Much like a turtleneck tightly encircling your neck, your bone and gum tissue should fit snugly around your teeth. When you suffer from periodontal disease, over time the supporting bone and tissue are destroyed and this forms pockets around the teeth. These pockets become deeper and provide a large space for bacteria to live in. As the pockets collect bacteria it results in further bone and tissue loss. When these pockets become too deep to clean with daily at-home oral hygiene and professional cleanings, your periodontist may recommend periodontal surgery.