الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Periodontal diseases are chronic inflammatory diseases that cause destruction of the supporting tissues of teeth.It is triggered by periodontopathogens and the clinical outcome is highly influence d by the host local immune response.The interaction between periodontopathogenes and host local immune response result in PMN production of reactive oxygen species.Increased levels of reactive oxygen species result in tissue destruction of periodontal diseases and it is involved in pathogenesis of periodontal disease.
One of the reactive oxygen species, nitric oxide has potential role in periodontal diseases.Increased levels of nitric oxide in GCF is involved in pathogenesis of periodontal disease.The development of antioxidant system from human body as vitamin E combacts and lessen the level of nitric oxide.
Doxcycycline is one antioxidant drugs.It protects against increased levels of nitric oxide and oxidative stress that is induced by an imbalance between excessive ROS production and anti-oxidant mechanisms.Increased levels of nitric oxide leading to a state of oxidative Stress have been implicated in the pathogenesis of periodontitis.
The present study was conducted to evaluate the effect of doxcycycline combined non surgical periodontal therapy on the levels nitric oxide in gingival crevicular fluid of chronic periodontitis patients. The study involved 60 patients divided into three groups.One group received non surgical periodontal therapy and doxcycycline 100 mg , other group received non surgical periodontal therapy only. The third group is healthy control group.
Samples of gingival crevicular fluid of 40 chronic periodontitis subjects were collected at baseline, day15 and day30 .Samples of 20 healthy subjects were collected at baseline. Filter paper was used in samples collection and the samples were analyzed using ELISA technique to evaluate the level of nitric oxide on the studied groups. Pocket depth, clinical attachment level , plaque index and gingival index was recorded in the studied groups at baseline , day15 and day30 .
Results revealed that doxycycline group gingival index, plaque index , pocket depth , clinical attachment level and nitic oxide levels were improved after day15, day30 compared with the baseline.
The statistical analysis showed that there was significant difference between group1 and group2 in probing pocket depth and nitric oxide level at the end of the study. The nitric oxide level of group1 were insignificant with group3 (control group) at follow up period day30 .