• The Journal of Korean Academy of Prosthodontics
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• v.32 no.1
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• pp.120-147
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• 1994

This study was performed for the purpose of evaluating the stress distribution around threaded type implants, cylindrical type implants and teeth connected with rigid or non-rigid connector. The stress distribution around the surrounding bone was analyzed by three-dimensional photoelastic method. Twelve mandibular photoelastic epoxy resin models and a circular polariscope were used to record the isochromatic fringes. After the stress distribution around the implant and tooth was observed, the results were as follows ; 1. In threaded type implants, stress concentrated patterns were observed at the neck either vertical or 25 degree lateral force. 2. The stress concentrated patterns were observed at the tooth apical portion and neck portions of the implant and tooth when a threaded implant was connected with the tooth by either a rigid or non-rigid connector. More force was generated at the tooth neck portion by a rigid connector and more force at the implant neck portion by a non-rigid connector. 3. The stress concentrated patterns were observed at the apical portion of the implant and tooth when a cylindrical type ,implant was connected with the tooth either by a rigid or non-rigid connector. More force was generated at the tooth apical portion by a rigid connector and more force at the neck portion of the tooth and implant by a non-rigid connector. 4. The stress around the tooth was more equally distributed in a threaded type implant than in a cylindrical implant when the tooth was connected with either a rigid or non-rigid connector. 5. The stress around a threaded type implant was progressively more equally distributed in the following order : 1) when used a single implant, 2) a non-rigid connection with the implant and tooth, 3) a rigid connection with the implant and tooth, 4) a rigid connection with two implant fixtures.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.1
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• pp.61-69
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• 2009

Statement of problem: Porcelain veneers have become a popular treatment modality for aesthetic anterior prosthesis. Fitting porcelain veneers in the mouth usually involve a try-in appointment, which frequently results in salivary contamination of fitting surfaces. Purpose: An in vitro study was carried out to investigate the effect of silane treatment timing and saliva contamination on the resin bond strength to porcelain veneer surface. Material and methods: Cylindrical test specimens (n=360) and rectangular test specimens (n=5) were prepared for shear bond test and contact angle analysis. Whole cylindrical specimens divided into 20 groups, each of which received a different surface treatment and/or storage condition. The composite resin cement stubs were light-polymerized onto porcelain adherends. The shear bond strengths of cemented stubs were measured after dry storage and thermocycling (3,000 cycles) between 5 and $55^{\circ}C$. The silane and their reactions were chemically monitored by using Fourier Transform Infrared Spectroscopy analysis (FTIR) and contact angle analysis. One-way analysis of variance (ANOVA) and Dunnett's multiple comparison were used to analyze the data. Results: FT-IR analysis showed that salivary contamination and silane treatment timing did not affect the surface interactions of silane. Observed water contact angles were lower on the saliva contaminated porcelain surface and the addition of 37% phosphoric acid for 20 seconds on saliva contaminated porcelain increased the degree of contact angle. Silane applied to the porcelain, a few days before cementation, resulted in increasing the bond strength after thermocycling. Conclusion: Within the limitation of this study, it can be concluded that it would be better to protect porcelain prosthesis before saliva contamination with silane treatment and to clean the contaminated surface by use of phosphoric acid.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.3
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• pp.474-480
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• 2004

The purpose of this in vitro study was to compare the remineralizing effects of three glass ionomer cements (high filled glass ionomer cement, compomer, resin modified glass ionomer cement) with resin composite (control group) on incipient interproximal caries, and to assess long-term change of remineralization effect, in each material, evaluated by microtomography. Proximal restoration was simulated with tooth specimen and Glass Ionomer Cements. And each of these groups was placed into a closed container with artificial saliva at $37^{\circ}C$ and pH 7.0 for a time period of thirty days with constant circulation. At the end of thirty and sixty days, tomographic images were taken from these specimens with micro CT scanner. Materials used in this study were as follows. Group 1: Fuji IX GP (GC Corp., Tokyo, Japan) Group 2: Vitremer (3M ESPE, St. Paul, Minn., USA) Group 3: F2000 (3M ESPE, St. Paul, Minn., USA) Group 4: Z250 (3M ESPE, St. Paul, Minn., USA) Using density-measuring program, the micro-density of carious lesions on the specimens were measured. The mean density changes of each group were compared to the other groups to evaluate the effect of remineralization. The results were as follows: 1. The lesion density of all groups increased. 2. The mean density increase of Group 1, 2, 3 were higher than that of Group 4 every month(p<0.05). 3. There were significant differences of density increase among glass ionomer group(Group 1, 2, 3).

• Journal of Bio-Environment Control
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• v.7 no.1
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• pp.63-70
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• 1998

This study was carried out to investigate the interaction of selenate and sulfate ion in nutrient solution supplyed with selenate ion. At early growth stage, the growth of Mongolian wormwood was best at 3mM sulfate ion and 2mg/$\ell$Na$_2$SeO$_4$ treatment. As they were grown and matured, at the later growth stage, the effect of antagonism between selenate and sulfate ion on the growth of each plant decreased. At supplying with selenate ion in nutrient solution, the uptake of selenate by plant had negative correlation with sulfate ion concentration in nutrient solution. The higher sulfate ion concentration, the less selenium uptake. However, the effect of antagonistic interaction of selenate and sulfate ion on the selenium uptake increased with plant age. Whereas, the uptake of sulfate ion had positive correlation with sulfate ion concentration in nutrient solution at supplying with selenate ion in nutrient solution. The uptake of sulfate ion increased with increase of sulfate ion concentration in nutrient solution. The effect of this interaction with selenate and sulfate ion increased with growth and maturity of plant. However, at 3mM sulfate ion concentration in nutrient solution, sulfate ion concentration in plant tissue decreased markedly.

• Restorative Dentistry and Endodontics
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• v.34 no.1
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• pp.51-60
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• 2009

The purpose of this study was to perform quantitative comparisons of water permeable zones in both the adhesive and the hybrid layer before and after thermo cycling in order to assess the integrity of the bonding interface. Twenty eight flat dentin surfaces were bonded with a light-cured composite resin using one of four commercial adhesives [OptiBond FL (OP), AdheSE (AD), Clearfil SE Bond (CL). and Xeno III (XE)]. These were sectioned into halves and subsequently cut to yield 2-mm thick specimens; one specimen for control and the other subjected to thermocycling for 10,000 cycles. After specimens were immersed in ammoniacal silver nitrate for 24 h and exposed to a photo developing solution for 8 h, the bonded interface was analyzed by scanning electron microscopy (SEM) and wavelength dispersive spectrometry (WDS) at five locations per specimen. Immediately after bonding. the adhesive layer of OP showed the lowest silver uptake, followed by CL, AD. and XE in ascending order (p < 0.0001); the hybrid layer of CL had the lowest silver content among the groups (p = 0.0039). After thermocycling, none of the adhesives manifested a significant increase of silver in either the adhesive or the hybrid layer. SEM demonstrated the characteristic silver penetrated patterns within the interface. It was observed that integrity of bonding was well maintained in OP and CL throughout the thermocycling process. Adhesive-tooth interfaces are vulnerable to hydrolytic degradation and its permeability varies in different adhesive systems, which may be clinically related to the restoration longevity.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.2
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• pp.312-320
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• 2005

The purpose of this study was to evaluate the polymerization contraction and the microhardness of compostie resin($Supreme^{(R)}$, Filtek $Flow^{(R)}$, 3M-ESPE, USA) according to irradiation modes of LED curing unit(Elipar $Freelight^{(R)}$, 3M-ESPE, USA). The strain guage method was used for determination of polymerization contraction. Sample were divided by 6 groups according to curing modes and filling method. Group A: $Supreme^{(R)}$, Filtek $Flow^{(R)}$ lining, 10seconds curing, Group B: $Supreme^{(R)}$, Filtek $Flow^{(R)}$ lining, 15seconds curing, Group C: $Supreme^{(R)}$, Filtek $Flow^{(R)}$ lining, 15seconds soft start curing, Group D: $Supreme^{(R)}$ only, 10seconds curing, Group E: $Supreme^{(R)}$ only, 15seconds curing, Group F: $Supreme^{(R)}$ only, 15seconds soft start curing. Preparations of acrylic molds were followed by filling and curing. Strain guage attached to each sample were connected to a strainmeter. Measurements were recorded at each second for the total of 10 minutes including the periods of light application. And microhardness of each group after 24hours from light irradiation were measured. Obtained data were analyzed statistically using Repeated measures ANOVA and Tukey test. The results of the present study are as follows: 1. In flowable resin liner group, soft start curing group was not found decrease of polymerization contraction. But, In Supreme only filling group, the lowest polymeriation contraction was found in soft start curing group. 2. 10 seconds curing group showed statistically significant reduction of polymerization contraction compared with 15 seconds curing group(p<0.05). 3. The microhardness values of each group not revealed significant difference(p>0.05). But, lower surface microhardness was not reached 80% of upper surface microhardness.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.1
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• pp.62-72
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• 2007

The purpose of present study was to determine whether different kinds of curing lights can alter microtensile bond strength(MTBS) of class I cavity pulpal and axial wall specimens in primary molar. Thirty clean mandibular 2nd primary molar's occlusal enamel were removed and class I cavity, size of $2{\times}4{\times}2mm$ was prepared. Dentin bonding agent was applied according to manufacturer's manual. Each group was cured with Halogen Curing Unit, Plasma Curing Unit and LED Curing Unit. Composite resin was bulk filled and photo cured with same curing unit. MTBS specimens which size is $0.7{\times}0.7{\times}4mm$ were prepared with low speed saw. Specimens were coded by their curing lights and wall positions (Halogen - Axial wall group, Halogen - Pulpal wall group, Plasma - Axial wall group, Plasma - Pulpal wall group, LED - Axial wall group, LED - Pulpal walt group). MTBS were tested at 1 mm/min cross Head speed by Universal Testing Machine. Fractured surface and bonding surface was observed with SEM. T-test between axial and pulpal specimens in each curing lights, one-way ANOVA among different curing light specimens in each wall positions were done. Weibull distribution analysis was done. The results were as follows : Mean MTBS of pulpal wall specimens were significantly greater than that of axial wall specimens at each curing units(p<.05). There was no significant difference in the MTBS among three curing units at axial wall and pulpal wall. In Weibull distribution, pulpal wall specimens were more homogeneous than axial wall specimens.

• Journal of agricultural medicine and community health
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• v.36 no.2
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• pp.101-112
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• 2011

Objectives: The aim of this study is to determine arterial stiffness levels as measured by brachial-ankle pulse wave velocity (baPWV) and to identify the association between arterial stiffness and inflammatory markers, in healthy adults over 50 years old. Methods: The study population consisted of 4617 persons over the age of 50 years who participated in the baseline survey of the Dong-gu Study, which was conducted in 2007 and 2008. Arterial stiffness was measured using baPWV. A multiple regression analysis was performed to assess the relationship between conventional cardiovascular risk factors and inflammatory markers, including white blood cell (WBC) counts, high-sensitive C-reactive protein (hs-CRP), and gamma glutamyltransferase (GGT). Results: After adjustment for conventional cardiovascular risk factors including sex, age, smoking status, body mass index, systolic blood pressure, fasting glucose, hypertension or diabetic medication, total cholesterol, triglycerides, uric acid, and alanine aminotransferase, baPWV was significantly associated with WBC counts (${\beta}$=0.158, p<0.0001), hs-CRP (${\beta}$=0.244, p=0.026), and GGT (${\beta}$=0.003, p<0.0001). Conclusion: This study shows that arterial stiffness correlates with inflammatory markers. Arterial stiffness may be used as a composite risk factor to identify persons with higher risk for cardiovascular disease. Additionally, arterial stiffness may be a marker for future cardiovascular disease and a target for prevention.

• Restorative Dentistry and Endodontics
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• v.31 no.4
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• pp.300-311
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• 2006

The purpose of this study is to evaluate prospectively the effect of different bonding systems and retention grooves on the clinical performance of resin restorations in non-carious cervical lesions (NCCLs). Thirty-nine healthy adults who had at least 2 NCCLs in their premolar areas were included in this study. One hundred and fifty teeth were equally assigned to six groups: (A) Scotchbond Multi-Purpose (SBMP, 3M ESPE, St. Paul, MN, USA, 4th generation bonding system) without retention grooves; (B) SBMP with retention grooves; (C) BC Plus (Vericom Co., Anyang, Gyeonggido, Korea, 5th generation bonding system) without retention grooves; (D) BC Plus with retention grooves; (E) Adper Prompt (3M ESPE, Seefeld, Germany, 6th generation bonding system) without retention grooves; (F) Adper Prompt with retention grooves. All cavities were filled with a hybrid composite resin. Denfil (Vericom Co., Anyang, Gyeonggido, Korea) by one operator. Restorations were evaluated at baseline and at 6-month recall, according to the modified USPHS (United States Public Health Service) criteria. Additionally, clinical photographs were taken and epoxy resin replicas were made for SEM evaluation. At 6-month recall, there were some differences in the number of alpha ratings among the experimental groups. But, despite the differences in the number of alpha ratings, there was no significant difference among the 3 adhesive systems (p < 0.05). There was also no significant difference between the groups with or without mechanical retention (p < 0.05). Follow-ups for longer periods than 6 months are needed to verify the clinical performance of different bonding systems and retention grooves.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.699-720
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• 1995

This study was conducted to evaluate the effect of benzalkonium chloride solution as a wetting agent instead of water on dentin bonding with NTG-GMA/BPDM system (All-bond 2, Bisco.) and DSDM system (Aelitebond, Bisco.). Benzalkonium chloride solution is a chemical disinfectant widely used in medical and dental clinics for preoperative preparation of skin and mucosa due to its strong effect of cationic surface active detergent. Eighty freshly extracted bovine lower incisor were grinded labially to expose flat dentin surface, and then were acid-etched with 10 % phosphoric acid for 15 second, water-rinsed, and dried for 10 second with air syringe. The specimens were randomly divided into 8 groups of 10 teeth. The specimens of control group were remoistured with water and the specimens of experimental groups were remoistured with 0.1 %, 0.5 %, and 1.0 % benzalkonium chloride solution respectively. And then, the Aelitefil composite resin was bonded to the pretreated surface of the specimens by use of All-bond 2 dentin bonding system or Aelitebond dentin bonding system in equal number of the specimens. The bonded specimens were stored in $37^{\circ}C$ distilled water for 24 hours, then the tensile bond strength was measured, the mode of failure was observed, the fractured dentin surface were examined under scanning electron microscopy, and FT-IR spectroscopy was taken for the purpose of investigating the changes of the dentin surface pretreated with benzal konium chloride solution followed by each primer of the dentin bonding systems. The results were as follows : In the group of bonding with NTG-GMA/BPDM dentin bonding agent(All-bond 2), higher tensile bond strength was only seen in the experimental group remoistured with 0.1 % benzal konium chloride solution than that in water-remoistured control group(p<0.05). In the group of bonding with DSDM dentin bonding agent (Aelitebond), no significant differences were seen between the control and each one of the experimental group(p<0.05). Higher tensile bond strength were seen in NTG-GMAIBPDM dentin bonding agent group than in DSDM dentin bonding agent group regardless of remoistur ization with benzal konium chloride solution. On the examination of failure mode, cohesive and mixed failure were predominantly seen in the group of bonding with NTG-GMAIBPDM dentin bonding agent, while adhesive failure was predominantly seen in the group of bonding with DSDM dentin bonding agent. On SEM examination of fractured surfaces, no differences of findings of primed dentin surface between the groups with and without remoisturization with benzal konium chloride solution. FT-IR spectroscopy taken from the control and the experimental group reve::.led that some higher absorbance derived from the primers binding to dentin surface was seen at the group pretreated with 0.1 % benzal konium chloride solution than at the control group of remoisturizing with water.