Tissue Conditioner Research Articles

Soft Denture Liners and Tissue Conditioners

Soft Denture Liners and Tissue Conditioners

Candida albicans growth on thermal cycled materials for maxillofacial prostheses in vitro.

In the present study, the growth of a single isolate of Candida albicans on saliva-, serum-coated or protein free (uncoated), thermocycled (4-70 degrees C for 1 min, respectively; 0, 1000 and 10 000 times) 15 commercial maxillofacial materials was investigated, by monitoring pH changes in growth media. The inhibitory effect of the tissue conditioners on fungal growth was analysed using three parameters viz: (i) delay in the onset of the rapid decline in pH (ii) reduction in the rate of pH change and (iii) the pH minima reached. In the case of control materials (non-thermocycled and uncoated), significant antifungal effect was observed with two products. However, the antifungal effect of the materials was significantly reduced both by thermal cycling (Analysis of covariance [ANOVA]; P < 0.01) and a layer of protein coating (saliva, P < 0.05; serum, P < 0.01). When the interrelation between three parameters of fungal growth and the surface hydrophobicity of the materials were analysed, minimum pH of fungal growth on 10 000-thermocycled materials correlated well with the contact angles of the materials (Student t-test, P < 0.01), suggesting that thermocycling process reduced the unpolymerized components of the materials which showed the antifungal effects, resulted in that the cell growth depends on the surface hydrophobicity of the specimens. These results, taken together, suggest that the ageing of the materials and the biological fluids of the host enhanced the fungal growth on maxillofacial materials.

The effect of particle size on the gelation of tissue conditioners

Tissue conditioner materials comprise a methacrylate polymer powder, usually poly(ethyl methacrylate) (PEM), and a plasticiser that also contains ethanol. The aim of this study was to investigate the effect of ball milling the PEM on gelation time. PEM was used as received and after ball milling for 2, 4, 8 and 16 h. Particle size was measured in each case and gelation time at 37°C when mixed with butyl phthalyl butyl glycollate (BPBG). Gelation time reduced with increasing milling time of the powder, however it was found that increase in the fines initially had a more significant affect than overall reduction in average particle size. The gelation time of unmilled and 16 h milled PEM were also measured when mixed with BPBG and various levels of ethanol. Unmilled PEM with 4% ethanol had a gelation time of 13.5±2.0 min compared to 5.5±1.0 min for the 16 h milled PEM which was similar to that for the commercial material, Viscogel™ (6.0±1.0 min). Ball milling the PEM reduces the level of ethanol required to produce a clinically acceptable gelation time.

One-year prospective evaluation of the early loading of unsplinted conical Brånemark fixtures with mandibular overdentures immediately following surgery.

Prospective evaluation of the early loading of unsplinted Brånemark implants with mandibular overdentures opposing conventional dentures is not evident in the implant-related literature. To clinically evaluate progressive and early loading of 20 unsplinted conical Brånemark implants in edentulous mandibles with overdentures. Ten edentulous patients all had two conical Brånemark implants placed in the anterior mandible with mandatory primary stability with bicortical anchorage. Ball abutment connection was performed simultaneously. Previously constructed conventional mandibular dentures were temporarily relined with tissue conditioner postoperatively and worn with moderation for the first 2 weeks to allow progressive loading. Early loading of the implants followed after 2 weeks, with inclusion of the respective matrices in the mandibular dentures, using a definitive reline procedure. All patients successfully functioned with their mandibular implant overdentures from 2 to 52 weeks postoperatively. Mean marginal bone loss was within established criteria for success: 0.22 mm (SD = 0.48 mm) mesially and 0.30 mm (SD = 0.39 mm) distally on the conical implants. Mobility tests using the Periotest instrument became more negative, although not at statistically significant levels. Difficulties in the management of the peri-implant mucosa between surgery and loading at 2 weeks were observed in 40% of the patients. These preliminary 1-year results show that successful early loading of unsplinted conical Brånemark implants with mandibular overdentures is possible.

Neutral zone approach for denture fabrication for a partial glossectomy patient: A clinical report

J Prosthet Dent 2000;84:390-3.

粘膜調整による義歯床下粘膜の生理的回復と被圧変位量の経日的変化

The purpose of this study was to investigate the physiological recovery for distorted tissues with tissue conditioners. The changes of pressure-displacement in the denture-supporting tissues were measured using a new device with strain gauges placed on the cantilever during tissue conditioning.To deform the underlying soft tissues, experimental dentures were fitted to six subjects with missing maxillary or mandibular first molar. Recovery of the distorted tissues was performed by one of two methods. In the first method, experimental dentures were removed from the mouth. In the second, a tissue conditioning treatment was used. Then the recovery effectiveness of the two methods was compared with measurement of pressure-displacement.The conclusions were as follows:1. By the calibration tests using the new device, it was confirmed that pressure-displacement could be accurately measured.2. The effectiveness of tissue conditioning could be quantitatively estimated using the new device.3. Distorted tissues were recovered with tissue conditioning, and the pressure-displacement became uniform.4. There were no significant differences (p>0.05) of pressure-displacement between the tissue conditioning and removal of the experimental dentures.

Efficacy of antifungal agents in tissue conditioners in treating candidiasis.

Chronic atrophic candidiasis is prevalent in up to 72% of institutionalized geriatric populations and is causally associated with Candida albicans. Topical antifungal treatments are difficult to implement in some geriatric patients due to cognitive impairment, reduced motor dexterity and memory loss. This in vitro study incorporated antifungal agents into tissue conditioners to investigate the effectiveness of this method of drug delivery. Combinations of nystatin, fluconazole, itraconazole and Coe Soft, Viscogel, Fitt were tested at 1, 3, 5, 7, 9 and 11 wt/wt%, with and without sterilized saliva. 6 mm diameter cores were punched in Sabouraud plates pre-grown with standardized C. albicans. Antifungal agents plus tissue conditioner mixtures were injected into each core. Inhibition diameters were measured for 14 days. Cores with only tissue conditioners acted as negative control and showed no significant inhibition activity (ANOVA, p > 0.05). Peak activity was between 65 to 89 hours; followed by a plateau. Itraconazole had greater fungicidal activity than fluconazole; while nystatin was found to have the least fungicidal activity (ANOVA, p < 0.05). The most effective concentration for nearly all combinations was 5% wt/wt (ANOVA, p < 0.05). Specimens with saliva showed greater antifungal activity than those without (t-test, p < 0.001). Itraconazole altered the physical properties of Viscogel hence this combination is not recommended for clinical use. The treatment of chronic atrophic candidiasis by incorporation of antifungal drugs into tissue conditioners is efficacious. 5% wt/wt itraconazole mixed with Coe Soft or Fitt is recommended for clinical study where compliance of patient or care giver cannot be relied upon. Peak antifungal activity at 3 days suggests that mixtures prepared for clinical study may be replaced soon after this time for maximum effectiveness.

Dynamic viscoelastic properties of antimicrobial tissue conditioners containing silver–zeolite

Objectives: The purpose of this study was to determine the effects of including the antimicrobial silver–zeolite (SZ) on the dynamic viscoelastic properties of various tissue conditioners. Methods: The dynamic viscoelastic properties of five commercially available tissue conditioners: Visco-gel (VG), GC Soft-Liner (SL), FITT (FT), SR-Ivoseal (IV) and Shofu Tissue Conditioner (TC) containing SZ were evaluated after 1 and 28 days of water- and artificial saliva immersions with the use of complex modulus and loss tangent parameters. Values for these two parameters for each tissue conditioner were statistically analyzed by one- and two-way ANOVA and Bonferroni’s test. Results: Complex modulus and loss tangent values of TC were not significantly different among specimens containing 0, 2, 5 and 10 wt.%-SZ, respectively. In FT and TC containing 2 wt.%-SZ, these values were not significantly different between 1 and 28 days in both water- and saliva immersions. Conclusion: The results suggest that incorporating SZ does not affect TC’s inherent dynamic viscoelastic properties, while the other tissue conditioners investigated may be found to have changed viscoelastic properties as a consequence of the inclusion of SZ.

市販ティッシュコンディショナーの組成と流動特性

In this study, the relationship between the composition and the flow properties of three commercial tissue conditioners was investigated. Analysis of the composition was chiefly done by infrared spectroscopy (IR). As for the liquid, plasticizer was qualitatively determined and the content of alcohol was measured by distillation. The characteristics of polymer powders were obtained by means of gel permeation chromatography (GPC), particle size analyzer and SEM. As for the flow property, the apparent viscosity of a mixture of liquid and powder was measured by a cone and plate rotational viscometer.As a result, the liquid was a mixture of a phthalic ester plasticizer (dibutyl phthalate) with up to 13% ethyl alcohol. The polymer powders generally consisted of polyethyl methacrylate (PEMA), but one was a blend of PEMA and polyisobutyl methacrylate (iso-PBMA).The viscosities of mixtures were found to increase rapidly with an increase in the ethyl alcohol content, and an increase in temperature. Further, the viscosity curve of the tissue conditioner, of which the powder was a blend of PEMA and iso-PBMA, showed characteristic behavior. Thus it was suggested that the flow property of the tissue conditioner was affected by the molecular structure of the polymer powder.

Viscoelastic properties of tissue conditioners--influence of molecular weight of polymer powders and powder/liquid ratio and the clinical implications.

The effect of the molecular weight of polymer powders and the polymer powder/liquid ratio on the viscoelastic properties after gelation of tissue conditioners was studied by means of a stress relaxation test. The results are summarized as follows. The lower-molecular-weight polymer powders produced the larger flow after gelation especially at long times. The use of a lower powder/liquid ratio produced a greater flow after gelation at both short times and long times. The difference in the molecular weight of polymer powders and the powder/liquid ratio was found to have no influence on changes in viscoelastic properties with the passage of time. It would be possible to control the viscoelastic properties of tissue conditioners suitable for each clinical purpose by making variations in composition and structure.

Rheology of tissue conditioners

Statement of Problem. Tissue conditioners can be used to condition abused tissues, record functional impressions, make temporary relinings, and for other clinical applications, mainly because of their specific viscoelasticity. However, little information is available on the rheology of the materials, manipulation, and suitability for various clinical applications. Purpose. This study evaluated the gelation times, the viscoelastic properties after gelation of tissue conditioners, and the influence of the powder/liquid (P/L) ratio. Material and Methods. Ten tissue conditioners were used and gelation times were obtained with an oscillating rheometer. A series of stress relaxation tests were also conducted to evaluate the viscoelastic properties after gelation and the changes with the passage of time by means of Maxwell model analogies. Results. Significant differences were found in the gelation times and flow properties after gelation among the materials mixed with the P/L ratios recommended by the manufacturers. The flow properties tended to increase with time of storage. Large differences in the limits of the clinically acceptable P/L ratios and the adjustable limits of elasticity and viscosity by altering P/L ratios were found among the materials. Conclusions. The results suggested that each material should be selected according to each clinical purpose because of the wide ranges of viscoelastic properties and changes in viscoelasticity with time among the materials. Furthermore, gelation times and the viscoelastic properties after gelation can be controlled to improve handling and suit various applications by altering the P/L ratios within the acceptable limits. (J Prosthet Dent 1998;79:188-99.)

In vivo and in vitro study of fungal presence and growth on three tissue conditioning materials on implant supported complete denture wearers.

In this study three type of tissue conditioning materials were used in vitro and in vivo to investigate the presence and growth of Candida albicans, considered to be the pathogenic member of the genus. In vitro test results of different tissue conditioners showed that they have a tendency to have an inhibiting effect on C. albicans at the third day of incubation. For the in vivo tests tissue conditioners were placed in existing maxillary prosthesis of 21 patients who had been treated with endosseous dental implants (seven in each group). The results showed that yeast forms were observed after 3 days in two patients' dentures which were relined with Fitt. Yeasts forms were also seen in three patients' dentures after 6 days, two of them relined with Fixo-gel and the other one relined with Visco-gel. The hyphal form of Candida was seen in four patients' dentures, relined with Fitt, and also in three patients' dentures, relined with Fixo-gel and Visco-gel.

全部床義歯の製作過程におけるＰｉｅｚｏｇｒａｐｈｙの適用 印象材の検討

Piezography used mainly within France and Spain is one of the functional approaches to obtain the proper denture space in complete and partial dentures. The purpose of this study was to find impression materials suitable for Piezography. Five subjects and five operators (mean age: 27.0±1.5 years) were selected for the study. Eleven kinds of commercially available soft impression materials were examined by using Visual Analog Scale (VAS) on six items, irritation to oral soft tissues, operability, aptness to pronounce and to hear words, hardening time, and surface smoothness.As a result, FITT (Kerr Co.) used in the original Piezography was the best impression material. Tissue Conditioner (Shofu Inc.) and Evatouch H-type (Neo Dental Chemical Products Co.) also obtained high evaluation among impression materials tested in this study. In consideration of economic efficiency, it was suggested that Tissue Conditioner was the best impression material for Piezography in Japan.

FACILITATING THE REMOVAL OF TISSUE CONDITIONER FROM THE DENTURE INTAGLIO

FACILITATING THE REMOVAL OF TISSUE CONDITIONER FROM THE DENTURE INTAGLIO

Prolonged antimicrobial effect of tissue conditioners containing silver-zeolite

Objectives: The purpose of this study was to elucidate the in vitro antimicrobial effect of tissue conditioners containing silver-zeolite on Candida albicans and nosocomial respiratory infection-causing bacteria, Staphylococcus aureus and Pseudomonas aeruginosa. Methods: Five commercially available tissue conditioners were selected: Visco-gel (VG), GC Soft-Liner (SL), Fitt (FT), SR-Ivoseal (IV) and Shofu Tissue Conditioner (TC). Samples, 10 × 10 × 2.5 mm in size, contained silver-zeolite (SZ sample) and no SZ (N sample). The antimicrobial effects of these two samples were evaluated as a percentage of viable cells (CFU) in a microbial suspension (100 μl) in phosphate-buffered saline with or without immersion in artificial saliva for four weeks. The borderline of the antimicrobial effect was determined at 0.1% viable cells. Results: With the SZ samples, all tested microbes were killed under both conditions of no immersion and immersion in saliva. In non-immersed N samples, however, no cells of C. albicans (except with VG) and S. aureus survived, whereas the percentage of viable cells of P. aeruginosa was similar to that found in the control. However, with immersion in saliva, viable cells of C. albicans in some N samples (VG, SL and TC) increased compared with non-immersion samples by more than 0.1%. Conclusion: Tissue conditioners containing SZ have been shown to have antimicrobial effects for four weeks on C. albicans and nosocomial respiratory infection-causing bacteria in saliva in vitro.

Effects of salivary or serum pellicles on the Candida albicans growth and biofilm formation on soft lining materials in vitro

summary The effects of salivary or serum pellicle on Candida albicans growth, biofilm formation and cavitation on the soft lining materials were examined. Both saliva and serum pellicles reduced the antifungal effects of soft liners. The fungal biofilm formation on these materials varied depending upon both the materials tested and protein‐coats, and the pellicles which significantly enhanced the biofilm formation. Similarly, the pellicles enhanced the firm colonization and hyphal invasion of the yeasts on the specimens, although the cavitation appeared to be regulated by the plasticizer used. These results suggest that the interactions between proteinaceous pellicle, tissue conditioners and fungi are complex. They also suggest that denture pellicles facilitate fungal plaque formation onto soft lining materials through several mechanisms such as reduction of the antifungal effects of soft liners, facilitation of biofilm formation, firm colonization and hyphal invasion. In addition, the composition of the materials is also involved in the susceptibility to the fungi.

Effects of salivary or serum pellicles on the Candida albicans growth and biofilm formation on soft lining materials in vitro.

The effects of salivary or serum pellicle on Candida albicans growth, biofilm formation and cavitation on the soft lining materials were examined. Both saliva and serum pellicles reduced the antifungal effects of soft liners. The fungal biofilm formation on these materials varied depending upon both the materials tested and protein-coats, and the pellicles which significantly enhanced the biofilm formation. Similarly, the pellicles enhanced the firm colonization and hyphal invasion of the yeasts on the specimens, although the cavitation appeared to be regulated by the plasticizer used. These results suggest that the interactions between proteinaceous pellicle, tissue conditioners and fungi are complex. They also suggest that denture pellicles facilitate fungal plaque formation onto soft lining materials through several mechanisms such as reduction of the antifungal effects of soft liners, facilitation of biofilm formation, firm colonization and hyphal invasion. In addition, the composition of the materials is also involved in the susceptibility to the fungi.

Antifungal effect of zeolite‐incorporated tissue conditioner against Candida albicans growth and/or acid production

summary A new antimicrobial material, Ag‐zeolite (Zeomic°), was combined with a commercial tissue conditioner (GC‐Soft Liner (GC); 1–5%) and, through monitoring the pH of the growth medium, examined for effects on the in vitro growth and/or acid production of Candida albicans on protein‐free and saliva‐coated specimens. The effect of incorporation of this agent on the physical property of the lining material was also examined according to the ISO penetration test. Comparison studies were carried out using GC, Coe Comfort (CC) or undecylenate combined GC (1–5%) specimens. Although the pH changes in the media varied depending upon the materials on which the Candida was grown, reverse sigmoidal pH curves were observed with most samples. As compared with GC, the soft lining materials showed, to some extent, an inhibitory effect on the acid production and/or the growth of C. albicans. These inhibitory effects consisted of a delay in the onset of rapid pH decline, decreases in the rate of pH change and increases in minimum pH. In most cases, the inhibitory effects of test specimens were dose‐dependent, and zeolite specimens showed a significantly higher antifungal effect, followed by CC and undecylenate‐combined GC; GC showed the least antifungal effect. The inhibitory effects of these materials on fungal growth were decreased by the presence of a saliva‐coat, particularly with zeolite specimens and CC. However, four of eight 5%‐Zeomic° specimens still exhibited perfect growth inhibition in the presence of the salivary pellicle. Furthermore, test specimens containing 2–5% Zeomic° showed a significantly greater effect on the delay in rapid decline of pH, as compared with the other specimens examined. In addition, the significantly higher minimum pH was observed where the yeasts were grown on 4%‐ and 5%‐Zeomic° specimens. The physical properties of all the test specimens conformed with the ISO standard as examined by penetration test. These results taken together suggest that an antimicrobial zeolite‐combined tissue conditioner would be a potential aid in denture plaque control.

補綴的処置によって縮小したＤｅｎｔｕｒｅ ｆｉｂｒｏｍａ様の増殖性病変の１例

Clinical examination of a partially edentulous 66-year-old male revealed a large asymptomatic denture fibroma-like hyperplasia in the junction of the floor of the mouth and the posterior alveolar ridge on the right side of the oral cavity which was arbitrarily named a fibrosis. A chord of gingival and mucosal tissue was found in the same area on the left side.The fibrosis was 38mm in length, 7mm in width, and 8mm in height.As a consequence of the loss of posterior mandibular occlusal support, the right upper molars over-erupted and the third molar was in contact with the corresponding inferior alveolar ridge.An immediate partial denture was made and lined with tissue conditioner in the area corresponding to the fibrosis. This denture was designed to prevent the mechanical stimulus of chewing the fibrosis. The size of the fibrosis reduced gradually, and denture base adjustment and linings were made respectively. The fibrosis became a chord of tissue similar to the one on the left side and not shown any apparent change in a 5-month period.It was thought that the chronic mechanical stimulation of masticatory function played an important role in the development of the fibrosis.

Effect of composition on the gelation of tissue conditioners

Tissue conditioners comprise poly(ethyl methacrylate) powder (or related copolymer) and a liquid containing a plasticizer and ethanol. Gelation times for two butyl/ethyl copolymers and one poly(ethyl methacrylate) polymer with buty phthalyl butyl glycollate or di-2-ethyl hexyl maleate and varying amounts of ethanol have been measured in the range 20–40 °C. The proprietary material “Viscogel” was used as a standard. Results were plotted according to the Arrhenius equation enabling activation energies to be determined. Values for activation energies ranged from 55 to 110 K J mol −1 K −1. The 60/ 40 butyl/ethyl methacrylate copolymer gave the lowest values and those containing poly(ethyl methacrylate) the highest.