Although of low prevalence, aggressive periodontitis is a rapid destructive form of periodontal disease that initiates at a young age, leading to premature loss of first molars and incisors. Little is known on the mechanisms of this disease. It is imperative to understand mechanisms of disease to establish proper treatment. We have established a controlled study in a comparable population presenting similar aggressive disease characteristics to evaluate the mechanisms of this disease. It is the goal of this study to determine immunological and microbiological mechanisms responsible for the rapid tissue destruction in children with localized aggressive periodontitis and how traditional periodontal intervention affects these mechanisms. Important knowledge gained with this proposal will aid in defining specific treatment approaches to better control disease progression and prevent disease initiation in susceptible individuals.