Growth and potential pathogens in denture-soaking solution of myelosuppressed cancer patients

Surface detail, compressive strength, and dimensional accuracy of gypsum casts after repeated immersion in hypochlorite solution

STATEMENT OF PROBLEM

One method used to disinfect a dental cast is immersion in a disinfecting solution. Repeated immersion of a cast in disinfectant may affect surface detail as well as other physical properties.

PURPOSE

The purpose of this study was to evaluate the changes in surface detail quality, dimensional accuracy, and wet compressive strength of dental casts as a result of repeated disinfection in slurry containing 0.525% sodium hypochlorite solution.

MATERIAL AND METHODS

Two different test specimen configurations were used, one for evaluating surface detail quality and dimensional accuracy and the other for compressive strength. Sixty specimens each were made of type III and type IV dental stone (Excalibur). Thirty specimens were immersed in slurry, a supernatant solution of calcium sulfate in distilled water (control casts), and 30 in slurry with sodium hypochlorite (test casts) solutions for 30 minutes and air dried for 24 hours. This process was repeated 7 times before testing. Linear dimensional change, surface detail quality, and wet compressive strength were determined according to American National Standards Institute/American Dental Association (ANSI/ADA) standards. The data were analyzed using 2-way analysis of variance and 2-sample independent t tests (alpha=.05).

RESULTS

For specimens prepared with type III and type IV stone, treatment by immersion in slurry (control casts) and in slurry with sodium hypochlorite (test casts) resulted in an increase (P<.0001) in linear dimensional change. The type IV casts treated with slurry with sodium hypochlorite showed significantly less (P<.0001) mean linear dimensional change (0.025%) compared with type III stone casts (0.063%), and the values remained within the ANSI/ADA specified standards. Both test solutions caused some degree of erosion or damage to the surface quality of casts made from type III and type IV stones. However, the difference between the control and test casts was not significant. Slurry with 0.525% sodium hypochlorite solution decreased the compressive strength of both types of stones significantly (P<.001) compared with distilled water slurry. However, the values remained close to ANSI/ADA standards.

CONCLUSION

The results demonstrated that repeated immersion of type III and type IV stone specimens in slurry with distilled water and slurry with 0.525% sodium hypochlorite, along with drying in air, caused a significant increase in linear dimension and a significant decrease in wet compressive strength. Although both the solutions caused some degree of damage to surface details for type III and type IV stones, the difference was not significant.

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.

Prevalence of Candida albicans in denture wearers in an Israeli geriatric hospital

Thirty-seven patients wearing complete dentures were investigated for Candida albicans. Twenty-five of the patients suffered from denture stomatitis and twelve had clinically normal mucosa. Candida albicans was isolated and identified from Sabouraud dextrose agar culture medium models constructed from impressions of the maxilla and from the upper dentures. The presence of Candida albicans was demonstrated in all denture wearers suffering from denture stomatitis and in 82% of denture wearers in a control group. A higher concentration of Candida was found in the denture stomatitis group. Large quantities of Candida resided in the denture base and not in the palate. Candida was also found in the denture base in areas not related to the lesion. The concentration of Candida was related to denture cleanliness.

Effects of sodium hypochlorite on denture base metals during immersion for short-term sterilization

The effects on Vitallium and Ticonium alloys immersed in different concentrations of sodium hypochlorite for various immersion times are described. The results of this investigation demonstrate that samples of these metals soaked in 2% sodium hypochlorite for at least 5 minutes or in 5.25% sodium hypochlorite for a minimum of 3 minutes were sterilized and not tarnished or corroded. Although Vitallium alloy was more resistant than Ticonium alloy to the deleterious effects of sodium hypochlorite, either metal can be safely immersed for sterilization purposes under the guidelines presented. Therefore, an effective and economical method for sterilizing removable partial denture frameworks made of chrome-cobalt or chrome-nickel alloys is attainable through the proper use of household bleach.

Model system for the in vitro testing of a synthetic histidine peptide against Candida species grown directly on the denture surface of patients with denture stomatitis

The denture surface provides a nidus for the growth of microbial species that act to initiate, aggravate, and maintain clinical disease. The present investigation describes the development of a model system for the testing of the effectiveness of agents against these microbial species inhabiting the denture surface. It was observed through in vitro growth patterns that the model permitted the testing of representative samples of the microbial flora. Poly-L-histidine was observed to inhibit both Candida albicans and C. glabrata from growing from the denture surface into nutrient broth. Scanning electron microscopy of control and treated denture disks revealed that poly-L-histidine had either eliminated most microbial flora from the denture surface or had effected a noticeable distortion of those Candida blastospores still present on the surface. From microbiologic studies, it appeared that poly-L-histidine had inflicted direct but not lethal damage to the still-attached distorted blastospores because the latter were still able to promote growth in agent-free broth. The antifungal effects of poly-L-histidine were observed to be dependent on the concentration of the polypeptide. The data obtained were consistent for all of the patients regardless of their denture stomatitis classification.