1.SHEAR BOND STRENGTH OF PRETREATED DENTIN SURFACE WITH RESIN-REINFORCED GLASS IONOMER CEMENT.
Hye Souk CHOI ; Cheong Hee LEE ; Kwang hun JO
The Journal of Korean Academy of Prosthodontics 2001;39(5):502-513
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
2.A STUDY OF THE STRESS DISTRIBUTION OF THE ABUTMENT AND SUPPORTING TISSUES ACCORDING TO THE SLOPES AND TYPES OF GUIDING PLANES OF THE LAST ABUTMENT IN DISTAL EXTENSION REMOVABLE PARTIAL DENTURE USING THREE DIMENSIONAL FINITE ELEMENTANALYSIS METHOD.
Yang Kyo KIM ; Cheong Hee LEE ; Kwang Hun JO
The Journal of Korean Academy of Prosthodontics 1999;37(5):581-596
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
3.FITNESS TEST USING THE PHASE-SHIFTING PROFILOMETRY ACCORDING TO THE DENTURE CURING METHODS.
Cheong Hee LEE ; Kwang Hun JO ; Boo Byung CHOI
The Journal of Korean Academy of Prosthodontics 1999;37(4):474-493
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
4.Non-obstructive Biliary Dilatation After Gastrectomy for Gastric Carcinoma.
Nak Kwan SUNG ; Ok Dong KIM ; Young Hwan LEE ; Hag Young CHEONG ; Kyoo Hyun OH ; Cheong Man LEE ; Won Hun LEE ; Duk Soo CHEONG
Journal of the Korean Radiological Society 1995;33(6):933-937
PURPOSE: To evaluate the incidence,. degree, and clinical significance of non-obstructive intrahepatic bile duct di'latation encountered on follow up CT after gastrectomy for gastric carcinoma. MATERIALS AND METHODS: We retrospectively analyzed follow-up abdominal CT of 65 patients who had undergone gastrectomy with truncal vagotomy and subtotal gastrectomy for gastric carcinoma. We classified those patients who showed intrahepatic duct dilatation into non-obstructive or obstructive groups depending on the presence or absence of the lesions obstructing the duct. We also evaluated the incidence, degree and pattern, and appearance time of non-obstructive type of duct dilatation. RESULTS: Non-obstructive and obstructive biliary dilatations were present in 8 cases(12.3%) and 9 cases(13. 8%), respectively. The degree of non-obstructive group was mild in 6 cases(75%) and moderate in 2 cases (25%) who had taken cholecystectomy during the follow up period, and patterns were proportional dilatation of the central and peripheral intrahepatic ducts. It appeared on follow up CT obtained 6 to 12 months after operation in 7 cases and 3.5 months in one case. No statistical significance was noted between the type of surgery and the incidence of non-obstructive dilatation(p>0.05). CONCLUSION: Mild dilatation of the central intrahepatic ducts without evidence of mechanical biliary obstruction can be seen on follow-up CT obtained more than 6 months after gastrectomy for gastric carcinoma, and the incidence is about 12%. We think that this finding is non-obstructive and clinical evaluation is unnecessary.
Bile Ducts, Intrahepatic
;
Cholecystectomy
;
Dilatation*
;
Follow-Up Studies
;
Gastrectomy*
;
Humans
;
Incidence
;
Retrospective Studies
;
Tomography, X-Ray Computed
;
Vagotomy, Truncal
5.Action Mechanisms of Hormone Binding to Nuclear Receptors: Transcriptional Coregulators of the Nuclear Receptor Superfamily.
Jae Woon LEE ; Jae Hun CHEONG ; Young Chul LEE ; Soon Young NA ; Soo Kyung LEE
Journal of Korean Society of Endocrinology 2000;15(3):402-412
No Abstract Available.
Receptors, Cytoplasmic and Nuclear*
6.Effect of Cobalt-Chromium Alloy Surface Treatment When Bonding With 4-Meta/mma-Tbb Resin.
Jae Sik JIN ; Kyo Han KIM ; Cheong Hee LEE ; Kwang Hun JO
The Journal of Korean Academy of Prosthodontics 2000;38(4):510-525
The effects of pretreatment of Co-Cr alloy, including two adhesive primers that contain either MDP or MAC-10, and silicoating on the bond. The results obtained as follows : Strength of 4-META/MMA-TBB resin were investigated using FT-IR SEM, and EDAX. in the SEM observation of surface morphologies, the sandblasted specimen exibited a very rough surface, whereas the surfaces of the two groups primed with either MDR or MAC-10 were covered with a layer of primer, and the surface morphology of the silicoated specimen remained almost the same after sandblasting. Before the thermocycling tests, the group treated with MDP demonstrated the highest mean tensile bond strength and the sandblasted group showed the lowest bond strength. After 20,000 themocyling, the mean tensile bond strength of the sandblasted group exhibited a 50% reduction in bond strength, while the other showed a 20~30% reduction. Observation of the metal-resin interface revealed that in all groups the resin permeated the rough surface formed by sandblasting thereby producing a mechnical bond between the metal and the resin, It was also found that thermocycling resulted in a gap formation at the metal-resin interface of the specimens, and the sandblasted group exhibited a larger gap width than the other groups. in fracture mode, all specimens indicated a cohesive fracture within the resin before thermocycling. However, thermocyling produced adhesive failure at the edge of the resin-metal interface in most specimens, The sandblasted group, which exhibited the lowest bond strength after thermocycling, also demonstrated the largest area of adhexive failure.
Adhesives
;
Alloys*
7.ANALYSIS OF STRESS DEVELOPED WITHIN THE SUPPORTING TISSUE OF ABUTMENT TOOTH WITH INDIRECT RETAINER ACCORDING TO VARIOUS DESIGNS OF DIRECT RETAINER AND DEGREE OF BONE RESORPTION.
Suk Hyun LEE ; Cheong Hee LEE ; Kwang Hun JO
The Journal of Korean Academy of Prosthodontics 1998;36(1):150-165
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*
8.Two Cases of The Salt-losing Congenital Adrenal Hyperplasia.
Sung Hun EUN ; Cheong Min LEE ; Young Chang TOCKGO ; Hyun Keum LEE
Journal of the Korean Pediatric Society 1985;28(5):499-504
No abstract available.
Adrenal Hyperplasia, Congenital*
9.A clinical study on the thyroid nodule in childhood.
Yong Ju KIM ; Ki Young CHEONG ; Jong Jin SEO ; Young Hun CHUNG
Journal of the Korean Pediatric Society 1991;34(8):1116-1122
No abstract available.
Thyroid Gland*
;
Thyroid Nodule*
10.The Effects of Lidocaine and Propranolol on Heart Rate and Blood Pressure of the Ketamine.
Hun CHEONG ; Sung Su CHUNG ; Woong Mo IM
Korean Journal of Anesthesiology 1986;19(6):530-536
It is well known that ketamine produces an increase in the heart rate and blood pressure. Lidocaine has a direct myocardial depressant effect with indirect stimulant effects mediated by the autonomic nervous system, and propranolol, beta-adrenergic receptor blockade, has negative chronotropic effects through the beta-adrenergic blockade. In order to investigate the effect of propranolol and lidocaine on the heart rate and blood pressure increased by ketamine, lidocaine, and/or propranolol were administered intravenously in awake patients. The results were as follows. 1) In ketamine(2 mg/kg) receiving group, the heart rate increased 16-19 beats per minute and systolic, diastolic and the mean blood pressure increased significantly. 2) In ketamine(2 mg/kg)-lidocaine(2 mg/kg) receiving group, the heart rate increased l2-14 beats per minute, and the systolic, diastolic and mean blood pressure increased significantly. 3) In ketamine(2 mg/kg)-propranolol(0.02 mg/kg) receiving group, the heart rate increased below 5 beats per minute and systolic, diastolic, and the mean blood pressure increased significantly. 4) In ketamine(2 mg/kg)-propranolol(0.02 mg/kg)-lidocaine(2 mg/kg) receiving group, the heart rate increased only 3-4 beats per minute and systolic, diastolic, and mean pressures increased significantly. From the above results, the chronotropic effect of ketamine was markedly attenuated by propranolol or propranolol-lidocaine but not attenuated by lidocaine, and the pressor effect was not attenuated by lidocaine, or propranolol and propranolol with lidocaine.
Autonomic Nervous System
;
Blood Pressure*
;
Heart Rate*
;
Heart*
;
Humans
;
Ketamine*
;
Lidocaine*
;
Propranolol*