Denture Disinfection Research Articles

Use of microwave energy to disinfect a long-term soft lining material contaminated with Candida albicans or Staphylococcus aureus

Statement of problem. Soft lining materials have been found to be more susceptible to microbial adhesion than acrylic resin base materials. Denture hygiene is essential to maintain the serviceability of the denture, and microwave energy has been suggested for denture disinfection. Purpose. The purpose of this study was to determine the effectiveness of microwave energy in the disinfection of a long-term soft lining material. Material and methods. A long-term soft lining material was contaminated with known microorganisms and the reduction of organism counts after test disinfection regimes calculated. The disinfection regimes were microwaving for 5 minutes, leaving dry overnight, and soaking overnight in a dilute sodium hypochlorite solution. The test microorganisms were Candida albicans or Staphylococcus aureus . Results. For both organisms, soaking in sodium hypochlorite reduced the number of viable adherent microorganisms recovered significantly more than exposure to microwave energy, which led to greater reduction than leaving the lining material dry overnight ( p < 0.001, Wilcoxon nonparametric signed rank test). Conclusion. With reference to the tested microorganisms, disinfection of Molloplast-b soft lining material in dilute sodium hypochlorite solution proved to be more effective than exposure to microwave energy, which in turn was more effective than leaving the lining dry overnight. (J Prosthet Dent 1998;79:454-8.)

Disinfection of removable dentures using ozone.

Over time, removable dentures tend to become unsanitary and emit unpleasant odors, and oral mucosa sometimes becomes inflamed or denture stomatitis is caused by denture plaque. Recently, various cleaning products designed to keep removable dentures sanitary have appeared on the market. It is known that denture plaque is mainly composed of Candida albicans (C. albicans), and that ozone seems to inhibit these micro-organisms. Accordingly, a denture cleaner using ozone bubbles (ozone concentration of about 10 ppm) was considered as clinically appropriate because of its strong disinfecting and deodorizing power, and high biological safeness. The effectiveness of this cleaner against C. albicans was investigated using. Results showed that C. albicans decreased to about 1/10 after 30 min and to 1/10(3) after 60 min.

Practical denture disinfection

Dental laboratory personel are at risk of contracting infections from dental prostheses that have not been properly disinfected. A 4% chlorhexidine scrub for 15 seconds followed by a 3-minute contact time with a chlorine dioxide solution was effective in disinfecting contaminated dentures. Chair-side disinfectinn of dental prostheses before laboratory procedures is the key to keeping microbial contamination out of the dental laboratory.

Effects of laboratory disinfecting agents on color stability of denture acrylic resins

This study determined the effects of chemical disinfecting agents on denture acrylic resins. Tested resins included the products CH Lucitone, Triad VLC, and Truliner. The disinfecting agents were sodium hypochlorite, Exspor, Cidex, and Wescodyne-D. Acrylic resin samples were placed in the various disinfecting agents and then evaluated for color changes at time intervals ranging from 15 minutes to 72 hours. No observable color change of any acrylic resin was seen before 2 hours. Both 1% sodium hypochlorite and 2% Cidex disinfectants produced the least discoloration of the acrylic resins, and Wescodyne-D disinfectant produced the most acrylic resin discoloration. Truliner resin discolored more than Triad VLC resin, and both underwent more color change than CH Lucitone resin. If manufacturers' recommended disinfecting times are followed, clinical and laboratory disinfection of acrylic resin dentures should cause no observable color change.

Etiology, pathogenesis, therapy, and prophylaxis of oral yeast infections

Etiologic factors in oral candidosis are immature antimicrobial host defenses, acquired suppression of immune defense mechanisms (AIDS, immunosuppressive or radiation therapy), or changes of the environmental conditions of the oral cavity (antibiotics, dentures, epithelial changes). After colonization and adhesion of Candida to the epithelial surface the subsequent mucosal lesion is due to tissue destruction by potent proteolytic enzymes or toxins and an inflammatory response to Candida antigens. Topical antimycotic treatment with nystatin, amphotericin B, or miconazole is important especially to prevent spread of the infection. Chronic Candida infections require long-term antifungal therapy, and patient compliance may be difficult to obtain. In denture stomatitis colonization of the fitting denture surface by Candida should be controlled by, for example, using a chlorhexidine solution as a denture disinfectant. However, recurrences are frequent if the local or the systemic predisposing conditions are not corrected. Fluconazole, a new bis-triazole, may be important for long-term treatment of immunocompromised patients.

ホルマリン・クレゾール製剤の殺菌作用 : 細胞毒性ならびに局所作用の比較検討

Though a medicament containing formalin and cresol shows potent effect of disinfection for root canal, it is only too caustic and irritating, resulting in injury to tissue, and toxic enough to kill the cultured cells even in a low concentration. In this study a comprehensive investigation has been made of FC, a mixture containing an equal quantity each of formalin and cresol, especially on the above effects in low concentration of it. FC was tested first for its microbicidal effect on Staphylococcus aureus (S. aureus), Streptococcus mutans (S. mutans), Escherichia coli (E. coli), Bacillus subtilis (B. subtilis) and Candida albicans (C. albicans), and for its cytotoxic effect on the cultured cells of L and HeLa strain in comparison with Liquefied-phenol (J. P. XI). Then the local reactin of rabbit skin to either FC or its serial dilutions, which had been injected intracutaneously, was observed and the injured tissue was examined histopathologically. The results were as follows : 1. FC and Liquefied-phenol varied distinctly with the test strain in the lowest microbicidal concentration from 5.50×10^<-4> to 2.25×10^<-3> g/ml and from 2.00×10^<-3> to 5.00×10^<-3> g/ml respectively, as they were contacted with microorganisms for 24 hours. Potency of microbicidal effect (P_m) of FC compared with Liquefied-phenol was found to be from 2.2 to 3.8. 2. The lowest concentrations of FC and Liquefied-phenol causing complete cytolysis of L and HeLa cells in 24 hours were 1.00×10^<-4> g/ml and 4.50×10^<-4> g/ml respectively. Potency of cytotoxicity (P_c) of FC compared with Liquefied-phenol was 4.5 for both cells. 3. The microbicidal concentration of FC was lower than the cytotoxic one, and quotient of the latter divided by the former varied distinctly with the test strains between 5.5 and 22.5. 4. Toxicity index showing relation between the disinfecting and the cytotoxic power was revised with use of a standard drug of Liquefied-phenol so as to be calculated by a formula P_c/P_m, and was from 1.2 to 2.0 for FC. 5. When FC was in a constant concentration of either 10^<-4> g/ml or 10^<-5> g/ml, shortening the time of cell-FC contact below 10 minutes caused the cytotoxicic effect to diminish markedly. 6. The higher the concentration of serum added, the more decreased the cytotoxic effect of FC was. Fifty percent inhibition of adhesion of suspended cells was caused in the concentration of 0.9×10^<-5> g/ml for 0%-serum group, 2.7×10^<-5> g/ml for 10%-serum group and 3.5×10^<-5> g/ml for 40%-serum group. 7. It was found that the lowest concentration of FC was 1.0×10^<-1> g/ml for cauterization and 3.3×10^<-3> g/ml for inflammation on rabbit skin. 8. The tissue examination showed that necrosis and fixation were caused at the full concentration, necrosis alone at 1.0×10^<-1> g/ml and at 1.0×10^<-2> g/ml, and under 1.0×10^<-3> g/ml no significant toxicity was found when compared with controls. From the above, the correlation between mocrobicidal and cytotoxic power in vitro and injurous effect to cause local reaction in vivo have been revealed on FC more clearly than before. Another point of interest is that the toxicity index revised may be useful to make evaluation of FC more reasonable in comparison with the other drugs of dental disinfectants.

Hibitane in the treatment of oral candidiasis

Denture stomatitis (chronic atrophic candidosis) is a very common complication to the wearing of complete dentures. The infection is due to a contamination of the denture by yeasts. In a number of studies the clinical effect of Hibitane when used as a denture disinfectant has been studied. It was found that Hibitane (0.2--2%) caused a significant amelioration of inflamed palatal tissues and a reduction in the number of yeast cells harbored on the palatal mucosa and the fitting surface of the dentures. However, relapse of the infection was frequent after treatment was sustained. It was concluded that Hibitane could not be recommended for routine denture disinfection, first, because it caused staining of the dentures, second, because of the relative resistance of the yeast to the action of the drug. However, it seems justified to use Hibitane prophylactically as a denture disinfectant in patients who are highly susceptible to developing disseminating or systemic candidosis. Hibitane is a valuable drug in the treatment of denture stomatitis when used as a denture disinfectant.

Relapse tendency and removal of acquired discolourations in long-term denture disinfection with chlorhexidine

Five patients with denture stomatitis were initially treated for 14 days with a combination of amphotericin B lozenges and denture soaking in 0.2% chlorhexidine. To prevent recurrence the dentures were then kept overnight in 0.2% chlorhexidine during five months. No relapse occurred, but the dentures (all-acrylic) became heavily discoloured by chlorhexidine. During this period fungi could not be grown either on palatal or on maxillar denture agar models, and clinical signs and symptoms were reduced further. At the end of treatment hypochlorite was used to remove chlorhexidine-induced denture stain. Brushing and soaking (0.16%) proved more efficient than brushing alone, and when a 0.60% solution was used, the stains were generally eliminated in two hours. Hypochlorites in the prevention and removal of chlorhexidine discolourations deserve further attention.