• The Journal of Advanced Prosthodontics
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• v.5 no.1
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• pp.44-50
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• 2013

PURPOSE. The aim of this study was to evaluate the effects of repeated porcelain firing process on the corrosion rates of the dental alloys. MATERIALS AND METHODS. Cr-Co, Cr-Ni and Pd-Ag alloys were used for this study. Each metal supported porcelain consisted of 30 specimens of 10 for 7, 9 and 11 firing each. Disc-shaped specimens 10 mm diameter and 3 mm thickness were formed by melting alloys with a propane-oxygen flame and casted with a centrifuge casting machine and then with the porcelain veneer fired onto the metal alloys. Corrosion tests were performed in quintuplicate for each alloy (after repeated porcelain firing) in Fusayama artificial saliva solution (pH = 5) in a low thermal-expansion borosilicate glass cell. Tamhane and Sheffe test was used to compare corrosion differences in the results after repeated firings and among 7, 9 and 11 firing for each alloy. The probability level for statistical significance was set at ${\alpha}$=0.05. RESULTS. The corrosion resistance was higher (30 mV), in case of 7 times firing (Commercial). On the other hand, it was lower in case of 11 times firing (5 mV) (P<.05). Conclusion. Repeated firings decreased corrosion resistance of Pd-Ag, Cr-Co and Cr-Ni alloys. The Pd-Ag alloy exhibited little corrosion in in vitro tests. The Cr-Ni alloy exhibited higher corrosion resistance than Cr-Co alloys in in vitro tests.

• Research in Community and Public Health Nursing
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• v.7 no.2
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• pp.410-419
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• 1996

This study was reviewed from 1000 articles related to family planning from 1970 to 1990 and 20 articles associated with natural family planning from 1980 until the present. The purpose of natural family planning(NFP) is to identify the time ovulation of women themselves, to have intercourse with periodic abstinence, and to deliver a healthy child. The ultimate goal of NFP is to promote the family's health. The NFP method is described as periodic abstinence of intercourse to avoid pregnancy by identifying the ovulation time in the menstration cycle. Clinical symptoms and signs of reflection underlying changes in Estrogen and Progesterone are the change of basal body temperature, the change of cervical mucus and cervix, abdominal pain and breast tenderness. The types of NFP are the calender rthythm method, basal body temperature methods, cervical mucus method, symptothermal method, cyclo-thermal method and home based ovulation test kits. Recently the cyclo-thermal method involved. It is calendar rhythm method applied to B.B.T. For the cervical mucus method, when the estrogen level in the blood concentration is increased, the mucus begins to excrete, the amount of moist mucus increases while the mucus is clear, slippery, and smooth. For 3 days, this timing can be considered contraception. Fertility is at a maximum on the day mucus appears, abstinence for 3 days is a type of contraception. Sexual intercourse on a maximum day of mucus maximizes pregnancy potential. But, the contraception depends on the practice of a perfect rule. For basal body temperature methods, at ovulation time, the temperature increases $0.2^{\circ}C-0.5^{\circ}C$. Through the review of literature a high temperature above $0.2^{\circ}C$ for 3 days indicates that the previous 6 day period was ovulation and fertilization. The Symptothermal method is used to determine the prediction of ovulation through the observation of mucus excretion, high temperature, the change of cervical mucus, low abdominal pain, vaginal discharge, and breast change. Home based ovulation test kits are cervico-vaginal fluid aspiration, test a digital electric thermometer, body fluid(blood, saliva, urine) test kits, They are on the market. However, research on the contraception method is still in progress. For pregnancy it is still too early to use home based ovulation test kits because of deficit of reliability and simplicity more research on the technology is needed. It is suggested that NFP methods be included in nursing curriculum in order to educate NFP users how to effectively use NFP methods. Furthermore, this study has implications for the dissemination of NFP methods in terms of Korean policies of family planning and the support of community welfare agences.

• Journal of Korean society of Dental Hygiene
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• v.8 no.1
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• pp.119-131
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• 2008

This study was peformed in order to find out the relationship between the causing factors and the production of each gas 01 oral malodor, to contribute the oral malodor control at dental clinic as well as to establish the effective application of malodor control project for public oral health program 127 patients from 20 to 40 years old who had been visited for preventive dental cares were participated for the study. Such items as caries status, periodontal status, salivary flow, viscosity, pH. Snyder test, plaque deposit and tongue plaque were checked through the oral examination in order to find out the contributing factors Hydrogen sulfide, Methyl mercaptan, Di-methyl sulfide and Ammonia gas components were checked with Oral-Chroma and Attain, the oral malodor check units. Not only the corelation coefficiencies but also the multi-way variance analysis were calculated between each causing factor and each component of oral malodor gases to estimate the contributing factors of the oral malodor. 1. There was no relationship between the caries status and each component pf the oral malodor such as sulfur compound or Ammonia, both in laboratory test and VAS test (pF0.05). It revealed negative relationship between Hydrogen sulfide and FT(rM-0.1904. pE0.05) as well as the VAS and FT (rM-0.210. pE0.05). S0, it was estimated that the less oral malador was recognized when caries state changed to filled state in Hydrogen sulfide laboratory test or VAS test 2. High relationship was showed between salivary flow and Hydrogen sulfide (rM-0.183, pM0.039), Methyl mercaptan(rM-0.234, p-0.008). Dimethyl sulfide(rM-0.234, pM0.008) and Ammonia(-0.361. pM0.001) gas(pE0.05). 3. There was a high relationship between M-PHP(Modified-Patient Hygiene Performance Index) and tong plaque all kinds of sulfide(rM0.249. pM0.005). Ammonia gas component(rM0.232, pM0.009). 4. It was found that considerable relationship was appeared between the periodontal status and Ammonia gas (rM0.274, pM0.002), so, it should be needed to control Ammonia. Such dental Cares as the prevention or early treatment of periodontal disease and the accelerating the salivary flow as well as reducing the amounts and activities of filament or spiral typed oral micro-organism were recommended for adults, not only for dental care program at the dental clinics but also for public health programs, in order to promote the oral health and quality of file for individual and community peoples.

• Journal of dental hygiene science
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• v.4 no.3
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• pp.103-109
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• 2004

The present study prepared 72 test samples - 24 made of amalgam alloy, 24 of Verabond (Ni-Cr alloy) for crown and 24 of Talladium $^{TM}alloy$ for denture - according to the manufacturers' manuals and general method in consideration of the width of the mesial-distal dental crown of the lower $1^{st}$ molar and MOD cavity in clinics, put them in a 200 ml beaker containing 80 ml of artificial saliva, and measured their galvanic corrosion at distances of 0 mm, 7 mm and 40 mm after 7 days. Isolated metals in the electrolyte such as Cu, Ag, Ni, Cr, Sn, Zn and Hg were quantitatively analyzed with Inductively Coupled Plasma - Atomic Emission Spectrometer (ICP-AES, JY-50P, VG Elemental Co. France), and from the results were drawn conclusions as follows. First, Cu, Sn, Ag, Hg and Zn were highly advantageous when amalgam contacted gold alloy compared to Ni-Cr alloy for crown and Talladium alloy for denture. In addition, although gold alloy was finest in terms of oral tissue and biocompatibility, it was most disadvantageous when it was with amalgam. Second, when amalgam contacted gold alloy, heavy metals such as Ni and Cr were not isolated at all because gold alloy did not contain such elements but Sn was isolated as much as $227.1{\pm}18.0035{\mu}g/cm^2$ although it was not included in the composition either. Hg was also isolated. These elements are assumed to have been isolated from amalgam itself. Third, when amalgam alloy was apart from gold alloy 0 mm, 7 mm and 40 mm, Cu and Ag showed significance but Hg did not. This suggests that gold alloy must not be used together with amalgam, and must not be used between dissimilar prostheses regardless of distance. Fourth, when amalgam alloy contacted Ni-Cr alloy for crown, Ag was not isolated from the amalgam, but Zn, Ni, Sn, Hg and Cu were isolated in order of quantity. Significance was observed according to distance - 0 mm, 7 mm and 40 mm. Hg was not isolated but heavy metals Ni and Cr were isolated. If amalgam alloy was in the opposite arch or it was apart from Ni-Cr alloy for crown, the isolation Hg was less than that when amalgam alloy contacted Ni-Cr alloy for crown. Fifth, when amalgam alloy contacted Talladium alloy for denture, significance was observed at distances of 0mm, 7 mm and 40 mm. Hg was not isolated but heavy metals Ni and Cr were isolated. If amalgam alloy was in the opposite arch or it was apart from Talladium alloy for denture, the isolation Hg was less than that when amalgam alloy contacted Talladium alloy for denture. Sixth, according to the result of ICPES test on Cu, Sn, Ag, Hg, Zn, Ni and Cr of amalgam alloy, gold ally, Verabond and Talladium alloy when these alloys contacted artificial saliva, significance was observed in Cu and Hg. Seventh, when amalgam alloy contracted two non-precious metals Ni-Cr alloy for crown and Talladium alloy for denture in artificial saliva, significance was observed in the isolated by-products of Hg, Ni and Cr according to distance.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.43 no.5
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• pp.299-304
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• 2017

Objectives: To test the feasibility of submandibular salivary gland (SMG) replantation techniques and the survival of the replanted glands. Such a study can provide a rationale for later allotransplantation procedures, along with implementation of conventional and advanced immunosuppression therapy. Materials and Methods: Six SMG replantations were performed in New Zealand white rabbits. One week postoperatively, $^{99m}Tc$ scintigraphy was performed and the uptake ratio and salivary excretion fraction were calculated. Two to four weeks later, submandibular glands were excised, fixed, and stained with H&E for histomorphometric evaluation. Results: Intraoperatively, all glands showed patent blood perfusion except gland 5. Positive tracer uptake and saliva excretion were documented by scintigraphy. On excision, all of the glands except glands 4 and 5 looked viable, with a red color and patent pedicles. Gland 4 was infected and filled with creamy pus, while gland 5 looked pale and necrotic. Histologically, glands 1, 2, 3, and 6 had preserved normal glandular tissue with slight variations from the contralateral normal glands, as their parenchyma was composed of mildly atrophic acini. Conclusion: Four out of six replanted SMGs successfully survived. The glands maintained good viability and function. Such success depends on safe harvesting, short anastomosis time, and strict control of infection.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.sup3
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• pp.77-80
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• 2016

Oral squamous cell carcinoma (OSCC) is one of the ten most common causes of cancer death worldwide. Assessment of molecular changes can help detect and control lesions. The aim of this study was evaluation of salivary levels of ErbB2 and CEA in OSCC patients. In this case-control study, 27 OSCC patients and 26 healthy controls participated. After obtaining consent and filling out a questionnaire, unstimulated saliva samples were collected from people in the morning for measurement of the two markers using ELISA. Data were analyzed using Mann Whitney U test in SPSS 19 software with P<0.05 considered significant. Subjects were in the age range of 40 to 65 years. \Salivary level CEA was elevated in OSCC samples ($42.6{\pm}21.1ng/ml$) as compared to those of controls ($22.6{\pm}22.1ng/ml$) (p< 0.01), but no significant variation was noted for ErbB2 ($5.2{\pm}1.8ng/ml$ and $4.93{\pm}2.14ng/ml$, p=0.28). The role of ErbB2 as a tumor marker in patients with OSCC must still be regarded as controversial and needs further studies to clarify any significance for early detection or screening. In contrast the salivary level of CEA may find application for early detection of patients.

• Journal of the Korean institute of surface engineering
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• v.41 no.2
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• pp.69-75
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• 2008

Electrochemical behaviors of surface modified and MC3T3-E1 cell cultured Ti-30Ta alloys have been investigated using various electrochemical methods. The Ti alloys containing Ta were melted by using a vacuum furnace and then homogenized for 6 hrs at $1000^{\circ}C$. MC3T3-E1 cell culture was performed with MC3T3-E1 mouse osteoblasts for 2 days. The microstructures and corrosion resistance were measured using FE-SEM, XRD, EIS and potentiodynamic test in artificial saliva solution at $36.5{\pm}1^{\circ}C$. Ti-Ta alloy showed the martensite structure of ${\alpha}+{\beta}$ phase and micro-structure was changed from lamellar structure to needle-like structure as Ta content increased. Corrosion resistance increased as Ta content increased. Corrosion resistance of cell cultured Ti-Ta alloy increased predominantly in compared with non cell cultured Ti- Ta alloy due to inhibition of the dissolution of metal ion by covered cell. $R_p$ value of MC3T3-E1 cell cultured Ti-40 Ta alloy showed $1.60{\times}10^6{\Omega}cm^2$ which was higher than those of other Ti alloy. Polarization resistance of cell-cultured Ti-Ta alloy increased in compared with non-cell cultured Ti alloy.

• Journal of Korean society of Dental Hygiene
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• v.13 no.2
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• pp.271-277
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• 2013

Objectives : The purpose of this study was to evaluate the effects of incremental dental care(IDC) program on kindergarten children. Methods : The subjects were 46 kindergarten children aged 6 who wished participation in IDC program during 5 weeks at oral health center in G-college from March to May, 2012. The data of subjects were examined into oral conditions such as toothbrushing method and frequency, modified O'leary plaque index and dental caries activity before and after IDC program. The collected data were analyzed by SPSS statistical package version 19.0. Results : 1. The rolling and fones methods of toothbrushing increased from 10.8% to 91.3% after IDC program(p<.001). The change of toothbrushing frequency showed that over 3 times a day increased from 52.2% to 76.0% after IDC program(p<.01). 2. The modified O'leary plaque index of before toothbrushing education increased from 1st visit(score 32.19) to 5th visit(score 57.14) and after toothbrushing education increased from 1st visit(score 64.45) to 5th visit(score 78.27) during IDC program(p<.001). 3. As a results of dental caries activity test before and after IDC program, it was found that the bacterial numbers in S.mutans and Latobacillus reduced from 0.74, 0.70 to 0.28, 0.41 (p<.01) and the saliva buffering capacity increased from 1.50 to 2.02(p<.001). Conclusions : It is considered very necessary that IDC program should be maintained and extended to dental clinic so as to enhance the oral health state of kindergarten children.

• Safety and Health at Work
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• v.9 no.2
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• pp.203-209
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• 2018

Background: Night shift work is associated with many problems such as sleep deprivation, sleepiness, decreased cognitive performance, increased human errors, and fatigue. This study set out to measure cognitive performance, melatonin rhythms, and sleep after different consecutive night shifts (7 vs. 4) among control room operators (CORs). Methods: The participants included 60 CORs with a mean age of 30.2 years (standard deviation, 2.0) from a petrochemical complex located in Southern Iran. Cognitive performance was assessed using the n-back task and continuous performance test. To evaluate melatonin, saliva was collected and tested by enzyme-linked immunosorbent assay. To assess sleep and sleepiness, the Pittsburgh Sleep Quality Index and Karolinska Sleepiness Scale were used, respectively. Results: Individuals who worked 7 consecutive night shifts had a significantly better cognitive performance and sleep quality than those who worked 4 consecutive night shifts. However, salivary melatonin profile and sleepiness trend were not affected by shift type. Conclusion: The main duty of CORs working night shifts at the studied industry included managing safety-critical processes through complex displays; a responsibility that demands good cognitive performance and alertness. It is suggested that an appropriate number of consecutive night shifts in a rotating shift system should be planned with the ultimate aim of improving CROs performance/alertness and enhancing safety.

• The Journal of Advanced Prosthodontics
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• v.8 no.1
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• pp.21-29
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• 2016

This in vitro study investigated and compared the durability and retention of three types of attachments. MATERIALS AND METHODS. Three commercially available attachments were investigated: $Clix^{(R)}$, Dalbo-$Plus^{(R)}$ and $Locator^{(R)}$. In total, 72 samples of these attachments were placed in the acrylic resin forms and subjected to mechanical testing (5400 cycles of insertion and removal) over the respective ball or Locator abutments immersed in artificial saliva at pH 7 and $37^{\circ}C$. The abutments were placed at angulations of $0^{\circ}$, $10^{\circ}$ and $20^{\circ}$. The retention force was recorded at the beginning and after 540, 1080, 2160, 3240, 4320 and 5400 insertion-removal cycles. RESULTS. The results revealed that there were significant differences in the average values of the insertion/removal force due to angulation ($F_{(2.48)}=343619$, P<.05) and the type of attachment ($F_{(7.48)}=23.220$, P<.05). CONCLUSION. Greater angulation of the abutments was found to influence the retention capacity of the attachments, and the fatigue test simulating 5 years of denture insertion and removal did not produce wear in the metal abutments.