The aim of this study was recording, the effect of conventional periodontal therapy (SRP) combined low dose doxycycline on nitric oxide level (NO) in gingival crevicular fluid (GCF) of patients with stage I periodontitis. Materials and methods: 40 patients had stage I Periodontitis were grouped into two groups: (group 1): 20 patients will receive SRP at three sessions + doxycycline 20 mg systemically twice daily (for 2 weeks). (Group 2): 20 patients will receive only SRP at three sessions for 2weeks. With 20 healthy subjects acting as control group (group 3). Clinical evaluation and GCF sample was collected from two groups (1& 2) at base line, 15 and 30 days intervals and from healthy group at base line only. Results: All the clinical indices and NO levels were found significantly higher in stage I Periodontitis groups compared to the control group at base line where (p < 0.001) with no statistically significant differences between (Group 1) and (Group 2) where (p < 0.05). When comparing the 2 studied patients groups and the healthy control group, founded improvement in clinical indices and NO levels at 15 and 30 days respectively with non-significant differences in all groups.
Conclusion: The current results provided that combined use SRP with low dose doxycycline had a reducing effect than SRP only for NO levels in GCF of patients with stage I periodontitis.