Effect of citric acid on soft tissue healing in the rat palate

The present study was carried out to determine the effects of citric acid (pH 1) on soft tissue healing. Standardised circular wounds were created in the palates of 24 rats using a modified trephine. Test animals had citric acid (pH 1) applied to the wounds for 3 min followed by rinsing with saline. In the control animals saline alone was applied for a similar time which was again followed by rinsing. Animals were sacrificed at 0, 1, 4 and 24 h, the palates dissected out and fixed in either neutral formalin, formol-sucrose for histochemical analysis or had epithelial sheets prepared for ATPase staining of Langerhans cells. At 0, 1 and 4 h less enzyme activity (non-specific esterase and acid phosphatase) was observed in the epithelium in the edge of the citric acid treated wounds compared to the controls. This was not seen at 24 h. No morphological difference was noted between the citric acid treated wounds and the controls at any of the time intervals. The morphology and distribution of ATPase positive Langerhans cells did not differ between the test and control wounds. These results indicate that the application of citric acid (pH 1) has little effect on the short-term healing of soft tissue wounds in the rat palate.