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PubMed1991

In vivo fungal presence and growth on two resilient denture liners.

To determine whether two intraoral-setting resilient denture liners supported the in vivo presence or growth of oral commensal fungi, the liners were randomly placed in the mandibular complete dentures of 14 patients. Cytologic smears were made from the liner surfaces at 1 hour and 1, 2, 7, 14 and 30 days after intraoral placement. Yeast forms were observed in six patient trials of material A and in two trials of material B. Hyphae were observed in only one patient trial of material A and in two trials of material B. When yeast forms and hyphae findings were combined and were considered as indicative of fungal presence or growth, the prevalence up to 30 days was seven for material A and four for material B. Statistical analysis revealed no significant difference in the prevalence of fungal presence or growth between the two resilient denture liners tested.

Acrylic Resins↗
PubMed1999

Color stability of heat-polymerized and autopolymerized soft denture liners.

STATEMENT OF PROBLEM: The physical and mechanical properties of soft denture liners are influenced by a number of factors. Aging is one factor that has an effect on the characteristics of polymers. The resistance of denture liners to aging can potentially influence the color stability of these liners. PURPOSE: This study attempted to determine the color stability of soft liners by subjecting them to an in vitro accelerated aging test. MATERIAL AND METHODS: Two autopolymerizing and 3 heat polymerizing commercially available soft denture lining materials were tested. Seven sample disks were made of each material according to manufacturers' instructions. Color measurements were recorded before and after the accelerated aging process. Color changes (DeltaE) were calculated by measuring tristimulus values at several wavelengths in the visual spectrum with the use of Commission International de l'Eclairge Lab (CIE-LAB) uniform color scale. RESULTS: Kruskall-Wallis variance analysis and Mann-Whitney U-Wilcoxon rank sum W tests were performed for statistical comparison of the DeltaE values. Ufigel P and Simpa liner materials showed significantly greater color changes than the other tested materials. There were no significant differences in color change among Ufigel L-Molloplast B, Ufigel L-Flexor, and Molloplast B-Flexor liner materials. However, a significant difference in color change was found between Ufigel P and Simpa liners. CONCLUSION: Heat-polymerized soft liners were more color stable than autopolymerized soft liners. No significant differences were found among heat polymerized materials; however, significant differences in color change were found between the 2 autopolymerized liners.

Analysis of Variance↗
PubMedDate not supplied

Impact absorption of four processed soft denture liners as influenced by accelerated aging.

The cushioning effect of soft denture liners was evaluated by using a free drop test with an accelerometer. Materials tested included SuperSoft (Coe Laboratories, Chicago, IL), Kurepeet-Dough (Kreha Chemical, Tokyo), Molteno Soft (Molten, Hiroshima, Japan), and Molloplast-B (Molloplast Regneri, Karlsruhe, Germany). All materials were found to reduce the impact force when compared to acrylic denture base resin. A 2.4-mm layer of soft denture material demonstrated good impact absorption, and Molloplast-B and Molteno had excellent impact absorption. When the soft denture liner was kept in an accelerated aging chamber for 900 hours, the damping effect recorded increased for all materials tested. Aging of all materials also affected the cushioning effect.

Acrylic Resins↗
PubMed2005

The influence of water storage on durometer hardness of 5 soft denture liners over time.

PURPOSE: This laboratory study investigated the influence of water storage on the durometer hardness of 2 RTV and 3 HTV soft denture liners over a 1-year period. MATERIALS AND METHODS: Five soft denture liners were used: 2 HTV silicone rubber (Luci-Sof and Molloplast-B), 1 RTV silicone rubber (Tokuyama), 1 HTV polyphosphazene (Novus), and an RTV plasticized acrylic (PermaSoft) that uses a surface sealer. They were processed following manufacturers' instructions, cured, and stored in tap water at 37 degrees C. The water was changed every 2 weeks. Five durometer A hardness measurements were made at logarithmically spaced intervals of 16.7 minutes, 27.8 hours, 11.6 days, 34.7 days, 115 days, and 347 days. Repeated measures analysis of variance (MANOVA), one-way analysis of variance (ANOVA), Pillai trace statistic, the difference scores (last-first) among the groups, and the Tamhane T2 multiple comparison test were used to compare the groups over time, all on SPSS V. 7.5 and 9.0. RESULTS: The order of highest initial indentation hardness was Luci-Sof, Molloplast-B, Novus (H(D)= 38 to 33). Tokuyama and PermaSoft as a group were softer (H(D)= 18 to 22). Tokuyama Soft Relining changed the least over 347 days, followed by Luci-Sof, Novus, Molloplast-B, and PermaSoft in that order (p < or = 0.05). Within the PermaSoft group, sealer applied only once changed the least over 347 days, followed by no sealer, and then sealer applied every month (p < 0.0005). CONCLUSIONS: After 347 days of water storage, Tokuyama had the lowest indentation hardness changes, followed by Luci-Sof, Novus, PermaSoft with sealer applied once; Molloplast-B, PermaSoft without sealer; and PermaSoft with sealer applied every month. All HTV soft denture liners had higher indentation hardness than RTV liners initially. After 347 days, PermaSoft without sealer and with sealer every month became the hardest.

Analysis of Variance↗
PubMedDate not supplied

Randomized controlled clinical trial on satisfaction with resilient denture liners among edentulous patients.

PURPOSE: The purpose of this study was to measure patients' satisfaction and their preference between mandibular dentures with permanent silicone-based resilient denture liner (SR) and conventional heat-activated acrylic resin (AR), both opposed by acrylic resin-based maxillary complete dentures. MATERIALS AND METHODS: Twenty-eight edentulous patients who had fulfilled selection criteria and provided informed consent were enrolled in this trial. Subjects were allocated randomly to either arm of cross-over groups (AR-SR/SR-AR), stratified by gender, using a random permuted block within the strata method. The AR-SR group received AR denture treatment followed by SR denture treatment. The SR-AR group received treatment in the reverse sequence. The primary outcome was patient satisfaction measured on 100-mm VAS, analyzed by two-way ANOVA and the Bonferroni multiple comparison as a post hoc test. The secondary outcome was patients' preference, evaluated by chi-square goodness-of-fit test. An intention-to-treat analysis was performed. RESULTS: Twenty-five subjects were enrolled in the analysis. There were no significant differences between AR and SR dentures 1, 2, and 3 months after the completion of control. Eighteen of 25 patients preferred SR dentures. CONCLUSION: Although there were no significant differences in patient satisfaction ratings between the two types of dentures, a significant majority of patients preferred those with a resilient denture liner.

Acrylic Resins↗
PubMed2004

Setting characteristics of silicone-based resilient denture liners.

The aim of this study was to investigate the setting characteristics of seven silicone-based resilient denture liners during setting. Maximum extrusion force--at the flow rate of 1 cm/min--ranged from 0.183 to 1.26 MPa. Working time and setting time ranged from 2.0 to 5.0 minutes and 1.9 to 6.8 minutes respectively. Consistency as described in JIS T6519-2000 was 32.4 to 46.5 mm. As normal load of 1 kgf was applied to a specimen held between two glass plates after mixing, the time at which film thickness reached up to 1 mm was 4.0 to 13.0 minutes at 23 degrees C and 2.2 to 5.5 minutes at 37 degrees C. These results suggested that the reaction rate of materials used in this study differed from one brand to another. Against this backdrop of differing reaction rates amongst brands, it is therefore vital that a denture liner material's setting characteristics be carefully considered whenever it is used in clinical dentistry to prevent any undesirable or unexpected results and outcome.

Analysis of Variance↗
PubMed2000

Microleakage study of various soft denture liners by autoradiography: effect of accelerated aging.

STATEMENT OF PROBLEM: The longevity of soft denture liners is a major clinical problem. Debonding of the soft liner from the denture base material is one of the factors that influence their longevity. Debonding of the soft liner can be attributed to microleakage at the interface. PURPOSE: This study investigated microleakage at the interface of various soft liners and base materials. MATERIALS AND METHOD: Six soft liners were investigated. Forty specimens of each material in disk form (10 mm in diameter, thickness of approximately 4 mm) were prepared. Twenty specimens of each material were stored in an accelerated weathering tester for 900 hours. For 2 days, all disks were immersed in (45)Ca radioisotope solution, then they were embedded in acrylic resin blocks and sectioned longitudinally. Autoradiographic imaging was used to determine microleakage at the interface of the soft liners and their bases. RESULTS: Significant differences between nonaged materials were found (P<.05).The difference between Molloplast B and Mucopren (silanized) was not significant (P<.05). Differences among aged materials were significant (P>.05). Differences between Mucopren (nonsilanized), Mucopren (silanized), and Ufigel P-Tokuyama were not significant (P<.05). Significantly decreased microleakage characteristics were determined for Molloplast B, Mucopren (nonsilanized) and Ufigel P liners after aging. CONCLUSION: Microleakage of Mucopren and Molloplast B lining materials was the lowest. However, the microleakage of Flexor and Simpa was the highest. The aging process did not significantly affect the microleakage characteristics of the Simpa, Flexor, Mucopren (silanized), or Tokuyama materials. Molloplast B, Mucopren (nonsilanized), and Ufigel P materials should significantly decrease microleakage properties after aging.

Autoradiography↗
PubMed2003

Clinical evaluation of a new resilient denture liner. Part 1: Compliance and color evaluation.

PURPOSE: A new experimental resilient denture liner (MPDS-SL; Lai Laboratories, Burnsville, MN) and Molloplast-B (Buffalo Dental Manufacturing, Syosset, NY) were clinically evaluated for compliance and color change over a 1-year period. MATERIALS AND METHODS: In this crossover study, each of 20 patients had 2 dentures fabricated with long-term, silicone-based resilient liners, 1 denture with Molloplast-B and the other with MPDS-SL. Each denture was used for 6 months, during which time each patient kept a journal detailing his or her use and cleaning regimen. The 2 materials were assessed for compliance and color at the beginning of the study and again after 3 months and 6 months of use. Compliance was determined by applying a 3-lb force to the surface of the material following a square-wave pattern, using a closed-loop servohydraulic testing system. The force and position values were recorded using a storage oscilloscope. Compliance was measured at 3 locations on each denture and analyzed using data-acquisition software. Images of the dentures were captured using a zoom stereomicroscope with a charge-coupled video camera and image analysis software. The color was measured at 3 locations on each denture; RGB and L* a* b* were calculated. RESULTS: Compliance increased from baseline to 3 months and from 3 months to 6 months for almost all locations on both materials. Molloplast-B and MPDS-SL differed in average change in compliance at 6 months; the average change in compliance from baseline to 6 months was 453 (standard error, 46) for Molloplast-B and 284 (standard error, 46) for MPDS-SL (p = 0.019). For both materials, color changed significantly from baseline to 3 months and from baseline to 6 months (p < 0.01). MPDS-SL changed significantly less than Molloplast-B from baseline to 6 months for R (p = 0.039), G (p = 0.037), B (p = 0.005), and L* (p = 0.042). CONCLUSION: For both materials, compliance increased over 6 months of wear. The color change for MPDS-SL was considerably less significant than that for Molloplast-B.

Aged↗
PubMedDate not supplied

Characterization of the physical properties of resilient denture liners.

The physical and viscoelastic properties of two resilient denture liners, the polyphosphazine-based Novus and silicone-based Molloplast b, have been characterized. The two materials were found to have comparable tensile strengths and frictional properties but differed in their tear strengths, water sorptions, and solubilities. Novus had a greater tear strength and lower solubility, but greater water sorption, than Molloplast b. Compressibility studies indicated that significantly less force was required to compress 2- and 3-mm thicknesses of Novus by 0.2 and 0.4 mm than for Molloplast b. Dynamic mechanical analysis indicated that Novus should have a greater propensity for energy/impact absorption.

Analysis of Variance↗
PubMed1997

[The development of light-curing soft denture liner].

In this study, a visible light-curing soft denture liner was developed, and 6 methacrylate polyurethane elastomer and a diluent were synthesised, their effect on tensile strength, compression set, Shore A hardness, absorption and solubility were also investigated. The results showed that the elastomer made of polyethylene adipate or polybutylene ether glycol possessed the highest tensile strength and hardness, the elastomer made of polypropylene ether glycol showed low tensile strength and low shore A hardness, the elastomer made of hydroxyl-terminated liquid polybutadiene rubber had a moderate tensile strength and hardness.

Denture Liners↗
PubMed2000

Dynamic viscoelastic properties and the age changes of long-term soft denture liners.

The dynamic viscoelastic properties of long-term soft denture liners were measured over a wide range of frequencies using a dynamic viscoelastometer based on a non-resonance-forced vibration principle. Changes in properties over a 3 yr period have also been monitored. One acrylic material, one fluoroelastomer, one heat cured silicone and one self-curing addition silicone were used. Complex dynamic tensile modulus (E*), tensile storage modulus (E'), tensile loss modulus (E") and loss tangent (tan delta) were determined over the frequency range from 0.01 to 100 Hz on administration of a 0.27% strain at 37 degrees C. The dynamic viscoelasticity of the acrylic and fluoroelastomer products was more sensitive to changes in frequency than that of silicone products. The acrylic material and fluoroelastomer exhibited viscoelastic behaviour whilst silicones exhibited elastic behaviour. The silicone products remained unchanged after soaking for 3 yr whilst the acrylic and fluoroelastomer products underwent significant change.

Acrylates↗
PubMed1975

Physical and mechanical properties of nystatin-containing denture liners.

The mechanical and physical effects of the presence of nystatin in three denture liners were investigated. In general, the modified materials were softer, showed greater strain, and demonstrated permanent set under compression for the duration of the tests. However, the degree of change in properties appeared unlikely to lead to reduced clinical performance. The most significant change was a great increase in the equilibrium capacity for water in the case of the modified liners. This may enhance the pharmacologic effectiveness of these liners by encouraging the release of nystatin at the tissue surface. Bacteriologic and clinical studies continue to investigate the possibility that modified semipermanent liners (Coe-Supersoft) may reduce the recurrence of denture stomatitis.

Absorption↗
PubMed2003

Clinical evaluation of resilient denture liners. Part 2: Candida count and speciation.

PURPOSE: The purpose of this study was to count and to speciate Candida isolated from 2 resilient denture liners, Molloplast-B and MPDS-SL. MATERIALS AND METHODS: A group of 20 patients each had 1 maxillary denture and 2 mandibular dentures fabricated. One mandibular denture was lined with Molloplast-B, and 1 was lined with MPDS-SL. Each denture was used for 3 months. At the end of the 3-month period, the mandibular denture was surrendered, and a 5 x 5-mm circular resilient liner sample was obtained from the tissue surface of the lingual flange. Samples were processed, and Candida was isolated and counted. Speciation of Candida was performed using CHROMagar Candida and API 20C AUX strips. RESULTS: Molloplast-B had, on average, 5 times as many CFU/sample as MPDSL-SL, but this difference was not significant (p = 0.26). A sign test gave a similar nonsignificant trend (p = 0.057). CHROMagar identified several Candida species, and confirmation was made using API 20C AUX strips. One patient was lost to follow-up. Of 19 Molloplast-B samples, 7 had no growth, 4 grew C. albicans, 3 grew C. parapsilosis, 2 grew C. glabrata, 1 grew C. tropicalis, 2 grew a Trichosporon spp., and 2 grew a nonidentifiable colony. The analogous counts for 19 MPDS-SL samples were 10, 4, 1, 3, 0, 1, and 1 (p = 0.45 for culture positively, exact McNemar test). CONCLUSIONS: Candida growth on Molloplast-B was not significantly different from growth on MPDS-SL. Several yeast species were cultured from each material. The rates of culture-positive testing did not differ between the 2 resilient denture liners.

Adult↗
PubMed1992

Evaluation of radiopaque denture liner.

Radiopacity is needed in polymeric biomaterials to facilitate noninvasive detection. Permanent denture liner material with barium sulfate filler is nearly as radiopaque as aluminum and would be useful in radiographic identification. If 1 mm to 3 mm thicknesses are used, it should be easily observable radiographically.

Barium Sulfate↗
PubMed2002

Effect of thermocycling on bond strength and elasticity of 4 long-term soft denture liners.

STATEMENT OF PROBLEM: Two problems found in prostheses with soft liners are bond failure to the acrylic resin base and loss of elasticity due to material aging. PURPOSE: This in vitro study evaluated the effect of thermocycling on the bond strength and elasticity of 4 long-term soft denture liners to acrylic resin bases. MATERIAL AND METHODS: Four soft lining materials (Molloplast-B, Flexor, Permasoft, and Pro Tech) and 2 acrylic resins (Classico and Lucitone 199) were processed for testing according to manufacturers' instructions. Twenty rectangular specimens (10 x 10-mm(2) cross-sectional area) and twenty cylinder specimens (12.7-mm diameter x 19.0-mm height) for each liner/resin combination were used for the tensile and deformation tests, respectively. Specimen shape and liner thickness were standardized. Samples were divided into a test group that was thermocycled 3000 times and a control group that was stored for 24 hours in water at 37 degrees C. Mean bond strength, expressed in megapascals (MPa), was determined in the tensile test with the use of a universal testing machine at a crosshead speed of 5 mm/min. Elasticity, expressed as percent of permanent deformation, was calculated with an instrument for measuring permanent deformation described in ADA/ANSI specification 18. Data from both tests were examined with 1-way analysis of variance and a Tukey test, with calculation of a Scheffé interval at a 95% confidence level. RESULTS: In the tensile test under control conditions, Molloplast-B (1.51 +/- 0.28 MPa [mean +/- SD]) and Pro Tech (1.44 +/- 0.27 MPa) liners had higher bond strength values than the others (P <.05). With regard to the permanent deformation test, the lowest values were observed for Molloplast-B (0.48% +/- 0.19%) and Flexor (0.44% +/- 0.14%) (P <.05). Under thermocycling conditions, the highest bond strength occurred with Molloplast-B (1.37 +/- 0.24 MPa) (P <.05). With regard to the deformation test, Flexor (0.46% +/- 0.13%) and Molloplast-B (0.44% +/- 0.17%) liners had lower deformation values than the others (P <.05). CONCLUSION: The results of this in vitro study indicated that bond strength and permanent deformity values of the 4 soft denture liners tested varied according to their chemical composition. These tests are not completely valid for application to dental restorations because the forces they encounter are more closely related to shear and tear. However, the above protocol serves as a good method of investigation to evaluate differences between thermocycled and control groups.

Acrylic Resins↗
PubMed2003

Effect of a denture cleanser on weight, surface roughness, and tensile bond strength of two resilient denture liners.

STATEMENT OF PROBLEM: Denture cleansers used in clinical practice can damage resilient denture lining materials. PURPOSE: This study evaluated the effects of a denture cleanser on weight change, roughness, and tensile bond strength on 2 denture resilient lining materials. MATERIAL AND METHODS: Forty specimens of microwave acrylic resin (Onda-Cryl), 30 mm in diameter and 4 mm thick, were prepared to verify weight change and surface roughness. The specimens were divided into 4 groups consisting of 10 specimens each, relined with a resilient liner (Coe Soft or Dentusoft), and treated (Polident or tap water). To evaluate tensile bond strength, 12 specimens were used for each group. All specimens were stored in artificial saliva for 15 days, immersed once a day in Polident or tap water, and evaluated at 0 hours and after 24 hours and 7 and 15 days. Roughness was evaluated by use of a profilometer. Weight changes were recorded in milligrams and expressed as the percentage of weight difference between the periods of evaluation. Tensile bond strength was determined with a universal testing machine. The specimens were placed under tension until failure by a cross-speed of 5 mm/min with a 500 Kg load cell. The type of failure was determined by use of stereoscopic microscopy at original magnification x8. The data were submitted to analysis of variance and compared by Tukey's test (alpha=.05). RESULTS: Specimens immersed in Polident showed higher and significant (P<.05) weight changes (%) than those immersed in water between 24 hours and 7 days (Coe Soft-Polident: 0.48 +/- 0.09; Coe Soft-water: 0.28 +/- 0.09; Dentusoft-Polident: 0.44 +/- 0.16; Dentusoft-water: 0.22 +/- 0.15) and between 7 and 15 days (Coe Soft-Polident: 0.08 +/- 0.04; Coe Soft-water: -0.17 +/- 0.05; Dentusoft-Polident: 0.01 +/- 0.04; Dentusoft-water: - 0.24 +/- 0.03). There was significant difference (P<.05) in roughness (in micrometers), between treatments after 7 days (Coe Soft-water: 4.07 +/- 0.22; Coe Soft-Polident: 3.36 +/- 0.52; Dentusoft-water: 3.68 +/- 0.72; Dentusoft-Polident: 3.26 +/- 0.41) and 15 days (Coe Soft-water: 4.88 +/- 0.29; Coe Soft-Polident:3.53 +/- 0.61; Dentusoft-water: 4.42 +/- 1.12; Dentusoft-Polident: 3.68 +/- 0.37). Tensile bond strength was highest (P<.05) after 15 days (Coe Soft-water: 5.19 +/- 0.93; Coe Soft-Polident: 4.40 +/- 0.38; Dentusoft-water: 4.42 +/- 1.15; Dentusoft-Polident: 4.84 +/- 1.14). Most failures were cohesive (Coe Soft: 76.04% and Dentusoft: 82.29%). CONCLUSION: Within the limitations of this in vitro study, specimens immersed in Polident demonstrated increased weight changes of resilient liners when compared with tap water, but surface roughness and tensile bond strength were unaffected.

Acrylic Resins↗