The purpose of this study was to evaluate clinical applications of electroplating method through investigation of the physical properties of orthodontic rectangular wires according to varying their cross section. For the study, it was accomplished to electroplate the 0.016-inched orthodontic rectangular stainless steel wire. The cross section of stainless steel orthodontic rectangular wire increased from 0.016 x 0.016 inch to 0.017 x 0.017 inch by electroplating. The wire was heat treated to improve an adhesion between the wire and electroplated metal. A three-point bending test and torsion test were conducted in order to compare physical properties among three wire groups; 0.016 x 0.016 wires (group 016), electroplated 0.016 x 0.016 wires (group 016P) and 0.017 x 0.017 wires (group 017). Through the investigations of each wire group, following results were obtained. 1. At three-point bending test, the group 016P showed higher tendency in the degree of stiffness, yield strength and ultimate tensile strength than the group 016. Stiffness and ultimate tensile strength showed statistically significant differences between two groups at three-point bending test (p<0.05). 2. Stiffness, yield strength, and ultimate tensile strength of the group 016P showed lower tendency than those of the group 017. Stiffness showed statistically significant differences between two groups at three-point bending test (p<0.05). 3. Torque/twist rate, yield torsional moment, and ultimate torsional moment of the group 016P showed higher tendency than those of the group 016. All measurements showed statistically significant differences between two groups after torsion test (p<0.05). 4. Torque/twist rate, yield torsional moment, and ultimate torsional moment of the group 016P showed lower tendency than those of the group 017. Yield torsional moment, and ultimate torsional moment showed statistically significant differences between two groups after torsion test (p<0.05).
Electroplating* ; Hot Temperature ; Stainless Steel* ; Tensile Strength

OBJECTIVETo improve the occupational health management levels in electroplating enterprises with quantitative classification measures and to provide a scientific basis for the prevention and control of occupational hazards in electroplating enterprises and the protection of workers' health.

METHODSA quantitative classification table was created for the occupational health management in electroplating enterprises. The evaluation indicators included 6 items and 27 sub-items, with a total score of 100 points. Forty electroplating enterprises were selected and scored according to the quantitative classification table. These electroplating enterprises were classified into grades A, B, and C based on the scores.

RESULTSAmong 40 electroplating enterprises, 11 (27.5%) had scores of >85 points (grade A), 23 (57.5%) had scores of 60∼85 points (grade B), and 6 (15.0%) had scores of <60 points (grade C).

CONCLUSIONQuantitative classification management for electroplating enterprises is a valuable attempt, which is helpful for the supervision and management by the health department and provides an effective method for the self-management of enterprises.

Acid erosion of teeth was studied in two factories. The A was the textile factory possessing dyeing process using acids. The B was the metal product manufactof,ing factory possessing electroplating process. The control group was selected at the same factory not exposed to acids. The results were summarized as below. 1. The pH of saliva was the range of 6.6+/-6.8 in both factories. 2. The prevalence rate of erosion of teeth was higher in case group at ,the B. It was statistically significant. 3. The rate of erosion of incisor were the range of 12%16% (case group), 7%21,0,o (control group) at the A and 10%-20%(case group), 2%-5%(control group) at the B. 4. The rate of erosion of degree 3 which is necessary for conforming, owing to occupational induction, were 8.9% (incisor: A) and 6.8/0,o(incisor: B).
Electroplating ; Hydrogen-Ion Concentration ; Incisor ; Prevalence ; Saliva ; Textiles ; Tooth

The screw loosening is one of the complications that happen frequently in dental implant prostheses. The purpose of this study was to evaluate the changes of reverse/loosening (opening) torque of the screw according to the surface modifications by sandblasting and 24K gold electroplating as well as to determine the possibility of the clinical use of a washer in dental implant. The reverse torque of 4 experimental conditions(control, sandblasted, use of washers, electroplasted) was measured by digital torque gauge (Model MGT50Z, Mark-10 Corp., 458 West John Street Hicksville, NY 11801 USA). Electronic torque controller (Nobel Biocare DEA 020) was used in fastening the gold screws into abutment replicas. Mixed Linear Model Analysis method was used for statistical analysis. To examine the changes of screw thread surface, microphotographs were taken by Olympus PME-3 metallurgic microscope (Olympus Optical Co. Ltd., Tokyo, Japan). Within the limitations of this study, the following results were drawn: 1. The surface modifications of the gold screws and the use of a washer have significantly affected the reverse torque value compared to the control group (p<0.01). 2. Sandblasting and electroplating treatments demonstrated significantly higher reverse torque val-ue than that of control group. 3. The use of a washer may be one of the useful clinical methods that prevent the screw loosening. However, further studies are necessary for the material selection and design of the washer.
Dental Implants ; Electroplating ; Linear Models ; Prostheses and Implants ; Torque*

The purpose of this study was to evaluate electroless plating as a method of increasing the diameter of an orthodontic wire in comparison with eletroplating. After pretreatment plating of the 0.016 inch stainless steel orthodontic wire, electroless plating was performed at 90 degrees C until the diameter of the wire was increased to 0.018 inch. During the process of electroless plating, the diameter of the wire was measured every 5 minutes to examine the increasing ratio of the wire' diameter per time unit. And to examine the uniformity, the diameter at 3 points on the electroless-plated orthodontic wire was measured. An X-ray diffraction test for analyzing the nature of the plated metal and a 3-point bending test for analyzing the physical property were performed. The electroless-plated wire group showed a increased tendency for stiffness, yield strength, and ultimate strength than the electroplated wire group. And there was a statistically significant difference between the two groups for stiffness and ultimate strength. In the electroless-plated wire group, the increasing ratio of the diameter was 0.00461 +/-.00003 mm/5 min (0.00092 mm/min). In the electroplated wire group, it was 0.00821 +/-.00015 mm/min. The results of the uniformity test showed a tendency for uniformity in both the plating methods. The results of this study suggest that electroless plating of the wire is closer to the ready-made wire than electroplating wire in terms of the physical property. However, the length of plating time needs further consideration for the clinical application of electroless plating.
Electroplating* ; Orthodontic Wires* ; Stainless Steel ; X-Ray Diffraction

Rigid fixation techniques with absorbable plates and screws are recently utilized for the repair of craniofacial skeletal injuries or congenital anomalies. But no domestic literature are presented in treatments of mandible fracture. We present our early experience of absorbable plates and screws in fixation of mandible fracture. Eleven patients underwent fixation procedures for mandible fracture with absorbable plates and screws. Intraoperative stability was satisfactory in all cases. Significant problems, such as nonunion, malunion, delayed union and malocclusion from the use of absorbable plating system were not found, but there were two cases of localized inflammation. We also experienced advantages of absorbable plating system which are biodegradation, radiolucency and enough stability for reduction state. The use of absorbable plating system would eliminate potential effects on skeletal growth- restriction in child, problems associated with long- term palpability and visibility in X-ray, and cold sensitivity caused by traditional metal plating system. There are also several disadvantages of absorbable plates and screws. This plating system takes increased operative time and needs delicate technique relative to the traditional metal plating system. Nevertheless we concluded that absorbable plates and screws are good fixatives for mandibular fracture.
Child ; Electroplating ; Fixatives ; Humans ; Inflammation ; Malocclusion ; Mandible ; Mandibular Fractures* ; Operative Time

Twenty-four factories registered at the Ministry of Labor as factories using or producing cadmium in 1991 were investigated to know the present state of occupational exposure to cadmium in 1992. Nine factories among 24 stopped using or changed to other substances and 1 factory didn't produce any more, but delivered it to other factories through imports. Therefore, only 14 factories were producing or using cadmium. But, alloying materials were uspplied to about 20 and more factories, however, they couldn't be investigated because of limited information. Three factories had less than 50 workers were 3, 6 had 50-300 and 5 had more than 300. About 167 workers were exposed to cadmium. According to the classification by process, there were 4 alloy processes, 2 refinary, 2 elctroplating, 2 dry cell making, 1 industrial battery and 1 copper refinary. 8 factories used metal cadmium, 3 cadmium oxide, 2 cadmium sulfide, and 1 cadmium hyroxide. One factory was importing cadmium stearates only and supplying them to the PVC making factories. The amount of metal cadmium producing in 2 refinary factories was about 50-65 ton per month. The other cadmium compounds were imported. According to exposure level of cadmium in air of the 10 factories examined, each factory could be divided into high, moderate and low exposure groups. 1 battery recycling factory and 3 alloy factories were in the high exposure group and their mean air concentrations were 0.06679, 0.05481, 0.02492, and 0.003mg/m3, respectively. Refinary and industrial battery making factories were in the middle exposure group and their mean air concentrations were 0.00773 and 0.00613 mg/m3, respectively. Finally, low exposure group were copper smelting, dry cell case making, duplicator drum making and electroplating factory and their mean air concentrations were 0.00096, 0.00071, 0.00057 and 0.00054 mg/m3 respectively.
Alloys ; Cadmium Compounds ; Cadmium* ; Classification ; Copper ; Electroplating ; Korea* ; Occupational Exposure* ; Osmeriformes ; Recycling ; Stearates

Craniofacial reconstructive procedures are frequently peformed with rigid fixation of the bone. During the period of active bone growth such manipulation may influence bone development. The purpose of this study was to determine the effects of metal plating of the mandible on the growth and morphology of the mandibulofacial skeleton. New Zealand white rabbits, 6 to7 weeks of age, were divided into 5 groups. They were designated as group I(nonoperated control, n=10), group II (rigid fixation of mandibular body after vertical osteotomy, n=10), group III(rigid fixation without osteotomy, n=10), group IV (interosseous wire fixation after osteotomy, n=10), and group V(rigid fixation and removal of plates and screws 4 weeks after osteotomy, n=7). Rabbits were sacrificed 12 weeks after operation and dry skull preparations were grossly measured and analyzed by direct measurement and by dorsoventral skull x-rays. Measurements taken were length, thickness, angle, and area of the mandibulofacial skeleton. Three-dimensional CT was used for volumetric measurement of the mandible. The data wee compared between the operated and nonoperated sides and significant differences between groups were evaluated using the paired t-test, the ANOVA test, and Dunn's test. The following results were obtained: 1. The length of the whole mandible and the anterior mandibular segment was decreased in groups II and III, compared with group I(p>0.05). These results show growth restriction of the plated mandible regardless of osteotomy. 2. The maxillary alveolus of the operated side was more anteriorly placed in groups II and III, compared with group I (p>0.05). 3. The thickness of the operated mandibular body showed a significant increase in groups II and III, compared with group I(p>0.05). 4. The length of the zygomatic arch of the operated side in all the experimental groups showed a significant decrease, compared with group I(p>0.05). The angular divergence of the mandibular ramus from the sagittal midline of the skull was increased in the operated side of groups II and III, compared with the nonoperated side (p>0.05). 5. Volume measurements of the mandible in groups II and III showed a significant reduction of the volume on the operated sides in the anterior mandibular segment, compared with group I(p>0.05). The volume of the operated mandibular body showed a significant increase in groups II and III, compared with group I(p>0.05). All gruops showed no significant difference in total hemiman dibular volume of the operated side compared with the nonoperated side. These results show that rigid fixation of mandibular fractures during the growth period causes a more severe growth restriction than either osteotomy or interosseous wiring.
Bone Development ; Electroplating ; Mandible ; Mandibular Fractures ; Osteotomy ; Rabbits* ; Skeleton ; Skull ; Zygoma

The purpose of this study was to examine the cytotoxicity of orthodontic wire which had an increased diameter through electroplating, and to evaluate its possible clinical applications. First, nickel plating was carried out on the commercially available stainless steel wire using an electroplating technique. For the comparison of the electroplated wire with ready made stainless steel wire and titanium or copper, each wire was incubated for 72 hours in a medium. The release of the metal ion was measured using ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrophotometer). Balb/c 3T3 mouse fibroblast was put on a microplate and placed in an incubated medium of 75%, 50%, and 20% dilation. An MTT analysis was used to compare with the medium only. The change in absorbency value of each wire group and the difference of absorbency value according to the change of dilution was measured. The results of ICP-AES analysis showed that great amount nickel ion was isolated from electroplated orthodontic wires and great amount copper ion was isolated from copper. The results of the MTT analysis showed that there was no difference in the absorbency value of titanium at any dilution. However, the electroplated wires (p < 0.001), the stainless steel wires (p < 0.05) and the copper (p < 0.001) were statistically significantly lower than those of medium only at all dilutions. Assessment as per ISO 10993, part 5, showed that electroplated wire was alloted to "moderate cytotoxic", the titanium and stainless steel wire were "non-cytotoxic". The results of this study indicate that the electroplated orthodontic wires need additional efforts to decrease cytotoxicity for their clinical applications.
Animals ; Copper ; Electroplating ; Fibroblasts ; Mice ; Nickel ; Orthodontic Wires* ; Plasma ; Stainless Steel* ; Titanium

The purpose of this study was to evaluate the possibile clinical application of electroplating to increase diameter of an orthodontic wire, through examining the change of physical properties. The diameter of stainless steel orthodontic wire was increased from 0.016 inch to 0.018 inch by electroplating in a bath of nickel sulfate 100g/L, nickel chloride 60g/L, boric acid 30g/L, and sodium chloride 50g/L, under the conditions of 1.7V, 25~29degrees C, and 3.1~3.3pH. During the electroplating, the rate of diameter increase was measured every minute. To investigate uniformity, the diameter was measured at three different locations of each wire specimen after electroplating. An X-ray diffraction test was performed to analyze the nature of the electroplated metal. Following heat treatment to improve adhesion between the wire and electroplated metal, a three-point bending test was conducted to compare stiffness, yield strength, and ultimate strength among four wire groups; 0.016 inch, electroplated 016, electroplated and heat-treated 016, and 0.018 inch wires. Through the comparison of each wire group, following results were obtained. 1. In the load-deflection graph, the curve of the electroplated group was placed between that of the 0.016 inch group and the 0.018 inch group, and the curve was closer to the 0.018 inch group by heat treatment. 2. In the electroplated and heat-treated 016 wire group, the values of stiffness, yield strength and ultimate strength showed higher tendency than in the original 0.016 inch group. Stiffness and ultimate strength showed statistically significant differences between two groups. 3. Stiffness, yield strength, and ultimate strength of electroplated wire presented lower values than those of 0.018 inch wire group. 4. Stiffness, yield strength, and ultimate strength of electroplated and heat-treated wire showed higher tendency than those of electroplated wire group, and ultimate strength showed statistically significant difference between two groups. 5. After electroplating, the difference in diameter between the three locations was within 0.1~0.3% variation, and showed no statistical significance.
Baths ; Electroplating* ; Hot Temperature ; Nickel ; Orthodontic Wires* ; Sodium Chloride ; Stainless Steel ; X-Ray Diffraction