogenic Cushing syndrome in the absence of any coagulation abnormality. It frequently represents an urgent surgical situation. We report the case of an 82-year-old woman with massive aortic thrombosis secondary to iatrogenic Cushing syndrome. A follow-up computed tomography scan showed a decreased amount of thrombus in the aorta after anticoagulation therapy alone.

A Case of Sweet's Syndrome Presenting as Subdermal Cystic Lesions and Arthritis / 대한내과학회지

Sweet's syndrome is characterized by a combination of clinical and pathologic findings including fever, neutrophilia, tender erythematous skin lesions, and a diffuse infiltration of mature neutrophils in the upper dermis. Numerous diseases and clinical manifestations have been associated with the disease; however, Sweet's syndrome associated with subdermal cystic skin lesions and arthritis is rare. A 71-year-old female patient presented with fever, erythematous plaques, multiple hypoglossal ulcers, and arthritis in both ankles. The skin lesions were variously sized areas of erythematous swelling on the forehead, back, and left shoulder. Musculoskeletal sonography revealed hypervascularity and a subdermal cyst in the erythematous plaque on her back. The results of a skin biopsy indicated the presence of mature neutrophilic infiltration in the dermis and thus led to the diagnosis of Sweet's syndrome. We herein present an unusual case of Sweet's syndrome presenting as erythematous subdermal cystic lesions, multiple hypoglossal ulcers, and bilateral ankle arthritis with a literature review.

Neuropsychiatric Lupus Presenting as a Thalamic Infarct in a Male Patient / 대한내과학회지

Systemic lupus erythematosus (SLE) is an autoimmune disease that can manifest systemically in many organs. It is most common in women of child-bearing age. Neuropsychiatric SLE is characterized by central nervous system (CNS) symptoms. CNS manifestations of SLE have been discovered in all parts of the brain, although thalamic infarcts associated with SLE are rare, especially in males. Here, we report a thalamic infarction in a 22-year-old male SLE patient.

Neuropsychiatric Lupus Presenting as a Thalamic Infarct in a Male Patient / 대한내과학회지

Systemic lupus erythematosus (SLE) is an autoimmune disease that can manifest systemically in many organs. It is most common in women of child-bearing age. Neuropsychiatric SLE is characterized by central nervous system (CNS) symptoms. CNS manifestations of SLE have been discovered in all parts of the brain, although thalamic infarcts associated with SLE are rare, especially in males. Here, we report a thalamic infarction in a 22-year-old male SLE patient.

Effect of wetness on the enamel bonding / 대한치과보존학회지

This study evaluated the microleakage and interfacial gap between enamel and composite resin under the dry and wet condition of the enamel surface. V shaped class 5 cavities were prepared on the occlusal portion of extracted human molars. Samples were divided into three groups: D group (air dry for 10-15 s), BD group (blot dry with moist cotton pellet), and DR group (air dry for 10-15 s and rewet with Aqua-Prep F for 20 s). Cavities were filled using Aelitefil composite resin after applied One-Step. Microleakage was tested by 2% methylene blue dye solution and the data were statistically analysed by Kruskal-Wallis test and Mann-Whitney test. Also Enamel-resin interface was observed under SEM. Group BD showed statistically lower microleakage than group D (p 0.05). At the enamel-resin interface, group D showed the gap of 2 microm thickness, but group BD and DR showed close adaptation. In conclusion, the use of blot dry and rewetting agent (Aqua-Prep F) resulted in decreased microleakage and improved adhesion between enamel and resin when using One-Step.

The effect of delayed composite resin filling on microtensile bond strength / 대한치과보존학회지

The purpose of this study was to evaluate the effect of immediate or delayed composite resin filling on dentinal microtensile bond strength (microTBS) after applied the adhesive. The coronal dentin of human third molars was exposed. Single-Bond or One-Step was applied on the dentin surfaces, and composite resin were constructed immediately (group 1) or 5 min., 10 min., 15 min., 20 min. and 30 min. (groups 2-6) after an adhesive was applied. The specimens were sectioned and made bar-shaped. Each surface area of them was about 1mm2. The microTBS test was performed by EZ test. The results were analysed by One-way ANOVA and Tukey's test at 95% significance level. The results suggested that the microTBS of Single-Bond to dentin was decreased when the composite resin was constructed 20 min. and 30 min. after Single-Bond was applied. But the microTBS of One-Step was not affected by delayed composite resin filling.

Effect of rewetting agent on dentinal microtensile bond strength / 대한치과보존학회지

This study investigated that the effect of rewetting agent on dentinal microtensile bond strength (microTBS). Human molars were sectioned to expose the superficial dentin surfaces. Samples were divided into two groups according to type of adhesives-Single Bond (S) and One-Step (O)], and again subdivided into five groups by different dentin surface treatment-dry for 15s (D), blot dry (BD) or dry for 15s, and rewet with different rewetting agents [distilled water (DW), Gluma Desensitizer (GD) and Aqua-Prep (AP)] for 30s. After application of adhesive, composite resin was built up on the bonding surface. Each tooth was sectioned to obtain stick with 1 mm2 cross sectional area and the microTBS was determined by EZ test. In the S group, the mean microTBS of GD, AP and BD group was significantly higher than that of DW and D group (p < 0.05). In the O group, the mean microTBS of AP, GD, BD and DW group was significantly higher than that of D group (p < 0.05). The data suggested that Gluma Desensitizer and Aqua-Prep could be successfully used as rewetting agents, and Distilled water could be acceptable in aceton based adhesive system only.

Marginal microleakage of single step adhesives / 대한치과보존학회지

This study evaluated the marginal microleakage of five single step adhesives. Class V cavity preparations with occlusal margins in enamel and gingival margins in dentin were prepared on both buccal and lingual surfaces of extracted human molar teeth. Prepared teeth were randomly divided into five groups and restored using one of the single step adhesives and composite resins: Prompt L-Pop/Filtek Z-250 (Group 1), AQ Bond/Metafil CX (Group 2), One-Up Bond F/Palfique Toughwell (Group 3), Futurabond/Admira (Group 4), Xeno III/Spectrum TPH (Group 5). The restored teeth were thermocycled. Microleakage was assessed by dye penetration using 2% methylene blue dye solution. The teeth were bisected buccolingually and evaluated for microleakage under steromicroscope. The data were statistically analysed by Kruskal-Wallis test and Mann-Whitney tests. The results of this study were as follows; 1. Microleakage of enamel margins in group 3 was statistically higher than that in groups 1, 2, 4, 5 (p < 0.05). 2. Microleakage of dentin margins in group 1 was statistically higher than that in groups 2, 5, and that in group 3 was statistically higher than that in groups 2, 4, 5 (p < 0.05). 3. Dentin marginal microleakage was higher than enamel marginal microleakage in all experimental groups. In conclusion, Prompt L-Pop showed the least leakage at enamel margin, and AQ Bond showed at dentin margin in this study. Marginal miroleakage in dentin was higher than that in enamel.