The dental profession is currently experiencing a technology explosion. Processes are being replaced by modern, inexpensive, and precise techniques that can be used to solve complex restorative problems. Electrical discharge machining (DEM, known as spark erosion in Europe) is a nonconventional, industrial technique that has application in dentistry. EDM may be defined as a metal removal process using a series of sparks to erode material from a workpiece in a liquid medium under carefully controlled conditions. EDM is recently adopted in the dental laboratory to fabricate precision attachments, hybrid telescope crowns, Ti-ceramic crowns. EDM has also been used to achieve a passive precision metalto-metal fit between the substructure bar and the removable superstructure and to correct the fit of implant retained restorations. in this article, a brief history and explanation of EDM is discussed and a description of the use of this process for fabricating attachments and crowns or for correcting the fit of cast restorations is presented.
Crowns ; Cytochrome P-450 CYP1A1 ; Dentistry ; Explosions ; Laboratories, Dental ; Telescopes

Cortical support is an important factor, as the engagement of the fixture in strong compact bone offers an increased load-carrying capacity and initial stability. Because of the poor bone quality in the posterior mandible and other anatomic considerations, it has been suggested that implant fixtures be placed in these locations with apical engagement of the lingual cortical plate for so-called bicortication. The purpose of this investigation was to determine the effect of cortical engagements and in addtion polyoxymethylene (POM) intramobile connector(IMC) of IMZ implant on implant load transfer in edentulous posterior segment of mandible, using three-dimensional(3D) finite element analysis models composed of cortical and trabecular bone involving single implant. Variables such as (1) the crestal peri-implant defect, (2) the apical engagement of lingual cortical plate, (3) the occlusal contact position (a vertical load at central fossa or buccal cusp tip), and (4) POM IMC were investigated. Stress patterns were compared and interfacial stresses along the bone-implant interface were monitored specially. Within the scope of this study, the following observations were made. 1) Offset load and angulation of fixture led to increase the local interfacial stresses. 2) Stresses were concentrated toward the cortical bones, but the crestal peri-implant defect increased the interfacial stresses in trabecular bone. 3) For the model with bicortication, it was noticed that the crestal cortical bone provided more resistance to the bending moment and the lingual cortical plate provided more support for the vertical load. But Angulaton problem of the fixture from the lingual cortical engagement caused the local interfacial stress concentrations. 4) It was not clear that POM IMC had the effect on stress distribution under the present experimental conditions, expecially for the cases of crestal peri-implant defect.
Finite Element Analysis* ; Mandible*

No abstract available.
Humans ; Mental Health* ; Paresis* ; Rehabilitation* ; Stroke*

This study was undertaken to investigate to compare the ratio of positive reactions to benzoic acid(BA), sorbic acid(SA) and cinnamic acid(CA) which are well known materials producing non-immunologic contact urticaria. Various concentrations(0.l% to 5%) and different vehicles(petrolatum, water, hydrophilic ointment base) were used in open and 20 minutes closed test using Finn chamber on Scanpor tape. One hundred total subjects were consisted of nonallergic patients and normal persons. The results were as follows ; 1. Total numbers of positive reactions were 69 in closed test(CT) and 60 in open test(OT), regardless of the materials and vehicles. 2. Total riumbers of positive reactions in BA, SA and CA were 68, 31, 35 in CT and 59, 20, 14 in OT respectably. 3. CT showed much more positive reactions than OT with all materials tested except 0.l% SA in water. 4. Hydrophilic ointment base showed a better reactivity than any other vehicles in CT. But in OT, petrolatum, water, hydrophilic ointment base showed better reactivity in BA, SA, CA respectably. 5. Almost all the reactions appeared within 45 minutes and disappeared within 3 hours. Erythema preceded edema and persisted 30 minutes to 1 hour after dissappearance of edema. 6 Itching, burning and tingling sensation were the only symptoms observed except. localized erythema and edema.
Benzoic Acid ; Burns ; Edema ; Erythema ; Humans ; Petrolatum ; Pruritus ; Sensation ; Sorbic Acid ; Urticaria* ; Water

No abstract available.
Child* ; Hepatitis* ; Humans

Congenital absence of the lower sternum, defect of the abdominal wall, defects of the anterior diaphragm, pericardial defects and cardiac anomalies had been described as a syndrome by Cantrell et al. Developing mechanism of the syndrome was embryologically defined. These defects arise apparently from combined anomalies of developing of the dorsal mesoderm. The authors present two cases of Cantrell's syndrome developed in one day old and eight months old female patient in which angiocardiography was done at the Department of Radiology, Seoul National University Hospital.
Abdominal Wall ; Angiocardiography ; Diaphragm ; Female ; Humans ; Mesoderm ; Seoul ; Sternum

Leukemia is the commonest malignancy in childhood, accounting for about one-third of all malignancies in thosebelow the age of 15 years. Authors analysed the chest PA findings of 177 cases of leukemia in childhood below theage of 15 years, diagnosed at Seoul National University Hospital in recent 5 years since 1978. The summaries ofthe analysis are as follows; 1. Among 177 cases, 121 cases were male and 56 cases were female. The malepredominant than the female with the ratio of 2.2:1. In 177 cases, 77% of the patients were under the 10 years ofage. 2. The incidence of subtype of leukemia was as follows; The acute form was 158 cases (89%), acute lymphocyticleukemia, 55%, acut myelocytic group, 31.6%, chronic myelocytic type, 10%. And acute lymphocytic leukemia was61.4% of acute form. 3. The incidence of abnormality in chest PA was 32.2%(57 cases) . Among these 57 cases,abnormality in lung field was 35 cases (19.8% of total patients) hilar and mediastinal lymph nodes enlargement was19 cases(10.7%). Pleural effusion was 13 cases (7.3%) and cardiac shadow enlargement in chest PA was 3 cases.
Child ; Female ; Humans ; Incidence ; Leukemia ; Lung ; Lymph Nodes ; Male ; Pleural Effusion ; Precursor Cell Lymphoblastic Leukemia-Lymphoma ; Seoul ; Thorax

This study measured the relative displacements of the five-unit fixed partial dentures as cast with the same fixed partial dentures sectioned and assembled by investment-soldering, soldering stand-soldering, and cast-joining techniques. A total of fifteen specimens using a type IV gold alloy wee one-piece cast as control and then sectioned and assembled five test specimens for each method were prepared. A computerized three dimensional coordinate measuring machine and specially designed cylinder for this study were used. Displacement was defined by six displacement variables for the each of cylinders incorporated in each casting: three component displacements ( Lx, Ly, and Lz) and rotational displacements( thetax, thetay, thetaz). The global displacement was computed using the mathematical formula R= Global displacement ={{{{rm SQRT { (x'-x)^2 +(y'-y)^2 + (z'-z)^2} }} }} Under the conditions of this study, the following conclusions were drawn: 1. The investment-soldering group showed the largest mean value of final global displacements, followed by stand-soldering group, cast-joining group and one-piece cast group. However, between the mean values of final global displacement for the cast-joining group and one-piece cast group, there was no significant difference. 2. For investment-soldering and stand-soldering groups, the greater global displacements were recorded in soldering phase than in indexing or investing phase. 3. For one-piece cast group, the displacements occured mostly in the casting phase. And for castjoining group, there was no significant difference in global displacements among the fabrication procedures. 4. Intercentroidal distance decreased in framework-pattering, solder-indexing, solder-standing, and soldering phases, but increased in investment block-investing and casting phases. 5. Specially designed cylinder for touch-trigger type coordinate measuring machine was validated.
Abstracting and Indexing as Topic ; Alloys ; Denture, Partial, Fixed ; Investments ; Methods

Chronic intestional pseudoobstruction syndrome is a rare clinical condition in which impaired intestinal peristalsis. Causes recurrent symptoms of bowel obstruction in the absence of a mechanical occlusion. This syndrome may involve variable segments of small or large bowel. And may be associated with urinary bladder retention. This study included 6 children(3 boys and 3 girls) of chronic intestinal obstruction. Four were symptomatic at birth and two were of the ages of one month and one year. All had abdominal distention and defication difficulty. Five had urinary bladder distention. Despite parenteral nutrition and surgical intervention(ileostomy or colostomy), bowel obstruction persisted and four patients expired from sepsis within one year. All had gaseous distention of small and large bowel on abdominal films. In small bowel series. Consistent findings were variable degree of dilatation. Decreased peristalsis(prolonged transit time) and microcolon or microrectum. This disease entity must be differentiated from congenital megacolon, ileal atresia and megacystis syndrome.
Dilatation ; Hirschsprung Disease ; Humans ; Intestinal Obstruction ; Intestinal Pseudo-Obstruction* ; Parenteral Nutrition ; Parturition ; Peristalsis ; Sepsis ; Urinary Bladder

Krukenberg tumor, which can account for 30-40% of metastatic cancers to the ovaries, arises in the ovarian stroma and is usually metastatic from the gastrointestinal tract, especially from the stomach. The pathognomonic feature is the presence of signet ring cells, which may be arranged in acini or appear as individual cells. We experienced a Krukenberg tumor which was bilateral and associated with left ovarian dermoid cyst. This patient was treated for a primary gastric carcinoma(Stage II) about 3 years ago. After bilateral salpingoophorectomy, she received adjuvant chemotherapy. But, she died about fow months after operation.
Chemotherapy, Adjuvant ; Dermoid Cyst* ; Female ; Gastrointestinal Tract ; Humans ; Krukenberg Tumor* ; Ovary ; Stomach