• The Journal of Korean Academy of Prosthodontics
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• v.58 no.1
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• pp.58-66
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• 2020

Implant-Assisted Removable Partial Dentures (IARPDs) treatment is being performed in a fully edentulous patient using implant surveyed prosthesis as an abutment. Implant-supported prosthesis as an abutment of IARPDs is classified into screw-retained and cement-retained type according to the retention type, and each has advantages and disadvantages. The EZ crown system (Samwon DMP, Yangsan, Korea) has a cylinder combined with abutment, and the nickel-titanium spring in this cylinder provides a constant force on the zirconia ball to obtain retention in EZ crown system. In this patient, the natural abutment teeth of the mandibular overdenture was hopeless. We planned implant assisted removable partial denture using anterior implant surveyed prosthesis considering functional and esthetical rehabilitation, cost and patient's needs. When fabricating IARPDs using implant as abutment, we could compensate for the shortcomings of existing implant-supported prosthesis retention type and made the design of removable partial denture easy due to using EZ crown system.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.2
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• pp.159-168
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• 2007

Statement of problem: Literature showed different results on the durability of bonded ceramic restoration. Purpose: The purpose of this article is to review the effect of surface treatment of ceramics in resin-ceramic bond to get predictable results. Material and method: PubMed data base was utilized to search the articles which were written in English and published in 1986 and 2006. Some electronic published articles which are forthcoming to publish in paper were also included for this review. This review article focused on the effect of acid etching and silane application on the silica based ceramics. The durability of resin-ceramic bonding, the methodology for bond strength test and resin bonding to alumina or zirconia based ceramics were compared in brief at the end of the review. Results and Conclusion: the effect of silane application can be influenced by the contaminations of saliva or solutions. Micromechanical retention by acid etching as well as silane application plays an important role in initial and durable bond strength between resin and ceramic. The use of phosphate modified resin cement following tribochemical silica coating and silane application produced best bond strength for alumina or zirconia based ceramics.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1018-1031
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• 2010

In order to investigate the applicability and suitability of the industrial by-products to landfill final cover, field pilot-scale lysimeter experiments were carried out. The mixture of loamy soil, bottom ash, and construction waste was placed as a cover material in lysimeter($2m{\times}6m{\times}1.2m$) which were constructed with cement brick, and then, volumetric water contents, pF value, and the quantity of runoff and seepage of treatment boxes filled with the mixture of loamy soil and the industrial by-products were monitored from July, 2007 to February, 2008. Among the cases tested, consequently, the case containing the mixture of bottom ash and loamy soil was most effective in engineering and hydrological properties and water retention ability.

• The Journal of the Korean dental association
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• v.54 no.3
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• pp.198-205
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• 2016

The purpose of this paper was to investigate the significance of splinted and non-splinted implant-supported restorations with an internal connection for multiple consecutively missing teeth. Upon examination of the effects of fixture-abutment connection, the distribution of occlusal load was favorable in splinted implant-prosthesis with an external connection, but effect of strain distribution was not significant in splinted implant-prosthesis with an internal connection. In splinted implant-prostheses for short implants, strain distribution was not affected by the method of retention. For cement-retained prostheses, the effect of strain distribution due to splinting was not significant. In clinical studies, non-splinted prostheses with an internal connection for multiple consecutively missing teeth showed high survival rate, mild marginal bone loss, and stable periodontal condition. However, failure to achieve optimal proximal contact between single-unit prostheses may lead to food impaction, and veneer fracture may be inevitable when the framework provides inadequate support in the proximal region. In conclusion, splinted implant-prosthesis is not an indication in all cases, and clinical consideration of its use should be based on the patient's oral condition, such as location and number of implants, formation of proximal contact, canine guidance, existence of parafunctional habit, and oral hygiene, when multiple consecutively missing teeth are replaced by internal connection type implant.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1655-1665
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• 2008

In order to investigate the applicability and suitability of the industrial by-products to landfill final cover, field pilot-scale lysimeter experiments were carried out. The mixture of loamy soil, bottom ash, and construction waste was placed as a cover material in lysimeter($2m{\times}6m{\times}1.2m$) which were constructed with cement brick, and then, volumetric water contents, pF value, and the quantity of runoff and seepage of treatment boxes filled with the mixture of loamy soil and the industrial by-products were monitored from July, 2007 to February, 2008. As a result, the case containing the mixture of bottom ash and loamy soil was most effective in engineering and hydrological properties and water retention ability.

• The Journal of Korean Academy of Prosthodontics
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• v.56 no.3
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• pp.206-211
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• 2018

Purpose: Recently, a method of forming a slot in the prosthesis lingual has been introduced to solve the occlusal and aesthetic disadvantages of screw-retained prosthesis in the manufacture of implant-fixed prosthesis and to ensure retrievability in cement retained prostheses. The purpose of this study is to investigate the effect of the internal gap on the removal of the prosthesis in the preparation of cement-retained implant prostheses with lingual slots. Materials and methods: Titanium abutment and internal gap of the zirconia prosthesis to be attached to the upper part were set to 30, 35, and $50{\mu}m$, respectively. Three for each type total 15 were produced for each type. The zirconia prosthesis formed a retrievable cement-type slot with a space of 1 mm at the location where the titanium abutment meets the shelf area. Autocatalytic resin cement was used for bonding of abutment and zirconia prosthesis, and the maximum removal stress value was measured in units of Ncm by using the customized equipment of the cemented specimen. The Kruskal-Wallis test was used to compare the three groups by statistical analysis (${\alpha}=.05$), modified by post hoc test the Mann-Whitney U-test and the Bonferroni correction method were used to compare the two methods (${\alpha}=.017$). Results: There was no statistically significant difference in removal stress between the $30{\mu}m$ group and the $35{\mu}m$ group in the internal gap (P = .032), and there was a significant difference between the $30{\mu}m$ group and the $50{\mu}m$ group, between the $35{\mu}m$ group and the $50{\mu}m$ group (P < .017). Conclusion: Thus, the internal gap of computer-aided design affected the retention between the zirconia prosthesis and the titanium abutment.

• Journal of the Korean Institute of Landscape Architecture
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• v.34 no.1 s.114
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• pp.21-36
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• 2006

This study was undertaken to analyze the effects of pavement thermal properties and water retention characteristics on the surface temperature of the gray permeable cement concrete pavement during the summer. Following is a summary of major results. 1) The hourly surface temperature of pavement could be well predicted with a heat transfer model program that incorporated the input data of major meteorological variables including solar radiation, atmospheric temperature, dew point, wind velocity, cloudiness and the evaporation rate of the pavements predicted by the time domain reflectometry (TDR) method. 2) When the albedo was changed to 0.5 from an arbitrary starting condition of 0.3, holding other variables constant, the peak surface temperature of the pavement dropped by 11.5%. When heat capacity was changed to $2.5\;kJm^{-3}K^{-1}\;from\;1.5\;kJm^{-3}K^{-1}$, surface temperature dropped by 8.0%. When daily evaporation was changed to 1 mm from 2 mm, temperature dropped by 5.7%. When heat conductivity was changed to $2.5\;Wm^{-1}K^{-1}\;from\;1.5\;Wm^{-1}K^{-1}$, the peak surface temperature of the pavement fell by 1.2%. The peak pavement surface temperature under the arbitrary basic condition was $24.46^{\circ}C$ (12 a.m.). 3) It accordingly became evident that the pavement surface temperature can be most effectively lowered by using materials with a high albedo, a high heat capacity or a high evaporation at the pavement surface. The glare situation, however, is intensified by raising of the albedo, moreover if reflected light is absorbed into surrounding physical masses, it is changed into heat. It accordingly became evident that raising the heat capacity and the evaporative capacity may be the moot acceptable measures to improve the thermal characteristics of the pavement. 4) The sensitivity of the surface temperature to major meteorological variables was as follows. When the daily average temperature changed to $0^{\circ}C\;from\;15^{\circ}C$, holding all other variables constant, the peak surface temperature of the pavement decreased by 56.1 %. When the global solar radiation changed to $200\;Wm^{-2}\;from\;600\;Wm^{-2}$, the temperature of the pavement decreased by 23.4%. When the wind velocity changed to $8\;ms^{-1}\;from\;4\;ms^{-1}$, the temperature decreased by 1.4%. When the cloudiness level changed to 1.0 from 0.5, the peak surface temperature decreased by 0.7%. The peak pavement surface temperature under the arbitrary basic conditions was $24.46^{\circ}C$ (12 a.m.)

• The Journal of Advanced Prosthodontics
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• v.6 no.3
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• pp.233-240
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• 2014

PURPOSE. To evaluate the effects of different abutment geometries in combination with varying luting agents and the effectiveness of different cleaning methods (prior to re-cementation) regarding the retentiveness of zirconia copings on implants. MATERIALS AND METHODS. Implants were embedded in resin blocks. Three groups of titanium abutments (pre-fabricated, height: 7.5 mm, taper: $5.7^{\circ}$; customized-long, height: 6.79 mm, taper: $4.8^{\circ}$; customized-short, height: 4.31 mm, taper: $4.8^{\circ}$) were used for luting of CAD/CAM-fabricated zirconia copings with a semi-permanent (Telio CS) and a provisional cement (TempBond NE). Retention forces were evaluated using a universal testing machine. Furthermore, the influence of cleaning methods (manually, manually in combination with ultrasonic bath or sandblasting) prior to re-cementation with a provisional cement (TempBond NE) was investigated with the pre-fabricated titanium abutments (height: 7.5 mm, taper: $5.7^{\circ}$) and SEM-analysis of inner surfaces of the copings was performed. Significant differences were determined via two-way ANOVA. RESULTS. Significant interactions between abutment geometry and luting agent were observed. TempBond NE showed the highest level of retentiveness on customized-long abutments, but was negatively affected by other abutment geometries. In contrast, luting with Telio CS demonstrated consistent results irrespective of the varying abutment geometries. Manual cleaning in combination with an ultrasonic bath was the only cleaning method tested prior to re-cementation that revealed retentiveness levels not inferior to primary cementation. CONCLUSION. No superiority for one of the two cements could be demonstrated because their influences on retentive strength are also depending on abutment geometry. Only manual cleaning in combination with an ultrasonic bath offers retentiveness levels after re-cementation comparable to those of primary luting.

• The Journal of Advanced Prosthodontics
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• v.15 no.4
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• pp.202-213
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• 2023

PURPOSE. This prospective clinical study was conducted to evaluate the clinical usefulness of the freely detachable zirconia ball- and spring-retained implant prosthesis (BSRP) through a comparative analysis of screw- and cement-retained implant prosthesis (SCRP). MATERIALS AND METHODS. A multi-center, randomized, prospective clinical study evaluating the clinical usefulness of the detachable zirconia ball- and spring-retained implant prostheses was conducted. Sixty-four implant prostheses in 64 patients were examined. Periodic observational studies were conducted at 0, 3, 6, and 12 months after delivery of the implant prosthesis. Factors such as implant success rate, marginal bone resorption, periodontal pocket depth, plaque and bleeding index, and prosthetic complications were evaluated, respectively. RESULTS. During the 1-year observation period, all implants survived without functional problems and clinical mobility, showing a 100% implant success rate. Marginal bone resorption was significantly higher in the SCRP group than in the BSRP group only at the time of implant prosthesis delivery (P = .043). In all observation periods, periodontal pocket depth was slightly higher in the BSRP group than in the SCRP group, but there was no significant difference (P > .05). The modified plaque index (mPI) scores of both groups were moderate. Higher ratio of a score 2 in modified sulcus bleeding index (mBI) was observed in the BSRP group in the 6- and 12-months observation. CONCLUSION. Within the limitations of this study, the newly developed zirconia ball- and spring-retained implant prosthesis could be considered as an applicable and predictable treatment method along with the existing screw- and cement-retained prosthesis.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.4
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• pp.323-334
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• 2002

The purpose of this study is to investigate which current densities and etching times will result in an optimal etching depth and surface roughness when an Ni-Cr-Be alloy is etched with 30% perchloric acid($HClO_4$). For this study, observations were made by means of an optical three-dimensional surface roughness measuring machine and a scanning electron microscope. The etchings took place under the following conditions using current densities of $300mA/cm^2\;450mA/cm^2,\;600mA/cm^2$ and $750mA/cm^2$, and using etching time of three, five, six, seven and nine minutes. Under the conditions, the experiments reached the following conclusions. 1. When the current density is above $450mA/cm^2$ and the etching time is longer than five minutes, the etching depth increased as the current density and etching time increased. And the surface roughness was significantly influenced by the interaction of the current density and etching time. 2. Under the etching conditions of $600mA/cm^2$ and five minutes, the optimal etching depth for a resin cement space and the highest surface roughness for mechanical retention were obtained. The etching depth and surface roughness were $32.86{\mu}m$ and $7.90{\mu}m$, respectively. 3. Observations under the scanning electron microscope showed that both the corrosion at the grain boundary and the corrosion within the grain occurred on the etched surface. It was also observed that the corrosion at the grain boundary became more severe as the current density and etching time increased. In addition. at higher current densities and longer etching times general corrosion appeared.