Silica-Based Advanced Nanoparticles For Treating Ischemic Disease

Recently, various attempts have been made to apply diverse types of nanoparticles in biotechnology. Silica nanoparticles (SNPs) have been highlighted and studied for their selective accumulation in diseased parts, strong physical and chemical stability, and low cytotoxicity. SNPs, in particular, are very suitable for use in drug delivery and bioimaging, and have been sought as a treatment for ischemic diseases. In addition, mesoporous silica nanoparticles have been confirmed to efficiently deliver various types of drugs owing to their porous structure. Moreover, there have been innovative attempts to treat ischemic diseases using SNPs, which utilize the effects of Si ions on cells to improve cell viability, migration enhancement, and phenotype modulation. Recently, external stimulus-responsive treatments that control the movement of magnetic SNPs using external magnetic fields have been studied. This review addresses several original attempts to treat ischemic diseases using SNPs, including particle synthesis methods, and presents perspectives on future research directions.

A Longitudinal Change of Spherical Equivalent in Anisometropic Children

PURPOSE: To demonstrate longitudinal refractive changes of anisometropia children. METHODS: This retrospective study included patients (or children) with anisometropia ≥ 1 diopters (D) for 5 years who visited our hospital between January 2013 and December 2014 with patients having annual refraction test data from 5-years-old to 10-years-old. RESULTS: A total of 37 children satisfied the inclusion criteria. Twenty-one children had hyperopic anisometropia and 16 children had myopic anisometropia. All hyperopic anisometropia and 12 myopic anisometropia children who had unilateral amblyopia were treated with occlusion therapy. The mean anisometropia at 5 years of age was 3.02 D and in the 37 children, the final degree of anisometropia was not significantly different between the 5-year-old and 10-year-old patients. In the high anisometropia and low anisometropia groups and in the myopia and hyperopia groups, the final degree of anisometropia was not significantly different at 5 years of age versus 10 years of age. CONCLUSIONS: In patients with anisometropia, spherical equivalent values did not show a significant difference when comparing 5-year-old versus 10-year-old patients and changes in the spherical equivalent values of eyes from both groups progressed to the same degree even if there was anisometropia in myopic and hyperopic patients.

Morphological assessment of the anterior loop of the mandibular canal in Koreans / 대한해부학회지

The mandibular canal divides into the mental and incisive canals at the premolar region, forms the anterior loop which crosses anterior to the mental foramen, and turns back to reach the mental foramen. The aim of this study was to elucidate the general anatomical structure of the anterior loop of the mandibular canal using morphometry. Twenty-six hemimandibles from 19 cadavers (16 males, 3 females; mean age at death, 54.4 years) were studied by meticulous dissection with the aid of a surgical microscope. The location of the anterior loop, the diameters of the mandibular, mental, and incisive canals, and their distances from bony landmarks were measured using digital calipers. The anterior loop of the mandibular canal was located 3.05+/-1.15 mm (mean+/-SD) anterior to the anterior margin of the mental foramen and 2.72+/-1.41 mm inferior to the superior margin of the mental foramen, and was 4.34+/-1.46 mm long. The diameters of the mandibular, mental, and incisive canals were 2.8+/-0.49, 2.63+/-0.64, and 2.22+/-0.59 mm, respectively. The distances between the inferior border of the mandible and each of these canals were 7.82+/-1.52, 10.11+/-1.27, and 9.08+/-1.66 mm, respectively. The anterior loop of the mandibular canal was located a mean of 3.1 mm anterior and 2.7 mm inferior to the mental foramen, and continued upward and backward into the mental canal, and forward into the incisive canal. These detailed morphological features of the anterior loop of the mandibular canal represent useful practical anatomical knowledge regarding the interforaminal region.

Clinical Analysis of Leukoplakia in the Larynx: Long-Term Follow-Up / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Leukoplakia is a clinical term solely designating a white patch or a plaque of the mucosa without considering its histological feature. Leukoplakia ranges microscopically from a hyperplasia to an invasive squamous cell carcinoma. This study attempted to find out the clinical progress and characteristics of leukoplakia in the larynx. SUBJECTS AND METHOD: Included in the study were 154 patients clinically diagnosed as leukoplakia from 1997 to 2010. We reviewed their medical records retrospectively for age, sex, smoking and drinking history, medical record, histopathologic finding, treatment method, and the follow-up records. RESULTS: Histopathologic findings of leukoplakia in the larynx showed hyperkeratosis (101 patients), invasive carcinoma (19 patients), dysplasia (14 patients), nodule (9 patients), papillomatosis (4 patients), chronic inflammation (4 patients) and tuberculosis (3 patients). Of the 128 patients, 39 patients who were diagnosed as hyperkeratosis, dysplasia, nodule or chronic inflammation in the larynx had recurrence and received re-biopsy over 2 times. Eight patients of these 39 who had recurrence had progression to invasive carcinoma. The mean interval between diagnosis of leukoplakia and invasive carcinoma was 53 months (ranged 7-114 month). Heavy smoking (more than 20 pack year) and drinking were significantly associated with recurrence or progression to invasive carcinoma. Age, gastroesophageal reflux disease and treatment method were not associated with recurrence. CONCLUSION: Leukoplakia in the larynx led to various histopathologic diagnoses, high recurrence rate, and progressed to invasive carcinoma even after 5 years. Smoking and drinking should be managed and longterm follow-up is needed.

Correlation and Agreement Between Peripheral Venous and Arterial Parameters

PURPOSE: To determine the correlation and agreement between perpheral venous and arterial values in emergency department patients. METHODS: The study was conducted at an urban teaching hospital emergency department with an annual volume of 80,000 patient visits. Prospective comparison of paired peripheral venous and arterial values were evaluated from October, 2009 to February, 2010. Peripheral venous and arterial samples were taken as simultaneously as possible when patients who were deemed by the attending doctor to require an peripheral arterial sample presented in the emergency department. Collected information included age, sex, vital signs, emergency department initial diagnosis, lactate, pH, base excess, bicarbonate, pO2, and pCO2. Statistical methods were Shapiro-Wilk test, Spearman rho test, linear regression analysis, and Bland-Altman plots. RESULTS: Among the 546 patients, 50 were excluded and 496 were included. The majority (59.5%) of patients were male. Correlation constant (rho) of pH and lactate were 0.907 and 0.901, respectively. Mean difference and CI (confidence interval) of pH were -0.04 and -1.34~1.56, respectively. Mean difference and CI of lactate were 0.11 mmol/L and -0.15~0.07 mmol/L, respectively. CONCLUSION: Moderate correlation and agreement between perpheral venous and arterial pH, lactate, base excess, and CO2 was evident. Especially, peripheral venous pH, lactate correlated very well and had reasonable agreement with peripheral arterial values to serve as substitutes.

Correlation and Agreement Between Peripheral Venous and Arterial Parameters

PURPOSE: To determine the correlation and agreement between perpheral venous and arterial values in emergency department patients. METHODS: The study was conducted at an urban teaching hospital emergency department with an annual volume of 80,000 patient visits. Prospective comparison of paired peripheral venous and arterial values were evaluated from October, 2009 to February, 2010. Peripheral venous and arterial samples were taken as simultaneously as possible when patients who were deemed by the attending doctor to require an peripheral arterial sample presented in the emergency department. Collected information included age, sex, vital signs, emergency department initial diagnosis, lactate, pH, base excess, bicarbonate, pO2, and pCO2. Statistical methods were Shapiro-Wilk test, Spearman rho test, linear regression analysis, and Bland-Altman plots. RESULTS: Among the 546 patients, 50 were excluded and 496 were included. The majority (59.5%) of patients were male. Correlation constant (rho) of pH and lactate were 0.907 and 0.901, respectively. Mean difference and CI (confidence interval) of pH were -0.04 and -1.34~1.56, respectively. Mean difference and CI of lactate were 0.11 mmol/L and -0.15~0.07 mmol/L, respectively. CONCLUSION: Moderate correlation and agreement between perpheral venous and arterial pH, lactate, base excess, and CO2 was evident. Especially, peripheral venous pH, lactate correlated very well and had reasonable agreement with peripheral arterial values to serve as substitutes.

The Current State of Airway Management and Ventilation at the Pre-Hospital Stage by Emergency Medical Technicians

PURPOSE: Airway management and ventilation at the pre-hospital stage are essential and very critical to patient welfare. In Korea, however, methods other than the use of a bag valve mask are hardly used at the pre-hospital stage by emergency medical technicians (EMTs). This study survey the current state of airway management and respiratory first aid at the pre-hospital stage. METHODS: A questionnaire survey of 356 EMTs was conducted by distributing questionnaires directly to first-class EMTs who participated in clinical training at emergency centers or by sending questionnaires and receiving answers by E-mail. The questionnaire solicited information concerning general characteristics of EMTs, monthly frequency of pre-hospital airway management of patients and the will of EMTs. Subjects were divided into two groups according to governmental subdivision or presence of training within 1-year. RESULTS: Concerning airway management and ventilation at the pre-hospital stage, the use of methods other than nasal prong and simple mask was very rare. As to the reasons, the respondents mentioned the shortage of manpower and lack of knowledge/experience. There was no significant difference in the ratio of pre-hospital airway management between urban and suburban/rural settings. Training within 1-year was not related to increased enforcement of airway management. CONCLUSION: In Korea, pre-hospital airway management is not well implemented by EMTs. Causes are deficiency of rescuer, less actual patient treatment experience and deficiency of knowledge/experience. Education and work experience can influence pre-hospital airway management. But, most pre-hospital airway management is unaffected by education and work experience.

VAP (Ventilator-associated Pneumonia) in Patients with Pulmonary Contusion / 대한구급학회지

BACKGROUND: This study was conducted to determine the incidence, risk factors, and outcome of ventilator-associated pneumonia in patients with pulmonary contusion. METHODS: The study was conducted at an urban teaching hospital emergency department with an annual volume of 80,000 patient visits. A retrospective analysis was conducted on thoracic injury patients admitted between Jan 2007 and Dec 2009. Among 122 patients investigated, 30 patients were excluded. Patient data included basal characteristics and information related to development of ventilator-associated pneumonia and ultimate mortality. Statistical methods included the Chi-square test and the Mann-Whitney test. Study data were stored and processed using Microsoft Office Excel 2007 & SPSS 18.0 for Windows. RESULTS: Ventilator-associated pneumonia developed in 46 patients (50%). The patients with ventilator-associated pneumonia were more likely to have a longer duration of hospitalization, longer length of ICU stay, longer duration of mechanical ventilation, a low initial GCS, a higher APACHE II score, and were more likely to require emergency intubation or tracheostomy. Factors associated with mortality included longer duration of hospitalization, longer duration of mechanical ventilation, low intial GCS and the need for dialysis. CONCLUSIONS: Ventilator-associated pneumonia in the patients with pulmonary contusion was not relevant to mortality, but was relevant to longer hospitalization, length of ICU stay and duration of mechanical ventilation.

Correlation of Serum Total Bilirubin Levels and the Severity of Acute Ischemic Stroke / 대한뇌혈관외과학회지

OBJECTIVE: We evaluated whether serum total bilirubin levels were related to large artery atherosclerosis (LAA), classified by the Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification, and stroke severity at admission in acute ischemic stroke. METHODS: We analyzed clinical features, laboratory tests, and radiologic findings such as brain MRI and MR angiography of patients admitted to our hospital within 24 hours of the onset of ischemic stroke between January 2004 and June 2007. By TOAST classification, 237 patients [115 with LAA and 122 with small artery occlusion (SAO)] were selected. We divided serum total bilirubin levels into three groups: Low (15). RESULTS: Total bilirubin levels were significantly higher in the Mild group than other groups, and high-sensitivity C reactive protein (hsCRP) levels were significantly higher in the Severe group than other groups in LAA. There were no differences for these factors in SAO. We found a significant correlation between total bilirubin levels and stroke severity in LAA (p=0.005). CONCLUSION: Higher serum total bilirubin levels were associated with lower stroke severity at admission in LAA but not SAO.

A study on the biological characteristics of modified titanium surface / 대한치주과학회지

PURPOSE: The purpose of this research is to study about initial adhesion, proliferation and activation of osteoblast to titanium surface treated with machined, hydroxyapatite coating, resorbable blast material blasting and anodizing method. MATERIAL AND METHODS: After treating the titanium surface of each block with machined, impurities were removed and sterilized. The number of cells attached from cultured osteoblast of respective experimental groups were measured at 1, 4, 7, and 14day and alkaline phosphatase, calcium, and inorganic phosphate concentration of cultured solution was measured. RESULT: Anodizing group showed the highest rate of cell attachment and proliferation activity. RBM treated group showed the highest increasing on their alkaline phosphatase activity, on the calcium apposition, on inorganic phosphate apposition of 1 and 4 days in cultured osteoblast to compare with other groups. CONCLUSION: On the basis of these findings, we conclude that surface modification of titanium was profoundly effected on the attachment, proliferation and activation of osteoblast in initial stage osseointegration.

Clinical Characteristics of Pediatric Cerebral Aneurysms / 대한뇌혈관외과학회지

BACKGROUND: Hypercholesterolemia is a major risk factor for ischemic stroke. It was reported that a low triglyceride (TG), not a low cholesterol concentration, was independently associated with the poor outcome of ischemic stroke. There are no reports on relationship between the serum TG level and the clinical outcome of acute stage of ischemic stroke. Moreover, the differences in clinical outcome of each subtype of ischemic stroke in relation to the serum TG level are unknown. This study examined relationship between the serum TG level upon admission and the clinical outcome at discharge in each subtype of acute ischemic stroke. METHODS: Four hundred and fifty consecutive patients with their first-ever ischemic stroke, who admitted between January 2004 and December 2006, were examined retrospectively. The serum TG level was measured within 24 hours after stroke onset. The subtypes of stroke were classified according to the Trial of ORG 10172 in the Acute Stroke Treatment (TOAST) classification. The severity and outcome of stroke were assessed using the National Institutes of Health Stroke Scale (NIHSS) score upon admission, at discharge, and 4 weeks after discharge. The population was divided into 3 groups according to the serum TG level (Normal TG group : serum TG level 150mg/dl, Borderline-high TG group : 150 degrees ¬ TG< 200mg/dl, High TG group : serum TG level 200mg/dl) and 2 groups by NIHSS score (Improved outcome group: NIHSS score decreased or unchanged, Worsened outcome group: NIHSS score increased). The relationship between the level of TG of each stroke subtype and the clinical outcome of those patients was analyzed. RESULTS: The study population was divided into three groups, according to the serum TG level. The Normal TG group consisted of 128 patients (mean serum TG level : 74.0 17.2mg/dl). The borderline-high TG group consisted of 230 patients (mean serum TG level : 168.9 20.4 mg/dl). The high TG group consisted of 92 patients (mean serum TG level : 474.5 197.0 mg/dl). Hypertension and diabetes are prevalent in the high TG group, which also had higher incidence of large artery disease in the TOAST classification. The normal TG group showed more severe stroke upon admission and a poor clinical outcome after 4 weeks than the other two groups (p<0.05). Each TOAST classification of TG group showed a similar clinical outcome. CONCLUSION: The normal TG group had a more severe the stroke and poorer clinical outcome than the other groups. TG may play a role as a protective factor in the acute stage of ischemic stroke.

Relations to Plasma Fibrinogen Concentration and Subtype, Prognostic Influence in Patients with Acute Ischemic Stroke / 대한뇌혈관외과학회지

OBJECTIVE: Previous epidemiological studies have suggested that hyperfibrinogenemia is an independent risk factor for cerebrovascular atherosclerosis. Fibrinogen is a key factor in the coagulation cascade, and it is suggested to play in a significant role in atherosclerosis. However, there have been relatively few studies regarding the relationship between the level of fibrinogen and prognostic influence in stroke subtypes. We prospectively evaluated that whether plasma fibrinogen levels in the acute stage were related to clinical outcome in each subtype of acute ischemic stroke. METHODS: Acute ischemic stroke was classified by the Trial of Org 10172 in the Acute Stroke Treatment (TOAST) classification. Large atrery atherosclerosis (LAA), and small vessel occlusion (SVO) were included in the classification; cardioembolic (CE) occlusion, and other causes and undetermined causes were excluded from the classficiation. The level of fibrinogen was determined within 24 hours after stroke. Stroke severity and outcome was assessed using the National Institutes of Health Stroke Scale (NIHSS) score at admission (baseline) and follow-up (4 weeks later). The NIHSS changes were compared from baseline to follow-up. Patients with NIHSS changes were divided into two groups: the good group (NIHSS had improved) and poor group (NIHSS had no change or had worsened). Patients were placed into two groups based on the plasma fibrinogen level: the normal group (plasma fibrinogen level of 200~400mg/dl) and high group (plasma fibrinogen level >400mg/dl). The level of plasma fibrinogen and changes of NIHSS were analyzed by the Chi-squared tests and multiple logistic regression. RESULTS: A total of 619 patients with acute ischemic stroke were studied. Among the 619 patients, there were 251 patients with LAA and 229 patients with SVO. Multiple logistic regression analysis indicated that a high level of plasma fibrinogen (p < 0.001), a high level of C-reactive protein (p < 0.001) and the presence of diabetes mellitus (p = 0.026) were related to poor prognosis with acute stage ischemic stroke. Partial correlation analysis showed that the plasma fibrinogen levels were related to LAA (p = 0.05) and NIHSS at admission (p = 0.007) in patients with a high plasma fibrinogen level. However, there was no statistical significance of ischemic stroke subtype and NIHSS in patients with a normal level of plasma fibrinogen. CONCLUSION: An elevated level of plasma fibrinogen seemed to be associated with LAA in acute ischemic stroke and with a poor clinical outcome.

The Effect of Latent Syphilis on Carotid Intima-Media Thickness in Acute Ischemic Stroke Patients

BACKGROUND: Neurosyphilis develops into ischemic stroke due to the occlusion of intracranial arteries, which has the histopathological change of intracranial syphilitic arteritis. There might be an association between a latent syphilis and arterial changes before the neurosyphilis develops. We evaluated the relationship between the latent syphilis and the carotid intima-media thickness (IMT) in acute ischemic stroke patients to study whether the latent syphilis affected pathological arterial changes. METHODS: Retrospectively consecutive 96 acute ischemic first ever stroke patients were selected from the Gachon stroke registration from January 2003 to May 2005. The latent syphilis group was made up of 44 patients and the non-syphilis group matched in the age and the sex and consisted of 52 patients. The stroke subtype was classified by TOAST classification. RESULTS: The mean carotid IMT of the latent syphilis group (3.06+/-3.78 mm right, 2.68+/-3.39 mm left) was thicker than that of the non-syphilis group (1.49 +/-2.37 mm right, 1.43+/-1.99 mm left)(p<0.05). The hs-CRP was more elevated in the latent syphilis group than the non-syphilis group (1.6+/-2.2 mg/dl, 1.0+/-2.3 mg/dl respectively) (p<0.05). There were no significant differences of in each of the risk factors between the two groups. CONCLUSIONS: Our results showed the patients with latent syphilis had thicker carotid IMT, and a higher level of hs-CRP than the non-syphilis patients. It could be possible that the latent syphilis attributed to the pathological changes by the inflammation in the extracranial carotid artery.

A Case of Orthostatic Dizziness Developed by Brainstem Tumor

Orthostatic hypotension rarely occurs as a result of central vasomotor failure. We report a 74-year-old man who presented with progressive orthostatic dizziness, and intermittent syncope that resulted from a ponto-medullary tumor. Orthostatic hypotension may develop due to the sympathetic failure of the vasomotor center, which is located in the rostral ventrolateral medulla.

Clinical Review of Chronic Otitis Media in Patients with Contracted Mastoid / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: High resolution computed tomography (HRCT) helps locating the anatomical structure within the temporal bone preoperatively. Contracted mastoid has lots of changed anatomical structure and outside in technique tympanomastoidectomy procedure cannot provide safe and effective access. The aims of this study are to analyze changed anatomical structure and to suggest safer and more effective surgical procedures in chronic otitis media patients with contracted mastoid. SUBJECTS AND METHOD: We measured distances between important surgical landmarks and cross sectional area of pneumatized air cells in contracted mastoid, and compared with normal groups. We analyzed postoperative complications between outside in technique and inside out technique tympanomastoidectomy. RESULTS: The shortest distance between the posterior wall of external auditory canal and the anterior edge of the sigmoid sinus, the vertical shortest distance between the superior wall of external auditory canal and the tegmen, and the cross-sectional area of mastoid air cells were significantly small in contracted mastoid group (p<0.05). There were 2 cases of postoperative facial weakness by outside in technique tympanomastoidectomy. CONCLUSION: Contracted mastoid has lots of changed anatomical structure. We suggest that inside out technique tympanomastoidectomy procedure is safer and more effective in patients with contracted mastoid.

Effects of the Body Position Changes on Upper Airway Caliber in Obstructive Sleep Apnea during Sleep / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Obstructive sleep apnea (OSA) is the intermittent cessation of breathing during sleep due to the collapse of the pharyngeal airway. Pharyngeal collapsibility and oropharyngeal caliber are affected by the respiratory cycle and the body position. Several methods have been used to evaluate the states of upper airway in patients with OSA according to body positions during wakefulness, but there were no reports about the upper airway states according to body positions during sleep. The aim of this study is to evaluate the states of upper airway in patients with OSA according to body position changes during sleep. MATERIALS AND METHOD: Using a multi detector CT, we studied 10 patients with OSA. Each patient was scanned at supine position during the awake state and then induced to sleep using Midazolam. According to body positions (supine, decubitus, and prone), images were acquired during sleep state. The following 4 transverse levels were obtained to evaluate the minimal cross sectional area, collapsibility index, and airway volume: 1) high retropalate level, 2) low retropalate level, 3) high retroglossal level, 4) low retroglossal level. RESULTS: During sleep, the upper airway cross sectional area was decreased and the airway wall collapsibility was increased. Cross sectional area and airway volume were larger at prone and decubitus positions than supine position. Airway wall collapsibility index was lower at prone and decubitus positions than at the supine position. CONCLUSION: In this study, we confirm that the upper airway collapsibility decreases and the airway caliber increases according to body position changes (prone, decubitus) during sleep. Furthermore, the decubitus position is better than the prone position for improving upper airway patency during sleep.

The Study on the Root Surfaces with SEM and EPMA Following Periodontal Treatment with Curet and Ultrasonic Scaler / 대한치주과학회지

One of the fundamental causes of periodontal disease is accumulation of bacterial plaque and calculus and most effective method of removing these plaque and calculus are scaling and root planning using hand curet and ultrasonic scaler. Many studies concerning residual degenerated mineral content after periodontal therapies have been carried out, but some problems about these studies were also known. This research studies mineral concents and distribution of residual root surfaces after perfoming hand curet and ultrasonic scaler on root surfaces of single rooted teeth which were extracted for periodontal reasons. EPMA were used to avoid errors from chemical quantative analysis and in addition SEM observation was also performed. The results were as follows. 1. No differences were found between curet group andultrasonic scaler group in Ca, P, Mg and Na level. 2. Concentration level was decreased in the sequence of Ca, P, Mg and Na. 3. Ca and P level were decreased as going to apical portion at curet group and ultrasonic scaler group. 4. More cementum was removed at cervical portion compared to other portion at curet group and ultrasonic scaler group. 5. Ca, P, Mg level was higher in dentin compared to cememtum. There was no difference in mineral level for Ca, P, Mg and Na between root surfaces treated with hand curet and ultrasonic scaler.

The change of tooth mobility following orthodontic tooth movement ; A short-term study / 대한치과교정학회지

The purpose of the present study was to evaluate the change of tooth mobility following orthodontic tooth movement. Six orthodontic patients which had been treated with edgewise appliance were used. Tooth mobility was measured with Periostest at the time of the removal of orthodontic appliance and 1, 2, 3, 4, 6, 8, 10, 12, 16, 20, 24 weeks after appliance removal. Following results were obtained. 1. Tooth mobility upon the removal of orthodontic appliance showed individual variation while incisor showed greater mobility than the other teeth. 2. Tooth mobility showed continued decrease pattern until 24 weeks after appliance removal. 3. While maxillary incisors showed continued decrease pattern during the study period, the other teeth showed steep decline pattern during the first 12 weeks and gentle slope during the second 12 weeks. 4. The tooth mobility of the maxillary second premolar showed the most typical change in terms of the consistency of the decline. 5. There were no significant differences of tooth mobility between heavy and light-contacted anterior teeth during experimental period. The results of the present study suggested that periodontal reorganization is not completed even in 24 weeks following orthodontic tooth movement.

Shear bond strength and failure patterns according to the thickness of resin base in bracket bonding / 대한치과교정학회지

The purpose of this study was to evaluate the possibility of the decrease of bond strength due to increased thickness of resin base in indirect bracket bonding technique. Metal brackets were bonded to the resin blocks involving bovine lower incisors and the thickness of resin bases was increased by increments of 0.5 mm from 0.0 mm to 2.0 mm. They were divided into two groups, one group is that the thickness of resin base was increased but the loading point from the tooth surface was maintained constantly, the other group is that the loading point from the tooth surface and the resin base thickness were increased concomitantly. The shear bond strength was tested on universal testing machine and the failure patterns were assessed with the adhesive remnant index(ARI). The results were as follows: 1. When the distance from the tooth surface to the loading point was maintained constantly, shear bond strength was increased significantly according to the decrease of distance from the bracket base to the loading point and the increase of resin base thickness. 2. When the distance from the tooth surface to the loading point and the resin base thickness were increased concomitantly, shear bond strength was decreased according to the increase of resin base thickness but significant differences were ignorable. 3. There were no significant differences in ARI scores according to the change in the thickness of resin base. The results of the present study indicated that shear bond strength was not much affected by the thickness of resin base, whereas was decreased according to the increase of distance from bracket base to the loading point.