When plaque is left on the tooth, enzymes in the saliva mineralize (harden) the plaque into calculus (tartar). Once it hardens, it can no longer be removed by a toothbrush or floss. It needs to be professionally removed with a scaler or curette. If the calculus is left in place and not removed and then moves to your gums, it is like having a pebble in your shoe that you walk on all day, every day. As you chew and talk, your gum is rubbing against that hardened “pebble-like” calculus, and it irritates the gum. This can make your gums red and swollen, or cause them to bleed when brushing or flossing. This is called gingivitis.
If this continues over a long period of time, the inflamed and swollen gums put pressure on the bone, and it begins to give way. Loss of bone around the teeth can cause receding gums, loose teeth, and eventually teeth can fall out or need to be removed.