IRCT2014111714333N24 IRCT 2014-12-23 Vice Chancellor for Research Affairs, Kermanshah University of Medical Sciences Study the effect of vitamin C on saliva antioxidant defense system of patients with periodontal disease Effect of using and avoiding to use vitamin C on defense system of saliva anti oxidant of periodontal patients 2014-12-06 anticipated 32 Complete https://irct.ir/trial/13960 interventional Randomization: N/A, Blinding: Double blinded, Placebo: Used, Assignment: Parallel, Purpose: Treatment. N/A Disease of salivary gland, unspecified. Intervention 1: Samples of experimental group received 500 mg of oral vitamin C power daily for three weeks. Unstimulated saliva of patients was tested in the morning and patients were asked to brush their teeth and avoid eating and drinking at least 90 minutes before saliva test on the test day. Samples were sitting while saliva gathering process. After three weeks, saliva samples were again gathered from patients and total anti oxidant capacity was measured using Randox kit and the results were recorded. Intervention 2: Samples of control group received 500 mg of water with permissible oral essence and color for three weeks. Unstimulated saliva of patients was first gathereded in the morning and patients were asked to brush their teeth and avoid eating and drinking at least 90 minutes before saliva test on the test day. Samples were sitting while saliva gathering process. After three weeks, saliva samples were again gathered from patients and total anti oxidant capacity was measured using Randox kit and the results were recorded.