• The Journal of the Korea Contents Association
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• v.10 no.6
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• pp.352-359
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• 2010

The objective of this paper is to study on the property transformation for materials and to evaluate the precision through marginal gap depending on heat-treatment of metal-porcelain by the gold electro-forming system. Specimens for evaluating property of hardness treat non-treat(HC), once(H1), twice(H2), and three times(H3) by heating, respectively. Specimens for marginal gap classified as each groups of special bonder(FS), special bonder, opaque(FO), special bonder, opaque, body(FB) and non-treatment(FC). As a result for micro-hardness test, the level of hardness on each groups of H1, H2, H3 decreased rather than HC group(p<0.05). In addition, marginal gap was not affected by the number of times being treated by heating. Therefore, the marginal fitness and the precision for mterials were not affected by the heat-treatment on the process to make GES metal-porcelain.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.3
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• pp.191-196
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• 2011

Purpose: In this study, we evaluated the bond-strength between a few metal ceramic-alloys and veneered-porcelain and found if the bond strength of metal-ceramic alloy with lower gold content than the presently used gold alloy was high enough. Materials and methods: For this study, after plasticizing porcelain only for gold alloy, metal specimen was fabricated using Ni-Cr alloy and gold alloy with different gold content. Three point flexural test were performed to measure their bond-strength. Results: The bonding strength of Group 1 to porcelain was $40.62{\pm}3.32$ MPa, which was the highest (P<.05). In sequence of decreasing value, Group 2 (75%) was $37.47{\pm}1.57$ MPa, Group 3 (52%) $35.85{\pm}1.48$ MPa, Group 4 (51.5%) $35.04{\pm}1.34$ MPa, Group 5 (32%) $33.17{\pm}1.62$ MPa, Group 6 (10%) $30.75{\pm}1.21$ MPa. Bonding strength of Group 3 and Group 4 to porcelain did not show statistically significant difference with comparison to that of Group 5 (Duncan's test, P>.05), while there was a significant difference between that of Group 2, Group 3 and Group 4 and that of Group 6 (Duncan's test, P<.05). The bonding strength between gold alloy and porcelain increased according to the content of gold. In all experimental groups showed higher value than 25 MPa, which is the least value recommended by ISO 9693. Conclusion: In all groups, bonding strength was higher than 25 MPa, which is the least value of ISO9693. Therefore, it is considered that metal gold alloy with low gold content is clinically usable.

• Journal of Oral Medicine and Pain
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• v.20 no.2
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• pp.317-325
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• 1995

This study was performed to investigate the mean life expectancy of dental prosthetic restorations. The author has examined 352 dental prosthesis clinically and radiologically, and decided the success(survival) and failure(mortality) of the dental prosthesis. The dental prosthesis which had been treated in the Seoul National University Dental Hospital, two private clinics in Seoul, one university dental hospital, and two private clinics in local province were included in this study. The survival analysis using product limit estimator was used and the mean life expectancy of each type of dental prosthesis was calculated. The results were as follows : 1. The life expectancies were 10.5 years in gold crown and bridge, 8.5 years in porcelain fused to metal crown and bridge, 8.3 years in nonprecious metal crown and bridge, 8.1 years in removal partial denture, and 7.7 years in full denture. 2. The causes of mortality were in the order of dental caries(24.6%), fracture of dental prosthesis(19.2%), periodontal problems(18.6%), chronic chewing difficulty and dysfunction due to dental prosthesis(15.0%), excessive exposure of abutments due to the marginal defect of dental prosthesis(14.4%), abnormal occlusion due to severe attrition of artificial teeth in dentures(3.0%), periapical problems(2.4%), perforation of dental prosthesis(1.8%), and loose contacts with neighboring tooth(1.2%). 3. Among survival cases, 66.5% showed normal chewing ability and 31.9% showed partial chewing ability. However, 1.6% of them complained loss of chewing ability. 4. Among failure cases, 6.6% showed normal chewing ability and 38.9% showed partial chewing ability. However, 54.5% of them complained loss of chewing ability.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.1
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• pp.80-86
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• 2011

When a tooth adjacent to implant has coronal damages caused by severe dental caries or fracture, the clinical crown lengthening by forced eruption makes it possible to get esthetic restoration due to the prevention of alveolar crestal bone resorption and loss of interdental papilla. A 54-years-old male patient wanted prosthetic treatment because his anterior 3 unit bridges had fallen out. A right maxillary central incisor showed mild dental caries but a right maxillary canine lost most clinical crowns. Forced eruption combined with a gingival fiberotomy of a right maxillary canine was performed for 1 month after the dental implant had been simultaneously placed with bone grafts on a right maxillary lateral incisor. About 5 months after implant placement, 2nd surgical operation was performed. The provisional restorations were adjusted to make esthetic gingival contour for 8 weeks. The porcelain fused gold restorations were fabricated and set. The patient was satisfied with the final restorations in esthetic and functional aspect.

• 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.