• The Journal of Korean Academy of Prosthodontics
• /
• v.34 no.1
• /
• pp.125-142
• /
• 1996

Bond strength of four different cements to dental casting alloys which were treated with #600 emery, tin-plating, and $50{\mu}m$ sandblasting were evaluated. The alloy specimens were Type III Gold alloy(Degulor C), Palladium-Silver alloy(Pors on 4), Nickel-Chromium(Rexillium III) alloy, which were embedded in acrylic resin disc. The specimens were treated with #600 emery and tin plating, #600 emery and sandblasting, then bonded using Fuji I, Ketac Cem(Glass ionomer cements), Poly F, Livcarbo(Polycarboxylate cements). The specimens were immersed in water for 24 hours and shear bond strengths were evaluated by Instron Machine. Tin plated, sandblasted, and debonded alloy surfaces were observed using scanning electron microscope. On the basis of this study, the following conclusions could be drawn. 1. In the tin plated alloy group, increase in bond strength of glass ionomer cements was statistically insignificant. 2. In the tin plated alloy group, increase in bond strength of polycarboxylate cements was statistically significant, except nickel-chromium alloy. 3. Sandblasted alloy group showed higher bond strength than that of tin-plated alloy group.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.12
• /
• pp.2445-2448
• /
• 2007

Self-assembled monolayers (SAMs) were formed by adsorption of thioacetyl-terminated tolanethioacetate (TTA) on Au(111) in a 0.5-mM ethanol solution after one day immersion at room temperature. Molecular-scale STM imaging revealed that the TTA SAMs were composed of two mixed phases; an ordered phase with small domains describing a ( × 2 )R30° structure and a disordered phase. Interestingly, after annealing the precovered TTA SAMs on Au(111) at 90 °C for 1 h, the small ordered domains grew unidirectionally, resulting in the formation of unique rod-like domains, which were assigned a ( × 2 )R7° structure. These results will be very useful in understanding the formation and thermal behavior of TTA SAMs on gold surfaces.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.12
• /
• pp.1337-1340
• /
• 2004

The self-assembled monolayers of alkane derivatives with sulfur containing head groups on gold substrates have been widely examined recently, since the binding between S atoms and Au surface is strong. The viologen has been widely investigated their well-behaved electrochemistry including electron transfer mediation, the surface-enhanced of the adsorption and the behavior of supramolecular assemblies at electrode surfaces in theses and various studies. Yiologen monolayers are formed onto QCM by self-assembly method. We studied the relationship of electron transfer from changing the anions in 0.1 M NaCl and NaClO$_4$ electrolyte solution. The EQCM measurements revealed the anions transfer during reduction and oxidation, respectively From the EQCM data, the well-defined shape peaks were nearly equal charges by cyclic voltammetry.

• Tribology and Lubricants
• /
• v.29 no.4
• /
• pp.235-241
• /
• 2013

The tribological characteristics of dental metal alloys and zirconia were studied by carrying out a friction and wear performance test. In this study, a pin-on-disk-type tester was used and dead weight was employed as the normal load applied to the test specimen. The friction coefficient of dental metal alloys was investigated in terms of their weight and sliding velocity. Microscopic observations were carried out on worn surfaces of specimens. The results indicated that among all metal alloys, Super-A had the highest friction coefficient. Super-A had the lowest amount of wear among all metal alloys, and the amount of wear increased in the following order: Crown & Bridge, Porcelain, and Partial. Crown & Bridge had the best friction coefficient, but the hardness of Crown & Bridge was lower than that of Porcelain and Partial. Experimental measurement results indicated that the disk weight before and after the experiment was the same.

• Journal of fish pathology
• /
• v.27 no.2
• /
• pp.99-105
• /
• 2014

Biosensors consist of biochemical recognition agents like antibodies immobilized on the surfaces of transducers that change the recognition into a measurable electronic signal. Here we report a piezoelectric immunosensor made to detect Vibrio vulnificus. A 9MHz AT-cut piezoelectric wafer attached with two gold electrodes of 5mm diameter was used as the transducer of the QCM biosensor with a reproducibility of ${\pm}0.1Hz$ in frequency response. We have tried different approaches to immobilize antibody on the sensor chip. Concerning the orientation of antibody for the best antigen binding capacity, the antibody was immobilized by specific binding to protein G or by cross-linking through hydrazine. In addition, protein G was cross-linked on glutaraldehyde activated immine layer (PEI) or EDC/NHS activated sulfide monolayer (MPA). PEI was found to be more effective to immobilize protein G following glutaraldehyde activation than MPA. However, hydrazine chip showed a better capability to immobilize more IgG than protein G chip and a higher sensitivity. The sensor system was able to detect V. vulnificus in dose dependent manner and was able to detect bacterial cells within 5 minutes by monitoring frequency shifts in real time. The detection limit can be improved by preincubation to enrich the bacterial cell number.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.45 no.4
• /
• pp.426-435
• /
• 2018

The aim of this study was to evaluate the proximal caries detecting ability and identify the optimal cut-off values of two types of laser fluorescence (LF) devices; classic type (DD) and pen type (DDpen). The number of proximal surfaces participated in this study were 164 surfaces in primary dentition and 438 surfaces in permanent dentition. Each tooth surface was sequentially assessed by two types of LF devices, and bitewing radiograph. The radiographs were classified into 3 groups in primary dentition ($pR_0$, $pR_1$, $pR_2$), and 4 groups in permanent dentition ($PR_0$, $PR_1$, $PR_2$, $PR_3$) according to the depth of caries, and used as gold standard. In primary dentition, the area under the curve (AUC) values of DD were 0.851 and 0.890, and those of DDpen were 0.883 and 0.917, respectively in enamel caries and dentin caries. In permanent dentition, the AUC values of DD were 0.762 and 0.886, and those of DDpen were 0.828 and 0.958, respectively in enamel caries and dentin caries. When detecting proximal caries in posterior teeth with LF devices, DDpen is more useful than DD in both primary and permanent dentition. However, in primary dentition, DD can also be useful to detect proximal caries.

• Restorative Dentistry and Endodontics
• /
• v.16 no.2
• /
• pp.43-61
• /
• 1991

Present - day inlay casting procedures have been developed for more than 100 years and experimentation has focused on the perfect adaptation to the cavity preparation. Marginal adaptation is considered to be an important indicator of the acceptability of the cast restotration, especially on the gingival margin. The purpose of this study was to evaluate the effects of a dissecting microscope and burnishing on vertical discrepancies, horizontal discrepancies, and cement thicknesson master die. Extracted premolars were prepared for class II gold inlays and master dies were made with conventional techniques. The experiments consisted of 4 groups. Group 1 : unaided eye, no burnishing on master die. Group 2 : unaided eye, burnishing on master die. Group 3 : microscope, no burnishing on master die. Group 4 : microscope, burnishing on master die. Cemented inlays were embedded in the hard resin and sectioned with microcutter through the gingival margins. The sectioned surfaces were polished with emery paper and finally with aluminum oxide powders. The results of the experiments were measured for vertical discrepancies, horizontal discrepancied and cement thickness under the scanning electron microscpe at the beveled gingival margin. The results of the study were summarized as follows. 1. Group 1 showed the vertical discrepancies of $81.6{\mu}m({\pm}48.6{\mu}m)$, horizontal discrepancies of $60.1{\mu}m({\pm}41.1{\mu}m)$, and cement thickness of $59.6{\mu}m({\pm}24.6{\mu}m)$. 2. Group 2 showed the vertical discrepancies of $78.6{\mu}m({\pm}30.9{\mu}m)$, horizontal discrepancies of $36.9{\mu}m({\pm}20.7{\mu}m)$, and cement thickness of $54.0{\mu}m({\pm}21.6{\mu}m)$. 3. Group 3 showed the vertical discrepancies of $57.5{\mu}m({\pm}26.4{\mu}m)$, horizontal discrepancies of $28.4{\mu}m({\pm}17.5{\mu}m)$, and cement thickness of $37.2{\mu}m({\pm}17.4{\mu}m)$. 4. Group 4 showed the vertical discrepancies of $56.7{\mu}m({\pm}35.0{\mu}m)$, horizontal discrepancies of $31.8{\mu}m({\pm}24.2{\mu}m)$, and cement thickness of $45.6{\mu}m({\pm}19.8{\mu}m)$. 5. Vertical discrepancies were not significantly different at any groups(p>.050). 6. Microscope groups(Group 3, 4) showed significantly improved horizontal marginal adaptation (p<.050). 7. Although cement thickness showed the subset of Group 3. 4, 2 and Group 4, 2, 1. Group 3 showed significantly smaller thickness than Group l(p<.050). 8. Finishing and polishing by means of a microscope produced significantly smaller discrepancies than doing so with the unaided eye(p<.050).

• Journal of the Microelectronics and Packaging Society
• /
• v.15 no.4
• /
• pp.65-70
• /
• 2008

The mechanical shear strength of BGA(Ball Grid Array) solder joints under high impact loading was investigated. The Sn-37Pb solder balls with a diameter of $500{\mu}m$ were placed on the pads of FR-4 substrates with ENIG(Electroless Nickel Immersion Gold) surface treatment and reflowed. For the High Temperature Storage(HTS) test, the samples were aged a constant testing temperature of $120^{\circ}C$ for up to 250h. After the HTS test, high speed shear tests with various shear speed of 0.01, 0.1, 1, 3 m/s were conducted. $Ni_3Sn_4$ intermetallic compound(IMC) layer was observed at the solder/Ni-P interface and thickness of IMC was increased with aging process. The shear strength increased with increasing shear speed. The fracture surfaces of solder joints showed various fracture modes dependent on shear speed and aging time. Fracture mode was changed from ductile fracture to brittle fracture with increasing shear speed.

• Restorative Dentistry and Endodontics
• /
• v.24 no.2
• /
• pp.381-391
• /
• 1999

A new 5th generation adhesive system(ONE-STEP) has been supplied which operators can apply to conditioned tooth surfaces by one simplified step. The purpose of this study was to determine whether different methods of adhesive application and various air drying duration after applying adhesive affect the shear bond strength of composite resin to dentin, and to evaluate the adhesive pattern of composite resin and dentin under SEM. Seventy-seven extracted human molar teeth were cleaned and mounted in palstic test tubes. The occlusal dentin surfaces were exposed with Diamond Wheel Saw and smoothed with Lapping and Polishing Machine (South Bay Technology Co., U.S.A.). Teeth were randomly divided into 7 groups (n=11), In experimental A group, adhesive was applied to dentin with agitation for 20 sec. In experimental N-A group, adhesive were continuously applied to dentin for 20 sec. Also control and experimental 1, 2, 3, 4 groups were dried for 10, 0, 5, 20, 30 seconds after applying adhesive, respectively, Adhesives were light cured for 10 sec. A gelatin capsule 5mm in diameter was filled with Aelitefil$^{TM}$ composite resin, placed on the treated dentin surface and light cured for 40 see, from three sides, All specimens were stored in distilled water at room temperature for 24 hours. The shear bond strengths were measured using a universal testing machine(AGS-1000 4D, Japan) at a crosshead speed of 5mm/min. An one-way ANOVA and LSD test were used for statistical analysis of the data. For SEM evaluation, seven specimens were made and sectioned. Representive postfracture and seven specimens were mounted on brass stubs, sputter-coated with gold and observed under SEM. The results were as follows : 1. The shear bond strength of experimental A group which adhesive were applied to dentin with agitation was higher than that of experimental N-A group (continuous application), and there was significant difference between two groups (p<0.01). 2. The interface between composite and dentin according to different application methods showed close adaptation in experimental A group and showed tinny gap in experimental N-A group. 3. The shear bond strength accoding to various air drying duration was the lowest value(7.57${\pm}$2.60 MPa) in experimental 1 group, so there was significant difference between experimental 1 group and other four groups (p<0.05). But there was no significant difference of shear bond strength between four groups (p>0.05). 4. The interface between composite and dentin according to various air drying duration showed close adaptation in control group and tinny gap in experimental 3 and 4 groups. But experimental 1 and 2 groups showed $30{\mu}$ and 6 - $10{\mu}m$ thick gaps, respectively.

• Restorative Dentistry and Endodontics
• /
• v.18 no.1
• /
• pp.38-53
• /
• 1993

The purpose of this study was to observe the resin infiltration pattern into dentin by various dentin bonding agents. Freshley extracted 36 sound human molars were used in this study. They were stored at $4^{\circ}C$ physiologic saline solution before experiment. All the teeth were cross-sectioned to expose dentin below about 3.0mm at the cusp tip and above 2.0mm at the cemento-enamel junction with Crystal Cutter (MC411 D, Maruto Co., Japan), and were made into specimens for this study (Fig. 1). The specimen experimental groups were divided into 9 groups by dentin surface treatment as following procedures: Group I: Treated with Gluma Cleanser followed by Gluma Primer and Sealer Group 2. Treated with Gluma Cleanser followed by Scotch bond 2 Adhesive Group 3: Treated with Gluma Cleanser followed by Tenure Solution A, Band Visar Seal Group 4: Treated with Scotchprep followed by Scotch bond 2 Adhesive Group 5: Treated with Scotchprep followed by Gluma Primer and Sealer Group 6: Treated with Scotch prep followed by Tenure Solution A, Band Visar Seal Group 7: Treated with Tenure Conditioner followed by Tenure Solution A, Band Visar Seal Group 8: Treated with Tenure Conditioner followed by Scotchbond 2 Adhesive Group 9: Treated with Tenure Conditioner followed by Gluma Primer and Sealer 27 specimens of 36 specimens were divided into 9 groups (Group 1-9), and were used for observation of resin tags. Remaining 9 specimens were divided into 3 groups (Group 1,4 and 7), and were used for observation of fractured dentin surfaces. Specimens to observe the resin tag were demineralized with 20% HCl for 14 hours, specimens to observe the fractured dentin surfaces were demineralized with 10% HCl for 3 minutes. All the specimens were gold-coated with Eiko ion coater (Eiko-engineering Co.), and observed under Scanning electron microscope (Hitachi S-2300) at 20 KV. The following results were obtained: 1. In group 1 treated with Gluma Cleanser, Gluma Primer, and Sealer, most resin tags were more than $100{\mu}m$. 2. In group 4 treated with Scotch prep and Scotchbond 2 Adhesive, most resin tags were about $10{\mu}m$. 3. In group 7 treated with Tenure conditioner, Tenure Solution A, B, and Visar Seal, most resin tags were about $10{\mu}m$ but occasionally resin tags were more than $100{\mu}m$. 4. In groups 2,3,5,6,8 and 9, the lengths of resin tags were inconsistent and the amount of resin tags were reduced.