When going to the dentist, the dental hygienist will use an instrument called a probe to measure the area around your teeth to see if you have any pocketing (area between the tooth and gum where bacteria will form). The depth of the gum tissue between the teeth and gums are called pockets when it is five millimeters or more. The American Academy of Periodontology recommends that every adult receive a periodontal evaluation each year to determine whether additional treatment is needed. Measuring pocket depth is just one part of a comprehensive dental evaluation.