A term used to describe the space that forms between where the gum is located on a tooth (the gumline) and where the gum and bone actually connect to the tooth below the gumline. It is deeper and inflamed in someone with periodontitis or gum infection. Pocket depths are 1 to 3mm around healthy teeth. Pockets in the 4 to 5mm range indicate early gum infection. Pockets in the 6 to 9mm range indicate moderate to advanced gum infection and pockets greater than 9mm indicates severe gum infection that mat result in the loss of the tooth.