Please select the eligibility criteria that correspond to the clinical trial below.
Title: Influence of Moment of Systemic Metronidazole and Amoxicillin Administration in the Treatment of Chronic Periodontitis: a Randomized Clinical Trial.
Brief Summary: The aim of this multicenter randomized clinical trial is to compare the clinical, microbiological and immunological effects of the adjunctive use of systemic metronidazole plus amoxicillin administered in different phases of the treatment of generalized chronic periodontitis.


Options:
A: Inclusion Criteria:

* \> 20 teeth
* \> 5% sites (approx. 8 sites) with pocket depth \> 4 mm and / or 5% sites with attachment level \> 4 mm and mean AL \< 4.5 mm and mean PD \< 3.9 mm (not including tooth brush abrasions).

Exclusion Criteria:

* \> 50% of sites with pocket depth or attachment level \> 4 mm
* Pregnancy or nursing
* Periodontal or antibiotic therapy in the previous 6 months
* Any systemic condition which might influence the course of periodontal disease or treatment (e.g. diabetes, AIDS)
* Any systemic condition which requires antibiotic coverage for routine periodontal procedures (e.g. heart conditions, joint replacements etc.)
* Liver disease
* Any known allergy to amoxicillin, metronidazole or doxycycline
* Lactose intolerance
B: 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
C: Inclusion Criteria:

* 18 years of age and up
* clinical and radiographic signs of severe (CAL 5 mm or more) chronic periodontitis.
* at least 20 natural teeth in situ
* pocket probing depths (PPDs) of ≥ 5 mm at a minimum of eight tooth sites
* willingness to participate and to be available at all times required for participation
* over 30% of the teeth present must have a PPDs)≥ 4 mm and insertion loss ≥ 5 mm evaluated by an experienced periodontist
* informed consent signed by the patient

Exclusion Criteria:

* if they (or parents or siblings) show confirmed or assumed allergies or hyper-sensitive skin reactions against moxifloxacin, ciprofloxacin (or other quinolones as listed in the "summary of product characteristics, Version Juli 2005"), metronidazole (or other 5-nitroimidazoles and ingredients of Flagyl® 400mg as listed in the "summary of product characteristics, Version Juli 2007"), systemic diseases or conditions as listed in the above mentioned "summary of product characteristics"
* subjects who have undergone antibiotic therapy three months before the start of the study under interrogation
* have Down's syndrome
* known AIDS/HIV
* regularly take systemic medication affecting the periodontal conditions, e.g. phenytoin, nifedipine, and/or steroid drugs
* professional periodontal therapy during 6 months prior to baseline
* require antibiotic treatment for dental appointments
* are pregnant or breastfeeding
D: Inclusion Criteria:

* ≥35 years of age;
* at least 15 teeth (excluding third molars and teeth with advanced decay indicated for extraction);
* a minimum of 6 teeth with at least one site each with probing depth (PD) and clinical attachment level (CAL) ≥5 mm;
* at least 30% of the sites with PD and CAL ≥4 mm and bleeding on probing (BOP).

Exclusion Criteria:

* pregnancy;
* breastfeeding;
* current smoking and former smoking within the past 5 years;
* systemic diseases that could affect the progression of periodontitis (e.g. diabetes, immunological disorders, osteoporosis);
* scaling and root planing an in the previous 6 months;
* antibiotic therapy in the previous 6 months;
* long-term intake of anti-inflammatory medications;
* need for antibiotic pre-medication for routine dental therapy;
* use of orthodontic appliances;
* extensive dental prosthetic rehabilitation;
* allergy to metronidazole and/or amoxicillin.

Answer: D