Soft Denture Liners Research Articles

Chemical and Molecular Weight Analyses of Prosthodontic Soft Polymers

A number of studies have been made investigating the properties of dental prosthodontic soft polymer materials. In such materials, which are used as short-term denture soft liners, the polymer component is complexed with one or more plasticizers. This lowers the glass transition temperature, Tg, of the polymer by allowing greater chain mobility and produces a more flexible material. Little information is available relating to the polymer components of such soft-lining materials. The chemical composition and molecular-weight distribution of a polymer help to determine its ability to form a plasticized soft polymer-gel. In the present work, both pyrolysis depolymerization/gas chromatography (GC) and size exclusion chromatography (SEC) have been used to characterize 11 commercial polymer powders. By use of SEC and polymer standards having a narrow molecular-weight range, it has been possible for accurate molecular-weight distributions to be determined for all 11 powders. The peak molecular weights were found to be between 1.79 x 10(5) and 3.28 x 10(5). These values are above the molecular weight at which chain entanglement occurs. The polydispersity ratios (Mw/Mn) were between 2.09 and 4.48. Methacrylate polymers can be readily decomposed thermally to their constituent monomers, which, once recovered, can be analyzed by gas chromatography. The simple pyrolysis apparatus used in the present study was easily assembled and was capable of producing both qualitative and quantitative results. None of the commercial polymers analyzed gave methacrylate decomposition products with pendant chains greater than ethyl (-CH2-CH3). All of the commercial polymers successfully studied by the pyrolysis test method proved to be poly(ethyl [100-79%]/methyl [0-21%] methacrylate) polymers or co-polymers.

New Light Curing Soft Denture Liner Consisting of Fluoropolymer and Fluoromonomer

New Light Curing Soft Denture Liner Consisting of Fluoropolymer and Fluoromonomer

義歯用軟性裏装材の弾性ならびにクリープ特性の変化

義歯用軟性裏装材の弾性ならびにクリープ特性の変化

Denture soft linings: materials available.

Denture soft lining materials are products which are applied to the fitting surfaces of dentures for the purpose of achieving a more equal distribution of load and reduction of local point pressures. These materials have provided a focus for research and controversy for over 100 years. In that time large numbers of products have been advanced as the ideal soft denture liner. This paper discusses the five main groups of materials that have been available to dentists: the natural rubbers, vinyl co-polymers, hydrophilic polymers and the silicone and acrylic based soft lining materials.

Dental soft polymers: plasticizer composition and leachability

The objective of this investigation was to identify the type and quantify the leachability of plasticizer constituents from dental soft polymer gel systems. The clinical implications are that some plasticizers are known to be potentially toxic and in addition, loss of plasticizer results in changes in physical properties of dental soft polymers. A total of 7 different constitutents were quantitatively identified in the 8 solutions analysed by GC and GC-MS. Specimens of gel material (plasticized polymer) were evaluated for loss of plasticizer while subjected to both static and cyclic tests (1 Hz, 5 min, ± 12 N) in H 2O at 37°C. With one exception, cycled specimens did not yield greater extraction of ester. The use of 1- 14C EtOH indicated complete diffusion of ethanol from the gel within 24 h. The data indicate that a typical denture soft lining would leach between 10–40 times the level of ester that would normally be obtained from food and the environment, but would leach about one-tenth of the most stringent ADI value.

A metal-based denture with soft liner to accommodate the severely resorbed mandibular alveolar ridge

A technique is described for designing and making a mandibular denture, for patients with severely resorbed and compromised residual alveolar ridges. The denture base is stabilized by a mucostatic impression technique, myostatic denture base design, weight of a cast metal denture base, and noninterceptive occlusion with monoplane or Centrimatic posterior teeth. The hard metal denture base is made tissue-compatible by means of a soft denture liner attached to a specially relieved cast metal denture base. Over a 2-year period, this technique has successfully provided, in my practice, an alternative to residual alveolar ridge implants and other surgical interventions for 22 edentulous patients with severely resorbed and compromised mandibular residual alveolar ridges.

The use of a soft denture liner for chronic residual ridge soreness

Chronic residual ridge soreness in patients with complete dentures can be caused by various factors. A differential diagnosis between physiologic or anatomic problems (or both) and functional deficiencies in the patient's present dentures must be made. The functional deficiencies can often be eliminated easily, whereas physiologic and anatomic problems may be more difficult to correct, especially in the geriatric patient. If the functional deficiencies in the patient's dentures have been corrected and surgical procedures are not a viable alternative, placement of a long-term resilient liner can often resolve the chronic residual ridge soreness that is present in denture patients. Properly placed and properly cared for silicone or silicone rubber resilient denture liners can provide comfort for over 70% of patients with chronic residual ridge soreness for 3 to 5 years and often longer.

Soft denture liner of fluoroethylene copolymer and its clinical evaluation

The acrylic resins are acrylic copolymers to which plasticizers are added occasionally. Inasmuch as the monomers used are generally solvents for the denture base resins, reasonably good adhesion of the liner to the denture should be expected. On the other hand, acrylic soft resins absorb water, swell, and eventually deteriorate; the plasticizer molecules are leached out by the saliva, and the liners gradually harden. Their intraoral efficacy is short lived, and they are not satisfactory for extended clinical use. The silicone rubbers excel in their resiliency and their initial resistance to water absorption. However, in time they also will absorb water and begin to deteriorate. The liners are attached to denture base resins by an adhesive; but the bond is a poor one, and separations between the two materials often occur. Furthermore, they cannot be polished or trimmed properly. Another objection to the silicone lining materials is the possibility of microbial degradation. We developed fluoropolymer soft liners (Kurepeet, Kurecha Co., Tokyo, Japan) that are chemically stable and show good resistance to solvents and abrasion. In addition, their water absorption is low. We have used the liners clinically and observed their behavior in vivo more than 2 years. The objective of this

Properties of experimental elastomers for permanent soft denture liners

Properties of experimental elastomers for permanent soft denture liners

Creep and stress relaxation of soft denture liners

Creep and stress relaxation of soft denture liners

The elastic modulus of soft denture liners.

Under certain circumstances, e.g., when treating "denture sore mouth" or after the provision of immediate dentures, dentures may be lined with soft rubberlike materials which have Young's moduli within the range congruent to 10(5) N m-2. Measurement of the compression modulus Ec of such soft liners is described and Gent and Lindley's method of calculating Young's modulus E was evaluated. It was established that the Young's modulus may be calculated using: Ec = E(1 + 2kS2), where k = 1 for soft rubbers, and for disks S is a shape factor and = radius/2 X thickness. It is also shown that Young's modulus is a linear function of log(rate of strain) for both tension and compression measurements. When gellation has occurred subsequent to mixing there is an increase in Young's modulus due to loss of ethanol. When immersed in brine the elastic modulus remains approximately constant from a day to a week or longer.

Characterization of the rupture properties of denture soft lining materials.

Rupture properties of soft lining materials are characterized by their resistance to tearing. The energy necessary for their rupture depends upon rate of deformation, temperature, and conditions of storage or use. After storage in water for six months, some silicone rubber materials are no stronger than irreversible hydrocolloid materials.

Microbiological Aspects of Filth on Acryl Soft Denture Liners

Microbiological Aspects of Filth on Acryl Soft Denture Liners

A Laboratory Evaluation of the Effect of Two Surface-Wetting Treatments on Soft Denture Liners

The wettability of acrylic and silicone soft denture-liners was improved by two methods of surface treatment. They consisted of formation of a thin film of silica from the application of silicon tetrachloride, and by cross-linking the surface molecules and bombarding with hydroxyl free radicals. Softness and water sorption were monitored throughout the study.

Viscoelastic properties of soft lining materials.

Viscoelastic properties of denture soft liners were measured with a torsional pendulum apparatus. Several soft acrylic and silicone materials and one natural rubber compound were studied. Available proprietary materials exhibit a wide range of elastic moduli; soft acrylic materials have high mechanical hysteresis compared with silicone materials.

Study on a new soft denture liner of the Sofdent type.

AbstractIt has been shown that the admixture of diacetins in the capacity of a diluent in the polymerization of hydrophilic poly(ethyleneglycol methacrylate) gels improves the properties of products used as soft denture liners, especially by inhibiting the volume changes caused by swelling, and by improving the mechanical properties of gels as well as the strength of bond between the gel and the basic material of the prosthesis.

Fungus growth on tissue conditioners and soft denture liners

A preliminary report on the ability of silicone and methacrylate soft liners and tissue conditioners to sustain the growth of Candida albicans in vitro. Since both of these materials have the potential for supporting growth of C. albicans, an effective, nontoxic fungicide should be introduced into both tissue conditioners and silicone soft liners. A preliminary report on the ability of silicone and methacrylate soft liners and tissue conditioners to sustain the growth of Candida albicans in vitro. Since both of these materials have the potential for supporting growth of C. albicans, an effective, nontoxic fungicide should be introduced into both tissue conditioners and silicone soft liners.

The Use of a Soft Denture-Base Material in the Management of the Post-Radiation Denture Problem

One of the problems in treating malignant tumors about the oral cavity has been that of maintaining adequate dentition or a substitute following high doses of radiation to that area. With therapeutic doses of radiation to the salivary glands there is an induced dryness of the mouth, which is associated with or precipitates caries of any teeth remaining in the oral cavity (1). Because of this and the difficulty of removing teeth after radiation, it has been a policy in our institution to remove the teeth before radiation therapy to the oral cavity. Occasionally, following treatment we have seen sores develop when the denture has been improperly fitted or fitted too soon after completion of therapy. In these situations and in other denture-sore problems related to diabetes and other diseases, it has been observed that by introducing a soft denture liner between the methyl methacrylate dental base and the epithelium covering the alveolar ridges, the sore could be treated (2, 3). Since this observation, we have instituted a program of using the soft denture base prophylactically in the post-treatment reconstruction of the dentures. Figure 1 shows a cross section of the denture base in relation to the mucosa and bone. The mandible has the shape shown with slight flanges or ridges laterally. It is logical to see why the introduction of additional cushioning material between the hard denture base and the patient's alveolar ridge prevents trauma to the epithelium covering the ridge and effectively distributes the pressure of mastication evenly over the irradiated epithelium. In designing the soft liner it is important to make sure that it adequately covers the denture base at both the apex and the base. Soft denture liners have been tried in the past (4), but a material of permanent resiliency has not been available until recently. This material is durable, nontoxic, is dimensionally stable, odorless, tasteless, and easy to work and to mold by technics not uncommon to the dental office and laboratory. It has excellent bonding characteristics to the methyl methacrylate denture base (5). Technic (6, 7) During the fabrication of the denture it is necessary to press the acrylic denture-base material, then in a doughy state, into a two-part combination metal and dental stone flask. One half of the flask contains the denture teeth and the other half an exact stone model representation of the tissue of either the maxilla or mandible against which the denture will be seated. It is over this model that a wax layer or spacer is formed which is designed as a prototype of the eventual soft denture liner. As the acrylic dough material is pressed into the mold cavity it not only fills the cavity, but takes the contour of the wax layer covering the model of the oral denture-bearing areas.