To compare several porcelains made by various manufacturers in shrinkage after firing and investigate the effect of condensation on shrinkage, specimens were prepared and the volume of each body was measured by the phase-shifting profilometry. Baseplate wax was cut by 2.5cmx2cm and cast in nonprecious metal (Verabond, U.S.A.). then any surfaces of specimens were abrased and polished on the SiC abrasing papers, preparing 120 specimens. specimens were divided into six groups according to the porcelain used, and the porcelain used in each group were as follows. Group I : Ceramco dentin porcelain Group II : Creation dentin porcelain Group III : Creation margin porcelain Group IV : Vintage margin porcelain Group V : Vita dentin porcelain Group VI : Vintage dentin porcelain Porcelain was built up on the metal plates using a small spoon and then solution matching to each porcelain was added. The six groups are subdivided into a and b. In subgroup a, only excessive solution was absorbed with tissue and in subgroup b, porcelain was condensed sufficiently. When build-up was completed, the shape was measured using the phase-shifting profilometry. After that, specimens were fired in the furnace programed for each porcelain and then their changed shape were measured again. Using the difference between the two above measurements, the ratio of shrinkage was calculated. Obtained results were as follows ; 1. Regardless of condensation, the volume of fired specimens were not different significantly between the two subgroups a and b in the same group. 2. The ratios of shrinkage were significantly higher in the groups porcelain built-up was condensed than in the groups not condensed. 3. The ratios of shrinkage were in the range of 36.81-27.19% in the groups porcelain built up was condensed and 44.52-37.54% in the other groups not condensed.
Dental Porcelain* ; Dentin ; Fires*

Segmental Spinal Instrumentation is effective operative procedure in unstable fracture and fracture-dislocation of the thoracolumbar spine, providing rigid spinal stability and reduces needs of external support and complications. Fifty nine patients with unstable fracture and fracture-dislocation of thoracolumbar spine were treated with Harrington rod instrumentation and sublaminar wiring(31 patients) and Luque rod instrumentation with sublaminar wiring(28 patients) in Hyun Dai Hae Seong Hospital, Ulsan, Paik Hospital, Pusan from Dec. 1983 to April 1986. We have analyzed the results of treatment about two type of S.S.I. and obtained following conclusions; l. In 59 patients, T12 level injury was 17 cases, Ll level was 25 cases and so T12 and Ll involvement were 71%. 2. By Francis Denis classification, 28 cases were burst type fracture, 20 cases were fracture-dislocation type, 6 cases were seat belt type and 5 cases were wedge compression type. 3. In Harrington rod with S.S.I., initial kyphotic angle was 22.4° and postoperative angle was 7.4° and correction rate was 66.9%; in Luque rod with S.S.I., preoperative kyphotic angle was 21.7° and postoperative angle was 6.5° and correction rate 69.6%. So there was no difference of correction rate in two type of S.S.I. 4. In Harrington rod with S.S.I., the loss of reduction was 1.2° and the loss was 7%; in Luque rod with S.S.I., the loss of reduction was 7.2° and the loss rate was 48%. So the loss of reduction of Luque rod with S.S.I. was greater than that of Harrington rod with S.S.I. 5. After removal of implants, Luque rod with S.S.I. patients have better range of motion than Harrington rod with S.S.I. patients clinically, but it needs more follow-up because of a few cases(18 cases).
Busan ; Classification ; Follow-Up Studies ; Humans ; Range of Motion, Articular ; Seat Belts ; Spine ; Surgical Procedures, Operative ; Ulsan

According to repeated measurements and correction procedures, the accuracy of the phase-shifting profilometry was developed. At first, after 20 final models for maxillary complete denture were duplicated, the mucosa surfaces of models were measured with the phase-shifting profilometry and each mirror view of these was calibrated. Maxillary cats were divided into 4 groups of 5 casts per each, and wax dentures with 2 sheets of baseplate wax and artificial teeth were made and then cured according to the curing method of each group. Group I ; quick curing with QC-20 acrylic resin Group II ; 9 hour curing with QC-20 acrylic resin Group III ; SR-Ivocap system Group IV ; metal base and quick curing with QC-20 acrylic resin After curing, polishing, and storing at 37degrees C n saline for 30 days, the forms of the impression surface of the dentures were measured with the phase-shifting profilometry. Then, the impression surface form of each denture was placed in the optimal position of comparison with the mirror view of the same final cast. The amount and direction of distortion of each denture was analyzed and the effects of polishing and storage in each denture were compared. The obtained results were as follows : 1. In Group I, the denture was observed as the appearance distorted in the opposite direction of the mucosa and the postero-lateral part of palatal portion of the denture was observed as the appearance separated from the mucosa. Also, the buccal flanges of the denture were observed as the appearance distorted in the direction of the mucosa. 2. In Group II, the postero-lateral part of palatal portion of the denture was observed as the appearance separated slightly from the mucosa. The bilateral buccal flanges of denture were observed as the appearance distorted severely in the direction of the mucosa. 3. In Group III, the bilateral part of the residual ridge crest portions and the buccal flanges of the denture were observed as the appearance distorted in the direction of the mucosa, and specially, the buccal flanges of the maxillary tuberosities were distorted severely. 4. In Group IV, the acrylic resin base of the buccal portion of the denture was observed as the appearance distorted in the opposite direction of the mucosa. 5. The phase-shifting profilometry, done with repeated measurements and correction procedures, was effective in comparing the amount and direction of distortion at every position after the laboratory work and the delivery of maxillary complete denture.
Animals ; Cats ; Denture, Complete ; Dentures* ; Mucous Membrane ; Tooth, Artificial

The purpose of this study was to investigate the stress distribution of the abutment and supporting tissues according tot he slopes and types of the guiding plane of distal extension removable partial dentures. The 3-dimensional finite element method was used and the finite element models were prepared as follows. Model I : Kratochvil type guiding plane with 90degree to residual ridge Model II : Kratochvil type guiding plane with 95degree to residual ridge Model III : Kratochvil type guiding plane with 100degree to residual ridge Model IV : Krol type guiding plane with 90degree to residual ridge Distal extension partial denture which right mandibular first and second molar were lost was used and the second premolar was prepared as primary abutment with RPI type retainer. Then 150N of compressive force was applied to central fossae of the first and second molars and von Mises stress and displacement were measured. The results were as follows : 1. Model I and Model IV showed a similar stress distribution pattern and the stress was concentrated on the apex of the root of the abutment. 2. The stress was increased and concentrated on mesial side of the root of the abutment in Model II. The stress was concentrated on buccal and mesiobuccal side of the root of the abutment in Model III. 3. In Model I, the root of the abutment displaced and twisted a little in clockwise. In Model IV, the root of the abutment displaced to distolingually at apical region of the root and mesiobucally at cervical region of the root. 4. In Model II, the root of the abutment displaced to mesiolingually at apical region of the root and more displaced and twisted in counterclockwise at cervical region of the root. In Model III, the root of the abutment displaced to mesiobucally at apical region of the root and more displaced and twisted in clockwise at cervical region of the root.
Bicuspid ; Denture, Partial ; Denture, Partial, Removable* ; Molar

The purpose of this study was to evaluate the effect of dentin pretreatment with Dentin Conditioner,Ultra-Etch,conditioner of Fuji Plus cement on the shear bond strength of resin-reinforced glass ionomer cements to dentin and analyze the fractured surfaces. To evaluate the bond strengh, the extracted human teeth which had uniform area of exposed dentin were cemented with conventional glass ionomer cement. 3M RelyX TM Luting (Vitremer luting cement). Fuji Plus cement after dentin pretreatment. The shear bond strengh was measured using the Universal testing machine(Instron Co., USA) with a crosshead speed of 1mm/m. The effect of dentin pretreatment was evaluated by observing pretreated dentin surfaces under the scanning electron microscope,measuring the shear bond strength and observing the fractured surfaces under the scanning electron microscope. The results were as follows: On the SEM observation of surface morphology, the specimens treated with Dentin Conditioner, Ultra-Etch and conditioner of Fuji Plus cement were removed the smear layer and funneled dentinal tubules in dentin surfaces. In RelyX TM Luting cement group, shear bond strengh of pretreated group was significantly higher than control group. In Fuji Plus cement group and Fuji I group, regardless of the type of pretreatment agents, there was tendency of increase in the shear bond strength. On the SEM observation of fractured surfaces, as the shear bond strength increase, it were shown thicker cement layers and were not shown dentinal tubules. According to these results, it were shown that dentin pretreatment have much effect on bonding states.
Dentin* ; Glass Ionomer Cements* ; Glass* ; Humans ; Smear Layer ; Tooth

No abstract available.

For the purpose of evaluating the effect of both direct retainer design and bony absorption degree around abutment of indirect retainer on the supporting tissue of abutment of indirect retainer, dislodging force was transmitted to unilateral distal extension RPD bases. Analysis of stress distributed within the supporting tissue around abutment of indirect retainer was carried out. Using three-dimensional photoelastic stress analysis method and the conclusion is a follows. 1. According to the extent of force which the direct retainer of the most distal abutment tooth, the amount of force transmitted to the abutment tooth of indirect retainer was small. 2. Of all the cases, Mandibular first premolar which was used abutment tooth of indirect retainer, buccal, mesial and distal sides represented compression stress and lingual side represented tensile stress. 3. The more bone resorption of abutment tooth of indirect retainer, the more distortion of buccal and distal side of abutment tooth was existed and the extent of compression stress which was existed and distal side to abutment tooth was large. 4. When the alveolar bone around the abutment with indircet retainer is normal. The amount of force transmitted on abutment with indirect retainer was small in the order of Akers clasp, RPA clasp, RPI clasp. 5. When the alveolar bone around the abutment with indirect retainer has been absorbed 20% and 30%, the amount of force transmitted on abutment with indirect retainer was small in the order of RPA calsp, RPI clasp, Akers clasp. 6. When denture is displaced, shape of the direct retainer reciprocating abutment affect much the function of indirect retainer.
Absorption ; Bicuspid ; Bone Resorption* ; Dentures ; Tooth*

BACKGROUND: During the last three decades, the resistance of S. pneumoniae to penicillin has been rapidly increasing in many parts of the world, especially in Korea. To characterize the clinical features and epidemiology of penicillin-resistant S. pneumoniae (PRSP) infections in the community and hospital, as well as to investigate the possible spread of resistant clone, we performed the antimicrobial susceptibility tests, pulsed filed gel electrophoresis (PFGE) and penicillin-binding protein (PBP) profile analysis of PRSP isolates. METHODS: A total 48 PRSP isolates from patients who visited or were admitted to Korea University Guro hospital during the period form July 1998 to June 1999 were studied. Anitimicrobial susceptibility tests for 48 isolates were performed with microbroth dilution method to determine the minimal inhibitory concentration of 11 antibiotics. 39 isolates and 35 isolates were subjected to PFGE and PBP profile analysis, respectively to investigate the genetic relatedness between PRSP isolates. RESULTS: Pneumonia was most common site of infection in the community and the hospital as 50%. There were no significant differences of clinical features and prognosis between community and hospital isolates. But, patients with serious underlying diseases had poor prognosis despite of acquisition site. High level penicillin resistance were observed in 69%, multi-drug resistance were 64.6% of isolates. PFGE showed that 13 of 29 community acquired infection were identical PFGE pattern but not that of 23F Spanish clone. There were various PFGE patterns were observed from community and hospital acquired infection isolates. Some of them were existed in both. PBP profiles showed more diverse, even if in isoaltes of the same PFGE pattern. CONCLUSOIN: In our study, high level penicillin resistance and multi-drug resistance were observed in PRSP clinical isolates. No clinical and prognostic differeces were observed between community and hospital acquired infections. Molecular epidemiology study were suggest the there were various genotypes of PRSP within our society. Some of them were observed in the hospital and community. Therefore, there was an evidence of communication of PRSP clones between the community and hospital.
Anti-Bacterial Agents ; Clone Cells ; Drug Resistance, Multiple ; Electrophoresis ; Epidemiology ; Genotype ; Humans ; Korea ; Molecular Epidemiology ; Penicillin Resistance ; Penicillin-Binding Proteins ; Penicillins ; Pneumonia ; Prognosis ; Streptococcus pneumoniae* ; Streptococcus*

PURPOSE: There is evidence that folic acid given before and during the first 4 weeks of pregnancy can prevent more than 50% of neural tube defect. It suggested that folic acid play a great role when a neural tube closes. Methylenetetrahydrofolate reductase (MTHFR) is an important enzyme in folate metabolism. Since the gene locus and mutation of MTHFR were identified, increased frequency of MTHFR variant was reported in neural tube defect. We studied the frequency of the 677C=>T mutation in the MTHFR gene to determine whether this MTHFR gene variant is more common in persons with neural tube defect and their families compared to a control population. METHODS: The study group consisted of 21 patients with meningomyelocele, 40 their parents and 7 siblings who were managed in Seoul National University College of Medicine and Dankook University Hospital during the period from Jan. 1997 to Dec. 1997. The control group consisted of 25 parents aged between 25 to 50 years who had given birth to, at least, one normal infant and 18 children under 16 years without neural tube defect. DNA was extracted from peripheral blood and a segment of the MTHFR gene was amplified using PCR technique. And treated with restriction enzyme, Hinf1. The restriction pattern was analyzed. RESULTS: The frequency of the three genotypes were as follows: normal (-/-), 47.0%; heterozygote (+/-), 41.2%; and homozygote (+/+), 11.8% in neural tube defect group and (-/-), 25.6%; (+/-), 58.1%; (+/+), 16.3% in control group. The MTHFR gene variant was present 9.5% of those with meningomyelocele, 13.3% of their mothers 10% of their fathers, and 10.3% of siblings. CONCLUSION: 1)There is no increase of the frequency of MTHFR variant polymorphism in neural tube defect compared to control group. These observations indicate that while there maybe racial differences in the mutation frequency, expanded studies involving larger numbers of subjects are required. 2) To elucidate the role of various genetic factors influencing on homocysteine levels and vitamin nutrition, research on other genetic variants, such as folic acid and vitamin B12-related enzymes and receptors, are recommended,
Child ; DNA ; Fathers ; Folic Acid ; Genotype ; Heterozygote ; Homocysteine ; Homozygote ; Humans ; Infant ; Meningomyelocele ; Metabolism ; Methylenetetrahydrofolate Reductase (NADPH2)* ; Mothers ; Mutation Rate ; Neural Tube Defects* ; Neural Tube* ; Parents ; Parturition ; Polymerase Chain Reaction ; Pregnancy ; Prevalence* ; Seoul ; Siblings ; Vitamins

STATEMENT OF PROBLEM: Stress concentration on the neck bone affects the bone resorption, and finally the implant survival. PURPOSE: In order to examine the stress distribution on the neck bone and prosthesis abutment for implants, decreasing abutment sizes were used. MATERIAL AND METHODS: Axisymmetric models were used to obtain the data required. These models were composed of 4mm implants with 3.4mm and 4mm abutments, 5mm implants with 3.4mm and 5mm abutments and 6mm implants with 3.4mm and 6mm abutments. All abutments were designed to received a 10mm high by 10mm diameter gold crown. Functional element analysis was used to obtain these results using data that consisted of 50 N vertical and 45 degree inclination forces. RESULTS: 1. Changing the diameter of the abutment on the implant affects the effect of the inclination forces more than the effect of the vertical forces. 2. Changing the diameter of the abutment on the implant affects the effect of the inclination forces more than the effect of the vertical forces. 3. Experimentation showed that the larger diameter implants provided a decreased neck bone stress, whereas a larger diameter abutment provided a decrease marginal abutment stress. 4. Experimentation showed that the neck bone and abutment received more stress from inclination forces than vertical forces. CONCLUSIONS: By decreasing the size of the abutment on the implant we were able to diminish neck bone stress.
Bone Resorption ; Crowns ; Neck ; Prostheses and Implants