• 폴리머
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• 제27권5호
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• pp.493-501
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• 2003

의치상 레진 (틀니)의 기본 물질로 사용되는 폴리(메틸 메타아크릴레이트) (PMMA) 입자를 폴리(비닐 알코올) (PVAL)을 안정제로 사용하여 현탁중합법으로 중합하였고, PVAL 농도와 교반속도, 공단량체의 도입에 따른 PMMA의 입자 크기 변화 및 분자량의 변화를 관찰하였다. 또한 합성된 PMMA 수지와 메틸 메타아크릴레이트 단량체를 이용하여 고체/액체 비 (P/L ratio)를 2:1 로 하여 병상물을 제조하고, 일정한 가압성형 조건하에서 제작된 시편으로 수지의 입자 크기 및 분자량에 따른 PMMA에 기초한 틀니용 수지의 기계적 물성 변화를 관찰하였다. 그 결과 평균입자 크기가 100 $\mu$m 이하에서는 분자량이 커질수록 기계적 물성이 높게 나타났으며, 그 이상인 영역에서는 분자량에 상관없이 입자 크기가 증가할수록 기계적 물성의 저하 현상이 관찰되었다. 아울러 중합시 교반속도와 PVAL의 농도를 조절하여 크기와 분자량을 조절 가능하였는데, P/L 부피비가 2인 조건에서 제조된 열경화성 틀니용 수지로 이용되는 입자의 평균크기는 100 $\mu$m 정도가 적절하며, 분자량은 3.0${\times}$$10^{5}$ 전후가 적절함을 알 수 있었다.다.

• 대한치과보철학회지
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• 제46권3호
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• pp.261-268
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• 2008

STATEMENT OF PROBLEM: Detachment of the magnetic assembly from the denture base has been a problem in magnetic overdenture patients. PURPOSE: The objectives of this study were to compare the dislodging force by the fixing materials and the designs of the magnetic assembly, and to compare the effect between the fixing materials and the designs of the magnetic assembly. MATERIAL AND METHODS: Two fixing materials, Jet denture repair $acrylic^{(R)}$ and Super-$Bond^{(R)}$ C&$B^{(R)}$ and two types of magnetic assembly designed with or without wing were used. Each magnetic assembly was fixed in the chamber of the denture base resin block ($Lucitone^{(R)}$199) with each fixing material respectively. These specimens were thermocycled 2,000 cycles in the water held at $4^{\circ}C$ and $60^{\circ}C$ with a dwell time of 1 min each time. Each specimen was seated in a testing jig and then a push-out test was performed with a universal testing machine at a cross head speed of 0.5 mm/min to measure the maximum dislodging forces. RESULTS: Comparing the fixing materials, Super-Bond C&$B^{(R)}$ showed superior dislodging force than Jet denture repair $acrylic^{(R)}$. Comparing the design of the magnetic assemblies, the wing design magnetic assembly showed better dislodging force. Combination of the Super-Bond C&$B^{(R)}$ as a fixing material and wing design magnetic assembly revealed a greatest dislodging force. The kind of fixing material was more influential than the type of magnetic assembly. CONCLUSION: The dislodging force of Super-Bond C&$B^{(R)}$ was significantly higher than Jet denture repair $acrylic^{(R)}$. And the dislodging force of magnetic assembly which have wing design was significantly higher than magnetic assembly which have no wing design.

• 대한치과기공학회지
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• 제31권1호
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• pp.63-74
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• 2009

Partial or complete prosthesis is needed when teeth are lost due to various kinds of reason. Artificial teeth recover occlusion instead of natural teeth. Artificial teeth are required of esthetics, fragile resistance and abrasive resistance. Artificial tooth is made of acrylic resin or porcelain. Nowadays, acrylic resin artificial teeth are mainly used. Acrylic resin teeth are occluded with natural teeth, gold alloy, Ni-Cr alloy or porcelain etc. Acrylic resin teeth have similar translucency, gloss of natural teeth. And it has good chemical bond with denture base material, but it has low wear resistance. The aim of this study is to compare wear resistance among several denture teeth(Endura, SR-orthosit-PE, Planustar) and between artificial resin denture teeth and opposing 3 restorative materials(gold, Ni-Cr alloy, porcelain). Wear tests were conducted with a rotating wear testing apparatus(pin-on-disk type wear tester) under conditions of rpm 180, 75 minutes and constant loading of 50N. The upper part was the cusp of maxillary first molar and the lower part was a disk type restorative materials. To make similar oral environment, water was supplied continually. The acrylic resin teeth wear was determined by weighing the cusp each 5 minutes during 75 minutes test. Vicker's hardness tester was used to evaluate the surface hardness of test specimens. The SEM was used to evaluate the wear surfaces. The results were as follows: 1. Wear rates of acrylic resin teeth opposing to the restorative materials were high in order of Porcelain, Gold, Ni-Cr alloy (p<.05). 2. Wear resistance rate opposing to the Porcelain disk, was shown in order of Endura, SR-orthosit-PE, Planustar. The wear rate of opposing to porcelain disk was above two times more than that of other groups (p<.05). 3. Wear resistance rates opposing to the Gold, Ni-Cr alloy disk, was shown in order of Endura, SR-orthosit-PE, Planustar (p<.05). 4. A degree of the surface hardness is directly proportional to the degree of wear resistance. There are statistically significant differences between each groups (p<.05).

• 대한치과보철학회지
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• 제38권4호
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• pp.500-509
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• 2000

In general, the three major oral functions of edentulous patients-mastication, phonation, esthetics-can be rehabilitated by the complete dentures, and both the resin based complete denture and the metal based complete denture are commonly used by many clinicians today. For the sake of many advantages such as the excellent thermal conductivity, low volumetric change, high strength, low risk of fracture and the better patient's adaptation, the metal based complete dentures are indicated to the several cases. But, there are common failures of these type of dentures mainly by the fracture or the debonding between the resin structures and the metal frameworks which is caused by the discrepancies of the flexural strength and the coefficient of thermal expansion. This is aggravated by the water contamination of the interface when exposed to the oral environment and results in the failure of complete denture treatment. So, the purpose of this study is to compare the bond strength and the fracture patterns of the gold alloy based and the Co-Cr alloy based complete dentures using the PMMA resins and the 4-META adhesive resins. The results of this study were as follows. 1. Both to the PMMA resin and the 4-META resin, the flexural bond strength of gold alloy is lower than that of Co-Cr alloy(P<0.05) 2. To the Co-Cr alloy, the bond strength of the 4-META resin is significantly higher than that of PMMA resin(P<0.05). 3. The flexural strength of the group with the mechanical retention form is significantly higher than that of the group without retention form(P<0.05). 4. Comparing with the other groups, the fracture patterns of the group 3 are quite different from the group 1,2,5.

• The Journal of Advanced Prosthodontics
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• 제9권5호
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• pp.402-408
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• 2017

PURPOSE. The goal of this study was to compare the adhesion of Candida albicans to the surfaces of CAD/CAM and conventionally fabricated complete denture bases. MATERIALS AND METHODS. Twenty discs of acrylic resin poly (methyl methacrylate) were fabricated with CAD/CAM and conventional procedures (heat-polymerized acrylic resin). The specimens were divided into two groups: 10 discs were fabricated using the CAD/CAM procedure (Wieland Digital Denture Ivoclar Vivadent), and 10 discs were fabricated using a conventional flasking and pressure-pack technique. Candida colonization was performed on all the specimens using four Candida albicans isolates. The difference in Candida albicans adhesion on the discs was evaluated. The number of adherent yeast cells was calculated by the colony-forming units (CFU) and by Fluorescence microscopy. RESULTS. There was a significant difference in the adhesion of Candida albicans to the complete denture bases created with CAD/CAM and the adhesion to those created with the conventional procedure. The CAD/CAM denture bases exhibited less adhesion of Candida albicans than did the denture bases created with the conventional procedure (P<.05). CONCLUSION. The CAD/CAM procedure for fabricating complete dentures showed promising potential for reducing the adherence of Candida to the denture base surface. Clinical Implications. Complete dentures made with the CAD/CAM procedure might decrease the incidence of denture stomatitis compared with conventional dentures.

• 대한치과기공학회지
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• 제46권1호
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• pp.8-14
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• 2024

Purpose: This study compares the deformation of traditional resin dentures to resin dentures printed with digital light processing (DLP). Methods: Eleven edentulous research models were developed. Ten of them were made with traditional resin dentures. The remaining one was prepared for scanning and 3D (three-dimensional) printing. Ten traditional resin dentures were made, with the remaining artificial teeth created using 3D software and a DLP printer. Traditional resin dentures, 3D printed resin denture artificial teeth, and a denture base with artificial teeth were all cleaned simultaneously in an ultrasonic cleaner for 3 minutes. Three groups were assigned four artificial tooth measurement points, which were then measured with digital calipers. The measured data was analyzed using descriptive statistics. The significance test was conducted using a nonparametric test Kruskal-Wallis test due to the small number of specimens (α=0.05). Results: The traditional resin dentures had the lowest strain rate at -0.04%, while the group that manufactured only artificial teeth had the highest strain rate at -0.09%. However, no statistically significant difference was observed between the 3 groups (p>0.05). Conclusion: During ultraviolet-type ultrasonic cleaning, traditional resin dentures (TD group) and denture base with artificial teeth made of DLP (DD group) demonstrated stable durability, whereas the artificial teeth made of DLP (AD group) with only artificial teeth did not show a good deformation rate.

• 대한치과보철학회지
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• 제40권4호
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• pp.386-395
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• 2002

This study would like to measure and compare water sorption and solubility of acrylic resins, with 3 different polymerizing methods, and tensile strength between denture base resin and relining rosins. For this experiment, 3 different acrylic resins were used; heat polymerizing resin: Vertex (Dentmex, Zeist, Holland), autopolymerizing resin: Tokuso Rebase (Tokuyama Corp, Tokyo, Japan), and light curing resin: Mild Rebaron LC(GC Corp, Tokyo, Japan) The results were as follows ; 1. Tokuso Rebase showed the lowest water sorption. followed by Mild Rebaron LC and Vertex. Among resins, there were some signigicant differences (P<0.05). 2. Vertex showed the lowest solubility, followed by Mild Rebaron LC and Tokuso Rcbase. Among resins, there were some signigicant differences (P<0.05). 3. Intact Vertex showed the highest tensile strength, and Mild Rebaron LC had a more tensile strength than Tokuso Rebase. Between Vertex and the other resins, there were some signigicant differences (P<0.05) However, between Mild Rebaron LC and Tokuso Rebase, there was no statistical difference (P>0.05). About 50% of Rebaron LC showed cohesive fracture. 4. Tensile strength has more decreased after thermocycling than before, but there was no statistical difference (P>0.05).

• 대한치과보철학회지
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• 제39권1호
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• pp.105-113
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• 2001

The purpose of this study is to compare effects of denture cleansers and disinfectants on the color. surface hardness, and surface roughness of reinforced acrylic resin using polyhedral oligosilsesquioxane molecules(POSS resin) to those of common resins. According to manufacturer's instructions, 45 specimens were made from three denture resins(Luciton 199, Paladent 20, POSS resin), and polished. Five denture cleansers(distilled water, glutaraldehyde, alkaline hypochlorites, chlorhexidine, alkaline peroxides) in combination with three denture resins were evaluated before and after immersion for 7 days. Color data in $L^*a^*b^*$ system were measured with a colorimeter. Surface hardness data were measured with a microhardness tester. Surface roughness data were measured with a 3-dimensional surface analyzer. Data were analyzed with two-way ANOVA, one-way ANOVA, and t-test. The results were as follows : 1. All resins(Luciton 199, Paladent 20, POSS resin) showed significant differences in color after immersion in hypochlorites(p<0.05). 2. POSS resin showed significant differences in color compared with Paladent 20 in all denture cleansers, but no statistically significant differences with Luciton 199(p<0.05). 3. Luciton 199 showed significant differences of surface hardness in chlorhexidine, Paladent 20 showed significant differences in glutaraldehyde and chlorhexidine. POSS resin showed a little change of surface in all denture cleanser, but no statistically significant differences(p<0.05). 4. Luciton 199 and Paladent 20 showed significant differences of surface roughness in hypochlorites and glutaraldehyde, and POSS resin showed no statistically significant differences in all denture cleansers(p<0.05).

• 대한치과기공학회지
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• 제39권1호
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• pp.25-33
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• 2017

Purpose: The aim of this study was to evaluate accuracy of glass fiber mesh complete denture of before and after curing. Methods: Edentulous model was selected as the master model. Ten study models were made by Type IV stone. Wax complete dentures were produced by the denture base and artificial teeth. CD and GD groups were measured six measurement distance before curing. The wax complete denture was investment after measurement is completed. Using a heat polymerization resin was injected resin. After injecting the resin it was curing. A complete denture was re-measured after curing. The measured data was verified by paired t-test. Results: Overall CD group was larger the value of the measured length. In the CD group, A-D point was larger. The smallest point was the B-D point. However, there was no statistically significant difference only C-D point(p>0.05). In the GD group, A-B point was larger. but B-D point was the smallest. A-D and B-C statistically points showed significant differences(p<0.05). Conclusion: Glass fiber mesh resin complete denture can be clinically applied to the edentulous patient.

• The Journal of Advanced Prosthodontics
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• 제5권2호
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• pp.110-117
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• 2013

PURPOSE. Polymethyl methacrylate (PMMA) is the most commonly used denture base material despite typically low in strength. The purpose of this study was to improve the physical properties of the PMMA based denture base resins (QC-20, Dentsply Ltd., Addlestone, UK; Stellon, AD International Ltd, Dentsply, Switzerland; Acron MC; GC Lab Technologies Inc., Alsip, Japan) by copolymerization mechanism. MATERIALS AND METHODS. Control group specimens were prepared according to the manufacturer recommendations. In the copolymer groups; resins were prepared with 5%, 10%, 15% and 20% acrylamide (AAm) (Merck, Hohenbrunn, Germany) content according to the moleculer weight ratio, respectively. Chemical structure was characterized by a Bruker Vertex-70 Fourier transform infrared spectroscopy (FTIR) (Bruker Optics Inc., Ettlingen, Germany). Hardness was determined using an universal hardness tester (Struers Duramin, Struers A/S, Ballerup, Denmark) equipped with a Vickers diamond penetrator. The glass transition temperature ($T_g$) of control and copolymers were evaluated by Perkin Elmer Diamond DSC (Perkin Elmer, Massachusetts,USA). Statistical analyses were carried out using the statistical package SPSS for Windows, version 15.0 (SPSS, Chicago, IL, USA). The results were tested regarding the normality of distribution with the Shapiro Wilk test. Data were analyzed using ANOVA with post-hoc Tukey test (P<.01). RESULTS. The copolymer synthesis was confirmed by FTIR spectroscopy. Glass transition temperature of the copolymer groups were higher than the control groups of the resins. The 10%, 15% and 20% copolymer groups of Stellon presented significantly higher than the control group in terms of hardness. 15% and 20% copolymer groups of Acron MC showed significantly higher hardness values when compared to the control group of the resin. Acrylamide addition did not affect the hardness of the QC-20 resin significantly. CONCLUSION. Within the limitation of this study, it can be concluded that copolymerization of PMMA with AAm increased the hardness value and glass transition temperature of PMMA denture base resins.