Ten chronic moderate to severe periodontitis patients selected according to the criteria currently adopted by Armitage 1999. Moderate destruction is generally characterized by periodontal probing depths up to 6 mm with clinical attachment loss of up to 4 mm. Advanced destruction is generally characterized by periodontal probing depths greater than 6 mm with attachment loss greater than 4 mm. Radiographic evidence of bone loss is apparent, Increased tooth mobility may be present.