Exploring ethanol's toxicity in the oral submucosa: chronic exposure versus abstinence in C57BL/6 mice.

Alcohol consumption is a recognised risk factor for the development of precancerous lesions in the oral cavity. This study investigates the effects of chronic ethanol exposure on inflammation and fibrosis in mice.Eighteen C57BL/6 mice were divided into three groups: Group I received only drinking water, while Groups II and III were exposed to 25% ethanol ad libitum for 14 weeks. Group II mice were sacrificed at the end of the 14^th week, whereas Group III underwent a 4-week abstinence period before sacrifice. Gene expression related to inflammation and fibrosis, along with histopathological changes in submucosal tissue, was analysed.Chronic ethanol exposure significantly upregulated MAPK signalling markers, as well as inflammatory and fibrotic markers, in submucosal tissue. In Group III, inflammatory markers such as NF-κB, p65, NLRP3, and caspase-1 partially returned to normal levels after abstinence, whereas fibrotic markers, particularly MMP-9, remained elevated. Histopathological analysis of oral submucosa revealed epithelial atrophy and extracellular matrix accumulation in ethanol-exposed mice.These findings suggest that 14 weeks of ethanol exposure induces persistent epithelial damage, inflammation, and fibrosis in the oral submucosa, with incomplete reversal after 4 weeks of abstinence. This underscores the lasting impact of alcohol on oral tissue, even after cessation.