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PubMedDate not supplied

Surface conditions and viscoelastic properties of the denture liner Permaflex.

This in vitro study evaluated the viscoelastic properties of Permaflex compared to other soft lining materials. The surface condition of this material was also investigated under both laboratory and simulated clinical conditions and with and without the application of a varnish. The tests provided practical instructions for the use of Permaflex, which showed good adaptive properties to stress and surface condition initially and after adjustment.

Chemical Phenomena↗
PubMedDate not supplied

The effect of finishing and polishing on surface roughness of a processed resilient denture liner.

A raised ridge on a Molloplast-B sample was removed using one of three burs, four stones, or a coarse sandpaper disc. Samples were polished using pumice alone, tin oxide alone, or both agents. A flat, unfinished sample served as a control. The average surface roughness was measured after reductions and subsequent polishings. The length of time required for initial reduction was recorded. Average surface roughness measurements ranged from 16.0 to 1.4 microns, with the control measuring 0.66 micron. Without polishing, burs produced rougher surfaces than stones and required longer times for reduction. Bur samples also remained rougher than stone samples after pumicing. No significant differences were found between treatments or controls after the use of either a combination of pumice and tin oxide or tin oxide alone.

Acrylic Resins↗
PubMed1993

A comparison of bond strengths of soft denture liners to polymethyl methacrylate polymerized by conventional water bath and microwave curing techniques.

This study compared the tensile bond strengths of soft lining materials polymerized by using conventional water bath methods and microwave energy. The soft lining materials used in this investigation were heat temperature vulcanizing (H.T.V.) silicon material Molloplast-B, and room temperature vulcanizing (R.T.V) acrylic material Getz Soft Oryl. The H.T.V. specimens were prepared with retention, additional retention and without retention, and the R.T.V. specimens were prepared by using bonding agent and bonding agent plus retention. All were cured by both conventional water bath and microwave energy. Results showed that the mean bond strength of H.T.V. specimens ranged from 9.6 to 13.12 kg/cm2, while the mean bond strength of R.T.V. specimens ranged from 0.36 to 1.75 kg/cm2. In both conventional and microwave groups, the specimens prepared with retention, additional retention and without retention or using bonding agent and bonding agent plus retention did not show any significant difference when they were compared separately. But the difference between conventional and microwave groups was found significant in both H.T.V. and R.T.V. specimens. It showed that conventional water bath technique is better than microwave technique.

Acrylic Resins↗
PubMed1999

Sorption and solubility of soft denture liners after accelerated aging.

PURPOSE: To determine the sorption and solubility properties of soft liners in relation to the aging process. MATERIALS AND METHODS: Five soft liners (Flexor, Molloplast B, Ufigel L, heat-cured; Simpa, Ufigel P, cold-cured) were used. The sorption and solubility tests were performed as outlined in the American Dental Association (ADA) specification 12 for denture base polymers. Ten specimens of each material were fabricated. One set of five specimens was subjected to accelerated aging process in the Weather-Ometer instrument. The test materials were dried in a desiccator and then immersed in distilled water at 37 +/- 1 degrees C for 15, and 30 days. The sorption behavior of the test specimens was calculated. The solubility behavior of the test materials was determined only after 30 days. RESULTS: Aged materials immersed in water for 15 days showed different sorption properties related to the material. After water immersion for 30 days, the materials showed increased sorption properties. Negative increase in solubility was determined after aging for all liners except Flexor.

Absorption↗
PubMedDate not supplied

Comparison of the hardness and microbiologic adherence of four permanent denture soft liners.

Resilient denture linings cannot be used for extended periods due to the loss of softness and the adhesion of microorganisms on their surfaces. This study investigated the hardness and microbiologic adherence of four permanent soft denture lining materials. In addition, the adherence of Candida albicans and Staphylococcus aureus was studied in vitro by quantitative culture method and scanning electron microscopy (SEM). Surface properties of the materials also were observed with SEM. The hardness of all materials increased throughout the study. Molloplast-B was the most adequate permanent soft lining material for clinical use under these laboratory conditions.

Analysis of Variance↗
PubMed1999

Simplified methods for fabricating tissue-supported implant-retained overdentures with retention from a resilient liner.

Resilient denture liner materials can be useful for tissue-supported implant-retained overdentures. They allow physiologic movement of the denture toward the tissues. This article presents a technique that offers several advantages over other methods of fabricating the overdenture with a resilient liner, and of transferring the superstructure: the acrylic resin base and the heat-cured resilient liner material are cured simultaneously; superstructure blockout is performed in the laboratory instead of in the mouth, where blockout is difficult; and direct transfer of the superstructure bar is more accurate and eliminates possible fracture of the duplicated superstructure if formed in die stone.

Acrylic Resins↗
PubMed1977

Making complete dentures for research purposes.

A method for construction of complete dentures for research purposes has been described. According to this method, a baseplate is fabricated of hard acrylic resin in combination with resilient denture liner. These dentures can be repeatedly used by interchanging denture teeth of the same mold.

Acrylic Resins↗
PubMed2006

The evaluation of microleakage and bond strength of a silicone-based resilient liner following denture base surface pretreatment.

STATEMENT OF PROBLEM: The failure of adhesion between a silicone-based resilient liner and a denture base is a significant clinical problem. PURPOSE: The purpose of this study was to examine the effects of denture base resin surface pretreatments with different chemical etchants preceding the silicone-based resilient liner application on microleakage and bond strength. The initial effects of chemical etchants on the denture base resin in terms of microstructural changes and flexural strength were also examined. MATERIAL AND METHODS: Forty-two polymethyl methacrylate (PMMA) denture base resin (Meliodent) specimens consisting of 2 plates measuring 30 x 30 x 2 mm were prepared and divided into 7 groups (n = 6). Specimen groups were treated by immersion in acetone for 30 (A30) or 45 (A45) seconds, methyl methacrylate monomer for 180 (M180) seconds, and methylene chloride for 5 (MC5), 15 (MC15) or 30 (MC30) seconds. Group C had no surface treatment and served as the control. Subsequently, an adhesive (Mollosil) and a silicone-based resilient denture liner (Mollosil) were applied to the treated surfaces, and all specimens were immersed in the radiotracer solution (thalium-201 chloride) for 24 hours. Tracer activity (x-ray counts), as a parameter of microleakage, was measured using a gamma camera. For bond-strength measurement, 84 rectangular PMMA specimens (10 x 10 x 40 mm) were surface-smoothed for bonding and treated with the different chemical etchants using the same previously described group configurations. The adhesive and the silicone-based denture liner were applied to the treated surfaces. Tensile bond-strength (MPa) was measured in a universal testing machine. Flexural strength measurement was performed with 49 PMMA specimens (65 x 10 x 3.3 mm according to ISO standard 1567) in 7 groups (n = 7), with 1 flat surface of each treated with 1 of the chemical etchants preceding adhesive application. The flexural strength (MPa) was measured using a 3-point bending test in a universal testing machine. The data were analyzed by 1-way analysis of variance and the Tukey HSD test (alpha = .05). RESULTS: Significant differences were found between the groups in terms of microleakage (P < .0001). The lowest microleakage was observed in group M180 (30,000 x-ray counts) and the highest in the control group (44,000 x-ray counts). The mean bond strength to PMMA resin ranged from 1.44 to 2.22 MPa. All treated specimens showed significantly higher bond strength than controls (P < .01). The flexural strength values all significantly differed (P < .05). All experimental specimens that had chemical surface treatments showed lower flexural strength than controls (P < .05). CONCLUSION: Treating the denture base resin surface with chemical etchants increased the bond strength of silicone-based resilient denture liner to denture base and decreased the microleakage between the 2 materials. Considering the results of both tests together, the use of methyl methacrylate monomer for 180 seconds was found to be the most effective chemical treatment.

Acid Etching, Dental↗
PubMedDate not supplied

The effect of polishing on surface roughness of tissue conditioners.

PURPOSE: Surface roughness can affect microbial colonization of long-term denture liners, alloys, and denture acrylic. The purpose of the present study was to examine the effect of finishing and polishing procedures on surface roughness of 4 temporary resilient denture liners (tissue conditioners). MATERIALS AND METHODS: Mean surface roughness was measured for 4 materials (Lynal, Visco-gel, Coe-Soft, and Functional Impression Tissue Toner [FITT]) finished in 4 ways: unfinished (control); polished; reduced, unpolished; and reduced, polished. Samples were allowed to polymerize at 37 degrees C for 24 hours, and the surface roughness was measured using a Mitutoyo Surftest 212. RESULTS: Mean surface roughness ranged from 1.8 +/- 0.8 microns for polished Lynal to 7.8 +/- 1.1 microns for reduced, unpolished FITT. All polished samples were smoother than unpolished samples (including controls), whether or not the samples were reduced with a bur. CONCLUSION: Polished samples of tissue conditioning material had lower mean surface roughness measurements than control or reduced, unpolished samples at the 95% level of confidence. There was no difference in mean surface roughness measurements of control samples and unpolished samples reduced with a bur at the 95% level of confidence. Mean surface roughness differed significantly between the materials tested.

Acrylic Resins↗
PubMed2004

Evaluation of the sanitization effectiveness of a denture-cleaning product on dentures contaminated with known microbial flora. An in vitro study.

OBJECTIVES: To see if dentures contaminated with Staphylococcus aureus, Pseudomas aeruginosa, Bacillus cereus, Candida albicans, and herpes simplex virus 1 could be effectively decontaminated by using Medical Tabs for Dentures. METHOD AND MATERIALS: Ten methylmethacrylate dentures with processed soft liners (soft-liner dentures) and 10 methylmethacrylate dentures without processed soft liners (hard dentures) were aseptically fragmented and individually incubated with a target microorganism. Test denture fragments were immersed in Medical for 5 minutes, vortexed for 5 minutes, and serially diluted onto media. The control denture fragments were similarly treated in sterile water. For virus contamination, denture fragments were contaminated with 1.2 x 10(9) tissue culture infective dose (TCID)50/mL. They were treated with either Medical for 5 minutes (test fragments) or water (controls) for 5 minutes. Serial dilutions were performed and viral (TCID)50/mL titers were calculated using the Reed-Muench method. RESULTS: Medical treatments effectively eliminated C. albicans, S. aureus, and P. aeruginosa from soft-liner dentures. Treatment of hard dentures eradicated C. albicans and reduced the numbers of S. aureus and P. aeruginosa to < 10. B. cereus showed a reduction of 10 microorganisms in hard dentures while the soft-liner dentures did not show an appreciable reduction. Viral analyses found that both types of dentures retained large amounts of virus when washed with water, but no virus was recovered from any of the 40 samples treated with Medical. CONCLUSION: A single use of Medical Tabs for Dentures is effective in eliminating certain species of microorganisms, including selected viruses, in vitro.

Bacillus cereus↗