A b s t r a c t : T h e p o t e n t i a l fo r m a l i g n a n t transformation of oral lichen planus is still controversial.The expression of proteins related to cell proliferation and apoptosis in oral lichen planus and epithelial dysplasia was analyzed to evaluate the true potential for malignant transformation of this disease. Twentyfour cases of each lesion were subjected to the streptoavidin-biotin technique for identifying the immunohistochemical expression of PCNA, p53, bax, and bcl-2 proteins. Of the 24 cases of oral lichen planus, 14 (58.33%) were positive for PCNA, 10 (41.67%) for p53, 4 (16.67%) for bcl-2 and 12 (50%) for bax, whereas of the 24 cases of epithelial dysplasia, 20 (83.33%) were positive for PCNA, 10 (41.67%) for p53, 6 (25%) for bcl-2, and 20 (83.33%) for bax. Chi-squared test showed no statistically significant differences between the expression of p53 and bcl-2 in oral lichen planus and epithelial dysplasia, regardless of the grade (P > 0.05). However, the expression of PCNA and bax was significantly increased in epithelial dysplasia (P < 0.05). The results of this study showed that alterations in expression of these proteins are observed in oral lichen planus and epithelial dysplasia, suggesting the potential for malignant transformation in both lesions. IntroductionOral lichen planus is a chronic inflammatory disease of unknown cause, and its potential for malignant transformation is a subject of much controversy (1). Since the first case was reported in 1910, several studies have suggested that patients with oral lichen planus are at an increased risk of developing cancer (1-7).However, many authors believe that there is insufficient data to prove an association between oral lichen planus and cancer. For these authors, most cases of malignant transformation are the result of errors in the initial diagnosis of the disease (1,8-13).The true potential for malignant transformation of oral lichen planus can be evaluated by analyzing the expression of proteins related to cell proliferation and apoptosis, as alterations in the expression of these proteins are essential for carcinogenesis (14)(15)(16)(17)(18)(19).Therefore, the aim of this study was to evaluate the immunohistochemical expression of PCNA, p53, bax and bcl-2 proteins in oral lichen planus and epithelial dysplasia in order to explain the controversy regarding the potential for malignant transformation of oral lichen planus and emphasize the importance of long-term follow-up of patients with this disease. Materials and MethodsThe samples used in this study consisted of 24 cases of oral lichen planus and 24 cases of epithelial dysplasia (4 mild, 12 moderate, 8 severe) obtained from the records of

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Since the first confirmed cases in the end of 2019 in the city of Wuhan, Hubei province in China, COVID‐19 has spread around the world, totaling, until July 25th, 2020, 15.785.641 confirmed cases and 640.016 deaths [1] . This article is protected by copyright. All rights reserved.

http://www.medicinaoral.com/medoralfree01/v14i11/medoralv14i11p563.pdf AbstractBackground: Although oral lichen planus has been classified by the World Health Organization (WHO) as a potentially malignant disorder, such classification is still the target of much controversy. Aim: To evaluate the cell proliferation rate in oral lichen planus, comparing it to the rate observed in epithelial dysplasia and oral squamous cell carcinoma, aiming at indications which might indicate the potential for malignant transformation . Material and Methods: Twenty-four cases of each lesion were submitted to the streptoavidin-biotin and AgNOR technique to evaluate the immunohistochemical expression of PCNA and the mean NORs/nucleus, respectively. Results: Positivity for PCNA was observed in 58.33% of oral lichen planus cases, 83.33% of epithelial dysplasia cases and 91.67% of oral squamous cell carcinoma cases. Chi-squared test showed that the number of positive cases for PCNA was significantly lower in oral lichen planus than in oral squamous cell carcinoma (p<0.05). No significant statistical difference between oral lichen planus and epithelial dysplasia (p>0.05) and between the epithelial dysplasia and oral squamous cell carcinoma (p>0.05) was observed. The mean NORs/nucleus in oral lichen planus, epithelial dysplasia and oral squamous cell carcinoma were 1.74±0.32, 2.42±0.62 e 2.41±0.61, respectively. Variance analysis (ANOVA) revealed significant statistical difference between oral lichen planus and the other studied lesions (p<0.05). Conclusion: Oral lichen planus cell proliferation rate was less than in oral epithelial dysplasia and oral squamous cell carcinoma which might explain the lower malignant transformation rate.

The purpose of this study was to evaluate the effect of 5% sodium bicarbonate on the adherence of Candida albicans to thermally activated acrylic resin. Fifty 4 mm² specimens of acrylic resin were obtained using a metallic matrix. The specimens received chemical polishing, were sterilized and then immersed in Sabouraud broth, inoculated with Candida albicans standardized suspension. After 24 hours of incubation at 37°C, the specimens were divided into four groups according to the substance used for disinfection (5% sodium bicarbonate, 0.12% digluconate chlorhexidine, vinegar and Corega Tabs). A control group was included, in which distilled water was used. The adhered microorganisms were dispersed, diluted and plated onto culture media to determine the number of colony-forming units (cfu/mL). The results were analyzed through the Mann-Whitney statistical test at the 5% level of significance. Only 0.12% digluconate chlorhexidine and 5% sodium bicarbonate presented a statistically significant difference (p = 0.0010 and p = 0.0156, respectively) compared to the control group, decreasing the number of cfu/mL. However, when the different disinfecting solutions were compared with each other, only 0.12% digluconate chlorhexidine presented a statistically significant difference in the reduction of cfu/mL. It was concluded that although 0.12% digluconate chlorhexidine was more effective in the reduction of Candida albicans adherence values to thermally activated acrylic resin, 5% sodium bicarbonate also proved to be a viable alternative.