A novel acrylic resin palatal device contaminated with Candida albicans biofilm for denture stomatitis induction in Wistar rats

Abstract

A novel acrylic resin palatal device contaminated with Candida albicans biofilm for denture stomatitis induction in Wistar rats Denture stomatitis is the most frequent oral lesion in removable prosthesis wearers, with high recurrence rates and a complex treatment. Objective: This study describes a protocol to obtain and to contaminate a palatal device with Candida albicans biofilm that could be used for an animal model of denture stomatitis. Methodology: Acrylic resin devices (N=41) were obtained from impressions of the palates of Wistar rats with individual trays and polyether.The efficacy of microwave irradiation (MW), ultraviolet light (UV), or ultrasonic bath (US) was assessed by colony viability and spectrophotometric analyses (n=5) in order to select the most appropriate method for sterilizing the devices. Then, different devices (n=5) were contaminated with C. albicans and evaluated by CFU/mL determination, scanning electron microscopy, and laser confocal microscopy. Device stabilization was assessed with either autopolymerizing acrylic resins or a self-adhesive resin cement (n=2). The spectrophotometric data were analyzed by one-way ANOVA followed by the Tukey's HSD post-hoc test (α=0.05). Results: MW was the only method capable of sterilizing the devices, and the contamination protocol developed a mature and viable C. albicans biofilm (~1.2 x 10 6 CFU/mL). The self-adhesive resin cement was the best stabilization material. Conclusions: This acrylic resin palatal device was designed to be similar to the clinical situation of contaminated prostheses, with easy manufacturing and handling, effective stabilization, and satisfactory contamination. Thus, the acrylic device can be a valuable tool in the development of denture stomatitis in rats.

Experimental animal models for denture stomatitis: A methodological review

“…Ill fitted devices can either be lost through the course of the experiment or make the palatal tissue more susceptible to fungal infestation, considering it would probably cause more local trauma. 31 Moraes et al 4 modified the design developed by Hotta et al 33 by proposing the use of a colorless autopolymerizing acrylic resin to fabricate the palatal devices, in order to allow visibility during adaptation and fixation (Figure 6). The authors stated that visibility during experiments is essential, since any defect on the surface of the devices might compromise their adaptation and stabilization in the oral cavity.…”

“…These authors also tested different fixation methods for the devices (two autopolymerizing acrylic resins or a self-adhesive resin cement) and concluded that the latter was the best stabilization material, especially because it does not promote any thermal reaction that may compromise the palatal mucosa of the animals. 4 Lee et al 36 developed a more complex device consisting of a fixed part that is anchored to the posterior palate by orthodontic wires and acrylic resin and a removable part fitted to the anterior palate that is retained by magnets embedded in the fixed part (Figure 7). One of the main advantages of this type of device is the ability to monitor fungal colonization longitudinally.…”

“…SEM micrographs can also be of value to study C. albicans biofilm formation and architecture on acrylic devices 4,34,37,39 and on the palatal mucosa. 37,39 Confocal laser scanning microscopy.…”

“…34 Furthermore, quantitative data can be obtained from the confocal micrographs and be expressed as total, viable and non-viable biovolume, percentage of cell viability, and area covered by C. albicans biofilm. 4 Some studies performed this analysis to evaluate the contamination on the palatal device surfaces 4,34,39 and/or to observe 39 and quantify the biofilm 37 on the palatal tissue of rats after denture stomatitis induction.…”

“…1 However, prior to clinical studies, it is crucial to guarantee that any alternative treatment is safe and effective. 4 Alternative methods, such as invertebrate models 5,6 and non-animal models, 7,8 are ethically acceptable, have a good correlation to animal models, and do not require specialized facilities and personnel for maintenance. 9,10 However, these models also have limitations.…”