This study is being conducted to test the ability and accuracy of a new instrument in the diagnosis of periodontitis (gum disease) by using fluids from the mouth. The diagnosis instrument will test two types of fluids, gingival crevicular fluid (GCF) and saliva. GCF is the fluid that accumulates between your teeth and gum tissue. The fluids will be collected in three ways: 1. Direct GCF sampling 2. GCF rinse sampling and 3. Whole saliva. A total of 100 adult patients will participate in this study. These subjects will be of two patient populations: 1) diseased population, with active gum disease; and 2) a low-risk disease population, with no active gum disease. Patients will be seen 6 times over the course of the study over a period of approximately 12 months. At each visit the patient will undergo oral fluid collection, as previously described, and thorough examinations of the mouth, including the taking of measurements for study purposes. Patients will also have radiographs taken at baseline, month 6, and end of study visits.