The ideal restorative material should mimic the properties of the tissues it replaces. Dental composite resins have been used widely as restorative materials due to its advantages such as excellent esthetics and ease of manipulation. But inadequate wear resistance has been a major factor limiting the use of composite restorative materials. Improved manufacturing techniques have allowed the development of hybrid composites, with a greater percentage volume filler loading, which have improved physical an mechanical properties. However they are lacking the study wear resistance. The purpose of this study was to evaluate the wear of human enamel against ceromer by the use of a pin-on-disk type wear testers. Discs of ceromer(Targis : Ivoclar, Vivadent, Amherst. NY) and discs of type III gold alloy as a control were used for test specimens. Intact cusp of premolar and molar were used for enamel specimens. The wear of enamel was determined by weighing the cusp before and after each test, and the weight converted to volumes by average density of enamel. Surface profilometer was used to quantify wear of the ceromer and gold specimens. Vicker's hardness tester was used to evaluate the surface hardness of test specimens. The SEM was used to evaluate the wear surfaces. The results were as follows; 1. Ceromer produced less enamel wear than gold(p<0.05). 2. The wear volume of ceromer was greater than that of gold(p<0.01). 3. The hardess of ceromer was lower than that of gold, but there was no correlation between the hardness and wear of the ceromer and gold. 4. SEM analysis revealed that there were many voids and microcracks in the wear tract of ceromer. in gold group, many minute V-shaped grooves were examined.
Alloys ; Bicuspid ; Composite Resins ; Dental Enamel* ; Esthetics ; Hardness ; Hardness Tests ; Humans* ; Molar

Although tubuloglomerular feedback (TGF) is involved in ureteral obstruction-induced increase in renal blood flow (RBF), its contribution to RBF is not well established due to the concommitant increases in prostaglandin (PG) and renal interstitial fluid pressure (Pisf), both of which affect RBF one way or the other. Since Pisf and TGF are closely affected by renal hemodynamics, RBF will respond differently to increases in ureteral pressure depending on renal hemodynamic conditions. Therefore, the purpose of the present study was to investigate how the changes in renal hemodynamics affect the response of RBF to increases in ureteral pressure. The effect of PG on RBF was assessed by comparing the effects obtained before and after indomethacin, a cyclooxygenase inhibitor. Six anesthetized dogs were prepared with flow probes and inflatable silastic occluder around the renal artery, the ureteral catheter with its free end attached to a water reservoir, and the arterial and venous catheters. RBFs were obtained at ureteral pressures of 0, 15, and 40cmH2O during the maintenance of the renal artery pressure (RAP) at the level of systemic arterial pressure, 10mmHg above and below the lower autoregulatory limit of RBF (65+/-4 mmHg) both before and after indomethacin administration (10mg/kg). In response to the ureteral pressure of 40cmH2O, RBF increased from 172+/-6 to 185+/-10ml/min when RAP's were equal to systemic arterial pressure and decreased from 162+/-10 to 120+/-9 ml/min when RAP's were 55+/-4mmHg. Indomethacin pretreatment, depending on the level of RAP either prevented an increase or augmented a decrease in RBF in response to ureteral pressure elevation. This suggests that RAP-dependent changes in susceptibility of the renal venous system to compression by increased Pisf is the main mechanism by which the changes in renal perfusion pressure modulate the response of RBF to ureteral pressure elevation.
Animals ; Arterial Pressure ; Catheters ; Dogs* ; Extracellular Fluid ; Hemodynamics ; Indomethacin ; Perfusion ; Prostaglandin-Endoperoxide Synthases ; Renal Artery ; Renal Circulation* ; Ureter* ; Ureteral Obstruction* ; Urinary Catheters ; Water

No abstract available.
Maxillary Sinus* ; Maxillary Sinusitis*

Augmentation rhinoplasty is one of the most popular aesthetic procedures in Asians. Numerous alloplastic implants have been used, however alloplastic implants may cause many problems in nasal and perinasal areas because of thin soft tissue cover. For these reasons, an ideal implant should be nonpalpable, readily exchangeable and biocompatible. Among these alloplastic implants, Gore-Tex(R) is a polymer of carbon bound to fluorine composed of solid nodes connected by very fine fibers. It has been reported that this material become permeated and surrounded by mature connective tissue, forming a strong supporting envelop for the material, yet the implant is easily removed because of limited tissue ingrowth. Since it's development, Gore-Tex(R) has found many applications in the field of facial plastic and reconstructive surgery. From November, 2001 to December, 2002, Gore-Tex(R) implants were removed from 17 patients due to several problems such as; decreased dorsal height, tip deformity, chronic inflammation. The implants were very hard to remove and coinciding injury of the surrounding tissue were inevitable. An analysis of the length and thickness changes in these removed implants was made. The results showed, decrease in length and thickness with a volume loss averaging, 46.3% in 45x4.0mm implants, 49.3% in 50x5.0mm implants. In view of the experiences of 17 cases of Gore-Tex(R) implants in rhinoplasty, we have concluded that Gore-Tex(R) implants were structurally unstable, fibrovascular tissue ingrowth into pores were minimal, the implants were very hard to remove and the implants caused a postoperative volume reduction. Therefore, Gore-Tex(R) use in augmentation rhinoplasty should be approached with caution.
Asian Continental Ancestry Group ; Carbon ; Congenital Abnormalities ; Connective Tissue ; Fluorine ; Humans ; Inflammation ; Plastics ; Polymers ; Polytetrafluoroethylene* ; Rhinoplasty*

PURPOSE: The aim of this study was to evaluate the periodontal and prosthodontic complications of multiple freestanding implants in the posterior jaws for up to 1 year of function. MATERIAL AND METHODS: Eight patients received 20 implants posterior to canines. Two or more implants were consecutively inserted to each patient. Single crowns were delivered onto the implants. Marginal bone loss, implant mobility, probing depth, and screw loosening were examined to evaluate the clinical success of such restorations for maximum 1 year of functional loading. RESULTS: All the implants performed well during the observation period. Neither periodontal nor prosthodontic complications were found except a slight porcelain chipping. While the marginal bone level was on average 0.09 mm lower around the implant after 6 months of loading, it was 0.15 mm higher after 1 year. CONCLUSION: Within the limits of this investigation, separate single-tooth implant restorations to replace consecutive missing teeth may clinically function well in the posterior jaw.
Cohort Studies ; Crowns ; Dental Implants, Single-Tooth ; Dental Porcelain ; Humans ; Jaw ; Prospective Studies ; Prosthodontics ; Tooth

Traumatic injury to the lower legs has been increasing in Korea and often leads to skin and soft tissue loss, exposing blood vessels, nerves, tendons or bones. Salvaging these legs often requires free flaps. Over the past two decades, the use of free tissue transfer has produced an increasing salvage rate for severely injured lower leg. Between April. 1988 to July, 1997, 47 cases of lower soft tissue defects were reconstructed with free flaps, and retrospective analysis was performed to determine more about the factors associated with free flap failure or immediate vascular complications. We evaluated wound status before operation, operation time after injury, vascular status of recipient site, use of vein graft, use of reverse flow, salvage protocol in compromised anastomosis, survival rate and complications. There were 9 cases of venous thrombosis and 2 cases of arterial insufficiency while 7 out of 9 cases of venous thrombosis were reexplorated. However, 2 cases of partial flap necrosis and 1 case of total necrosis. Two cases of arterial insufficiency were necrotized, so the overall free flap failure rate was 9.6%. The results were analyzed to determine the factors promoting either failure or vascular complication, Many factors which are often blamed for failure (trauma cause, preoperative general condition, preoperative infection status, intraoperative ischemic time) were not significant in this study, but prolonged time after injury correlated with free flap failure, We concluded the adequate debridement and infection control, adequate selection of recipient vessel, accurate vascular anastomosis and most of all, early free flap transfer after injury, will improve the success rate.
Blood Vessels ; Debridement ; Free Tissue Flaps* ; Infection Control ; Korea ; Leg* ; Necrosis ; Retrospective Studies ; Skin ; Survival Rate ; Tendons ; Transplants ; Vascular System Injuries ; Veins ; Venous Thrombosis ; Wounds and Injuries

59 children seen from Jan. 1990 to Jun. 1994 with epilepsy were retrospectively reviewed to evaluate the tendency of recurrence and the risk factors after the antiepileptic drug discontinuation. The population consisted of 59 children who were seizure free for more than 2 years and followed up for more than 1 year after the discontinuation via department of pediatrics, Yonsei University, Wonju College of Medicine. We analyzed risk factors of recurrence(age of seizure onset, seizure frequency before treatment, interval from seizure onset to start of treatment, duration from neurologic disorders, and EEG done just before discontinuation) between non-recurrent group(43 patients) and recurrent group(16 patients). The results were as follows: 1) In 59 patients with epilepsy, 16(27.1%) patients showed recurrence after the discontinuation and 14(87.5%) patients of those were developed during taperring and within less than 1 year. The probability of recurrent seizure by Kaplan-Meier curve at 12 and 24 months after discontinuation are 23.7% and 33.6% respectively. 2) There were significant differences on seizure frequency before treatement, duration from start of treatment to control (9.5months vs 31.1months), and associated neurologic disorders(11.6% vs. 56.2%) between non-recurrent and recurrent group. 3) There were no significant differences on age at seizure onset(70.6 months vs. 58.5months), interval from seizure onset to start of treatment(9.5months vs. 6.6months), length of seizure free(49.7months vs 39.3months), abnormal EEG finding done just before withdrawal(23.2% vs. 25.0% ) between non-recurrent and recurrent group.
Child ; Electroencephalography ; Epilepsy* ; Gangwon-do ; Humans ; Nervous System Diseases ; Pediatrics ; Recurrence* ; Retrospective Studies ; Risk Factors* ; Seizures

We have experienced a 14 year old female patient who had suffered from headache, dizziness, exertional dyspnea and chest pain during 6 months. She was diagnosed as primary pulmonary hypertension by ultrasonogram and cardiac cathererization. On the cardiac catheterization, there was elevated pulmonary artery pressure and normal pulmonary wedge pressure. We report this case with related literature review.
Adolescent ; Cardiac Catheterization ; Cardiac Catheters ; Chest Pain ; Dizziness ; Dyspnea ; Female ; Headache ; Humans ; Hypertension, Pulmonary* ; Pulmonary Artery ; Pulmonary Wedge Pressure ; Ultrasonography