Drinks that contain phosphoric acid have been shown to have erosive effects and cola drinks are strongly acidic (pH 2.5). Gingivitis may be caused by dietary acids. Therefore, this study analyses the interaction of Coca Cola consumption and oral mucosal damage. Thirty rats were divided into three groups of 10. The animals received saline (pH 7.0) or HCI acid buffered to pH 2.6 or Coca Cola (pH 2.6) per os with 24-h free access to these solutions. A biopsy was taken from the front of the gingiva and the tongue. Histopathological analysis showed no specific lesion and there were no differences among saline, Coca Cola and HCl groups. Flow cytometric analysis was used to assess proliferative activity. In the HCI acid and Coca Cola groups, cell cycle analysis showed that the effects of Coca Cola and HCI acid in inducing oral mucosal damage are similar. In both Coca Cola [G0/G1, 70.38 +/- 7.9; S, 28.06 +/- 10.13; G2/M, 1.62 +/- 2.80; proliferative index (PI), 28.68 +/- 7.98] and HCI (G0/G1, 67.7 +/- 18.9; S, 27.8 +/- 17.5; G2/M, 4.4 +/- 3.8; PI, 30.9 +/- 20.98), the rat cell population G0/G1 and G2/M phases were found to be low (p < 0.05) and the cell population S and PI phases were found to be significantly elevated compared with the control group (p < 0.05) (G0/G1, 86.92 +/- 8.69; S, 9.8 +/- 1.21; G2/M, 3.25 +/- 2.87; PI, 13.2 +/- 8.7). This result was reflected in the proliferative index, which is used as a measure of the regeneration index. The data show that Coca Cola and HCI acid have similar proliferative and regenerative effects on oral mucosa, and it is possible that their regenerative effects are caused as a result of an irritant effect.