CYTOTOXIC EFFECTS OF SHORT-CHAIN CARBOXYLIC-ACIDS ON HUMAN GINGIVAL EPITHELIAL-CELLS

Previous studies showed that foods that are retained on the dentition can accumulate high levels of short-chain carboxylic acids (acetic, fo rmic, lactic and propionic). Since gingival epithelium is the first pe riodontal tissue to be challenged by oral factors, a study was underta ken to determine whether short-chain carboxylic acids can affect epith elial cells in vitro. Immortalized human oral epithelial cells were gr own in supplemented keratinocyte growth medium at 37 degrees C, and th e effects of short-chain carboxylic acids were determined with tetrazo lium-based and trypan blue exclusion assays. Low concentrations of sho rt-chain carboxylic acids inhibited the growth of human oral epithelia l cells, while higher concentrations led to cell death. The effects of short-chain carboxylic acids on the cells were dose-dependent and var ied among the individual acids (propionate >formate >lactate >acetate) . Growth inhibition was partly reversible and growth resumed after rem oval of the acids. However, the time needed for recovery of the cells increased with short-chain carboxylic acids concentration, consistent with progressively greater damage to the cells at higher short-chain c arboxylic acids concentrations. The observed effects of short-chain ca rboxylic acids on gingival cells in vitro supported our hypothesis tha t short-chain carboxylic acids can damage the integrity of gingival ep ithelium in situ.