PURPOSE: The aim of this study was to evaluate the effects of relining materials on the flexural strength of relined thermoplastic denture base resins (TDBRs). MATERIALS AND METHODS: For shear bond strength testing, 120 specimens were fabricated using four TDBRs (EstheShot-Bright, Acrytone, Valplast, Weldenz) that were bonded with three autopolymerizing denture relining resins (ADRRs: Vertex Self-Curing, Tokuyama Rebase, Ufi Gel Hard) with a bond area of 6.0 mm in diameter and were assigned to each group (n=10). For flexural strength testing, 120 specimens measuring 64.0×10.0×3.3 mm (ISO-1567:1999) were fabricated using four TDBRs and three ADRRs and were assigned to each group (n=10). The thickness of the specimens measured 2.0 mm of TDBR and 1.3 mm of ADRR. Forty specimens using four TDBRs and 30 specimens using ADRRs served as the control. All specimens were tested on a universal testing machine. For statistical analysis, Analysis of variance (ANOVA) with Tukey's test as post hoc and Spearman's correlation coefficient analysis (P=.05) were performed. RESULTS: Acry-Tone showed the highest shear bond strength, while Weldenz demonstrated the lowest bond strength between TDBR and ADRRs compared to other groups. EstheShot-Bright exhibited the highest flexural strength, while Weldenz showed the lowest flexural strength. Relined EstheShot-Bright demonstrated the highest flexural strength and relined Weldenz exhibited the lowest flexural strength (P < .05). Flexural strength of TDBRs (P=.001) and shear bond strength (P=.013) exhibited a positive correlation with the flexural strength of relined TDBRs. CONCLUSION: The flexural strength of relined TDBRs was affected by the flexural strength of the original denture base resins and bond strength between denture base resins and relining materials.
Denture Bases ; Denture Liners ; Denture Rebasing ; Dentures

PURPOSE: The purpose of this study was to investigate the bonding properties of denture bases to silicone-based soft denture liners immersed in isobutyl methacrylate (iBMA) and 2-hydroxyethyl methacrylate (HEMA) for various lengths of time. MATERIALS AND METHODS: Polymethyl methacrylate (PMMA) test specimens were fabricated (75 mm in length, 12 mm in diameter at the thickest section, and 7 mm at the thinnest section) and then randomly assigned to five groups (n=15); untreated (Group 1), resilient liner immersed in iBMA for 1 minute (Group 2), resilient liner immersed in iBMA for 3 minutes (Group 3), resilient liner immersed in HEMA for 1 minute (Group 4), and resilient liner immersed in HEMA for 3 minutes (Group 5). The resilient liner specimens were processed between 2 PMMA blocks. Bonding strength of the liners to PMMA was compared by tensile test with a universal testing machine at a crosshead speed of 5 mm/min. Data were evaluated by 1-way ANOVA and post hoc Tukey-Kramer multiple comparisons tests (alpha=0.05). RESULTS: The highest mean value of force was observed in Group 3 specimens. The differences between groups were statistically significant (P<.05), except between Group 1 and Group 4 (P=.063). CONCLUSION: Immersion of silicone-based soft denture liners in iBMA for 3 minutes doubled the tensile bond strength between the silicone soft liner and PMMA denture base materials compared to the control group.
Denture Bases* ; Denture Liners* ; Immersion ; Polymethyl Methacrylate ; Silicones

OBJECTIVETo compare shear bond strength (SBS) between two types of silicone soft liner and polymethyl methacrylate (PMMA) under the condition of heat curing and room temperature curing.

METHODSA total of 48 PMMA specimens (50 mm x 10 mm x 3 mm) were made by water-bath heating method, and randomly divided into four groups. By using Ufi Gel P (UGP) as soft liner material, group A1 was prepared under heat curing, and group A2 was prepared under room temperature curing. To form the other two groups, Silagum-Comfort (SLC) as soft-liner material was used. Group B1 was prepared under heat curing, and group B2 was prepared under room temperature curing. Shear bond strength (SBS) was tested by using the electronic universal testing machine. The adhesives layer and surface of silastic and PMMA were observed by optical microscope and scanning electron microscopy (SEM).

RESULTSThe SBS of groups A1, A2, B1, B2 were (2.39 +/- 0.24), (1.74 +/- 0.27), (3.09 +/- 0.26), and (2.21 +/- 0.29) MPa, respectively. Significant differences were found between A1 and A2, B1 and B2, A1 and B1, and A2 and B2 (P < 0.05). Optical microscope showed numerous bubbles in the cured UGP, and no air bubbles in the SLC. The surface of PMMA was rough. SEM images showed that each group had continual consistent adhesive interface and a whisker hump on the adhesive layer of A2 and B2.

CONCLUSIONThe SBS ofUGP, SLC, and PMMA achieved minimum clinical standard of 0.44 MPa. The SBS of UGP and PMMA were higher than that of SLC and PMMA. The polymerization method of heat curing was higher than room temperature curing.

PURPOSE: This study investigated the effect of laser parameters and air-abrasion on the peel strength of silicon-based soft denture liner to different denture resins. MATERIALS AND METHODS: Specimens (N=180) were prepared out of three different denture base resins (Rodex, cross-linked denture base acrylic resin; Paladent, heat-cured acrylic resin; Deflex, Polyamide resin) (75 mm x 25 mm x 3 mm). A silicon-based soft denture liner (Molloplast B) was applied to the denture resins after the following conditioning methods: a) Air-abrasion (50 microm), b) Er,Cr:YSGG laser (Waterlase MD Turbo, Biolase Technology) at 2 W-20 Hz, c) Er,Cr:YSGG laser at 2 W-30 Hz, d) Er,Cr:YSGG laser at 3 W-20 Hz, e) Er,Cr:YSGG laser at 3 W-30 Hz. Non-conditioned group acted as the control group. Peel test was performed in a universal testing machine. Failure modes were evaluated visually. Data were analyzed using two-way ANOVA and Tukey's test (alpha=.05). RESULTS: Denture liner tested showed increased peel strength after laser treatment with different parameters (3.9+/-0.4 - 5.58+/-0.6 MPa) compared to the control (3.64+/-0.5 - 4.58+/-0.5 MPa) and air-abraded groups (3.1+/-0.6 - 4.46+/-0.3 MPa), but the results were not statistically significant except for Paladent, with the pretreatment of Er,Cr:YSGG laser at 3 W-20 Hz. Polyamide resin after air-abrasion showed significantly lower peel strength than those of other groups (3.1+/-0.6 MPa). CONCLUSION: Heat-cured acrylic resin, PMMA, may benefit from Er,Cr:YSGG laser treatment at 3 W-20 Hz irradiation. Air-abrasion of polyamide resins should be avoided not to impair their peel bond strengths to silicon-based soft denture liners.
Collodion ; Denture Bases ; Denture Liners ; Dentures ; Nylons ; Polymethyl Methacrylate

PURPOSE: This study was aimed to determine the effect of two chemically distinct denture cleansers and water on the surface hardness of acrylic and silicone based soft denture liners at various time intervals. MATERIALS AND METHODS: Two commonly used commercial resilient liner material were selected based on their chemical composition (silicone- and acrylic-based soft liners) for this investigation. 120 cylindrical specimens were made of 15 mm x 10 mm dimensions (according to ASTM: D-2240-64T) in a custom made metal mold. All specimens were stored in artificial saliva throughout the study. Forty specimens were cleansed daily in 0.5% sodium hypochlorite solution; forty were cleansed in sodium perborate and remaining forty specimens were daily rinsed in water. Testing was done at 1 week, 1 month, 3 months and 6 months for surface hardness using a Shore A Durometer. A mean of 3 reading for each sample was subjected to one-way ANOVA, Post Hoc test and pair-t test for statistical analysis. P values of less than 0.05 were taken as statistically significant. RESULTS: Surface hardness of all the samples was significantly higher after a period of 6 months irrespective of the cleansing treatment. Minor changes were observed between control, sodium hypochlorite and sodium perborate groups with time. Greater change was observed in surface hardness of acrylic-based soft denture liners as compared to silicone-based soft liners for all groups, as time progressed. CONCLUSION: Silicone-based soft denture liners performed significantly better in all cleansing treatments than acrylic-based soft denture liners.
Borates ; Denture Cleansers ; Denture Liners ; Dentures ; Fungi ; Hardness ; Saliva, Artificial ; Silicones ; Sodium ; Sodium Hypochlorite ; Water

OBJECTIVETo research the effects of incorporating tetrapod-like zinc oxide whisker (T-ZnOw) of different proportions on the antibacterial activity of different kinds of soft denture liners.

METHODSThe minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of T-ZnOw against Saccharomyces albicans (S. albicans) were examined by the broth dilution test. Add T-ZnOw 0%, 1%, 2%, 3% to Silagum soft denture liners and soft denture liners respectively. The antimicrobial rate of S. albicans was determined by the membrane covering method.

RESULTSThe MIC of T-ZnOw against S. albicans was 78 microg mL(-1) and the MBC was 156 microg mL(-1). Comparing 1%, 2%, 3% T-ZnOw group with control group, the results showed significant difference (P<0.05). And as the T-ZnOw antibacterial agent added ratio increased, antibacterial increased significantly.

CONCLUSIONThe soft denture liners incorporating with 1%, 2%, 3% of T-ZnOw can improve antibacterial activity. Following the increased proportions of T-ZnOw, antibacterial rate was significantly increasing.

We tried to find the effects of the application of the antibacterial solution containing silver ions on the surface of the denture soft lining material. We selected the right concentration of the silver-containing solution and coated a soft lining material with the solution so that the soft lining material could be antibacterial. The antibacterial solution containing silver ions was prepared by sol-gel method. MIC of C. a and S. a were tested by broth dilution test. The surface property and thickness were tested after coated. The in vitro antibacterial ratio against C. a and S. a were demonstrated by the method of plate-counting. A film was formed after coating, while the adequacy was not changed. Antibacterial ratio of 0.64 mg/ml group against C. a was 90.82%, and that against S. a was 94.96% in 24 hours, respectively. It was found that the antibacterial property of the soft lining material can be acquired by coating this antibacterial solution with silver ion, without changing the adequacy.
Anti-Bacterial Agents ; chemistry ; pharmacology ; Candida albicans ; drug effects ; Denture Cleansers ; pharmacology ; Denture Liners ; microbiology ; Membranes, Artificial ; Microbial Sensitivity Tests ; Silver ; pharmacology ; Staphylococcus aureus ; drug effects

Six groups of soft liner/base resin were made into standard test samples of 60.0 mm x 25.0 mm x 3.0 mm, with different soft lining materials/base resin ratios of 0: 3.0, 0.5: 2.5, 1.0: 2.0, 1.5: 1.5, 2.0: 1.0, 2.5: 0.5. The yield strength and resilience of each group were tested by universal testing machine. We found that when the thickness of soft liner increased, the yield strength of samples was reducing, whereas the resilience was enhancing. The change of yield strength and resilience became stabilized between the ratio of 1.5: 1.5 to 2.03: 1.0. We concluded that, under this testing condition, the thickness of soft liner should not exceed 2.0 mm, and we suggested that the ratio of soft liner/base resin should be controlled within the scope of 1/1 to 2/1 according to the whole base thickness.
Acrylic Resins ; chemistry ; Dental Bonding ; Denture Bases ; Denture Liners ; Dentures ; Humans ; Materials Testing ; Stress, Mechanical ; Surface Properties ; Tensile Strength

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 acrylicbased 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.
Acetone ; Americas ; Denture Bases* ; Denture Liners ; Dentures* ; Japan ; Methylene Chloride

STATEMENT OF PROBLEM: The clinical criteria of soft lining materials are resilience over an extended period, capability of forming a strong bond with denture base materials, dimensional stability, adequate tear strength, and color stability. Many researches and reports dealt with food colorants or denture cleanser, but not with fermented foods. PURPOSE: This study was designed to assess what fermented foods, such as soy sauce and red pepper paste that many Koreans have eaten, influence on the color stability of soft denture liners. MATERIAL AND METHODS: The color differences(delta E*) were measured by spectrophotometer with different immersion time. For the procedure, thirty disk-shape specimens per 4 soft denture liners(Molloplast-B(R), Ufi Gel SC(R), Dura Base(R), Sofreliner MS(R)) were fabricated with a thickness of 2mm and 16mm in diameter. Each 10 specimen were immersed into the beakers of fermented foods and distilled water, and L*, a*, and b* values were measured for the color difference(delta E*), on the 1st, 7th, and 28th day with spectrophotometer. RESULT AND CONCLUSION: 1. There were significant differences between samples(soy sauces, red pepper pastes, and distilled water) in Sofreliner MS(R) of 1st day after immersion(p<0.05). There were significant differences between samples in Sofreliner MS(R) and Ufi Gel SC(R) of 7th days after immersion(p<0.05). There were significant differences between samples in Molloplast-B(R) of 28th day after immersion(p<0.05). 2. In red pepper pastes, delta E* values of Molloplast-B(R), Ufi Gel SC(R), Sofreliner MS(R) were higher than 3.3. Those values were not clinically acceptable. In soy sauces, delta E* values of all denture liners were lower than 3.3. delta E* values of Ufi Gel SC(R) were higher than those of other denture liners. 3. Based on the above results, red pepper paste causes more discoloration than soy sauce.
Capsicum ; Denture Bases ; Denture Cleansers ; Denture Liners* ; Dentures* ; Food Coloring Agents ; Immersion ; Ointments ; Soy Foods ; Tears ; Water