title: Dynamics of plaque microbiota reveal distinct mechanisms of oral hygiene regimens in natural human gingivitis population
design: Experiments were conducted at Procter & Gamble (Beijing) Technology Co., Ltd. Oral Care Department, with approval from the P&G Beijing Technical Center (China) Institutional Review Board and in accordance with the World Medical Association Declaration of Helsinki (1996 amendment). ICH Guidelines for Good Clinical Practice (GCPs) were followed. Generally healthy adult subjects with evidence of gingivitis were recruited in China.   Informed consent was provided. Individuals meeting the following criteria were included: be at least 18 years of age; have a minimum of 18 natural teeth with facial and lingual scorable surfaces; have at least 10 bleeding sites as measured by Mazza Gingival Index at visits 1-3; be in good general health as determined by the Investigator/designee based on a review of the medical history/update for participation in the study. Exclusion criteria for individuals includes: severe periodontal disease, as characterized by presence of four or more teeth in two quadrants with >5mm pockets, purulent exudates, generalized mobility, and/or severe recession; any condition that requires antibiotic premedication for the administration of a dental prophylaxis; self-reported pregnancy or intent to become pregnant during the course of the study and nursing females; fixed facial orthodontic appliances; atypical discoloration or pigmentation in the gingival tissue; any diseases or conditions that could be expected to interfere with the subject safely completing the study.   All subjects reviewed and signed an informed consent and receive a copy and were instructed to use acclimation products including: Crest® Cavity Protection toothpaste (0.243% sodium fluoride) and a standard Meililiangjie soft manual toothbrush for two weeks from visit 1. Medical history, demographic information, inclusion/exclusion criteria will be collected. Oral Soft Tissue exam and gingivitis exam will be conducted at visits 1, 2 (week 1) and 3 (week 2). Number of bleeding sites recorded at visits 1-3 will be used to compute the level and consistency of gingivitis and may be used in combination of other inclusion criteria to screen subjects. 10591 subjects were enrolled in the study and were randomized to one of the treatment groups, the regimen A group: China Crest® Pro-health 7 complete toothpaste with 6100 ppm stannous, Crest® pro-health manual toothbrush and Crest® pro-health Gum protection rinse with 0.074% CPC or regimen B group: China Crest® Cavity Protection toothpaste and Crest® meililiangjie manual toothbrush.  Subjects will be asked to used twice daily for 27 days. A trained operator will do gingivitis and plaque exam for each subject at baseline, day 3, 11 and 27. For each subject, along the gumline plaque will be collected up to 14 teeth in 1/3 quadrants. Plaque samples will be collected along with gingival gum line within 2 mm depth.  Gingivitis was assessed in each host subject using the Mazza Gingival index. The Mazza Gingival index for a subject was defined as the mean Mazza Gingival index of all teeth in the subject. The Mazza Gingival index is similar to frequently used Papillary Inflammation Bleeding Index (PIBI) which measures both the signs of inflammation as well as the degree of the severity of bleeding. Specifically, probing was performed by a dentist on the mesiobuccal and the distolingual of each tooth, for a maximum of 56 sites. Scores range from 0-5, with 0 assigned for normal appearing and healthy gingiva up to a score of 5 for spontaneous bleeding (without provocation). The Mazza Gingival index of all subjects were measured by the same well-trained dentist to reduce technical variation. Gingival bleeding numbers upon examination were also recorded for each subject.  The plaque deposits on the teeth will be scored on six surfaces (distobuccal, midbuccal, mesiobuccal, distolingual, midlingual and mesiolingual) of all 28 teeth (excluding 3rd molars, crowns and surfaces with cervical restorations) according to the Quigley-Hein Index as modified by Turesky et al which emphasizes plaque in contact with the gingival.  Buccal, lingual, and whole mouth average plaque scores will be calculated for each subject and tooth surfaces by totaling the scores and dividing by the number of gradable sites examined.