Apical periodontitis is an inflammatory disease that affects the periapical tissues in response to a polymicrobial infection in the root canal system (Siqueira & Rôças, 2007). That response develops a highly vascular granulomatous tissue in the periapical region with a complex concentration of inflammatory cells and cytokines (Mehrazarin et al., 2017; Siqueira & Rôças, 2007). As a result, there is intense osteoclastic activity that degrades the organic and inorganic components of the alveolar bone surface (Petean et al., 2022, Yu et al., 2016). Evidence suggests that the treatment outcome of endodontic infections is influenced by general health and nutrition (Holland et al., 2017). Some substances, such as omega-3 fatty acids, curcumin, lactobacilli, and red wine with its phenolic compounds, can contribute to systemic health with positive effects on apical periodontitis through dietary supplementation (Azuma et al., 2021; Cosme-Silva et al., 2019; Dal-Fabbro et al., 2021b; Justo et al., 2022).

Nutraceutical science states that bioactive phenolic compounds are related to health benefits (Souza-Bomfim et al., 2022, Piccolella et al., 2019). Wine contains several components, including bioactive phenolic compounds more than water, ethanol, glycerol, polysaccharides, and various acids (Finicelli et al., 2019, Snopek et al., 2018). The benefits of red wine are related to the French paradox once it was noted that the presence of this drink in the Mediterranean diet was associated with the reduction of cardiovascular diseases (Artero et al., 2015, Finicelli et al., 2019; St Leger et al., 1979). On the other hand, the consumption of alcoholic beverages cannot be promoted due to the association of ethanol with adverse health effects (WHO, 2019). More promising results were found when only polyphenols instead of red wine were used during the development of apical periodontitis, evidencing that the presence of ethanol in wine could reduce the beneficial effects (Dal-Fabbro et al., 2021b). Moreover, alcohol was related to the increase in the severity and osteoclastogenesis of apical periodontitis (Dal-Fabbro et al., 2019, Dal-Fabbro et al., 2021b).

To retain the benefits of red wine's phenolic compounds without the drawbacks of alcohol, the industry has developed techniques for dealcoholization (Belisario-Sanchez et al., 2009, Liguori et al., 2019, Sam et al., 2021). Several beneficial effects were already associated with dealcoholized red wine, such as reduction of oxidative stress (López et al., 2007); increased oxidative defence (Modun et al., 2008); inhibition of atherosclerosis (Wang et al., 2005); reduced blood pressure and increased plasma nitric oxide (Chiva et al., 2012); anti-cancer properties (Lan et al., 2023); and antimicrobial potential (Muñoz-González et al., 2014). Considering the effects of dealcoholized red wine and the sparse information regarding its potential role in developing oral infections, this is the first study that aimed to investigate the impact of dealcoholized red wine supplementation on the severity of established apical periodontitis in rats. The null hypothesis tested was that supplementation with dealcoholized red wine would not affect the severity of apical periodontitis in these animals.