• Korean Journal of Materials Research
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• v.15 no.3
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• pp.209-215
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• 2005

Titanium dioxide films $(TiO_2)$ doped cobalt transition metal were prepared on titanium metal by water spray pyrolysis technique. Micro-morphology, crystalline structure, chemical composition and binding state of sample groups were evaluated using field emission scanning microscope(FE-SEM), X-ray diffractometer(XRD), Raman spectrometer, X-ray photoelectron spectrometer(XPS). $TiO_2$ films of rutile structure were predominately formed on all sample groups and $Ti_2O_3$ oxide was coexisted on the surface of cobalt doped-sample groups. The optical absorption peaks measured by using UV-VIS-NIR spectrophotometer were observed at specific wavelength region in sample groups doped cobalt ion. This result could be analyzed by introducing crystal field theory.

• Korean Journal of Dental Materials
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• v.42 no.2
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• pp.95-106
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• 2015

Hardening mechanism associated with post-firing heat treatment of softening heat treated and then firing simulated Pd-Ag-Au alloy for bonding porcelain was examined by observing the change in hardness, crystal structure and microstructure. By post-firing heat treatment of as-cast, solution treated and pre-firing heat treated specimens at $650^{\circ}C$ after casting, the hardness value increased within 10 minutes. Then, hardness consistently increased until 30 minutes, and gap of hardness value among the specimens was reduced. The increase in hardness after post-firing heat treatment was caused by grain interior precipitation in the matrix. The softening heat treatment did not affect the increase in hardness by post-firing heat treatment. The precipitated phase from the parent Pd-Ag-Au-rich ${\alpha}$ phase with face-centered cubic structure by post-firing heat treatment was $Pd_3$(Sn, In) phase with face-centered tetragonal structure, which has lattice parameters of $a_{200}=4.0907{\AA}$, $c_{002}=3.745{\AA}$. From above results, appropriate post-firing heat treatment in order to support the hardness of Pd-Ag-Au metal substructure was expected to bring positive effects to durability of the prosthesis.

• Journal of Korean society of Dental Hygiene
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• v.3 no.1
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• pp.59-72
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• 2003

The purpose of this study was to examine what the role of denial hygienist was. The subjects were 751 dental hygienists from dental clinics, dental hospitals, general hospitals, public dental clinics and their branches throughout the nation. After a survey was conducted, the collected data were analyzed with SPSS WIN 10.0, and variance analysis and post-analysis were implemented. And Forgarty's 8th integrated model, out of 10 ones, was selected to delve into the practical role of dental hygienist in detail. The findings of this study were as follows: 1. The three age groups had a significantly different opinion on the significance of individual subjects. The dental hygienists of thirty six and over found the basic and preventive public dental care courses most important, and the 31~35 age group placed most stock in education and research. Overall, the post-analysis results showed that prevention and clinical courses were considered most vital, followed by education and fundamental courses. 2. There was a significant gap between four groups from the different work places in their view of the weight of the individual subjects. According to the post-analysis, the dental hygienists from the general hospitals, public dental clinics and their branches gave more weight to fundamental, education and research areas. Those who were with the dental clinics, dental hospitals and general hospitals put higher value on clinical course than the dental hygienists from the public dental clinics and their branches. 3. Two groups with a different career also had a different outlook on the importance of the individual subjects. The post-analysis results illustrated that the dental hygienists who had worked for three years or more put higher stress on the fundamental course than those with a less career, and the dental hygienists with a five-year or higher career attached more importance to the education and research field than those with a smaller career. 4. There was a significant difference between the three age groups in their clinical role. The post-analysis results indicated thai the younger dental hygienists were more of assistants than of professionals, as they chiefly took X-ray photograph, handled treatment materials or performed treatment-related works. Overall, handling treatment materials was most common. 5. The three groups from the different work places significantly varied in their clinical role. According to the post-analysis, those from the dental clinics and dental hospitals took more x-ray photographs, handled more treatment materials and performed more relevant works, compared to those from the general hospitals, public dental clinics and their branches. 6. The two groups with a different career differed significantly in their clinical role. The post-analysis results suggested that the dental hygienists with a less career played an assistant role more, which handled treatment materials or carried out other relevant works. 7. The fundamental courses (I) and (II), preventive class (I) and (II) and its practice course were regarded as integrated subjects that they should take 10 offer preventive treatment, which was one of the dental hygienist missions. What's needed to act as dental-care educators was the basic courses (I) and (II), dental hygiene education and its practice. Finally, integrated clinical courses (I) and (II) and clinical practice were viewed as necessary for their role performance as dental treatment collaborators.

• Journal of Technologic Dentistry
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• v.29 no.2
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• pp.105-117
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• 2007

As a dental technician, the aim of the present study on maxillofacial prosthesis was to research its relation with dental technology and further development aspects by looking into its history, kinds, production materials and process. Dental technicians are to expect a great potential to work as maxillofacial prosthetist if having an interest in education of maxillofacial prosthesis field, and developing and operating the education process by expanding the range of dental technology. This article is to present overall history of maxillofacial prosthesis and some background information on the materials which have been used from the past. The maxillofacial field plays essential functions of mastication and speech, as well as performs appearance, which evokes good or bad feelings as an instant and instinctive response. The use of maxillofacial prostheses is not merely the replacement of a missing part of the face, resulted from injuries, but a rehabilitation process to help individuals come back to society. Rehabilitation includes both patient's physical and psychological recovery, such as self-esteem and selfconfidence. There has been a rapid development in application potentials of maxillofacial prosthesis technology which include implant, which can penetrate skin, and new materials. In order to produce maxillofacial prosthesis, general procedures of maxillofacial laboratory work should be understood first. Maxillofacial prosthesis and the dental prosthesis have many similarities in its academic perspective and originality. Maxillofacial prosthesis should be added into the curriculum for dental technology to achieve co-enhancement of the two fields.

• Molecular & Cellular Toxicology
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• v.4 no.3
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• pp.192-198
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• 2008

A variety of titanium (Ti) and its alloys are used in the clinical procedures of bone regeneration for periodontal and dental implant therapies. This study was performed to determine the effect of different surface dental implant materials on biologic responses of a MG-63 human osteoblast-like cell line. MG-63 cells were cultured on Ti coated with hydroxyapatite (HA), calcium metaphosphate (CMP), anodized (A), which compared with non-coated Ti (control). The appearances of surface of dental implant materials and the morphology of these cells were assessed by scanning electron microscopy (SEM). The gene expression profiles of MG-63 cells cultured on Ti were examined by human cDNA microarray (1,152 elements). The expression of several genes was up- and down-regulated by different surfaces of dental implant materials. Interesting, the genes correlated with cellular adhesion and extra cellular matrix (ECM) formation were enhanced, in accordance surface morphology of the dental implant materials used.

• The Journal of Advanced Prosthodontics
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• v.7 no.4
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• pp.323-328
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• 2015

PURPOSE. This in-vitro study was designed to evaluate retention forces, microleakage and plastic deformation of a prefabricated 2-implant bar attachment system (SFI-Bar, Cendres+$M{\acute{e}}taux$, Switzerland). MATERIALS AND METHODS. Two SFI implant-adapters were torqued with 35 Ncm into two implant analogues. Before the tube bars were finally sealed, the inner cavity of the tube bar was filled with liquid red dye to evaluate microleakage. As tube bar sealing agents three different materials were used (AGC Cem (AGC, resin based), Cervitec Plus (CP; varnish) and Gapseal (GS; silicone based). Four groups with eight specimens each were tested (GS, GS+AGC, AGC, CP). For cyclic loading, the attachment system was assembled parallel to the female counterparts in a chewing simulator. The mean retention forces of the initial and final ten cycles were statistically evaluated (ANOVA, ${\alpha}{\leq}.05$). RESULTS. All groups showed a significant loss of retention forces. Their means differed between 30-39 N initially and 22-28 N after 50,000 loading cycles. No significant statistical differences could be found between the groups at the beginning (P=.224), at the end (P=.257) or between the loss of retention forces (P=.288). Microleakage occurred initially only in some groups but after 10,000 loading cycles all groups exhibited microleakage. CONCLUSION. Long-term retention forces of the SFI-Bar remained above 20 N which can be considered clinically sufficient. The sealing agents in this study are not suitable to prevent microleakage.

• Journal of dental hygiene science
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• v.21 no.3
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• pp.178-184
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• 2021

Background: As the importance of the esthetic function of teeth increases, the use of esthetic restoration materials and whitening treatment are increasing. The purpose of this study was to investigate the color change of esthetic restoration materials upon using staining and whitening toothpaste. Methods: Light curing (LC) packable composite resin, LC flowable resin, LC glass ionomer (GI), and self-curing GI specimens were colored in coffee or curry for three hours a day for seven days. After that, regular toothpaste, whitening toothpaste containing hydrogen peroxide, and whitening toothpaste containing activated charcoal were applied for three minutes three times a day for two weeks. Luminosity (L), chromaticity a (a), and chromaticity b (b) were measured using a spectrophotometer once a week. Results: In the coffee-colored group, the change in L^2*a^2*b² (E²) with time was significant (p=0.004), there was no difference for different toothpaste types (p=0.646), and there was significant difference (p<0.001) for different esthetic restorative materials. The change of E² in the curry-colored group was significant only for different esthetic restorative materials (p<0.001). In the coffee-colored group, the L, a, and b values of the light-curing GI showed greater change than other materials after staining and one week after whitening, turning dark, red, and yellow. In the curry-colored group, L did not differ for different materials and times, and a and b showed the greatest difference in light-curing GI after staining and one and two weeks after whitening. Conclusion: The use of whitening toothpaste for two weeks was not different from the use of general toothpaste in the removal of staining or whitening. Since light-curing GI is the most vulnerable to coloration, it is recommended that coloring by food chromogen should be explained in advance, before using light-curing GI for teeth restoration.

• Korean Journal of Materials Research
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• v.12 no.7
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• pp.560-567
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• 2002

Titanium (Ti) is a bioinert material and has lower elastic coefficient and better strength/volume property than other metals. Ferroelectric materials show alignment of positive and negative charges by poling treatment. This study was purposed to develop a new implant system by combining the advantages of Ti and ferroelectric property of $BaTiO_3$ (BTO). It was performed with the assumption that the $Ca^{2+ }$ ions would be easily attracted on negatively charged surface and the attracted cation might behave as nuclei for bone-like crystal growth in biological solutions. A ferroelectric BTO thin film on Ti was fabricated and the effect of poling treatment on the improvement of calcium phosphate (Ca-P) formation in biological solutions was evaluated. After immersion in Eagle’s minimum essential media (MEM) solution, NaCl was formed on Ti, and Ca-P layer containing NaCl was formed on Ti-O. Weak and sparse Ca-P layers were formed on BTO, while thick, homogeneous, and dense Ca-P layer was formed on negatively polarized BTO (N-BTO), which was confirmed by FE-SEM and EDX. In summary, these results demonstrate that poling the ferroelectric BTO surface negatively is effective for the formation of Ca-P layer in MEM solution, and that N-BTO coating on Ti could be used as a possible alternative method for enhancing the osseointegration of the implants.

• The Journal of the Korean dental association
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• v.53 no.3
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• pp.178-186
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• 2015

Dental polymer-based luting materials are classified into esthetic resin cement, adhesive resin cement and self-adhesive resin cement. Due to the different component of each type of resin cement, the preconditioning method of tooth surface and the steps are different from each type of resin cement. The pre-treatment of adherend (ceramic, resin and metal) surface also varies with the type of resin cement and the manufacturer. In this study, the characteristics of each type of resin cement, mechanical properties, indication and advantages were investigated. Through these, clinical tips on using resin cements were suggested.

• The Journal of the Korean dental association
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• v.52 no.2
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• pp.96-104
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• 2014

The aim of this study was to investigate the frequency of positive patch test reaction to dental materials in patients with oral mucosal diseases. Epicutaneous patch test was performed in 110 patients with oral mucosal diseases; 41 patients with oral lichen planus(OLP), 44 patients with burning mouth syndrome(BMS), 25 patients with other oral mucosal diseases including recurrent aphthous ulcer and mucous membrane pemphigoid. The obtained results were as follows: Oral gold restorations were most common in patents with oral mucosal diseases and porcelain fused metal crown, implant appeared in the order. 33 of 110 patients did not appear skin reactions (negative, 30%) and 77 patients (positive, 70%) had skin reactions including redness, rash, blisters. Dental materials causing positive reaction to patch test were mainly as gold-sodium-thiosulfate (26.7%), nickel sulfate(Ni) (22.7%), cobalt chloride(Co) (14.7%), palladium chloride(Pd) (11.9%), potassium dichromate (10.7%) in order, respectively. In conclusion, old metal restorations could be the cause of oral mucosal diseases and epicutaneous patch test could be used as a tool to improve the oral conditions.