Please select the eligibility criteria that correspond to the clinical trial below.
Title: The Treatment of Periodontal Diseases. A Randomized, Blinded, Five Years Follow-up, Four-arm, Placebo Controlled Clinical Intervention Trial
Brief Summary: The purpose of this study is to examine if the correct use of antibiotics, as well as the application of one-day-treatment, in the therapy of periodontal diseases. The population of treated patients (184) are divided in 4 groups; Group 1: Metronidazole + mechanical treatment in one day, Group 2: Placebo + mechanical treatment in one day Group 3: Metronidazole + mechanical treatment on day 1 and 21 Group 4: Placebo + mechanical treatment on day 1 and 21 End points, BOP, Plaque, PPD, CAL, RAL, Microbiology will be recorded on all sites at 3 months, 1 -, 3 -, and 5 years post-treatment


Options:
A: Inclusion Criteria:

1. diagnosis of GAgP (AAP, 1999);
2. presence of ≥20 teeth;
3. presence of ≥ 6 sites presenting PD ≥ 5mm with bleeding on probing (BOP) and ≥2 sites with PD ≥7mm (including incisors and first molars, in addition to other two non-contiguous teeth);
4. good general health;
5. ≤ 35 years old; and
6. agree to participate in the study and sign a written informed consent. All subjects will be individually informed about the objectives, probable risks and benefits of the protocol treatment (according to Resolution nº196 of October 1996 and to the Professional Code of Dental Ethics - 179/93).

Exclusion Criteria:

1. pregnancy or lactating;
2. suffer from any systemic disease (e.g. cardiovascular disorders, diabetes, blood dyscrasias, immunodeficiency, etc) which could alter the course of periodontal disease;
3. took antimicrobials in the previous 6 months;
4. taking long-term anti-inflammatory drugs;
5. previous periodontal treatment within the last 12 months;
6. smokers.
B: Inclusion Criteria:

* Subjects must be 20 years of age or older
* Have at least 18 natural teeth
* Four or more clinical attachment level(CAL) ≥ 3mm
* Four or more periodontal pockets with a probing depth (PD) ≥ 4mm
* Have Bleeding on probing
* Provide informed consent and willingness to cooperate with the study protocol

Exclusion Criteria:

* Forbidden History of Panax Notoginseng and Rehmanniae Radix Preparata
* Hypersensitivity of Doxycycline
* Hypersensitivity of Zea mays L. extract
* Critical diseases such as HIV previous three years
* Patients with mental retardation and dementia
* Systemic diseases such as diabetes and hypertension
* Patients who take Anticoagulants or Antiplatelet Agents
* Patients who have malignant tumor
* Smoker
* Continually use for 2weeks of phenytoin, calcium channel blocker, cyclosporin, coumarin, nonsteroidal anti-inflammatory drugs and aspirin use in the previous one month
* Patients who need malignant tumor
* Patients who received periodontal treatment within the last 6 months
* Pregnant or lactating females
C: Inclusion Criteria:

* Females and males with advanced periodontal disease referred between November 2007 and January 2009.
* No diseases known to be associated with periodontal diseases, i.e. diabetes mellitus, rheumatoid arthritis, pregnancies.
* No continuous medication known to affect the severity or progression of periodontal diseases.
* No previous systematic periodontal treatment.
* More than 5 pockets 5mm \< PPD \< 9 mm after a 3 month hygiene phase - i.e. before inclusion into study.
* Oral hygiene; \< 5% of surfaces with plaque at inclusion time.
* Signing an informed consent.

Exclusion criteria:

* diseases known to be associated with periodontal diseases, i.e. diabetes mellitus, rheumatoid arthritis.
* pregnancy
* continuous medication known to affect the clinical expression of periodontal diseases
* subgingival microbiological diagnosis which reveals bacteria with reduced/no sensitivity to metronidazole
D: Inclusion Criteria:

* under 30 years old and systemically healthy, with at least 20 teeth present. Be willing to participate in the study which is corroborated by signing the informed consent form.

Commit to attend post-therapeutic controls and stop drinking alcohol during the time of ingestion of antibiotics.

Exclusion Criteria:

* Subjects in whom are contraindicated or with hypersensitivity to quinolones - Subjects who have undergone periodontal, surgical or mechanical antibiotic therapy six months before the start of the study according to interrogation.

Women in pregnancy or lactation, corroborated with previous medical history and medical consultation.

Answer: C