The aim of this study was to examine that thick dentin bonding agent application or low modulus composite restoration could reduce stresses on dentin bonding agent layer. A mandibular first premolar with abfraction lesion was modeled by finite element method. The lesion was restored by different composite resins with variable dentin bonding agent thickness (50microm, 100microm, 150microm). 170N of occlusal loading was applied buccally or lingually. Von Mises stress on dentin bonding agent layer were measured. When thickness of dentin bonding agent was increased von Mises stresses at dentin bonding agent were decreased in both composites. Lower elastic modulus composite restoration showed decreased von Mises stresses. On root dentin margin more stresses were generated than enamel margin. For occlusal stress relief at dentin boning agent layer to applicate thick dentin bonding agent or to choose low elastic modulus composite is recommended.
Bicuspid ; Composite Resins ; Dental Enamel ; Dentin ; Elastic Modulus

OBJECTIVES: Supraorbital route through eyebrow incision, mini-pterional craniotomy, and midline interhemispheric route are most generally used methods for key hole surgery on anterior circulation aneurysm. Surgical route is determined according to aneurysm architecture and patient status. The approaching route can be selected according to the findings of 3-dimensional computed tomography (CT) angiography simulation. Prospective decision-making protocol, surgical technique of key hole surgery, and the results are presented in this paper. METHODS: 173 patients with anterior circulation aneurysms were treated by direct surgical neck clipping during last two years. Twenty patients of poor grade (Hunt-Hess grade IV,V) were treated by craniectomy with clipping. Decision making protocol was applied to 153 unruptured and good grade ruptured aneurysm patients. Simulation of key hole surgery was conducted by CT work station using conventional software InSpace (Siemens, Germany), and direction and shape of aneurysm was observed from the perspective of microsurgery. RESULTS: 113 ruptured and 40 unruptured aneurysms were secured through one of the three approaching routes. Supraorbital approach had been performed in 82 cases (unruptured 24, ruptured 58) while 64 cases were treated by mini-pterional craniotomy. Midline key hole surgery were carried out in seven distal anterior circulation aneurysms (DACA) using brain navigation system. After locating the aneurysm, supraorbital approach was applied to 46 cases involving anterior cerebral artery (ACA), 16 in internal carotid artery (ICA) and 20 in middle cerebral artery (MCA). Mini-pterional craniotomy was carried out in aneurysms located in ACA (9), ICA (18), and MCA (37). In most cases, the results of clipping were good. The average follow-up time was 16.7months (ranging 2 to 32months) and the results were cosmetically excellent. CONCLUSION: Simulating surgical approaches with 3-D CT angiography is a highly useful method for determining various surgical routes in anterior circulation aneurysm treatment. Therefore, minimally invasive and tailored surgical approaches are recommended since optimal route can be found through simulation. Thus, minimal invasive and tailored surgical approach is available through this method. These procedures have clear advantages; shorter surgical time and hospital stay, less operative trauma, reduced costs and less pain, and better cosmetic outcomes compared to standard craniotomy. Optimal surgical results are expected from minimally invasive and tailored surgical craniotomy.
Aneurysm ; Aneurysm, Ruptured ; Angiography ; Anterior Cerebral Artery ; Brain ; Carotid Artery, Internal ; Cosmetics ; Craniotomy ; Decision Making ; Eyebrows ; Follow-Up Studies ; Humans ; Length of Stay ; Microsurgery ; Middle Cerebral Artery ; Neck ; Operative Time

OBJECTIVE: We performed the surgery using titanium double cylindrical cage for anterior cervical discectomy and interbody fusion in various degenerative cervical diseases. We compared the clinical results and radiologic results in cervical anterior disectomy. Method: From October 2007 to October 2008, 19 patients diagnosed with degenerative disease underwent anterior cervical disectomy and interbody fusion. The postsurgical clinical results were analyzed retrospectively by classifying them into four levels based on Odom's criteria(excellent, good, fair, and poor) after a more than 6-month follow-up period. RESULTS: In all cases, a single segment was involved, and surgery was performed for 19 segments. The C5-C6 inter-vertebral disc was the most commonly affected(9 cases). The clinical outcome was excellent, good, and fair in 5(26.3 %), 10(52.6%), and 4(21.0%) cases, respectively. An excellent or good outcome was considered as a successful result, showing an approximately 78.9% cure rate. No patient had aggravated symptoms compared with their preoperative status. CONCLUSION: Relatively satisfactory clinical and radiographic results were obtained with double cylindrical cages. The surgical method is relatively simple, allows good synostosis, and prevents many complications associated with autografting. It is also less traumatic to the spinal cord during cage insertion. Therefore, double cylindrical cages are generally more recommended for treating cervical spondylosis accompanied with flat cages.
Diskectomy ; Follow-Up Studies ; Humans ; Retrospective Studies ; Spinal Cord ; Spondylosis ; Synostosis ; Titanium ; Transplantation, Autologous

OBJECTIVE: To identify the accuracy and efficiency of the computed tomographic (CT)-based navigation system on upper cervical instrumentation, particularly C1 lateral mass and C2 pedicle screw fixation compared to previous reports. METHODS: Between May 2005 and March 2014, 25 patients underwent upper cervical instrumentation via a CT-based navigation system. Seven patients were excluded, while 18 patients were involved. There were 13 males and five females; resulting in four degenerative cervical diseases and 14 trauma cases. A CT-based navigation system and lateral fluoroscopy were used during the screw instrumentation procedure. Among the 58 screws inserted as C1-2 screws fixation, their precise positions were evaluated by postoperative CT scans and classified into three categories : in-pedicle, non-critical breach, and critical breach. RESULTS: Postoperatively, the precise positions of the C1-2 screws fixation were 81.1% (47/58), and 8.6% (5/58) were of non-critical breach, while 10.3% (6/58) were of critical breach. Most (5/6, 83.3%) of the critical breaches and all of non-critical breaches were observed in the C2 pedicle screws and there was only one case of a critical breach among the C1 lateral mass screws. There were three complications (two vertebral artery occlusions and a deep wound infection), but no postoperative instrument-related neurological deteriorations were seen, even in the critical breach cases. CONCLUSION: Although CT-based navigation systems can result in a more precise procedure, there are still some problems at the upper cervical spine levels, where the anatomy is highly variable. Even though there were no catastrophic complications, more experience are needed for safer procedure.
Cervical Vertebrae ; Female ; Fluoroscopy ; Humans ; Male ; Spine* ; Tomography, X-Ray Computed ; Vertebral Artery ; Wounds and Injuries

Dental caries is a chronic disease that causes the destruction of tooth structure by the interaction of plaque bacteria, food debris, and saliva. There has been attempts to induce remineralization by supersaturating the intra-oral environment around the surface enamel, where there is incipient caries. In this study, supersaturated remineralized solution "R" was applied to specimens with incipient enamel caries, and the quantitative ananlysis of remineralization was evaluated using microradiography. Thirty subjects volunteered to participate in this study. Removable appliances were constructed for the subjects, and the enamel specimen with incipient caries were embedded in the appliances. The subjects wore the intra-oral appliance for 15 days except while eating and sleeping. The removable appliance were soaked in supersaturated solution "R", saline, or Senstime(R) to expose the specimen to those solutions three times a day, 5 minutes each time. After 15 days, microradiography was retaken to compare and evaluate remineralization. The results were as the following: 1. The ratio of remineralized area to demineralized area was significantly higher in the supersaturated solution "R" and Senstime(R) than in the saline. (p<0.05) 2. Remineralization in the supersaturated buffer solution "R" occurred in the significantly deeper parts of the tooth, compared to the Senstime(R) group containing high concentration of fluoride.(p<0.05) As in the above results, the remineralization effect of remineralized buffer solution "R" on incipient enamel caries has been proven. For clinical utilization, further studies on soft tissue reaction and the effect on dentin and cementum are necessary. In conclusion compared to commercially available fluoride solution, remineralization solution "R" showed better remineralization effect on early enamel caries lesion, so it is considered as effecient solution for clinical application.
Bacteria ; Chronic Disease ; Dental Caries ; Dental Cementum ; Dental Enamel ; Dentin ; Eating ; Fluorides ; Microradiography ; Tooth

The present study in angulated coronary stenosis used human in vivo hemodynamic parameters and computed simulation, both qualitatively and qualitatively, to evaluate the influence of flow velocity and wall shear stress (WSS) on coronary atherosclerosis, the changes of hemodynamic indices following coronary stenting, and their effect on evolving in-stent restenosis. Initial and follow-up coronary angiographies in patients with angulated coronary stenosis were performed (n=60). The optimal degree of coronary stenting for angulated coronary stenosis had two models, the less than 50% angle changed group (model 1, n=33) and the more than 50% angle changed group (model 2, n=27). This angle change was based on the percentage change of vascular angle between pre- and post-intracoronary stenting. The flow-velocity wave obtained from in vivo intracoronary Doppler study data was used for in vitro numerical simulation. Spatial and temporal patterns of the flow-velocity vector and recirculation area were drawn throughout the selected segment of coronary models. WSS of pre- and post-intracoronary stenting was calculated from three-dimensional computer simulation. As results, follow-up coronary angiogram demonstrated significant difference in the percentage of diameter stenosis between the two groups (group 1: 40.3 +/- 30.2 vs. group 2: 25.5 +/- 22.5%, p < 0.05). Negative shear area on 3D simulation, which is consistent with the re-circulation area of flow vector, was noted on the inner wall of the post-stenotic area before stenting. The negative WSS disappeared after stenting. High spatial and temporal WSS before stenting fell within the range of physiologic WSS after stenting. This finding was more prominent in model 2 (p < 0.01). The present study suggests that hemodynamic forces exerted by pulsatile coronary circulation, termed WSS, might affect the evolution of atherosclerosis within the angulated vascular curvature. Moreover, geometric characteristics, such as the angular difference between pre- and post- intracoronary stenting might define optimal rheologic properties for vascular repair after stenting.
Adult ; Aged ; Biomechanics ; *Coronary Circulation ; Coronary Stenosis/*physiopathology/therapy ; Female ; *Hemodynamics ; Human ; Male ; Middle Age ; *Stents ; Stress, Mechanical

Treatment of ventricular arrhythmias (VA) usually involves managing the underlying cardiac conditions that cause the arrhythmia. However, managing the underlying disease is often challenging, and catheter ablation, or treatment targeting the VA itself might be required in a few patients. In this article, we explored evidence and recommendations regarding the treatment of VA in patients with structural heart disease focusing on the utilization of catheter ablation in these patients. The administration of optimal medical therapy, insertion of an implantable cardioverter-defibrillator, or resynchronization therapy improves survival in patients with left ventricular dysfunction. The role of catheter ablation in preventing sudden cardiac death remains uncertain in this population. In patients with coronary artery disease, reversing myocardial ischemia via revascularization is important in managing VA. Catheter ablation is recommended in patients with recurrent ventricular tachycardia in a setting of ischemic heart disease. In patients with non-ischemic cardiomyopathies such as dilated cardiomyopathy or hypertrophic cardiomyopathy, catheter ablation may be considered for those presenting with drug-refractory ventricular tachycardia.
Arrhythmias, Cardiac ; Cardiomyopathies ; Cardiomyopathy, Dilated ; Cardiomyopathy, Hypertrophic ; Catheter Ablation ; Catheters ; Coronary Artery Disease ; Death, Sudden, Cardiac ; Defibrillators, Implantable ; Heart Diseases ; Humans ; Myocardial Ischemia ; Tachycardia, Ventricular ; Ventricular Dysfunction, Left

The recommendations outlined constitute the first clinical practice guidelines of the Korean Heart Rhythm Society regarding catheter ablation of ventricular arrhythmias (VA). This is a guideline PART 2, which includes VA in the structurally normal heart, inherited primary arrhythmia syndromes, VA related to congenital heart disease, as well as VA and sudden cardiac death observed in specific populations. In the structurally normal heart, treatment is guided by the occurrence of symptoms or the frequency of arrhythmias that cause ventricular dysfunction over time. Catheter ablation can be recommended in patients in whom anti-arrhythmic medications are ineffective. The sites of origin of arrhythmic activity are known to be the outflow tract, fascicles, papillary muscle, or the annulus. Specific cardiac channelopathies include congenital long QT and Brugada syndrome. This guideline discusses the diagnostic criteria, risk stratification, and treatment of these syndromes. We have included recommendations for adult congenital heart disease. Moreover, we have discussed the management of VA occurring in specific populations such as in patients with psychiatric and neurological disorders, pregnant patients, those with obstructive sleep apnea or drug-related pro-arrhythmias, athletes, and elderly patients.
Adult ; Aged ; Arrhythmias, Cardiac ; Athletes ; Brugada Syndrome ; Catheter Ablation ; Catheters ; Channelopathies ; Death, Sudden, Cardiac ; Heart ; Heart Defects, Congenital ; Humans ; Nervous System Diseases ; Papillary Muscles ; Sleep Apnea, Obstructive ; Ventricular Dysfunction

Ventricular arrhythmias (VA) are a major cause of sudden cardiac death (SCD) in patients with known heart disease. Risk assessment and effective prevention of SCD are key issues in these patients. Implantable cardioverter defibrillator (ICD) insertion effectively treats sustained VA and reduces mortality in patients at high risk of SCD. Appropriate anti-arrhythmic drugs and catheter ablation reduce the VA burden and the occurrence of ICD shocks. In this guideline, authors have described the general examination and medical treatment of patients with VA. Medications and catheter ablation are also used as acute phase therapy for sustained VA.
Arrhythmias, Cardiac ; Catheter Ablation ; Catheters ; Death, Sudden, Cardiac ; Defibrillators ; Heart Diseases ; Humans ; Mortality ; Risk Assessment ; Shock