[Histological study on the effects of ethanol injection on mouth mucosa contraction loss]

We previously reported that a loss of contraction in the mucosal tissue of the palate arch is effectively induced by ethanol injections of moderate concentration and dosage. The present study was performed to obtain more information on how such ethanol injections induce contraction loss in mucosa tissue. Guinea pigs of both sexes were used in this study. The left arch of the palate mucosa was injected with 2 microliters of 70% ethanol and used as the experimental group. The right arch of the palate mucosa of the same animal was injected with saline and used as a control. One, three, five, eight, 10, 30, 50, and 90 days after injection, the mucosal tissues that received the injection were resected under anesthesia and processed for light microscopy using standard procedures. One day after the ethanol injection, severe coagulative degeneration of the mucosal tissue of the palate was seen. However, the damaged area was strictly restricted to the arch of the palate. Coagulative degeneration of the tissue peaked three days after the injection. Thereafter, the mucosal epithelial and mucosal connective tissues regenerated, and the damaged mucosal tissue quickly began to repair. An apparent cicatricial contraction loss was observed 10 days after the ethanol injection, along with the progression of fibrotic changes in the submucosal connective tissue of the arch of the palate. The regenerative action of the mucosal arch of the palate abated 30 days after the ethanol injection, and the reduced mucosal tissue appeared to have become denser as a result of an increase in dense fibrous connective tissue in the submucosal layer. No cell malignancies were seen throughout the entire 90-day observation period. In conclusion, cicatricial contraction loss of the mucosal arch of the palate resulting from the injection of an appropriate concentration and dosage of ethanol leads to the regeneration of the mucosal epithelium and fibrotic changes in the submucosa. The ethanol injection described here seems to be extremely safe, since it exerted no malignant effects on the cells and tissues either morphologically or functionally.