• Journal of the Korean Applied Science and Technology
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• v.16 no.2
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• pp.171-177
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• 1999

The objectives of this study is to investigate the optimum reaction conditions and to identify the product formula in the synthesis of a silicone/acrylic resin that curing in moisture at room temperature. By the addition polymerization of monomers, n-butyl acrylate, methyl methacrylate, n-butyl methacrylate, and 3-methacryloxypropyltrimethoxysilane. a quarter polymer was obtained. Among various initiators investigated in this study, 2.2'-azobisisobutyronitrille was found to be the most suitable initiator. The optimum reaction conditions found in this study are 70 wt% of initial solvent amount, 120 minutes of dropping time, 3 times of initiator addition, $82{\sim}105^{\circ}C$ of reaction temperature, and 8 hrs of reaction time. Also, number average molecular weight of $11700{\sim}33100$ and molecular weight distribution of $1.81{\sim}3.44$ were obtained.

• Journal of the Korean Applied Science and Technology
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• v.21 no.3
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• pp.191-196
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• 2004

An emulsion of octadecamidoethylaminoethyl dodecate (which provides softness) and an emulsion silicone oil KF-96 (which provides lubricity) were separately synthesized. Then PP finishing softeners (SSA-7) was prepared by blending of the synthesized emulsions with beef tallow hardened oil (a softness improving agent). PP finishing treatment was carried out with the prepared SSA-7 and PP finishing resin by a one bath method, and several physical properties were tested. As a result, crease recovery, tear strength, softness, lubricity, and bending resistance were all good, indicating that the prepared SSA-7 is a good PP finishing softener.

• Journal of Dental Rehabilitation and Applied Science
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• v.16 no.1
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• pp.27-36
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• 2000

One of the methods to improve the softness and comfortness of denture base is the use of soft denture liners. In this study, specimens were made by 2 kinds of acrylic based soft lining materials and 2 kinds of silicone based soft lining materials, and bonded to acrylic resin(Lucitone $199^{(R)}$). Then they were tested the differences of tensile bond strengths according to the materials, thickness, surface treatment and failure mode. 1. Tensile bond strength according to soft lining materials was increased in order of Coe-$soft^{(R)}$, $Mollosil^{(R)}$, $Trusoft^{(R)}$, Ufi-Gel $C^{(R)}$. The differences between groups were statistically significant at level of 0.05. 2. Tensile bond strength according to thickness of soft lining materials was increased in order of 3mm, 2mm, 1mm. The differences between groups were not statistically significant. 3. Tensile bond strength of treated surface showed higher bond strength than nontreated surface. The difference between groups was not statistically significant. 4. The failure mode of Coe-$soft^{(R)}$, $Trusoft^{(R)}$, $Mollosil^{(R)}$ were mainly cohesive failure, and that of Ufi-Gel $C^{(R)}$ were mainly adhesive failure.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.2
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• pp.191-199
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• 2000

Wettability of addition silicone impression material is very important property for making an accurate restoration. This study examined the impression quality in clinical condition and the wettability of impression and die material. Four commercially available addition silicone impression material (Express, Examix, Contrast, Perfect) and three die materials (Die-Keen, Vel-Mix, Fuji-Rock) were studied. A total of 50 putty/wash and heavy body/wash impressions of wet intact permanent molar teeth were examined for definition of the gingival sulcus reproduction and then classified in quality ranking. The percentage of the sulcus reproduction ability of each material was calculated from the sulcus depths of cross-sectioned epoxy resin casts from the impressions and clinically measured sulcus depths, The same impression materials were used to produce 3 groups of die stone casts form void entrapment die had been exposed to milk. Voids in the impression body and stone casts ere counted under a stereoscopic microscope. From the experiment, the following results were obtained : 1. Sulcus reproduction ability of additional silicone impression material were diminished in order of Express, Examix, Perfect, Contrast. The significant difference was found between Perfect and other material. Heavy body/wash combination was superior In putty/wash method n Perfect impression material. 2. In direct observation, Contrast showed least void in impression body but correlations ere not found between sulcus reproduction and void production. 3. In void entrapment laboratory test, wettability were diminished in order of Examix, Contrast, Express, Perfect. Clinical impression recording seems not to correlate with laboratory test. 4. The wettability of die material to impression material was not different in Express, Examix, Contrast. But, in Perfect, Die-Keen had superior wettability to others.

• The Journal of Advanced Prosthodontics
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• v.12 no.4
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• pp.225-232
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• 2020

PURPOSE. This study aimed to fabricate provisional crowns at varying build directions using the digital light processing (DLP)-based 3D printing and evaluate the marginal and internal fit of the provisional crowns using the silicone replica technique (SRT). MATERIALS AND METHODS. The prepared resin tooth was scanned and a single crown was designed using computer-aided design (CAD) software. Provisional crowns were printed using a DLP-based 3D printer at 6 directions (120°, 135°, 150°, 180°, 210°, 225°) with 10 crowns in each direction. In total, sixty crowns were printed. To measure the marginal and internal fit, a silicone replica was fabricated and the thickness of the silicone impression material was measured using a digital microscope. Sixteen reference points were set and divided into the following 4 groups: marginal gap (MG), cervical gap (CG), axial gap (AG), and occlusal gap (OG). The measurements were statistically analyzed using one-way ANOVA and Dunnett T3. RESULTS. MG, CG, and OG were significantly different by build angle groups (P<.05). The MG and CG were significantly larger in the 120° group than in other groups. OG was the smallest in the 150° and 180° and the largest in the 120° and 135° groups. CONCLUSION. The marginal and internal fit of the 3D-printed provisional crowns can vary depending on the build angle and the best fit was achieved with build angles of 150° and 180°.

• The Journal of Korean Academy of Prosthodontics
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• v.30 no.1
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• pp.65-72
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• 1992

The purpose of this study was to evaluate the flexure stregth of posterior 4-unit acrylic resin bridge with different pontic designs : 1) Conventional pontic 2) Hygienic pontic and 3) Modified hygienic pontic. All specimens were made of self-curing acrylic resin for provisional restorations. Self-curing acrylic resin was filled in a silicone mold by the drop-on technique ; and was polymerized in a pressure spot under 20 psi pressure. The test specimens which were simply shaped posterior 4-unit bridge were 38mm ion 4mm wide, and 35mm thick(connector : 3mm thick). Each specimen was subjected to an increasing load of Instron machine with its tip centered on the specimen at 90-degree angle, and the machine was operated with its load cell of 50kg and its crosshead speed, 2mm/minute : and then the load values at the moment of the fracture of them were recorded. This study was also performed to analyze their stress distributions by the finite element method. The obtained results were as follows : 1. Flexure strength of the hygienic pontic(9.78kg) and the modified hygienic pontic(10.17kg) was higher than that of conventional pontic(6.96kg). But no significant difference was found between the hygienci pontic and the. modified hygienic pontic. The above statistic values were appraised by ANOVA and Duncan's multiple range test 2. Stress was concentrated on the middle portion in every group : and the stress of conventional pontic was found the greatest of all pontic designs.

• Restorative Dentistry and Endodontics
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• v.41 no.4
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• pp.271-277
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• 2016

Objectives: In this study, we evaluated the influence of different radiant exposures provided by single-peak and polywave light-curing units (LCUs) on the degree of conversion (DC) and the mechanical properties of resin cements. Materials and Methods: Six experimental groups were established for each cement (RelyX ARC, 3M ESPE; LuxaCore Dual, Ivoclar Vivadent; Variolink, DMG), according to the different radiant exposures (5, 10, and $20J/cm^2$) and two LCUs (single-peak and polywave). The specimens were made (7 mm in length ${\times}$ 2 mm in width ${\times}$ 1 mm in height) using silicone molds. After 24 hours of preparation, DC measurement was performed using Fourier transform infrared spectrometry. The same specimens were used for the evaluation of mechanical properties (flexural strength, FS; elastic modulus, E) by a three-point bending test. Data were assessed for normality, after which two-way analysis of variance (ANOVA) and post hoc Tukey's test were performed. Results: No properties of the Variolink cement were influenced by any of the considered experimental conditions. In the case of the RelyX ARC cement, DC was higher when polywave LCU was used; FS and E were not influenced by the conditions evaluated. The LuxaCore cement showed greater sensitivity to the different protocols. Conclusions: On the basis of these results, both the spectrum of light emitted and the radiant exposure used could affect the properties of resin cements. However, the influence was material-dependent.

• Journal of the Korean Applied Science and Technology
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• v.31 no.4
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• pp.595-601
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• 2014

The microstructures of NATM were examined by SEM, FT-IR spectra, tensile properties, mole % of [NCO/OH], and particle size analyzer. Growing concerns in the environment-friendly industries have led to the development of solvent-free formulations that can be cured. We had synthesized NATM(New Austria Tunnel Method) resin having the ability to protect stainless steel against corrosion. Comparing with general NATM resin and coatings, this resin that synthesized with polyurethane and epoxy was highly stronger in intensity and longer durability. Hybrid resin was composed of polyols, MDI, epoxy, silicone surfactant, catalyst and crosslink agent, and fillers. Moreover, fillers such as fume silica not only accelerated the curing rate but also improved the physical property as thermal barriers. The rigid segments of synthetic resin in mechanical properties were due to fume silica and the increase the mole% of [NCO/OH] for corrosion protection. In conclusion, the hybrid resin microstructure with crosslink agent and fume silica are good material for thermosetting coating of metal substrates such as stainless steel.

• Journal of Technologic Dentistry
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• v.41 no.1
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• pp.21-27
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• 2019

Purpose: To evaluate 2D and 3D of occulsal, mesial-occlusal and mesial-occlusal-distal cavity of composite resin inlay. Methods: Abutment tooth 16, 36 of FDI system was selected for the study. Inlay prostheses classified as occlusal cavity (OC group), mesial-occlusal (MOC) and mesial-occlusal-distal cavity (MODC) were prepared using composite resin. Composite resin was injected with composite resin in prepared tooth cavity and then photopolymerized with UV light. Additional thermal polymerization was performed. Marginal gap of composite resin inlays were measured by digital microscope(x160) with silicone replica technique. The data was analyzed from statistical software for Kruskal-Wallis test (${\alpha}=0.05$). 3-dimensional analysis was analyzed through superimposition method. Results: The smallest 2D marginal fit measure of the three groups was $47.0{\pm}21.6{\mu}m$ in the MOC group. The largest 2D marginal was $69.1{\pm}33.8{\mu}m$ in the MODC group. In the trueness of the three groups, the most accurate figure was $14.4{\pm}2.3{\mu}m$ for the MODC group. In Precision, the most accurate figure was $14.5{\pm}4.3{\mu}m$ for the MODC group. Conclusion : In this study, 2D marginal fit of OC, MOC, and MODC cavities fabricated with composite resin was applicable to all clinical applications. In the 3D inner surface accuracy evaluation, the MODC group showed the accuracy results.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.3
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• pp.236-245
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• 2002

The acrylic resin was first introduced as denture base materials in 1937 and it is commonly used for denture base fabrication nowadays. Three different curing cycles (Conventional curing cycle, short curing cycle and long curing cycle) and three commercially available heat-activated acrylic resins (Vertex RS, Lucitone 199 and ProBase Hot) were investigated to find the curing cycle and material that showed the minimum shrinkage of the resin during polymerization process. A brass master mold was fabricated and duplicated by additional silicone impression material. Stone molds were made by pouring of type III dental stone (SILKY-ROCK YELLOW, Whip-Mix, Louisville, Kentucky). It was embedded in the flask. Strain gauge and thermocouple were embedded in the specimen. Strain gauge and thermocouple were connected to signal conditioning amplifier and data was recorded by pre-programmed software. The parameters ESmax (Maximum expansion strain), Sb (Strain measured just before deflasking procedure), Sa (Strain measured just after deflasking procedure) and Sf (Strain measured at the end of the experiment) were measured. ${\Delta}$S was calculated from Sb and Sa (${\Delta}$S=Sb-Sa). In the experiment concerned about materials, the parameters 90-ESmax (Maximum expansion strain measured during early 90 minutes of curing procedure), 180-ESmax (Maximum expansion strain measured from 90 minutes to 180 minutes), Sb, Sa, ${\Delta}$S and Sf were measured and the following conclusions were made. 1. The ESmax value of conventional curing cycle showed the largest value and the 180-ESmax value of Lucitone 199 showed the smallest value. 90-ESmax values showed no significant difference (p<0.05). 2. ${\Delta}$S values of conventional curing cycle showed the positive values. ${\Delta}$S values of short curing cycle and long curing cycle showed the negative values. All three materials cured by conventional curing cycle showed the positive values. 3. The Sf values of long curing cycle and ProBase Hot (cured by conventional curing cycle) showed the smallest values.