Surface roughness and adherence of Candida albicans on soft lining materials as influenced by accelerated aging.

J Contemp Dent Pract. 2007;8(5):18-25

Authors: Tari BF, Nalbant D, Dogruman Al F, Kustimur S

AIM: Candida albicans (C. albicans) has been widely associated with the etiology of denture-related stomatitis and has been found on soft denture lining materials. The aim of this study was to examine the surface roughness and adherence of C. albicans to saliva coated and non-coated soft lining materials by subjecting them to an in vitro accelerated aging test. METHODS AND MATERIALS: Samples were prepared from three soft lining materials (Visco Gel, Ufi Gel P, Molloplast B). Surface roughness measurements and adhesion of C. albicans were examined before and after an aging process. The stimulated human whole saliva was used to assess its effect on adhesion. RESULTS: The aging process promotes the surface roughness of soft lining materials. The aging surface roughness of Visco Gel was significantly higher than Ufi Gel P and Molloplast B. No significant difference was observed between non-aged and uncoated materials, but aged and uncoated soft lining materials showed a greater adherence of C. albicans. No significant difference was observed between non-aged and saliva coated materials, but aged and saliva coated soft lining materials showed a greater adherence of C. albicans. CONCLUSIONS: Candidosis induced by C. albicans is the most common fungal infection. Awareness of susceptibility of soft lining materials to the adherence of C. albicans is an important factor in their selection. The use of soft lining materials with smooth surfaces minimizes the adherence of C. albicans.

PMID: 17618326 [PubMed - indexed for MEDLINE]

[A clinical study of the difference in the application of soft and hard relining materials for complete denture]

Shanghai Kou Qiang Yi Xue. 2003 Jun;12(3):229-31

Authors: Yang H, Wu ZP, Zhu XF

PMID: 14661341 [PubMed - indexed for MEDLINE]

Dentures and alcohol.

J Am Dent Assoc. 2003 Oct;134(10):1306, 1308; author reply 1308

Authors: Hannie EJ

PMID: 14620003 [PubMed - indexed for MEDLINE]

Effects of heart isolation, voltage-sensitive dye, and electromechanical uncoupling agents on ventricular fibrillation.

Am J Physiol Heart Circ Physiol. 2003 May;284(5):H1818-26

Authors: Qin H, Kay MW, Chattipakorn N, Redden DT, Ideker RE, Rogers JM

We tested whether the interventions typically required for optical mapping affect activation patterns during ventricular fibrillation (VF). A 21 x 24 unipolar electrode array (1.5 mm spacing) was sutured to the left ventricular epicardium of 16 anesthetized pigs, and four episodes of electrically induced VF (30-s duration) were recorded. The hearts were then rapidly excised and connected to a Langendorff perfusion apparatus. Four of the hearts were controls, in which 24 additional VF episodes were then mapped. In the remaining 12 hearts, four VF episodes were mapped after isolation, four more episodes were mapped after exposure to the voltage-sensitive dye di-4-ANEPPS, and six more episodes were mapped after exposure to the electromechanical uncoupling agents diacetyl monoxime (DAM; 20 mmol/l, n = 6) or cytochalasin D (CytoD; 10 micromol/l, n = 6). VF episodes were separated by 4 min. VF activation patterns were quantified using custom pattern analysis algorithms. From comparisons with time-corrected control data, all interventions significantly changed VF patterns. Most changes were broadly consistent with slowing and regularization due to loss of excitability. Heart isolation had the largest effect on VF patterns, followed by CytoD, DAM, and dye.

PMID: 12679330 [PubMed - indexed for MEDLINE]

Dynamic viscoelasticity of soft liners and masticatory function.

J Dent Res. 2002 Feb;81(2):123-8

Authors: Murata H, Taguchi N, Hamada T, Kawamura M, McCabe JF

Soft denture liners are used for edentulous patients to cushion functional forces. We hypothesized that the application of soft liners having viscoelastic properties would lead to the most marked improvement in masticatory function. The shear storage modulus (G'), shear loss modulus (G''), and loss tangent (tan delta) were determined for 6 materials by means of a dynamic viscoelastometer. Masticatory function of ten subjects was evaluated by measurements of maximum bite forces and chewing times and frequencies for 2 food samples, and by the use of visual analogue scales. The acrylic materials exhibited viscoelastic behavior, while the silicones exhibited elastic behavior. The improvement in masticatory function compared with hard resin was found to be in the order: acrylic permanent materials > silicone > acrylic temporary materials. The results suggest that the use of materials with higher tan delta and G' provides the most optimum masticatory function for patients requiring the provision of soft liners on their dentures.

PMID: 11827257 [PubMed - indexed for MEDLINE]

Undecylenic acid inhibits morphogenesis of Candida albicans.

Antimicrob Agents Chemother. 2000 Oct;44(10):2873-5

Authors: McLain N, Ascanio R, Baker C, Strohaver RA, Dolan JW

Resilient liners are frequently used to treat denture stomatitis, a condition often associated with Candida albicans infections. Of 10 liners tested, 2 were found to inhibit the switch from the yeast form to hyphae and a third was found to stimulate this switch. The inhibitor was determined to be undecylenic acid.

PMID: 10991877 [PubMed - indexed for MEDLINE]

Denture plaque and adherence of Candida albicans to denture-base materials in vivo and in vitro.

Crit Rev Oral Biol Med. 1999;10(1):99-116

Authors: Radford DR, Challacombe SJ, Walter JD

The aim of this paper is to review our understanding of the mechanisms and clinical significance of adhesion of C. albicans to denture-base materials in relation to denture plaque and denture-related stomatitis. Earlier reports in the literature of a 65% prevalence level of denture-related stomatitis seem to be exaggerated. More recent studies indicate that denture-related stomatitis is considerably less common, particularly in normal healthy subjects. The etiology of the condition is discussed in this review, and although much of the literature supports the view that the condition is strongly associated with C. albicans, this is not always so. In some subjects, the cause appears to be related to a non-specific plaque. This review also considers the role of denture plaque in the pathogenesis of denture-related stomatitis, the sequential development of denture plaque, and its colonization by Candida organisms. Designing controlled in vivo studies is difficult, and as a consequence, many investigators have had to resort to in vitro studies. The majority of these studies have attempted to investigate the hydrophobicity of C. albicans, relating the surface free-energy of denture-base materials, particularly acrylic resin, to that of the organism. Surprisingly little work has been directed at surface roughness and how it affects retention of organisms. Further, no attention has been paid to the properties and character of the surface, other than average surface roughness, as it affects adhesion. A comparison of results from in vitro studies on the effect on adhesion of pre-coating the surfaces of denture-base materials with saliva has produced equivocal conclusions. This is largely due to little standardization of experimental protocols between studies, particularly in the collection and handling of the saliva used. In conclusion, the review strongly supports the suggestion that adherence of C. albicans to denture-base materials in vitro is related to the hydrophobicity of the organism. The clinical significance of the observation and the mechanisms for the development and maturation of denture plaque are yet to be understood. There is a clear need for further investigation of other factors that may moderate the adhesion of organisms and subsequent colonization of denture-base materials.

PMID: 10759429 [PubMed - indexed for MEDLINE]

Facilitating the removal of tissue conditioner from the denture intaglio.

J Am Dent Assoc. 1997 Dec;128(12):1707

Authors: Dumbrigue HB

PMID: 9415770 [PubMed - indexed for MEDLINE]

Relining, rebasing partial and complete dentures.

J Am Dent Assoc. 1995 Apr;126(4):503-6

Authors: Christensen GJ

PMID: 7722112 [PubMed - indexed for MEDLINE]

Hamster cheek-pouch testing of dental soft polymers.

J Dent Res. 1991 Jun;70(6):991-6

Authors: Harsanyi BB, Foong WC, Howell RE, Hidi P, Jones DW

The hamster cheek pouch provides a suitable model system for the mucous-membrane irritation testing of dental materials. Poor retention of materials or difficulties in histopathological interpretation caused by surgical artifacts have been reported in published techniques. We describe a new "pouch-in-pouch" technique for mucous membrane irritation tests. The retention rate of polymer discs was 97% and 87% at 14 and 35 days, respectively. Clear differentiation was obtained between the tissue reaction to the test materials and the surgical procedure. Polymer discs containing dibutyltin diacetate (DBTD) or dibutyl phthalate (DBP) as plasticizer resulted in epithelial changes, including epithelial atypia, early papillomas, and areas resembling dysplasia. The potentially pre-malignant nature of these changes requires further investigation.

PMID: 2045582 [PubMed - indexed for MEDLINE]

Chemical and molecular weight analyses of prosthodontic soft polymers.

J Dent Res. 1991 May;70(5):874-9

Authors: Jones DW, Hall GC, Sutow EJ, Langman MF, Robertson KN

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.

PMID: 2022770 [PubMed - indexed for MEDLINE]

An in vivo and in vitro study of the loss of plasticizer from soft polymer-gel materials.

J Dent Res. 1991 May;70(5):870-3

Authors: Graham BS, Jones DW, Sutow EJ

Polymer-gel materials used as short-term denture soft linings are blended with plasticizers to lower the glass transition temperature (Tg). A lower Tg allows for greater polymer chain mobility, thus producing a more flexible material. The present work evaluated the loss of plasticizers due to leaching both in vivo and in vitro. Two commercial denture soft-lining materials (A and B) were tested. These were both poly(ethyl methacrylate) polymers, blended with alcohol and phthalate esters. A clinical study was conducted in which patients wore, sequentially, dentures bearing (on separate occasions) each of the two soft-polymer lining materials. The two materials A and B were randomly assigned for each of ten patients and were worn for 14 and 30 days, respectively. With one exception, patients wore dentures with both lining materials, for a total of 19 clinical evaluations. The plasticizer loss occurring during the clinical trial was determined by GC analysis from the initial and terminal day sampling of plasticizer content of the soft polymer-gel materials. The results of this analysis were compared with results obtained from an in vitro leachability study by use of sink conditions in water at 37 degrees C for the same two commercial soft polymers conducted over the same time periods of 14 and 30 days. The results indicated that a higher loss of plasticizer occurred in vivo, compared with the in vitro tests for 17 of the 19 clinical evaluations. The average plasticizer lost in vivo from material A at 14 days was 122 +/- 58 mg/g, and for material B at 30 days it was 33 +/- 27 mg/g.(ABSTRACT TRUNCATED AT 250 WORDS)

PMID: 2022769 [PubMed - indexed for MEDLINE]

The prevalence and significance of yeasts in persons wearing complete dentures with soft-lining materials.

J Dent Res. 1985 Feb;64(2):122-5

Authors: Wright PS, Clark P, Hardie JM

Fifty-three persons wearing soft-lined mandibular dentures and heat-cured acrylic-resin maxillary dentures were studied, using imprint cultures, to determine the isolation frequency and density of colonization of denture and mucosal surfaces by yeasts. Yeasts were isolated from 35 (66%) of the persons studied. Nine species of Candida and one each of Trichosporon and Saccharomyces were identified. Candida albicans, occurring either alone or together with another strain, was identified in 66% of the isolates and was associated with a higher mean density/cm2 than that of other strains. An association between the method of denture cleaning, denture hygiene, and smoking habits and the isolation of yeasts was demonstrated, but a similar association could not be demonstrated with the sex of the person, denture-wearing habits, type and condition of the soft lining, or the clinical appearance of the mandibular denture-bearing mucosa. Although yeasts are more likely to colonize soft-lining materials than the fitting surface of conventional lower dentures, their presence did not significantly affect the soft-lining material. Further, the increased isolation of yeasts on the fitting surface of the soft-lined mandibular denture was not associated with an increased incidence of inflammatory changes in the mandibular denture-bearing mucosa.

PMID: 3882794 [PubMed - indexed for MEDLINE]

Water absorption and water solubility of soft lining materials for acrylic dentures.

J Dent Res. 1983 Jun;62(6):764-8

Authors: Braden M, Wright PS

Soft lining materials undergo two processes when immersed in water. Plasticizers and other soluble materials are leached into the water, and water is absorbed by the polymer. The balance between these two processes affects both the compliance and dimensional stability of the materials.

PMID: 6574160 [PubMed - indexed for MEDLINE]

Characterization of the adhesion of soft lining materials to poly (methyl methacrylate).

J Dent Res. 1982 Aug;61(8):1002-5

Authors: Wright PS

The adhesion of nine soft lining materials to poly (methyl methacrylate) has been characterized in the laboratory using peeling tests. Applying the energy theory of fracture to an elastic film peeling from a rigid substrate, this method gives a direct measure of the work of detachment.

PMID: 7050197 [PubMed - indexed for MEDLINE]

Characterization of the rupture properties of denture soft lining materials.

J Dent Res. 1980 Mar;59(3):614-9

Authors: Wright PS

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.

PMID: 6937494 [PubMed - indexed for MEDLINE]

Viscoelastic and dynamic properties of soft liners and tissue conditioners.

J Dent Res. 1979 Aug;58(8):1801-7

Authors: Duran RL, Powers JM, Craig RG

The creep compliance and dynamic modulus of two tissue conditioners and five soft liners were determined after storage in water at 37 degrees C. Under static conditions the tissue conditioners functioned like viscous liquids, whereas the soft liners were more elastic. In general, linear viscoelasticity was not observed. Under dynamic conditions, the materials were stiffer.

PMID: 288757 [PubMed - indexed for MEDLINE]

Water sorption by a soft liner.

J Dent Res. 1977 Dec;56(12):1526

Authors: Ellis B, Lamb DJ, Al-Nakash S

PMID: 277474 [PubMed - indexed for MEDLINE]

A laboratory evaluation of the effect of two surface-wetting treatments on soft denture liners.

J Dent Res. 1977 Aug;56(8):953-9

Authors: Louka AN, Gesser HD, Kasloff Z

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.

PMID: 200638 [PubMed - indexed for MEDLINE]

Polyurethane elastomer as a possible resilient material for denture protheses: a microbiological evaluation.

J Dent Res. 1975 Sep-Oct;54(5):1039-45

Authors: Tang RY, Gonzalez JB, Roberts GD

A polyurethane elastomer was microbiologically evaluated in vitro for its potential use in resilient denture liners. Specimens were immersed in suspensions of ten selected oral microorganisms; this was followed by viable cell counts at intervals during a 16-week period. Results indicated that the polyurethane neither supported the growth of the organisms nor was it degraded.

PMID: 1058855 [PubMed - indexed for MEDLINE]

Viscoelastic properties of soft lining materials.

J Dent Res. 1972 Nov-Dec;51(6):1525-8

Authors: Braden M, Clarke RL

PMID: 4508961 [PubMed - indexed for MEDLINE]