치과용 콤포짓트 레진의 적정중합을 위한 최소 광조사 시간 평가

임범순,이용근,김철위,최기열,이중배 大韓齒科器材學會 2004 대한치과재료학회지 Vol.31 No.1

The aim of this study was to estimate the minimum irradiation time for dental composites using a dynamic mechanical analyzer (DMA) and FT-IR. Six commercially available dental composites with A3 shade were tested: Heliomolar RO (Vivadent, Liechtenstein), Charisma (Kulzer, Germany), Herculite XRV Enamel (Kerr, USA), Aelitefil (Bisco, USA), Z100 (3M, USA), and Z250 (3M, USA). Storage modulus was measured by using DMA (StressTech Rheometer, Rheologica Instrument, Sweden) with fast oscillation mode (1 Hz). After disk-type (4 ㎜ ?1 ㎜) samples were irradiated with 500 mW/cm2 for 1, 2, 3, 4, 5, 10, 15, 20, and 30 s, storage modulus was recorded continuously for 60 min. Degree of conversion was also measured using FT-IR spectroscopy (FTS-165, Biorad Win-IR, Perkin-Elmer, USA) at 60 min after irradiation with same curing condition as DMA test. Sample irradiated with 500 mW/cm2 for 120 s was used as a control. The average of results for five specimens was compared using Tukey multiple comparison test (p=0.05) and the minimum irradiation time of composites was determined. The minimum irradiation time to get adequate polymerization was different depending on the dental composites. Both Z100 and Z250 require short irradiation times (5 s) and Charisma requires long irradiation time (15 s).

치과용 합금의 부식성에 관한 연구

임범순,이용근,윤숙진,김철위 大韓齒科器材學會 1995 대한치과재료학회지 Vol.22 No.1

Corrosion of dental alloys in the oral cavity can affect the mechanical, esthetic properties and efficiency of metallic restorations, and has great influence upon the local and systemic health of patients. The purpose of this study was to clarify the corrosion behavior of various dental alloys, and to measure the galvanic currents between dissimilar alloys. Fifty-eight kinds of dental casting alloys such as twenty-nine high gold alloys, ten low gold alloys, fourteen silver-palladium alloys, five base metal alloys, and twenty kinds of ceramic alloys such as seventeen noble metal alloys, three base metal alloys, were used as the experimental alloys. Modified Fusayama's artificial saliva titrated to pH 6.7 with phosphoric acid was used as an electrolyte. The specimens were immersed in the modified artificial saliva of 37℃. The rest potentials, anodic polarization curves, corrosion potentials, and galvanic currents were measured by using the potentiostat / galvanostat and zero shunt ammeter. From the experiment, the following results were obtained : 1) The gold based alloys showed the high rest potentials and the low current densities within experimental potential range. 2) The rest potentials and the current densities of the palladium-based alloys were influenced by the content of platinum, palladium, and silver. 3) In the nickel-chromium base alloys, the formations of passivation film were influenced by chromium content. The copper-aluminum alloy showed very high current density which was more than 150 mV . 4) The corrosion potentials of ceramic alloys were lower than those of dental casting alloys, but the trend of anodic polarizations were generally similar to the other alloys. 5) The amount of galvanic current and the polarity in the bimetallic galvanic cell could not be predicted considering only the alloy composition. The galvanic current decreased while the measuring time passed, but flew continuously.

치과용 콤포짓트 레진의 중합수축 응력

임범순,이용근,김철위 대한치과기재학회 2001 대한치과재료학회지 Vol.28 No.2

티타늄 표면처리에 따른 조골세포의 반응

임영준,이용근,임범순,김철위 大韓齒科器材學會 2004 대한치과재료학회지 Vol.31 No.1

It is well known that surface modification of titanium for implant has been shown to improve the adhesion, migration and differentiation of adjacent cells and tissues. This study presented the results of an experimental study on the interaction between MC3T3-E1 (mouse calvarian osteoblast cell line) cells and cp-titanium treated by thermal oxidation at four different temperatures after TiO2 blasting and NaOH treatment, which could provide the benefits of surface roughening and favorable oxide layer formation. No heat treatment group was used as a control. Cell interactions were studied using the combination of phase contrast microscope and scanning electron microscope. Potential cytotoxicity was tested by MTT assay. The response of osteoblast cells was different according to the condition of surface modifications. Thermal oxidation at 600℃ showed the best early cell attachment and calcium nodule formation compared to other groups. Thermal oxidation at 800℃ showed the worst cell attachment and proliferation. In general, osteoblast cells were attached to accompanying the formation of cellular process, spreaded and differentiated on the specimen surfaces. Calcium nodules were formed on the surface after these cells were developed multiple cell layers. These early osetoblast/titanium interactions might play a critical role in the osteoinduction stage of osseointegration. There was no statistically significant difference in cytotoxicity among the heat treated surfaces from the MTT assay(p>0.05). The results of microstructure analysis of the characterized cp-titanium surface of this study will be published separately.

수종 유기산 용액에서 글라스 아이오노머 시멘트의 표면조도 및 색 변화에 관한 연구

김용대,문현정,임범순,김철위 대한치과기재학회 1997 대한치과재료학회지 Vol.24 No.2

The chemical bonding ability of glass ionomer cement to tooth structure and sustained fluoried release render glass ionomer cements advantageous over other restorative materials, such a amalgam and composite resins. Poor polishability and high solubility in organic solvents, however, are still a significant disadvantage of the existing glass ionomer cements. The purpose of this study was to estimate the aging effect of glass ionomer cements in organic acid solutions on surface change and color change. Using metal molds, disk type speciments, 100mm×1mm were prepared from three chemical-curing and three light-curing glass ionomer cements. Specimens were prepared from each material following the manufacturer's intructions, and setted against a mylay matrix strip supported by a glass slab. Three specimens were prepared for each experimental groups. Profilometric analyses were carried out using the surface roughness tester(Surtronic 3P, Rank Taylor Hobson Ltd. England). R?? valuse, which were the mathematical mean values of the departure of the roughness profile from the mean line calculated by the machine, recorded. Color measurements(CIE coefficients ; L, a, b) were peformed using the spectrophotometer(CM-3500d, Minolta, Japan). Before aging treatment and after 1, 7, 14, 21, and 28 days aged at 37℃ in a various organic and solutions(such as acetic acid, lactic acid and citric acid) and deionized water, surface roughness and color coefficients measuements were carried out. Then, surface roughness changes(ΔRa) and (ΔE) of specimens were calcuiated. From the experiment, the following results were obtained : 1. Chemical-cured glass ionomer cements showed statistically surface roughness changes after aged in the deionized water(P<0.10), and light-cured glass ionomer cements showed statistically significant color changes after aged in the deionized water(P<0.10). 2. Chemical-cured glass ionomer cements showed statistically color changes after aged in acetic acid solutions (P<0.10), and light-cured glass ionomer cements did not showed statistically significant surface roughness changes, but showed statisticall significant color changes after aged in acetic acid solutions (P<0.10). 3. Chemical-cured glass ionomer cements did not showed statistically significant color changes as a function of concentration of lactic acid solutions (p>0.10), and light-cured glass ionomer cements showed statistically significant color changes after aged in acetic acid solutions. 4. Chemical-cured glass ionomer cements did not showed statistically significant surface roughness changes as a function of concentration iof lactic acid solutions (p>0.10), but showed significantly less solubility in lactic acid solutions than chemical-cured glass ionomer cements.

배양조건에 따른 치수세포 RPC-C2A의 특성 : 배양용기 및 BMP 처리 Culture Ware and BMP Treatment

이용근,임범순,김철위 大韓齒科器材學會 2003 대한치과재료학회지 Vol.30 No.4

Odontoblasts are highly differentiated cells aligned at the periphery of the dental pulp. Pulp tissue responds to injury by generating reparative dentine elaborrated by odontoblast-like cells that differentiated from pulp cells. In vitro, dental pulp cells cultured under certain conditions are able to express typical markers of cell differentiation; however, no culture sysem can simulates clinical pulp response. The purpose of this study was to evaluate the effect of culture ware and BMP on the seeding. growth sne differentiation of pulp derived cell line, RPC-C2A. Large pore-sized PET membrane (0.4 ㎛, Cell Culture Insert, BD Science, USA), rhBMP-4 (R & D Systems, USA) and polystyrene modified by vacuum-gas plasma treated culture surface (Primaria, BD Science, USA) were tested. RPC-C2A cells are maxillary incisor pulp cells from male Wistar rats (Kasugai el al., 1988). Cells were cultured on a traditional polystyrene culture ware (PS), transparent PET membrane (MI), Insert + rhBMP-4 (20 ng/ml, MB), and Primaria culture ware (PM) up to 21 days. Culture media was 10% FBS added DMEM with 10 mM β-glycerophosphate, 10^-8 M dexamethasone, 50 ㎍/ml ascorbic acid and 50 mM sodium fluoride. Formation of multilayered cell layer and mineral nodule was determined with a phase contrast microscope and EDXA. There were no differences in cell attachment and growth rate among four culture conditions up to three-days culture. Multilayered cells were observed after six-days culture, and mineral nodules were observed in MB condition after seven-days culture. After nine-days culture, mineral nodules were observed in PS, and new nucleation of mineral nodules was prominest in MI and MB conditions. Exfoliation of cells from the dish was observed in PS after 13-days culture, and vaeuoles were formed in MI after 19-days culture. After 21-days culture, cell death was accompanied by increase of mineral nodules in MB. Growth and development of pulp cells were influenced by the culture ware and BMP. In MB condition, the duration for the formation of multilayered cells and mineral nodule was shortened compared to other conditions.

치과용 인산칼슘계 충전 및 재생재료 개발(Ⅰ)

이용근,임범순,김철위 대한치과기재학회 2001 대한치과재료학회지 Vol.28 No.3

Because calcium phosphate materials including hydroxyapatite are bioactive and exhibit good biocompatibility, these compositions are actively tried as the hard substituting materials. At the beginning of the development of the calcium phosphate materials, these materials were used as sintered ceramics. After then, plastic calcium phosphate cements were developed to make the shape of the material directly at the site of application. Reports on the dental calcium phosphate materials can be assorted into some categories; development of root apex sealing material or canal sealer, development of pulp capping material or cavity liner, or the reinforcement through addition of resin materials. Studies on the biocompatibility and drug delivery system may be other categories. The final purpose of this study is the development of dentine substituting materials based on calcium phosphate, which is highly biocompatible with the tooth pulp and additionally can stimulate or accelerate the dentine formation. In this preliminary study, PMVE-Ma (polymethy1 viny1 ether-maleic anhydride), HPMC (hydroxypropy1 methy1 cellulose), acrylic resin and acrylic-maleic copolymer was added into the PBS (phosphate buffered solution) to optimize the mechanical and chemical properties of calcium phosphate cement. From this study, AC-1 (4:1 mixture of cement powder and resin powder mixed chemical cure acrylic resin solution) showed the highest diametral tensile strength after storage in 100 % relative humidity for 24 hours, and AM-3, AM-2 (4:1 mixture of cement powder and resin powder mixed with 40 or 30 % acrylic-maleic copolymer) followed. The ranking of compressive strength from the highest in the same condition was AC-1, AM-2 and HP-4 (cement powder mixed with 15 % PMVE-Ma in DW). HP-4 showed the highest diametral tensile strength after storage in normal saline for 24 hours, and AC-1 and AC-2 (9:1 mixture of cement powder and resin powder mixed chemical cure acrylic resin solution) followed. The ranking of compressive strength from the highest in this condition was AC-1, HP-4 and HP-6 (cement powder mixed with the 1:1 mixture of 2 % HPMC in DW and 15 % PMVE in DW). From the point of the mechanical properties, AC-1, HP-4, AM-3 and AM-2 seemed proper for dentine filling material. Addition of resin materials did not influence on the speed and ratio of hydroxyapatite formation. From this study, appropriate compositions based on calcium phosphate for dentine filling materials can be found.

통일, 그것은 정신적 통일이어야 한다

최용철,임규정 군산대학교 현대이념연구소 1997 現代理念硏究 Vol.12 No.-

치과용 글라스 아이오노머 시멘트의 압축, 간접인장 및 전단 결합강도에 관한 연구

김철위,이용근,임범순 서울대학교 치과대학 치과생체재료학교실 1994 치과생체재료학 논문집 Vol.2 No.1

The purpose of this study was to evaluate the compressive strength, diametral tensile strength and shear bond strength of the glass ionomer cements and to compare strengths of the glass ionomer cements independent of their type. The present study utilized one brand of dental zinc phosphate cement and twelve brand of dental glass inomer cements. The load at failure was measured using a Instron universal testing machine (Instron Model 1122), with crosshead speed of 0.05㎝/min. for compressive and diametral tensile test, 0.02 ㎝/min. for shear bond test. From the load at failure, the strength of the specimen could be calculated. Testing of compressive strength, diametral tensile strength, and shear bond strength were carried out at 24 hours and specimens were maintained in distilled water at 37°±2℃ just prior to testing. From the experiments, the following results were obtained; 1.The glass ionomer cements presented a wide variance of compressive strengths. The light-cured glass ionomer cements showed higher compressive strength than self-cured glass ionomer cements. 2. No significant difference (P<0.05) in the diametral tensile strength was observed among self-cured glass ionomer cements. On the contrary, the light-cured glass ionomer cements showed 3∼4 times higher dimetral tensile strength than the self-cured cements. 3. The glass ionomer cements showed a good shear bond strength to dentin.

치과용 알지네이트 인상재의 국산화 및 개량에 관한 연구 : Ⅰ. 조성이 특성에 주는 영향

이용근,임범순,김철위 대한치과기재학회 2001 대한치과재료학회지 Vol.28 No.3

Dental alginate impression materials have become widely used to take study impression for orthodontic and other purposes and, to a limited extent, have been applied in inlay, crown and bridge procedures. The alginate impression products have good elastic properties and compare well with the agar materials. The final purpose of this serial study is to develop a domestic dental alginate impression material which is proper for use in Korea. The final purpose of this first year study was to find a proper composition of alginate impression material, which shows appropriate mechanical properties and high biocompatibility. Several kinds of experimental alginate impression materials were prepared by mixing sodium alginate, calcium sulfate dihydrate, diatomaceous earth as filler, borax, magnesium oxide, potassium chloride, sodium acetate, sodium phosphate, zinc fluoride and zinc oxide in varied proportions. Texture of powder and mixture, flexibility, recovery from deformation, setting time, compressive properties, compatibility with dental stone, reproduction of detail and cytotoxicity by MTT assay and neutral red inhibition zone of mixed experimental and commercial alginate impression materials were tested according to the specifications of Korean Food and Drug Administration, Korean Dental Association No. 8, American Dental Association No. 18 and International Standardization Organization 1563 (1990). From this study, proper compositions of experimental alginate impression material which showed flexibility of 5∼20% (in accordance with the specification), and proper setting time of 1.5∼5 minutes was found. Although the property of recovery from deformation was lower than that of the specification, these values were similar to those of commercial alginate impression materials. The compressive strength was in accordance with the specification of more than 0.35 Mpa. Some compositions showed proper detail reproduction. Cytotoxicity was not different regardless of the composition, and was similar to those of commercial materials. From the above results, two promising compositions were determined to be used as the basic composition for making a domestic alginate impression material. On this result, beneficial properties of fluoride release, reduced dust production and sufficient antibacterial effect will be added before marketing.