Inclusion Criteria:  systemically healthy, had 20 or more natural erupted teeth, and had gingivitis (bleeding on probing [BOP] in more than 15% of sites, less than 25% sites with > 4 mm probing pocket depths (PPD), and less than 5% sites with 5 mm depth PPD, who were a non-smoker, willing to participate, and verbally understood and signed an informed consent prior to enrollment  Exclusion Criteria:  unable or unwilling to provide informed consent or follow study protocol, current smoker, systemic condition including diabetes mellitus, liver disease, kidney disease, autoimmune disease, and any cardiovascular condition that would require premedication prior to dental treatment, use of systemic antibiotics within three months of study entry, use of over the counter or prescription medications known to have anti-inflammatory/immunosuppressant activities (e.g., nonsteroidal anti-inflammatory drugs (>14 day use in past 3 months), steroids, vitamin supplements, statin drugs, topical chlorhexidine on a daily basis, pregnancy as diagnosed by administered of a pregnancy test, cancer or cancer therapy within the last year, immunosuppression (e.g., organ transplant), orthodontic therapy (current or within the last 6 months), inability to communicate verbally or in writing, clinically detectable oral mucosal inflammatory condition (e.g., aphthous, lichen planus, leukoplakia, oral cancer), or febrile illness, persistent cough or current infectious condition (e.g., influenza, hepatitis), or any PPD of 6 mm or greater at the time of the baseline periodontal examination.