What is a characteristic sign of aggressive periodontitis in an adolescent?

A characteristic sign of aggressive periodontitis in an adolescent is drifting of the teeth. This occurs because the disease causes rapid and severe destruction of the tooth-supporting structures, leading to loose and shifting teeth. Option A, yellowing of the teeth, may be a sign of poor oral hygiene but is not specifically associated with aggressive periodontitis. Option C, sudden tooth loss, is more commonly seen in severe cases of aggressive periodontitis in older adults. Option D, formation of deep cavities, may occur in any type of periodontal disease but is not a defining characteristic of aggressive periodontitis. Therefore, option B is the most accurate choice.