The aim of this clinical study is to asses the effect of ultrasonic periodontal debridement associated to locally delivered doxycycline (20%) by PLGA microspheres on chronic generalized periodontitis treatment.

Thirty patients with chronic periodontitis and a minimum of seven pockets (>5

mm) in non-molars teeth that bled on probing will be selected. Patients will be randomly

assigned to ultrasonic periodontal debridement followed by local application of doxycycline

by PLGA microspheres (DB+DOX) and periodontal debridement followed by administration

of void PLGA microspheres (DB). Plaque, bleeding on probe, clinical attachment level

(CAL), and probing depth (PD) will be recorded at baseline, 3 and 6 months. Subgingival

biofilm samples will be collected from initially moderate (5 to 6 mm) and deep (≥7 mm)

pockets at baseline, 1, 3 and 6 months. Polimerase chain reaction (PCR) analysis will be

used to detect the frequency of Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf),

Treponema denticola (Td), Aggregatibacter actinomycetemcomitans (Aa), and Prevotella

intermedia (Pi).

Inclusion Criteria:

• Chronic generalized periodontitis (AAP,1999);
• At least 7 sites with probing depths >5mm, and 2 sites with probing depth >7mm;
• At least 20 teeth present;
• Systemically healthy.

Exclusion Criteria:

• Had received periodontal care 6 months prior to the study;
• Had taken medications known to interfere with periodontal health and healing 6 months prior to the study;
• Pregnants or lactants;
• Smokers;
• Sensitive to doxycycline.