Acrylic Strips Research Articles

Effects of dietary sugars and, saliva and serum on Candida bioflim formation on acrylic surfaces.

The effect of two dietary sugars, glucose and galactose, on biofilm formation of the oral fungal pathogen Candida on denture acrylic strips coated with saliva and serum pellicles was examined in vitro using Candida albicans (3 isolates), C. glabrata (2 isolates) and C. tropicalis (2 isolates). The degree of biofilm activity was affected by both the dietary sugar and the nature of the pellicle (ANOVA, p < 0.01). With most isolates the glucose grown yeasts demonstrated significantly more bioflim activity than the galactose grown fungi, in the presence of pellicles (ANOVA, p < 0.01 or P < 0.01). In contrast, one isolate of galactose-grown yeast elicited significantly higher biofilm activity than glucose-grown yeasts on the control strips (ANOVA, p < 0.01). Taken together, these results imply that a saliva or a serum pellicle, and the carbon source in the environment, act a complex manner modulating Candida bioflim formation.

The Role of Saliva and Serum inCandida albicansBiofllm Formation on Denture Acrylic Surfaces

The long term effect of either a salivary or a serum pellicle on Candida albicans biofilm formation on denture acrylic surfaces was investigated both by quantifying the ATP (adenosine triphosphate) content of the resultant biofilms and by scanning electron microscopy. When the biofilm formation on saliva-coated acrylic strips was examined, the yeasts initially colonised this surface at a slower rate than the controls although with increasing incubation time, at 72 h, the ATP content was almost ten-fold higher than the protein-free control strips. Ultrastructural studies revealed this to be due to cell aggregation and hyphal emergence, phenomena not observed in the controls. As compared with the control strips, biofilm activity of the serum-coated strips was almost 100-fold greater within 48 h incubation, and scanning electron microscopy revealed multilayer blastospore-blastospore co-adhesion, germ tube, hyphal and pseudohyphal emergence and blastospore-hyphal coadherence. Further immunocytochemical observation revealed that concanavalin-A binding material and fibronectin were involved in biofilm formation on both saliva and serum coated specimens and, in addition, mannan-binding protein and protein-A binding material also contributed to the biofilm formation on serum coated specimens. Keywords: Candida albicans , biofilm, saliva, serum, fibronectin, mannan-binding protein.

The effect of oral commensal bacteria on candidal adhesion to denture acrylic surfaces. An in vitro study.

The effect of four different species of oral bacteria (Streptococci (X 2); Escherichia; Porphyromonas) on the adhesion of Candida albicans and Candida krusei to denture acrylic surfaces was studied using a previously described in vitro adhesion assay. Clear acrylic strips immersed in known concentrations of bacterial suspensions and incubated for 45 min to 1 h, at 37 degrees C, were transferred to yeast suspensions of known concentrations and incubated for a similar period, and the adherent yeasts were quantified using an image analysis system. Pre-exposure to different bacterial concentrations resulted in suppression of candidal adhesion to varying degrees. Of three selected concentrations, exposure to the highest bacterial concentration (10(6) organisms/ml) resulted in a consistent reduction in candidal adhesion, except for E. coli-C. albicans and S. salivarius-C. albicans combinations. Candidal adhesion was significantly reduced on pre-exposure to S. sanguis and P. gingivalis, but not E. coli. There were also significant differences in relative adhesion between C. albicans and C. krusei. Taken together, these results indicate that the adhesion of yeasts to acrylic strips is modulated both by the quantity and the quality of pre-existing bacterial flora on acrylic surfaces.

The effects of antimicrobial acrylic strips on the subgingival microflora in chronic periodontitis

This study investigated the effects of root planing and/or the placement of acrylic strips containing chlorhexidine, metronidazole or tetracycline on the composition and antimicrobial susceptibility of the subgingival flora in chronic periodontitis. 101 periodontal pockets from 73 patients were entered into 6 treatment groups which were, chlorhexidine, metronidazole or tetracycline strips, root planing, root planing followed by metronidazole strips and a control, no treatment group. Total anaerobic counts and anaerobe/aerobe ratios were estimated from samples taken before treatment and 1, 2, 4, 8 and 12 weeks after treatment. In addition, a more detailed analysis of the effects of the treatments on the subgingival flora was carried out on 12 pockets in 12 patients. Tetracycline strips, metronidazole strips and root planing and metronidazole strips were more effective than chlorhexidine strips in causing reductions in total anaerobic count and anaerobe/aerobe ratio. However, the changes in microbial parameters rebounded to approach baseline levels 4 weeks after treatment. Chlorhexidine caused no detectable changes in the composition of the subgingival microflora, while metronidazole had a variable effect. Tetracycline appeared to effect major shifts in the composition of the microflora of treated pockets but caused a marked selection of tetracycline-resistant organisms.

Evaluation of acrylic strips containing amoxycillin with clavulanic acid for local drug delivery

The in vitro release of amoxycillin with clavulanic acid from acrylic strips at initial concentrations of 30,40 and 50 per cent w/w was monitored using a double-beam ultraviolet spectrophotometer and compared with release of tetracycline hydrochloride. Highest levels of the antibacterial agents were released during the first 24 h period. Therapeutic levels of the drugs continued to be released during the subsequent 9 day period and were shown to be biologically active. Furthermore, for amoxycillin with clavulanic acid, an initial concentration of 40 per cent gave the highest level of release on day 10; while, for tetracycline, 50 per cent provided the highest level of release. Local application of 40 per cent amoxycillin with clavulanic acid incorporated into acrylic strips placed in periodontal pockets in patients with established periodontitis produced a marked change in the subgingival microflora as monitored by dark-field microscopy and cultural techniques. These changes in the subgingival flora were concomitant with elimination of bleeding on probing at the treated sites and were still evident 3 weeks after removal of the acrylic strips. The sensitivity of Bacteroides gingivalis (syn. Porphyromonas gingivalis) and Bacteroides intermedius (syn. Prevotella intermedia) isolated before and after treatment to amoxycillin with clavulanic acid remained unchanged.

In Vitro Release of Doxycycline From Bioabsorbable Materials and Acrylic Strips

Treatment of marginal periodontitis may include use of local antibiotics. In the present in vitro study the bioabsorbable materials Surgicel, Tissell, and CollaCote and acrylic strips were examined for release of doxycycline into liquids and residual antibacterial activity of the materials. Pieces of material were incubated in 1 ml of water or human serum which was exchanged every day for 9 days. The concentration of doxycycline in the liquids was measured spectrophotometrically while the residual antibacterial activity of the materials was determined microbiologically. Surgicel constantly showed very high concentrations and level of residual activity. The acrylic strip and CollaCote decreased to low levels of both concentration and residual activity in a few days. Tissell was intermediate with a continuous decrease in concentration but rather high level of residual activity throughout the study. In serum the acrylic strip was partly dissolved and Surgicel was totally dissolved after 2 days. Left undisturbed in serum Surgicel was not dissolved for 2 weeks. These results indicate that Surgicel and Tissel may be capable of prolonged release of doxycycline in vivo.

The use of antimicrobial acrylic strips in the non-surgical management of chronic periodontitis

Evidence to date has demonstrated the potential value of acrylic strips to deliver antimicrobial compounds into periodontal pockets. The present study was designed to evaluate further the therapeutic effect of anti-microbial acrylic strips in the management of chronic periodontitis. A total of 101 pockets in 69 patients were randomly treated with (1) chlorhexidine strips, (2) metronidazole strips, (3) tetracycline strips, (4) root planing, and (5) combined root planing and metronidazole strips. Immediately before and after treatment clinical measurements of disease were recorded over a three-month period. For all treatment groups significant improvements in clinical parameters were seen compared to control untreated sites but the most effective treatment was combined root planing and metronidazole and the least effective chlorhexidine. Although not significant, combined root planing and metronidazole also appeared to produce some adjunctive effects on clinical parameters compared to root planing alone. Antimicrobial acrylic strips appear useful treatments for chronic periodontitis, but should be used primarily as an adjunct to conventional root planing.

The importance of water temperature in denture cleaning procedures

Laboratory tests have been carried out on sample strips of an acrylic denture-base material for a range of temperatures in excess of that recommended by the manufacturers of a leading proprietary denture cleaning agent. The results show that water temperatures of 80'C and above have adverse effects on the visual appearance of correctly cured acrylic strips, producing a bleached or whitened appearance. In these samples, changes in the physical properties were seen as a breakdown of the surface layer, a reduction in light transmission and transverse bend strength, and an increase in surface hardness. The conclusion from this study is that the temperature of the water used by patients in their cleaning procedures is critical, and that the effects observed might be the result of a thermal shock experienced on immersion with microcrazing of the surface layer.

Denture bleaching: a laboratory simulation of patients' cleaning procedures

Laboratory tests which simulate the cleaning procedures used by patients presenting with bleached or whitened dentures have been carried out on specimen strips of acrylic denture-base material. The results show that it is possible to produce, on correctly cured acrylic strips, this bleached or whitened appearance, but only in those samples subjected to very hot water, with or without the denture cleaning agent. In these samples, changes in the physical properties were indicated by a breakdown of the surface layer, a reduction in light transmission and a reduction in transverse bend strength. The conclusion from this study is that the bleaching of the denture-base material is, in reality, a surface opacification effect produced by the use of boiling water, irrespective of the presence of the proprietary denture cleaning agent.

Effect of saliva and serum on the adherence of Candida species to chlorhexidine-treated denture acrylic.

The effect of saliva and serum on the adherence of five strains of Candida albicans and one each of C. tropicalis and C. glabrata to chlorhexidine-pretreated acrylic was measured in vitro. A four-fold dilution of saliva or serum significantly inactivated the fungicidal effect of chlorhexidine gluconate. Pretreatment of the acrylic with unstimulated mixed saliva for 30 min led to a reduced adherence for all the Candida strains tested, whilst a similar pretreatment with serum slightly increased adhesion. Moreover treatment of saliva- or serum-coated acrylic with chlorhexidine gluconate 2% reduced adherence by between 19% and 86%. The inhibition of yeast adherence by chlorhexidine persisted for up to 19 days after the exposure of the acrylic strips to the disinfectant.

Extracellular polymer of Candida albicans: isolation, analysis and role in adhesion.

Extracellular polymeric material (EP) was isolated from culture supernatants of Candida albicans grown on carbon sources (50 mM-glucose, 500 mM-sucrose or 500 mM-galactose) known to promote yeast adhesion to different extents. Galactose-grown yeasts, which are the most adherent, produced more EP than sucrose-grown organisms, particularly after incubation for 5 d, while glucose-grown yeasts (the least adherent) gave the lowest yield. EP produced on all three carbon sources was of similar composition and contained carbohydrate (65 to 82%; mannose with some glucose), protein (7%), phosphorus (0.5%) and glucosamine (1.5%). Serological studies indicated that these EP preparations were immunologically identical but that galactose-grown yeasts had more antigenic determinants than sucrose-grown organisms while glucose-grown yeasts had the fewest determinants. Antigenic differences were apparent between EP preparations of some strains of C. albicans. Pretreatment of acrylic strips with EP to form a polymeric coating promoted yeast adhesion to the acrylic surface, but similar pretreatment of buccal epithelial cells with EP inhibited subsequent yeast adhesion. These results indicate that EP originates from the cell surface of C. albicans and that it contains the surface component(s), probably mannoprotein in nature, responsible for yeast adhesion.

Factors affecting the in-vitro adherence of Candida albicans to acrylic surfaces

The fitting surface of the upper denture is the main reservoir of yeasts in patients with chronic atrophic candidosis. Because little is known about the adhesion of Candida albicans to acrylic surfaces, an in-vitro technique was used to investigate the effect of sucrose, glucose, lactose, xylitol, mixed and parotid saliva, serum and Streptococcus salivarius on adhesion. Enhancement of candidal adhesion was seen on serum-coated acrylic strips and by yeasts incubated in sucrose, glucose and a dialysate of Strep, salivarius. Pre-coating acrylic strips with mixed saliva, 2 per cent chlorhexidine and Strep, salivarius reduced adhesion, while pre-coating strips with 0.2 per cent chlorhexidine and parotid saliva or pre-incubating yeasts in lactose and xylitol had no significant effect on adhesion. This study suggests that the factors involved in the adhesion of C. albicans to acrylic surfaces are complex, and that they may play an important role in the aetiology of chronic atrophic candidosis.

An in-vitro study of the adherence of Candida albicans to acrylic surfaces

An in-vitro system was designed to assess quantitatively the adhesion of Candida albicans to acrylic surfaces. Clear acrylic strips were placed in yeast suspensions and the number of yeasts attached per unit area was counted microscopically. A significant positive correlation was found between the concentrations of yeast in the suspension and their adhesion to the acrylic strips. Pre-incubation with sucrose greatly increased the adherence of C. albicans to the acrylic strips, and there was a direct linear increase in adhesion with increasing sucrose concentrations. The enhanced adhesion of yeasts induced by sucrose disappeared when Candida were heat-killed prior to incubation in a sucrose-containing medium. These observations, together with electron-microscopic studies, suggest that an extracellular metabolic product of the organism could be responsible for the enhanced adhesion associated with sucrose. The system can be effectively used to study the influence of other intra-oral factors on the adhesion of C. albicans to acrylic surfaces.