Modelo de indução de estomatite protética em ratos Wistar sob antibioticoterapia

Abstract

Objective: This Dissertation was divided into two stages. The first one evaluated the effectiveness of induction and duration of denture stomatitis using different protocols in immunocompetent Wistar rats under antibiotic therapy and the second one aimed to define the most appropriate protocol for the induction of denture stomatitis in immunocompetent rats under antibiotic therapy. Material and methods: Acrylic devices were made from impression of the animals' palates using individual trays and polyether. After sterilization, they were contaminated with Candida albicans inoculum (~ 2x108 CFU/mL). In Step I, the animals were submitted to antibiotic therapy with tetracycline (TTC; N=28) or amoxicillin with clavulanic acid (AAC; N=28) in drinking water before being submitted to the protocols until the end of the experiment. Then, they were divided into 3 groups: NC (n=2) = negative control; De (n=6) = use of a sterile device for 4 days; In+CD (n=6) = inoculation of C. albicans suspension on the palate and use of contaminated device for 4 days; in 2 periods: T0 or T6 (N=14) = euthanasia after removal of the device or after 6 days of removal, respectively. The presence of denture stomatitis was verified by visual analysis of the palate and tongue and by colony count (CFU/mL) from collections on the palate using swabs. The palates and tongues were removed for descriptive histopathological analysis. In Stage II, two groups were evaluated: In+CD TTC and In+CD AAC (n=7) = inoculation of C. albicans suspension on the palate and use of a contaminated device for 4 days under TTC or AAC administration in drinking water for 4 days, respectively. The animals were monitored for another 4 days after the removal of the devices (T4) for signs of denture stomatitis by visual analysis of the palates and tongues and CFU/mL count of C. albicans and Candida spp. from collections on the palates and devices. After euthanasia, the palates and tongues were removed for descriptive histopathological analysis, histometric analysis by digital planimetry, analysis of proliferating cell nuclear antigen (PCNA), and myeloperoxidase (MPO) and N-acetylglucosaminidase (NAG) measurements. The data were analyzed by: three-ways repeated measures ANOVA/Bonferroni (weight of animals and CFU/mL - Stage I), two-ways repeated measures ANOVA/Bonferroni (weight of animals - Stage II, CFU/mL of C. albicans and Candida spp. on the palate), one-way ANOVA (CFU/mL of C. albicans and Candida spp. from contaminated devices), Student's t-test (MPO and NAG on the palates and tongues, digital planimetry, and PCNA). Intra and inter-examiner agreements (n=2; Kappa coefficient ƙ) were established and evaluated in Stage I, scores of Edema and Erythema on the palate and Depapillation of the tongue (Kruskal Wallis/Dunn and Mann-Whitney) and Erosion on the palate (Fisher) and in Stage II, Edema and Erythema scores (Friedman/Dunn and Mann-Whitney) and Erosion on the palate (Q Cochran and Fisher) and Depapillation of the tongue (Friedman/Dunn and Wilcoxon). All analyzes were performed at a 95% significance level (α=0.05). Results: In Stage I, clinical changes were observed on the palates and tongues in the In+CD group for all periods and antibiotics used. There was a progressive reduction in the CFU/mL count over time for both antibiotics (p<0.05). Histologically, microabscesses, changes in the basal layer, intracellular edema, and inflammatory infiltrate in the palate and tongue were observed in both periods evaluated and antibiotics administered. In Stage II, similar findings to Stage I were obtained for clinical condition of palates and tongues of animals. There was no difference between antibiotics in the CFU/mL count of C. albicans on the palate and in the contaminated device. For the count of Candida spp. on the palates (T0) and devices and MPO dosage in the palate and tongue, higher values (p<0.05) were obtained for the administration of TTC. Higher levels of NAG were obtained in the tongue of animals submitted to AAC (p<0.05). There was no difference (p>0.05) between antibiotics for histometric and PCNA analyses. Conclusion: The animal model using a device contaminated with C. albicans for 4 days under antibiotic therapy with tetracycline resulted in significant clinical, enzymatic, and histological changes compatible with prosthetic stomatitis, a condition that lasted for 4 days after removal of the device. Keywords

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