Silicone Soft Lining Materials Research Articles

Comparative Analysis of Properties in Chairside Silicone Denture Liners versus Heat-Cured Molloplast-B: An In-Depth In Vitro Evaluation.

BACKGROUND We investigated the bond strength, tensile strength, and water absorption properties of 4 widely used chairside silicone long-term denture soft lining materials and compared properties with those of heat-cured silicone material. MATERIAL AND METHODS Four chairside materials (GC Reline Soft, Mucopren Soft, Sofreliner Soft, and Elite Soft Relining) and a heat-cured silicone material (Molloplast B) were investigated. For tensile and shear bond strength and tensile strength, samples were prepared according to the manufacturers' instructions and the testing machine used. For water absorption, IOS 1567 was followed to prepare specimens. Bond strengths were measured using a Lloyd Instruments materials testing machine. Ten specimens for each test were prepared for each soft liner, except for water absorption and solubility tests, for which only 5 specimens were prepared. ANOVA, Bonferroni, and Kruskal-Wallis tests were used to compare values of materials and assess changes over time. RESULTS There was strong evidence of differences in the properties between materials. GC Reline Soft showed comparable tensile bond (1.4±0.6 MPa), shear bond (1.1±0.4 MPa), tensile strength (5.44±0.98), water absorption (0.92±0.2 µg/mm³), and solubility values (0.3±0.2 µg/mm3) to that of Molloplast B (1.4±0.4; 1.6±0.5; 4.53±0.9 MPa, 1.7±0.3, and 1.0±0.3 µg/mm³, respectively). The water solubility of Sofreliner Soft was significantly lower (1.5±0.8 µg/mm³) than that of Molloplast B. CONCLUSIONS There were significant differences between some properties of 4 chairside denture soft lining materials and that of Molloplast B, which had higher shear and tensile bond strength than chairside denture silicone soft lining materials but had the highest water solubility.

Evaluate and Compare the Hardness and Tensile Bond Strength of a Silicone Soft Lining Material, after Short Term Immersion in Two Different Denture Cleansing Solutions and Water over Varying Time Periods

Background: Background: To evaluate and compare the hardness and tensile bond strength of a silicone soft lining material, after short term immersion in two different denture cleansing solutions and water over varying time periods. Materials & Methods: The study comprised of 3 groups followed by 3 subgroups under each groups of 10 specimens for evaluation of tensile bond strength with heat cure denture base acrylic resin, and 3 groups followed by 3 subgroups under each groups of 10 specimens each for the hardness test of soft liners. Group A: Heat polymerized silicone based resilient liner immersed in denture cleansing solution secure with 700mg of sodium perborate monohydrate, Group B: Heat polymerized silicone based resilient liner immersed in denture cleansing solution clinsodent with 480mg of sodium perborate monohydrate and Group C: Heat polymerized silicone based resilient liner immersed in water. Results: At day 1 and 1 week, Group B showed highest tensile bond strength (1.500.015) and (1.12  0.012) respectively whereas at 1 month, Group C showed highest tensile bond strength (0.96  0.016). Conclusion: A significant difference exists in the tensile bond strength and the hardness values of the soft liner specimen when immersed in water and two different denture cleansing solutions between the periods of immersion.

Evaluation of some physical properties of two permanent heat cure silicone soft lining materials

Background: Soft lining materials has a key role in modern prosthodontics because of their capability of restoring health of inflamed and distorted mucosa, but with two major problems; water sorption, solubility, and lack of bond to the underlying denture base materials. The aim of this study was to examine water sorption and solubility for two types of permanent heat cure silicone soft lining materials (Permaflex and Molloplast-B), applied for different types of acrylic denture base surface and stored in artificial saliva to evaluate the tensile bond strength. Materials and methods: Two types of permanent heat cure silicone soft lining materials was applied to different type of surfaces acrylic denture bases for tensile testing. Water sorption and solubility test was done according to ADA No. 12 specification for 1, 3, and 6 weeks intervals. Results: There was no significant changes in sorption and solubility with time of water storage from (1st-- 3rd week), for Permaflex soft lining materials, and significant decrease water storage from (3rd -- 6th week) for sorption only, and for Molloplast –B soft lining materials no significant changes for sorption of water storage from (1st–3rd– 6th week), solubility revealed a significant changes with time for water storage from (1st – 3rd – 6th week). Conclusion: This study indicated that heat cure soft lining materials shows some degree of water sorption and solubility, the lowest level was obtained by Permaflex soft lining material. Artificial saliva storage decrease the tensile bond strength for the two types of soft lining materials except for Permaflex sandblasted type of surface increase after artificial saliva storage.

A modified indirect method for fabricating silicone soft-lined complete dentures

A method is described of polymerizing silicone soft lining materials with a hard acrylic resin base by using a photoactivated spacer. The use of a photoactivated spacer is convenient because of the ease in determining the correct location covering the attached mucosa but not extending to the border margins. By using this method, the optimum shape and thickness of the spacer can also be ensured. Thus, the long-term durability of soft lining dentures is achieved without invasion by microorganisms or peeling away from the denture margin.

Influence of Adhesive on Shear Bond Strength Between Denture Base Materials and Self-Cured Silicon Soft Liner

Background: Soft lining materials play an important role in modern prosthodontics because of their capability of restoring health of inflamed and distorted mucosa. Gradual changes of oral tissues require that complete or partial dentures be relined to improve their adaptation to the supporting tissue. This study aimed to evaluate the shear bond strength (SBS) of heat cured acrylic and injection-molded ValplastTM denture base materials to silicone self-cure soft lining materials, with and without adhesive, after storage in two different times in artificial saliva. Materials and Methods: 40 rectangularspecimens were prepared from two types of self-cured silicone soft lining material,one with adhesive and the other without adhesive were applied to two types of denture base materials ( heat polymerized Polymethyl methacrylate and injection-molded nylon denture base materials). Shear bond strength of the specimens was measured, after immersionin artificial saliva for different periods (72 hours or 10 weeks), using Lloyd universal testing machine. Results: Acrylic denture base bonded to soft liner with adhesive at 72 hours of immersion in artificial saliva showed the highest shear bond strength. Comparing SBS values of the tested soft lining materials revealed significant differences between adhesively bonded and non-adhesively bonded types. Conclusions: This study concluded that the bond strength of the silicone soft lining materials with denture base materials increased with adhesive. Silicone soft lining materials are affected by artificial saliva storage.

PROTEZ TEMİZLEYİCİLERİNİN YUMUŞAK ASTAR MADDELERİNİN RENK STABİLİTELERİ ÜZERİNE ETKİSİNİN DEĞERLENDİRİLMESİ

Aim: The aim of this study was to evaluate the effect of denture cleansers on the color stability of long-term soft denture lining materials. Materials and Method: Two different silicone soft lining materials (Elite Soft and Ufi Gel P) and 3 different denture cleansers [Corega Tabs, Fittydent, 0.5% sodium hypochlorite (NaOCl)] were used in this study and distilled water was served as control group. Forty disc-shaped specimens, with 10 mm in diameter and 1 mm in thickness were fabricated from each soft lining material (n=10). CIE L*a*b* values of specimens were recorded with a spectrophotometer and then specimens were randomly divided into 4 groups according to the cleaning protocol. All of the specimens were immersed in denture cleansers for 8 hours, then washed under running water and after that stored in distilled water for 16 hours. This procedure was repeated for 96 days; every 3 days were considered as 1 week and thus 6-month of usage was simulated. Color measurements were repeated at the end of 48 and 96 (Nokta kaldirilsin) days and color differences (ΔE) were calculated. Data were statistically analyzed. Result: Ufi Gel P showed significantly lower ΔE values in comparison to Elite Soft (P 0.05). Conclusion: Since color stability of soft liners is an important indicator for clinicians of aging or damaging, the color difference in soft liners caused by the denture cleansers should be taken into consideration in material selection

Mechanical properties of experimental silicone soft lining materials

The purpose of this study was to evaluate the mechanical properties of experimental silicone elastomers, Silastic(®) MDX 4-4210 reinforced with silica fillers, to assess its potential as a denture soft lining material. The mechanical properties measured included tensile strength, percentage elongation, tear strength, and Shore A hardness. Using one-way ANOVA and Tukey's HSD test, the results indicated that silicone elastomers with filler loadings of 6, 8, and 10 phr had significantly greater tensile strength, percentage elongation, tear strength with a softer surface compared with commercial materials (p<0.001). In conclusion, the experimental silicone elastomers revealed acceptable mechanical properties to be used as denture soft lining materials.

Evaluation of the tensile bond strengths of heat cure acrylic and Valplast with silicone self cure soft liner

Soft lining materials have a key role in modern prosthodontics because of their capability of restoring health of inflamed and distorted mucosa. Gradual changes of oral tissues require that complete or partial dentures be relined to improve their adaptation to the supporting tissue. This study aimed to evaluate the tensile bond strength of heat cure acrylic and Valplast denture base materials to silicone self-cure soft lining material stored in artificial saliva. Materials and method: Two types of self cured silicone soft lining material (one with prime the other without prime or adhesive) applied to polymethylmet hacrylate and injection-molded nylon denture base materials for tensile bond strength testing using Instron machine. Results: The comparison between all test groups after (48) hours immersion in artificial saliva were highly significantly different from each other except for the comparison between groups PSP and VSP in which their means were non-significant. After (12) weeks, the comparison between all test groups were highly significantly different from each other when compared statistically. Conclusion: This study indicated that prime (adhesive) increase the bond strength of the silicone soft lining materials

Antifungal Activity of Denture Soft Lining Material Modified by Silver Nanoparticles—A Pilot Study

Soft liner materials in oral cavity environments are easily colonized both by fungi and dental plaque. These factors are the cause of mucosal infections. The microorganism that most frequently colonizes soft liner materials is Candida albicans. Colonization occurs on the surface of materials and within materials. A solution to this problem might involve modification of soft liner materials with silver nanoparticles (AgNPs). In this article, we present results showing the antifungal efficacy of silicone soft lining materials modified with AgNPs. The modification process was conducted by dissolving both material components (base and catalyst) in a colloidal solution of AgNPs and evaporating the solvent. Composites with various AgNP concentrations (10, 20, 40, 80, 120 and 200 ppm) were examined. The in vitro antifungal efficacy (AFE) of composite samples was 16.3% to 52.5%.

Dynamic viscoelastic properties of experimental silicone soft lining materials

The purpose of this study was to evaluate the dynamic viscoelastic properties of experimental silicone soft lining materials, Silastic MDX 4-4210 reinforced with silica fillers. Storage modulus (E'), loss modulus (E") and damping factor (tan delta) were determined using a dynamic mechanical analyzer under a deformation strain level of 0.27% at test frequency and a temperature range of 1 Hz and 0 to 60 degrees C, respectively. The degree of silica dispersion was also studied using a field emission scanning electron microscopy (FE-SEM). One-way ANOVA and Tukey's HSD test results indicated that the prepared silicone elastomers provided a significantly greater damping factor, but less storage modulus than GC Reline Soft and Tokuyama Sofreliner Tough (p<0.001). The storage moduli, loss moduli and damping factor of the experimental silicone elastomers increased with increasing amounts of fumed silica. In conclusion, the experimental silicone elastomers revealed acceptable dynamic viscoelastic properties to be used as denture soft lining materials.

Effect of thermocycling and treatment with monomer on mechanical properties of soft denture liner Molloplast B

Bonding between soft liner (Molloplast B) and denture base resins (poly(methyl methacrylate)) is a significant problem. Surface treatment with some adhesives of denture base resins increase bonding between these two materials. The purpose of this study was to investigate the effect of thermocycling and of surface treatment with MMA monomer on the mechanical properties of the silicone-based soft liner. A silicone soft lining material (heat-polymerized silicone rubber) and heat-polymerized denture base resin, PMMA, were chosen for this investigation. Transient mechanical and dynamic mechanical properties changed with monomer treatment and/or thermocycling.

Denture Cleansers, Soft Lining Materials and Water Temperature: What is the Effect?

To investigate the effect of water temperature, in association with four denture cleansers, on the colour and surface roughness of five soft lining materials. Two silicone soft lining materials (Molloplast B and Sofreliner) represented the heat-cured, laboratory-based and chairside materials that are available. The wide range of chairside, acrylic resin-based, temporary soft lining materials was represented by Coe-Soft, Viscogel and Eversoft. An alkaline hypochlorite (Dentural) and three effervescent peroxide solutions with a range of active pH values (Steradent Active Plus, pH 6; Steradent Extra Strength, pH 3; Superdrug Fresh, pH 11) were selected as the cleansers. The denture cleansers were used at two temperatures: 55 degrees C (manufacturers' recommended temperature) and 80 degrees C. The colour of the specimens was evaluated using a colorimeter and the surface roughness was assessed using a three-dimensional, non-contact surface profilometer. This study reported on the effect of using both the higher temperatures and the recommended temperature on the colour and roughness of permanent and temporary soft lining materials. The results of the study showed that the temperature of the water used with denture cleansers might have a detrimental effect on the colour and surface roughness of some permanent and temporary soft lining materials.

Bond Strength of a Silicone Soft Lining Material to Poly(methyl methacrylate) Resin Treated with Maleic Anhydride and its Terpolymers

This study investigated the effectiveness of surface treatment of Poly (methyl methacrylate) (PMMA) denture base resin on tensile bond strength between PMMA/silicone-based soft liner. A total of 25 specimens were fabricated and assigned into five groups (n = 5). The surfaces of PMMA were treated with maleic anhydride, maleic anhydride-styrene-vinyl-acetate, n-butylmaleate-styrene-vinyl-acetate, or n-pentamaleate-styrene-vinyl-acetate prior to Primo adhesive primer application and silicone liner placement. The Primo adhesive primer on applied group untreated dentuse base resin served as control. The tensile test was performed using a universal testing machine. Fractured surfaces were observed under Scanning Electron Microscopy (SEM) and spectroscopic interpretation of the interfaces was done by Fourier Transform Infrared (FTIR). Test results showed that surface treatment increased interfacial strength giving the highest value for n-butylmaleate-styrene-vinyl acetate treated group. SEM micrographs revealed that the specimens with n-butylmaleate-styrene-vinyl-acetate and n-penta maleate-styrene-vinyl-acetate terpolymers underwent cohesive failure. FTIR analysis indicated secondary interactions such as hydrogen bonding, possibly on acrylic resin surfaces, caused by the use of maleic anhydride and its terpolymers, and the adhesive.

A polyvinylsiloxane denture soft lining material

A new denture soft lining material based on a polyvinylsiloxane system, similar to that used in addition-curing silicone impression materials, has recently been developed. The purpose of the work reported here was to compare certain key properties of the new material with those of other commercially available materials. Setting characteristics, resistance to penetration, elastic properties, water absorption, peel strength and contact angle with water were determined for five materials including the new product. In addition, the change in properties following water storage were determined. In many respects the properties of the new material were noted to be similar to those of a heatcured silicone product. It is initially elastic and of “medium” softness as defined by ISO 10139-2. It was the only product which did not lose weight on storage in water and over 90 days of storage it gave only a small change in compliance as measured by surface penetration. Bond strength of the new material to an acrylic denture base appears only moderate. However, failure was cohesive within the soft material with no peeling, suggesting that peeling is unlikely to occur in practice. The affinity between the surface of the material and water, as determined by contact angle, is significantly better than for other silicone products. The properties of the polyvinylsiloxane denture soft lining material are in many respects similar to those of other silicone soft lining materials. However, the efficacy of the adhesive which prevents peeling combined with a convenient packaging, proportioning and mixing system suggests that the material may offer some advantages which warrant its clinical evaluation.

Adhesion and tear energy of a long-term soft lining material activated by rapid microwave energy

Statement of Problem. Construction of dentures with permanent soft linings is time-consuming in the laboratory and extra costs are related to equipment and materials used. Purpose.The purpose of this in vitro study was to determine whether using microwave energy to activate the polymerization of a silicone rubber denture soft lining material affected its properties. Material and Methods. Tear energy and adhesive properties were measured in a tensile testing machine by using a pants leg tear test and peel specimens. Tear energy was measured for specimens polymerized conventionally (control) and for 3, 5, and 10 minutes in a microwave. Data were analyzed with one-way analysis of variance and a two-sample Student t test. Results. The multiple comparison test failed to show a significant difference in tear energy between 3 minutes microwave activation and conventional heat curing. However, 3 minutes microwave activation revealed a significantly stronger material when compared with 5 minutes and 10 minutes ( p < 0.05). Application of a two-sample Student t test failed to demonstrate a significant difference between microwave energy and conventional heat activation groups in the adhesion test. In adhesion testing, all specimens presented cohesive failure. Conclusions. This method of polymerization does not compromise the strength of a soft lining material and its adhesion to polymethyl methacrylate. This study suggests the use of 3 minutes 650W microwave energy for processing a silicone soft lining material. (J Prosthet Dent 1998;79:182-87.)

Adherence of Candida albicans to experimental denture soft lining materials

Statement of problem. Colonization of denture soft lining materials by Candida albicans can result in clinical problems. Two experimental silicone soft lining materials have been developed and demonstrate good physical properties. Purpose of study. The aim of this study was to determine the extent of candidal adherence to these materials compared with a commercially available soft lining material and an acrylic resin denture base. Material and methods. The experimental materials were constructed in a stainless-steel mold, and their surface energies were determined with a dynamic contact angle analyzer. The adherence of three strains of C. albicans was determined with an in vitro assay. In addition, one test strain was used to determine the effect on adherence of precoating the materials with whole saliva. Results. Adhesion to all materials was strain variable, with the lowest adherence recorded for the two experimental materials. Decreased adherence was also apparent after precoating the materials with saliva. Correlation between surface energy of the material and the degree of candidal adhesion was seen for one strain, but no correlation was seen for the other two strains. Conclusion. Adherence of C. albicans to the two experimental silicone soft lining materials was significantly less than that for an acrylic resin denture base and a commercially available soft lining material. (J Prosthet Dent 1997;77:306-12.)

Water absorption of (RTV) silicone denture soft lining material

Objectives: The reason for high water absorption by room temperature vulcanizing (RTV) silicone denture soft lining materials has not been demonstrated previously. An experimental room-temperature vulcanizing (RTV) silicone soft lining material which had been shown to have good mechanical properties had high water absorption at equilibrium whilst losing only small amounts of soluble material after desorption. The volume change in the material was also high. A variety of formulations of the experimental material was devised in order to determine the cause of the high water sorption values. Methods: Water sorption values were determined using standard experimental techniques. Sections of the polymerized materials were examined by scanning electron microscopy for microporosity. Results: Neither removal of residual cross-linker nor changing the method of polymerization reduced the water absorption. Scanning electron microscopy did not demonstrate a porous structure of the polymerized material. A correlation was seen between filler content and water absorption. A formulation without filler showed a greatly reduced water absorption and volume change. Conclusion: It was concluded that the filler was directly responsible for the water absorption of the RTV material.

Clinical study of a heat‐cured silicone soft lining material

Thirty-seven mandibular dentures lined with Molloplast B silicone material were examined after they had been worn for 2-8 weeks and 6, 18 and 30 months. The denture wearers were also examined and interviewed. The colour was found to have become lighter in 46% and turned yellow or brown in 51%; the denture base had worn through in 24% and there was a failure on bond in 22%; no hardening of the material was noted; 24% of the dentures had broken. An unusual taste was reported by 22% and smell by 14% of the denture wearers; mucosal soreness was noted in 14%; denture stomatitis developed in 48%; hygiene was poor in 61% and fungal growth was traced in 81% of the dentures; 73% of the patients were satisfied with the soft lining.