RESULTS and SUMMARYIn the present research, bearing on 3 groups including each 16 subjects, the values of salivary pH were assessed. The first group consisted of periodontal disease - free subjects. The patients in the second group were selected as being indicated for gingivectomy and the third group for flap operation. The pH values of saliva were colorimetrically evaluated in the second and third groups before and after treatment. In the first group, the pH of saliva was also colorimetrically assessed.As a result, the following conclutions were drawn :1. The mean pH of saliva was found to be 6.78 in periodontal disease - and dental caries - free subjects.2. The mean pH of saliva was observed to be 6.05 in patients involved by chronic marginal gingivitis and periodontitis.3. The mean pH of saliva was 5.91 in patients involved by advanced periodontitis.4. The mean pH values following periodontal treatments were found to be very close to that of the control group.5. In conclusion, the periodontal disease seems to be one of the cause of the decrease of salivary pH and periodontal treatment effects on the salivary pH.