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

An epidemiological investigation was conducted on Metagonimus yokogawai infection in Hadong Gun (County), Gyeongsang Nam Do, Korea, and following findings were obtained. Overall prevalence rate of Metagonimus yokogawai infection was 29.1 percent from a total of 1,163 inhabitants examined. By area of river and stream, Seomjin-gang R.: 9.5 percent (out of 95 inhabitants examined) in Jeondo Ri in the lower river, 19.9 percent (156) at Dugog Ri near Hadong town, and 90.8 percent (65) in Tab Ri of Hwagae Myeon where Hwagae-cheon Stream joins; Hwagae-Cheon Stream: 42.2 percent (45) in Yonggang Ri of the middle stream and 27.5 percent (72) in Daeseong Ri of the upper stream; Hoengcheon-gang R.: 54.7 percent (161) in Gojeol Ri of the lower river, 40.6 percent (128) in Hoengcheon Ri of the middle stream, and 5.4 percent (93) in Jungi Ri of the upper stream, and 43.8 percent (89) in Uge Ri located along a tributary of the Hoengcheon-gang R. and 4.0 percent (101) in Jangam Ri which is located about 4 km away from the river; Deogcheon-gang R.: 18.5 percent (54) in Munam Ri; Gwangog-cheon Stream: 2.8 percent (107) in Gwangog Ri. The difference in prevalence rate of the infection by area was correlated with the opportunity and amount of raw eating of sweetfish by the inhabitants in the respective areas. By age and sex, the overall prevalence rate increased from young age group and reached a peak at 20-29 age group and then the rate decreased gradually. In high endemic areas, however, a peak level of the rate lasted up to 40-49 age group in male. On the other hand, in low endemic areas, the rate was significantly lower in female, though moderate level of the infection was seen in male. The overall prevalence rate was higher in male than in female and the difference was greater in middle age groups. The most significant mode of infection by the inhabitants was the raw eating of sweetfish which commonly harbour metacercariae of M. yokogawai during summer through autumn. Besides, it was noted that the infection can be acquired through contamination with the metacercariae on food of various side-dish and kitchen utensils as well as on hands of a cook when such fish are prepared or handled. The inhabitants usually begin to acquire infection from early June of a year when fishing of sweetfish opens and acquire infection more frequently in July and August when fish are caught more productively and favored for raw consumption by inhabitants. From September, sweetfish are no more favored for raw consumption and accordingly are dried and cooked in this season. The infection in the sweetfish Plecoglossus altivelis as the second intermediate host was first observed from May with low level of infection and the intensity of infection in a fish rapidly increased until reaching a peak in October when sweetfish season normally ends. The first intermediate host snail of M. yokogawai in this area was Semisulcospira coreana (Martens) which is widely distributed in the streams and rivers in this locality.
parasitology-helminth-trematoda ; Metagonimus yokogawai ; metacercaria ; Plecoglossus altivelis ; epidemiology

The purpose of this study was to evaluate the effect of wattage and curing time on surface hardness, three-point bending strength and internal porosity of microwave curing denture base resin. Two sizes of resin spicimens were made of Acron MC ; 3.5x10x60mm for surface hardness and three-point bending strength measurement and 5x12x60mm for internal porosity measurement. They were cured by microwave energy at varing wattages(500W, 700W) and curing times(2min., 3min., 4min.) to determine if a certain wattage/curing time combination would improve physical properties. Surface hardness was measured with Vikers hardness tester, three-point bend-ing strength with universal testing machine and internal porosity was calculated by measuring the weight in air and in water. The results obtained were as follows : 1. There was no significant difference in percent porosity among experimental groups(p>0.05). 2. 500W/3min, group showed the higher surface hardness than 700W/2, 3, 4min. groups(p<0.05), and 700W/4 min. group showed the lower surface hardness than 500W/2, 3, 4min. groups(p<0.05), but there was no significant difference among others(p>0.05). 3. 500W/3min. group yielded the higher value of bending strength than 500W/2min., 700W/3, 4min. groups(p<0.05), but there was no significant difference among others(p>0.05).
Denture Bases* ; Dentures* ; Hardness ; Hardness Tests ; Microwaves* ; Polymethyl Methacrylate ; Porosity ; Water

The Ross operation, a procedure of replacement of the diseased aortic valve with an autologous pulmonary valve, has many advantages such as no need for anticoagulation therapy and similar valve function and growth potential as native valves. However secondary aortic disease has emerged as a significant complication and indication for reoperation. We report a 48-year-old woman who had Ross operation in 1997 for a damaged bicuspid aortic valve and severe aortic regurgitation due to subacute bacterial endocarditis complicated by aortic root abscess. In 2009, 12 years later, progressive severe aortic regurgitation with incomplete coaptation and mild dilatation of the aortic root was shown on echocardiography and contrasted CT, while the pulmonary homograft retained normal function. She subsequently underwent aortic valve replacement. Histopathological examination of the explanted neo-aortic valve and neo-arterial wall revealed pannus formation at the nodulus Arantii area of the three valve cusps, ventricularis, and arterialis. The amount of elastic fibres in the neo-aorta media was less than usual for an aorta of this patient's age but was similar to a pulmonary artery. The pathological findings were not different from other studies of specimens removed between 7 to 12 years after Ross operation. However, the pathophysiology and long-term implications of these findings remain debatable. Considering the anatomical and physiological changes induced by the procedure, separate mechanisms for aortic dilatation and regurgitation are worthy of consideration.
Aorta/*pathology ; Aortic Valve/*surgery ; Aortic Valve Insufficiency/*etiology ; Cardiovascular Surgical Procedures/*adverse effects ; Dilatation, Pathologic ; Heart Valve Diseases/*surgery ; Prostheses and Implants ; Pulmonary Valve/*transplantation

STATEMENT OF PROBLEM: Second-generation indirect composite resins have been improved flexural strength, compressive strength, hydrolytic degradation resistance, wear resistance compared to first-generation indirect composite resins, but there are still some problems as hydrolysis and low wear resistance. Some manufacturers claim that wear resistance of their materials has been improved, but little independent study has been published on wear properties of these materials and the properties specified in the advertising materials are largely derived from in-house or contracted testing. PURPOSE: This study was to evaluate the wear of indirect composite resins (SR Adoro, Sinfony, Tescera ATL) and gold alloy against the human enamel. MATERIAL AND METHOD: Extracted human incisors and premolars were sectioned to 2*2*2mm cube and embedded in the clear resin and formed conical shaped antagonist to fit the jig of pinon-disk tribometer. Total 20 antagonists were stored in distilled water. Five disk samples, 24mm in diameter and 1.5mm thick, were made for each of three groups of indirect composite resins and gold alloy group, and polished to #2,000 SiC paper on auto-polishing machine. Disk specimens were tested for wear against enamel antagonists. Wear test were conducted in distilled water using a pin-on-disk tribometer under condition (sliding speed 200rpm, contact load 24N, sliding distance 160m). The wear of the enamel was determined by weighing the enamel antagonist before and after test, and the weight was converted to volumes by average density. The wear tracks were analyzed by scanning electron microscopy and surface profilometer to elucidate the wear mechanisms. Statistical analysis of the enamel wear volume, wear track depth and wear tract width of disk specimens were accomplished with one-way ANOVA and the means were compared for significant differences with Scheffe's test. RESULTS: 1. The enamel wear was most in gold alloy, but there were no statistically significant differences among all the groups (P>.05). 2. In indirect composite resin groups, the group to make the most shallow depth of wear tract was Sinfony, followed by Tescera ATL, SR Adoro (P<.05). Gold alloy was shallower than Sinfony, but there was no statistically significant difference between Sinfony and gold alloy (P>.05). 3. The width of wear tract of SR Adoro was larger than the other groups (P<.05), and there were no statistically significant differences among the other groups (P>.05). 4. SEM analysis revealed that Sinfony and gold alloy showed less wear scars after test, Tescera ATL showed more wear scars and SR Adoro showed the most. CONCLUSION: Within the limits of this study, Sinfony and gold alloy showed the least wear rates and showed similar wear patterns.
Alloys ; Bicuspid ; Cicatrix ; Composite Resins* ; Compressive Strength ; Dental Enamel* ; Humans* ; Hydrolysis ; Incisor ; Microscopy, Electron, Scanning ; Water

The proposed factors that affect the prognosis of osteosarcoma are the patient's age, site and size of the primary lesion, pathologic features(type and grade), duration of symptoms, spread of disease (local or regional extension, distant metastasis) at diagnosis, the patient's sex, serum alkaline phos- phatase(ALP) and lactic dehydrogenase(LDH) levels, chromosomal number or DNA index, response to initial chemotherapy, location of the lesion on the bone, presence or absence of pathologic fracture, and mode of therapy. The purpose of this study is to analyze the factors that affect the 5-year survival rates of osteosarcoma. Total 25 patients were included in this study who had treated form Jan. 1988 to Apr. 1994. The overall 5-year survival rate of 25 patients was 65.43%, and the 5-year survival rates were sig- nificantly higher(P < 0.1) in the groups in which limb salvage operation with neoadjuvant chemothera- py were performed(66.67%), with longer duration of symptoms(>2 months; 83.33%), with lower serum level of LDH( < 300 U/L; 100%), and with smaller mass size( < 10cm; 72.92%). However there were no significant differences in the 5-year survival rates according to age and sex of the patients. We also suggest that the better prognosis will be observed in the patients with the favorable radiologic response to the preoperative chemotherapy.
Diagnosis ; DNA ; Drug Therapy ; Fractures, Spontaneous ; Humans ; Limb Salvage ; Osteosarcoma ; Prognosis ; Survival Rate

STATEMENT OF PROBLEM: It could be hypothesised that attachments, which provide more retention against vertical and horizontal dislodgement, will be associated with more favorable parameters of oral function. PURPOSE: This study was to provide data of initial retentive force and retention loss of different bar attachment systems recommended for use with maxillary implant overdentures. MATERIAL AND METHOD: 4 implants were placed in the anterior region of edentulous maxilla, five different systems of bar attachment were fabricated as follows: cantilevered Hader bar using clips (Type 1), Hader bar using clips without cantilever (Type 2), Hader bar using clip and ERA attachment orange male (Type 3), Hader bar using clip and ERA attachment white male (Type 4), and Bar using magnets (Type 5). Each samples were placed in the universal testing machine for determination of retentive forces(at initial and after every 200 cycles up to 1,000 cycles). Results and Conclusion 1. Attachment type 1 showed the biggest initial retentive force followed by type 3, type 2, type 4, and lastly type 5( p<0.001). 2. After 1,000 cycles of repeated removals of attachments, significant loss of retentive forces was taken place except for attachment type 5. 3. After 1,000 cycles of repeated removals, the loss of retentive force between type 1 and type 2, which used Hader bar and clip attachments, was greater in type 1 that had wider clip formation. And between type 3 and type 4, which used ERA attachments, the loss of retentive force was greater in type 4 that had white male attached (p<0.001). 4. After 1,000 cycles of repeated removals, attachment type 3 showed the biggest retentive force followed by type 2, type 4, type 1 and lastly type. 5. There was no significant difference between attachment type 3 and 4, and type 4 and 1(p<0.001).
Citrus sinensis ; Denture, Overlay* ; Humans ; Male ; Maxilla

PURPOSE: The purpose of this study was to compare the fracture strength of the zirconia monolithic all-ceramic crowns according to the thickness (0.5mm, 0.8mm, 1.1mm) and metal-ceramic crowns (1.0mm, 1.5mm). MATERIAL AND METHOD: Twelve crowns for each of 3 zirconia crown groups were fabricated using CAD/CAM system (Kavo, Germany) and twelve crowns for each of 2 metal-ceramic crown groups were made by the conventional method. All crowns were luted to the metal dies using resin cement. Half of the specimens were exposed to thermocycling (5-55degrees C, 1 Hz) and cyclic loading (300,000 cycles, 50N). Subsequently, all crowns were mounted on the testing jig in a universal testing machine. The load was directed at the center of crown with perpendicular to the long axis of each specimen until catastrophic failure occurred. Analysis of variance and Tukey multiple comparison test (P<.05) were used for statistical analysis of all groups, and paired t-test (P<.05) was followed for statistical comparison between each groups'fracture load before and after cyclic loading. RESULTS: 1. The fracture strength of the zirconia monolithic crowns and the metal-ceramic crown increased as thickness increased (P<.05). 2. The cyclic loading and thermocycling significantly decreased the fracture strength of the zirconia monolithic crowns (P<.05). 3. The standard deviation of fracture strength of the zirconia monolithic crowns was very low. CONCLUSION: The fracture strength of the zirconia monolithic crowns for the posterior area tends to be higher with thickness increased and 0.8mm or over in thickness is recommended to have similar or over the fracture strength of metal-ceramic crowns.
Axis, Cervical Vertebra ; Crowns* ; Resin Cements

The purpose of this study was to investigate the effects of investing conditions on the marginal discrepancy of conical telescope outer crown with Co-Cr-Ti alloy(Dentitan) and to compare the marginal discrepancy and the retention force of outer crowns using different pattern materials (plastic foil, casting wax, pattern resin). To evaluate the effects of investing conditions on the marginal discrepancy, patterns with plastic foil were invested under three different liquid/powder ratio conditions using phosphate bonded investment (Univest-nonprecious): standard, 10% decreased and 10% increased. At each liquid/powder ratio condition, metal ring was lined with single or double layers of ceramic ring liner. The marginal discrepancy of outer crown at different investing conditions was measured by x 100 compact measuring microscope(STM5, Olympus, Japan). For measurement of the marginal discrepancy and the retention force of outer crown using different pattern materials, the investing condition of 10% decreased liquid/powder ratio and double layers of ring liner was selected because this investing condition resulted in the best fit of outer crown. Marginal discrepancy was measured in the same way above and retention force on universal testing machine. Under the conditions of this study, the following conclusions were drawn: 1. The thickness of ring liner had more influence on the marginal discrepancy of outer crown than the liquid/powder ratio, and the acceptable marginal fitness could not be expected at the investing condition directed by investment manufacturer. 2. There were no differences in the marginal discrepancy of outer crown among three different pattern materials 00.05). 3. Casting wax showed the greatest retention force(1640g) of outer crown, followed by pattern resin(1110g), plastic foil(820g). However, there was no significant difference between plastic foil and pattern resin(p>0.05). 4. Plastic foil showed the least variation in marginal discrepancy and retention force.
Alloys* ; Ceramics ; Crowns* ; Investments ; Plastics ; Telescopes*

This study evaluated the effect of dagassing on the ceramic bond strength of two Ni-Cr alloys under varying holding time at the upper limit temperature and atmospheric conditions. Metal specimens were divided into 5 groups for each alloy according to degassing conditions prior to porcelain application : no degassing, degassing under vacuum without hold, degassing under vacuum with hold for 5min. and 10 min. respectively at the upper limit temperature and degassing in air. Total number of metal ceramic specimens was eighty and each group had eight specimens : The ceramic bond strength was measured by four-point flexural test using Instron and the fractured surface was examined under SEM. The results obtained were as follows. 1. Degassing in air improved the ceramic bond strength of Ni-Cr alloys. 2. in degassing under vacuum, hold at the upper limit temperature was advantageous to the ceramic bonding of Ni-Cr alloys. 3. After ceramic metal bond test, metal surfaces were partially covered with the thin porcelain layer, and the cohesive failures in porcelain were predominant in groups showing higher ceramic bond strength.
Alloys* ; Ceramics* ; Dental Porcelain ; Vacuum