• The Journal of Advanced Prosthodontics
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• v.7 no.4
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• pp.278-287
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• 2015

PURPOSE. The aim of this study was to compare the color stability, water sorption and cytotoxicity of thermoplastic acrylic resin for the non-metal clasp dentures to those of thermoplastic polyamide and conventional heat-polymerized denture base resins. MATERIALS AND METHODS. Three types of denture base resin, which are conventional heat-polymerized acrylic resin (Paladent 20), thermoplastic polyamide resin (Bio Tone), thermoplastic acrylic resin (Acrytone) were used as materials for this study. One hundred five specimens were fabricated. For the color stability test, specimens were immersed in the coffee and green tee for 1 and 8 weeks. Color change was measured by spectrometer. Water sorption was tested after 1 and 8 weeks immersion in the water. For the test of cytotoxicity, cell viability assay was measured and cell attachment was analyzed by FE-SEM. RESULTS. All types of denture base resin showed color changes after 1 and 8 weeks immersion. However, there was no significant difference between denture base resins. All specimens showed significant color changes in the coffee than green tee. In water sorption test, thermoplastic acrylic resin showed lower values than conventional heat-polymerized acrylic resin and thermoplastic polyamide resin. Three types of denture base showed low cytotoxicity in cell viability assay. Thermoplastic acrylic resin showed the similar cell attachment but more stable attachment than conventional heat-polymerized acrylic resin. CONCLUSION. Thermoplastic acrylic resin for the non-metal clasp denture showed acceptable color stability, water sorption and cytotoxicity. To verify the long stability in the mouth, additional in vitro studies are needed.

• Journal of Technologic Dentistry
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• v.9 no.1
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• pp.51-55
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• 1987

One of the primary advantages of acrylic resin teeth is their ability to bond chemically to the denture base resins. Fracture od acrylic resin teeth from a maxillary denture, however, is not uncommon. Bonding failures have been attributed to faulty boil-out procedures that fail to eliminate all traces of wax from the ridge lap surfaces of the teeth and to contamination of the ridge lap surface by careless application of tinfoil substitute. Attempts to increase the strength of the bond between acrylic resin teeth and heat-cured denture base resin include grinding the glossy ridge lap surface (in fluid system), painting the ridgelap surface of the teeth with monomer-polymer solution, and cutting retention grooves in the ridge lap surface of the teeth. This latter method has been tested by applying a tensile force in a labial direction to the incisal part of the lingual surface of the acrylic resin teeth. A progressive shear compressive load was applied at an angle to the lingual surface of acrylic resin teeth bonded to denture base acrylic resin. No statistically singificant advantage was derived by preparing retention grooves of different shapes in the ridgelap surface of the denture teeth.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.4
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• pp.309-322
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• 2002

The purpose of this study was to investigate the cytotoxicity and mutagenicity of denture base resins. According to manufacturer's instructions, resin specimens were made. Group 1 : heat-polymerizing acrylic resin (Luciton $199^{(R)}$) Group 2 : heat-polymerizing acrylic resin containing polyhedraloligosilsesquioxane(POSS resin) Group 3 : auto-polymerizing acrylic resin (Repair $Acrylic^{(R)}$) Group 4 : direct relining auto-polymerizing acrylic resin (Tokuso $Rebase^{(R)}$). Fresh specimens 24 hrs. and 72 hrs. soaked specimens in distil)ed water were made. Responses with metabolic assay and mutagenesis assay to eluates from resin specimens were measured. Cultures with medium alone provided controls. Cytotoxicity was assessed with agar overlay test. The results were as follows; 1. Group 4 showed higher cytotoxicity than Group 1, Group 2 and Group 3 in fresh, 24-an4 72-hour immersion caries (p<.05). Group 3 showed higher cytotoxicity than Group 2 in fresh cases and showed higher cytotoxicity than Group 1 and Group 2 in 24-and 72-hour immersion cases (p<.05) . Group 1 and Group 2 showed no significant difference. 2. All acrylic denture base resins skewed significant increase of cell activity as immersion time increased (p<.05). 3. Auto-polymerizing acrylic denture base resins skewed higher cytotoxicity than heat-polymerizing acrylic denture base resins (p<.05). 4. All acrylic denture base resins showed lower mutagenicity than controls (p<.05).

• Journal of Technologic Dentistry
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• v.35 no.4
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• pp.287-293
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• 2013

Purpose: This study is to provide basic data of the dental acrylic denture base resin in the mechanical property difference investigation according to the monomer composition weight ratio of the acrylic denture base resin. Methods: The monomer composition of the acrylic denture base resin and weight ratio makes the different specimen. It measured the mechanical property with the specimens through Hardness Test, Tensile Test, Flexural Test, Flexural Modulus, FT-IR Test. Results: The control group Vertex was 18.4 Hv and the experimental group MED was 14.46~19.07Hv in the hardness test. Vertex was 364N, MED-3 was lowest in the tensile strength test and the Head of a family cursor declination was big. The result declination of the experimental specimens showed. Vertex and MED-2 was the highestest in the flexural test and after coming MED-6, MED-5, MED-1, MED-3, MED-4. Vertex and MED-2, as to a spectrum for $500{\sim}1800cm^{-1}$ peak can show the excellent degree of polymerization in the FT-IR Test. Conclusion: The ideal weight ratio of the monomer of the acrylic denture base resin of which the mechanical property is the highestest was MMA 100g, EDGMA 5g, DMA 0.2g, of MED-2.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.6
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• pp.712-721
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• 2006

Statement of problem. Acrylic resin is most commonly used for denture bases. However, acrylic resin has week points of volumetric shrinkage during polymerization that reduces denture fit. The expandability of POSS (Polyhedral Oligomeric Silsesquioxane) containing polymer could be expected to reduce the polymerization shrinkage of denture bases and would increase the adaptability of the denture to the tissue. Purpose. The purpose of this study was to compare the dimensional stability in the conventional acrylic resin base, POSS-containing acrylic resin base, and metal bases. Materials and methods. Thirty six maxillary edentulous casts and dentures of different base were fabricated. Tooth movement and tissue contour change of denture after processing (resin curing, deflasking, decasting and finishing without polishing) and immersion in artificial saliva at $37^{\circ}C$ for 1 week and 4 weeks were measured using digital measuring microscope and threedimensional laser scanner. Results. The results were as follows: 1. The conventional resin group showed significant (p<0.01) dimensional change throughout the procedure (processing and immersion in artificial saliva). 2. After processing, the metal group and POSS resin group showed lower linear and 3-dimensional change than conventional resin group (p<0.01). 3. There was no statistically significant linear and 3-dimensional change after immersion for 1 week and 4 weeks in metal and POSS resin group. 4. In all groups, the midline and alveolar ridge crest area presented smaller 3-dimensional change compared with vestibule and posterior palatal seal area after processing and soaking in artificial saliva for 1 week and 4 weeks (p<0.01). Conclusion. In this study, a reinforced acrylic-based resin with POSS showed good dimensional stability.

• Journal of Technologic Dentistry
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• v.8 no.1
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• pp.23-29
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• 1986

One of the primary advantage of acrylic resin teeth is their ability to bond chemically to the denture base resins. But, occasionally, failure have been observed in which acrylic resin teeth break lose from the denture, indicating that chemical bonding does not always occur. The most probable explanation for this type of failure was the presence of a trace of wax remaining as a residue on the surfaces of the teeth after the boiling-out procedure which adgered to the tooth surface and prevented bonding. The purpose of this stdy was preparing the specimens of denture base resin with acrylic resin teeth that four treatment method to ridge lap portion of the tooth and investigated bond between the teeth and denture base resin with tensile strength. Compared results of tensile strength on test specimens were as follows: 1. The mean of strength among the four test groups showed the difference was significant enough(P 0.01). The order of its strength mean was methylene chloride treatment group, detergent solution treatment group, kerosene-ether treatment grgoup, boiling water only group. 2. In compared results between the wax eliminating method groups, there were significant difference between the boiling water only group and other groups(P 0.01), no significant difference were found in the wax eliminating method groups except boiling water only group(P 0.05).

• The Journal of the Korean dental association
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• v.12 no.9
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• pp.667-677
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• 1974

A testing machine was devised and constructed for the purpose of measuring the retentive forces of maxillary complete denture bases in subjects. Forth complete denture bases were made for ten subjects with three different denture base materials, following the usual denture construction technique. Retentive forces of the forty dentures were determined at seven locations. The tests on each base were repeated three times at intervals of 5 minutes. Differences in retention values were evaluated statistically. 1) Differences in retention values were found by the differences of the denture base materials, but acrylic resin was similar to chromium cobalt alloy. 2) The chromium cobalt alloy and acrylic resin bases from master models revealed the best retention values, the gold alloy base from master model was the poor second and the acrylic resin base from snap model was the third. 3) The retention values for hook-1 revealed higher than that for hook-2 and the retention values for hook-3 revealed the lowest value.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.5
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• pp.621-632
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• 2007

Statement of problem: The failure of adhesion between the resilient denture liner and the denture base is a serious problem in clinic. Purpose: The purpose of this study was to evaluate the effect of denture base resin surface pretreatments (mechanical and/or chemical) on the tensile bond strength between a resilient liner and processed denture resin. Material and method. Acrylic-based resilient liners (Soft liner; GC co., Japan & Coe-Soft; GC America Inc. USA) and silicone-based resilient liners (Mucosoft, Parkell Inc., USA & Dentusil; Bosworth co., USA) were used. Specimens in each soft lining material were divided two groups with or without mechanical pretreatment. Each denture base specimen received 1 of 4 chemical pretreatments including: (1) no treatment, (2) 30-s acetone treatment, (3) 15-s methylene chloride treatment, (4) 180-s methyl methacrylate treatment. All specimens were thermocycled and placed under tension until failure in a universal testing machine. Results: 1. Silicone-based resilient liners exhibited significantly higher tensile bond strengths than acrylic-based resilient liners (P<.05). 2. Grinding the denture base resin improved tensile bond strengths of silicone-based resilient liners, but reduced tensile bond strengths of acrylic-based resilient liners (P<.05). 3. In acrylic-based resilient liners, treating with acetone significantly increased the bond strength of Soft liner and treating with methyl methacrylate significantly increased the bond strength of Coe-Soft (P<.05). However they were not effective compared to silicone-based resilient liner. 4. In silicone-based resilient liners, treating with all chemical etchants significantly increased the bond strength of Mucosoft to denture base, and treating with methylene chloride and methyl methacrylate increased the bond strength of Dentusil to denture base (P<.05). Conclusion: Although chemical and mechanical pretreatments were not effective on tensile bond strength of acrylic-based resilent liner to denture base, treating the denture base resin surface with appropriate chemical etchants after mechanical pretreatment significantly increased the tensile bond strength of silicone-based resilient liner to denture base.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.3
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• pp.250-259
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• 2001

Since the late 1930s, acrylic resins have been the materials of choice for the fabrication of complete denture bases. It has excellent esthetic properties, adequate strength, low water sorption, and low solubility. But acrylic resin has disadvantage of processing shrinkage that reduces denture retention and accuracy of denture occlusion. Metals also have been used in denture base material. Metals used in denture bases display excellent strength and dimensional stability. The major disadvantages associated with metal denture bases include increased cost, difficulty in fabrication, compromised esthetic qualities, and inability to re-base. The purpose of this study is to compare the artificial tooth movements of complete dentures with resin bases and metal bases after curing, deflasking, polishing immersion in water for 1 week and 4 weeks. Twenty-four maxillary complete resin denture bases with artificial teeth were fabricated. Twelve of them were resin based and other twelve of them were metal based. Fine crosses were marked on the incisal edges of right central incisors and distobuccal cusps of be second molars. Measurements were done for the changes of distances of reference points at the time of wax denture, after deflasking after decasting after polishing after immersion in water for 1 week and 4 weeks Meaurements were done to the accuracy of 0.001mm with a measuring microscope. The results were as follows : 1. Metal base showed significantly less tooth movement than resin base after curing and decasting (p<0.01). 2. Metal base showed significantly less tooth movement than resin base after polishing (p<0.01). 3. After immersion in water for 1 week and 4 weeks, metal base showed less movement than resin base. Difference was significant for anterior-posterior distances (p<0.01), but not significant for molar-to-molar distance (p>0.01). 4. 1 week and 4 weeks of immersion failed to compensate the initial processing shrinkage of metal and resin bases (p>0.01).

• The Journal of Advanced Prosthodontics
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• v.9 no.6
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• pp.482-485
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• 2017

PURPOSE. This laboratory study aimed to investigate the effect of doping an acrylic denture base resin material with nanoparticles of ZnO, CaO, and $TiO_2$ on biofilm formation. MATERIALS AND METHODS. Standardized specimens of a commercially available cold-curing acrylic denture base resin material were doped with 0.1, 0.2, 0.4, or 0.8 wt% commercially available ZnO, CaO, and $TiO_2$ nanopowder. Energy dispersive X-ray spectroscopy (EDX) was used to identify the availability of the nanoparticles on the surface of the modified specimens. Surface roughness was determined by employing a profilometric approach; biofilm formation was simulated using a monospecies Candida albicans biofilm model and a multispecies biofilm model including C. albicans, Actinomyces naeslundii, and Streptococcus gordonii. Relative viable biomass was determined after 20 hours and 44 hours using a MTT-based approach. RESULTS. No statistically significant disparities were identified among the various materials regarding surface roughness and relative viable biomass. CONCLUSION. The results indicate that doping denture base resin materials with commercially available ZnO, CaO, or $TiO_2$ nanopowders do not inhibit biofilm formation on their surface. Further studies might address the impact of varying particle sizes as well as increasing the fraction of nanoparticles mixed into the acrylic resin matrix.