자동혼합 부가중합형 실리콘고무인상재의 인장강도 및 유연성에 관한 연구

방몽숙,신미숙,박영준 大韓齒科器材學會 1995 대한치과재료학회지 Vol.22 No.1

The purpose of this study was to investigate the tensile strength and flexibility of four automixing additional silicone rubber impression materials. To evaluate the tear resistance of impression material, the automixed impression material was cured in a 32℃ water bath with the necked specimen preparation mold for 5 minutes. Three minutes after the withdrawl from the water bath the specimens were tested for their maximum tensile strength with universal testing machine(Instron 4302, England). To evaluate the flexibility of the impression materials, the cylindrical specimen was compress 10% of the original length, and the stress produced by that compression was evaluated. The flexibility of the cylindrical specimen was evaluated at 2 minutes-, 1 hour-, and 24 hours- after being withdrawn from the curing water bath by checking the stress at 10% compression. The results were as follows; 1. Examixfine showed the highest tensile strength value at 18.11 ㎏/㎠ followed by Provil L C.D. at 16.77 ㎏/㎠. The next was Express at 12.40 ㎏/㎠ and Correct VPS showed a significantly low value at 9.62 ㎏/㎠ when compared with other groups(P<0.01). 2. Under the 10% compression, Correct VPS showed significantly low stress at 1.511 ㎏/㎠ when compared with other groups(P<0.01). The other groups were Examixfine at 1.879 ㎏/㎠, Provil at 2.025 ㎏/㎠, and Express showed significantly higher stress at 3.689 ㎏/㎠(P<0.01). 3. The order of stress from lowest to highest for the 10% compression at 1 hour- and 24 hours- after being withdrawn from the curing water bath was Correct VPS, Examixfine, Provil L C.D., and Express. In all experimental groups the stress for dimensional shortening increased as the elapsed time increased.

지대치 형태에 따른 Post core의 치근내부 및 지지조직의 응력분석

김진,방몽숙 전남대학교 치과대학 1992 전남치대논문집 Vol.4 No.1

The Purpose of this study was to analyze the stresses and displacements of various post and core. The Finite element models of central incisors were divided into seven types according to the various amount of remaining tooth structures. 10kgf/㎟ force was applied respectively as follows: 1) Horizontal on the labial surface 2) 26˚ diagonal direction on the lingual surface Material property, geometry, and load condition of each model were inputted to the two dimensional ANSYS 4.4A finite element program ; stresses and displacements were analyzed. Results were as follows: 1. In the case of 130˚ shoulder post and core, Maximum tensile and shear stresses were observed in the crown margin. 2. Maximum shear stress was about 29% reduced by contrabevel. 3. In the case of 1㎜ axial tooth structure, Maximum tensile stress observed in the dentin. 4. In the case of butt joint of cervix, Maximum stress concentration was observed in the dentin by the inclined and horizontal force. 5. Horizontal force produced the extraordinary high stresses in dentin and supporting structures. 6. The amount of remaining tooth structure affected the level of stress significantly and it determined the location of stress concentration.

레진 시멘트와 상아질 접착제를 사용한 콤포지트 레진 코아의 전단결합강도에 관한 연구

김현오,방몽숙 전남대학교 치의학연구소 2003 구강과학 Vol.15 No.1

The purpose of this study was aimed to compare the shear bond strength on dentin of three dentin bonding agents and two resin cements used in conjunction with self-cured composite resin core material. Control group and six experimental groups were divided for study. Control group was designated as specimens bonded with Tenure A&B^�. And experimental groups were as follows; PB-BL group: specimens bonded with Prime & Bond NT^�, BondLink^� SB-BL group: specimens bonded with SingleBond�, BondLink^� PB group: specimens bonded with Prime & Bond NT^� SB group: specimens bonded with SingleBond^� PF group: specimens bonded with Panavia-F^� Bl group: specimens bonded with Bistite Ⅱ^� All specimens were stored in 37℃ distilled water for 24 hours. followed by the shear bond strength was tested by instron universal testing machine. The data was analysed statistically by Mann-whitney test. The results were as follows : 1. For Prime & Bond NT and SingleBond, the shear bond strength was 0.24 Mpa and 7.19 Mpa each by each, while Tenure A&B group control was measured at 13.93 Mpa (p<0.05). Especially for Prime & Bond NT, it did not get conjunction with dentin. 2. For Prime & Bond NT and SingleBond using BondLink, there was no significant difference as a result of 11.73 Mpa and 14.00 Mpa each by each (p,0.05). 3. For Panavia-F and Bistite Ⅱ, they showed the highest shear bond strength as measured by 18.24 MPa and 16.09 MPa each(p<0.05).

타액오염이 식각 금속 유지 장치의 레진 접착에 미치는 영향

박하옥,방몽숙 전남대학교 치과대학 1989 전남치대논문집 Vol.1 No.2

The purpose of this study was to evaluate the influence of saliva contamination on the resin bonding of the etched metal retainers. The test sampls were made of Verabond, and divided into 3 groups. Retainers in group 1 had normally etched metal surfaces. Retainers in group 2 had normally etched metal surfaces which were saliva-contaminated for 30 seconds and cleaned wih streaming, luke-warm water for 1 minute and dried thoroughly. Retainers in group 3 had normally etched metal surfaces which were saliva-contaminated for 30 seconds and dried thoroughly without water-cleansing. Each 3 group specimen was watched on SEM. A resin core, 5mm in diameter and 6mm in length, was made of Panavia using Teflon mold on the each specimen. These 3 groups were tested to evaluate shear bond strength, using universal testing machine. The results were as follows : 1. The shear bond strength showed no significant difference between group 1 and group 2 2. The shear bond strength showed significant difference between group 1 and group 3. 3. The shear bond strength showed significant difference between group 2 and group 3. 4. Scanning electron microscope photographs of group 1 and group 2 showed no signs of contamination but of group 3 showed somewhat contaminated.

환상형 클래스프의 유지력에 관한 연구

이재순,방몽숙 전남대학교 치과대학 1998 전남치대논문집 Vol.10 No.1

The purpose of this study was to compare the retentive force of cast half round circumferential clasps, cast round circumferential clasps and wrought wire clasps on three different depths of undercut (10G, 20G, 30G), and to determine the proper amount of undercut for cast round circumferential clasp. Three different lower second premolar crowns were cast and each of clasp was made. Each of clasp affixed to the different types of clasp. Their retentive forces were measured with universal testing machine. The results were as follows: 1. When the depth of undercut was same, the greatest retentive force was exerted by cast half round circumferential clasp, followed by cast round circumferential clasp and wrought wire clasp. 2. The degree of variation amount of retentive force according to depth of undercut was greatest for cast round circumferential clasp. 3. Not only elastic deformation but also permanent deformation of the retentive arm was observed after insertion and removal of the clasp. The results of this study show that the retentive force of cast round circumferential clasp falls between those of cast half round circumferential clasp and wrought wire clasp, and suggest that a 20G undercut is suitable for ensuring an appropriate degree of the retentive force.

침적 소독이 고무 인상재의 크기 안정성에 미치는 영향

민권남,박몽숙 전남대학교 치과대학 1998 전남치대논문집 Vol.10 No.1

The purpose of this study was to evalute the effect of immersion disinfection on the dimensional stability of rubber impression materials. The metallic master model was made in order to simulate the intraoral arch form. Impressions were made from four impression materials (Exaflex, Extrude, Reprosil, Impregum-F) and immersed in three disinfectant solutions (Wydex, Vi-Pon, Potadine). Casts from the impressions were measured according to the interpreparation distance. The A-B and The B-D abutment distance were compared with the control group and disinfected groups. The results were as follows; 1. The measurements of the stone cast increased relative to the master model and there was a significant difference (P<0.05). 2. The relative dimensional change of the stone cast as compared with master model ranged from 0.10% to 0.56% in the A-B distance and ranged from 0.04% to 0.27% in the B-D distance. 3. The dimensional change of the disinfected groups as compared with the control group was significantly different in the three impression materials except for Impregum-F (P<0.05). 4. The relative dimensional change of the disinfected groups compared with the control group ranged from 0% to 0.20% in the A-B distance and ranged from -0.09% to 0.11% in the B-D distance. These results suggest that immersion disinfection of rubber impression materials by chemical disinfectants causes very small dimensional change and the change is clinically acceptable for prothesis fabrication.

레진 표면 처리제의 도포에 따른 의치상 레진과 개상용 레진의 결합강도에 관한 연구

문병준,방몽숙 전남대학교 치과대학 1996 전남치대논문집 Vol.8 No.1

his study investigated the effects of resin surface primers for rebase resins on the surface texture of denture base resins by the use of scanning electron microscopy. This study also evaluated the bond strength of rebase resins to denture base resin. The denture base resin in this study was Vertex RS (Dentimex Co., Ltd., Holland). The rebase resins used were Tokuso Rebase (Tokuyama Co., Ltd., Japan), Metabase (Sun Medical Co., Ltd., Japan), New Tru Liner(Harry J. Bosworth Co., Ⅲ.), and Reverse (Nissin Co., Ltd., Japan). The test samples were divided into four parts: Group 1 : Treated with primer with brush. Group 2 : Immersed in the primer for 5 seconds. Group 3 : Immersed in the primer for 10 seconds. Group 4 : Immersed in the primer for 30 seconds. Control group : not treated with primer The results were as follows; 1. The bond strength of rebase resins to denture base resin is increased by application of primers. 2. Regardless of the rebase resin type, there was no significant difference among the bond strength in groups G1, G2, G3, G4. There was a significant difference with the control. (P<0.05) 3. Regardless of each group, the bond strength according to the rebase resin type was decreased in the following order: Tokuso Rebase, New Tru Liner, Reverse and then Metabase. 4. Under the scanning electron microscope, brush application produced a softening of the denture base surface. After immersion, all primers produced a spongelike structure on the denture base resin surface. The results of this study suggest that primers produce a significant effect by means of brush application, therefore it is recommended as the most convenient and logical procedure for application of the primers.

수종 의치상 레진의 세포반응에 관한 연구

전철오,방몽숙 전남대학교 치과대학 1991 전남치대논문집 Vol.3 No.1

The present study qantitates the in vitro cytotoxicity of a variety of denture base acrylic resins using cell culture techniques combined with image analysis to measure nuclear area and DNA contents. In this study, a comparison was made among direct curing, heat curing and microwave curing resins. The results obtained from this study were as follows ; 1. Morphologically, cell process and nucleus became prominent but macroscopic difference according to the resins were not observed. In addition, increased cellular density around the specimen were observed. 2. In DNA contents measurements, S-G2M phase cell was 15.47%, 14.58% in control and heat curing resin on 1st day and the others group 21.39~33.36% were measured. 3. Nuclear area and DNA contents were increased on 3rd day except DNA content of the microwave curing resin group. These results suggest that denture base acrylic resins stimulate gingival fibroblasts in vitro, especially stimulation of direct curing resin is larger and longer than the others.

임플란트 고정체와 지대주 연결 형태의 차이에 따른 유지 나사 안정성에 대한 연구

양재식,방몽숙 전남대학교 치의학연구소 2003 구강과학 Vol.15 No.3

Since the concept of osseointegrated dental implant by Branemark et al was first applied to mandibular full edentulous patients. Recently it is considerated the first treatment option on missing teeth. A common problem associated with dental implant restorations is loosening of screws that retain the prosthesis to the abutment and the abutment to the implant fixture. This study is to examine the influence on screw loosening of implant-abutment designs such as external hex, cone screw, beveled hex, cam cylinder, cylinder hex by means of evaluating the loosening torques, with respect to a range of tightening torques after repeated loading. The results of this study were as follows. (1) Cone screw, beveled hex groups are the highest initial tightening rate and cylinder hex, external hex groups are the lowest initial tightening rate(p<0.05). (2) Cone screw groups are the highest after repeated loading tightening rate and cylinder hex groups are lowest after repeated loading tightening rate(p<0.05). (3) Cone screw groups have the highest initial stability and final stability. (4) All groups are decreased tightening rate after repeated loading.

골유착성 임플랜트를 중간지대치로 사용한 고정성 보철물의 응력분석

박상수,방몽숙 전남대학교 치과대학 1992 전남치대논문집 Vol.4 No.1

The purpose of this study was to analyze the stress distribution of the natural teeth, the implant, the prosthesis and the supporting tissue according to the types of implant and connection modality in the five-unit fixed partial denture with a implant pier abutment. A Two dimensional stress analysis model was constructed to represent a mandible missing the first and second premolars and first molar. The model contained a canine and second molar as abutment teeth and implant pier abutments with and without stress-absorbing element. Finite element models were created and analyzed using software ANSYS 4.4A for IBM 32bit personal computer. The results obtained were as follows; 1. Implant group, compared to the natural teeth group, showed a maximum principal stress at the superior portion of implants and a stress concentration at the neck and end portion. 2. Maximum principal stress and maximum Von Mises stress were always lower in the case of rigid connection than nonrigid connection. 3. A cylinder type implant with stress absorbing element and screw type implant were generally similar in the stress distribution pattern. 4. A screw type implant, compared to the cylinder type implant, showed a relatively higher stress concentration at both neck and end portion of it. 5. Load B cases showed higher stress concentration on the posterior abutments in the case of nonrigid connector than rigid connector. 6. A maximum displacement was always lower in the case of rigid connection than nonrigid connection. These results suggest that osseointegrated implant can be used as an intermediate abutment.