Teeth become loose either because there is a root fracture or ( more likely ) gum disease.
Gum disease is the most common disease world wide affecting the majority of adults and even to a lesser extent teenagers . It is caused by the interaction between dental plaque and the immune system and charectorised mainly by the loss of root support( supporting jaw bone ).
Gum disease can be divided into 3 basic categories- mild , moderate and severe. The first is treated by teaching patients to remove plaque to a high standard with deep cleaning ( scaling ) either by the Dentist or Hygienist. This is easily curable and maintained by basic hygienist visits. The second is treated as above with more cleaning and is less easily curable. Generally more regular hygienist visits are required and bone regeneration technology ( Emdogaine ) may be appropriate. The third stage can be impossible to cure and likely leads to extractions.