There are several potential causes of receding gums. The two most often identified are gum abrasion caused by brushing too hard and gum recession caused by or associated with periodontal disease (PD) – the inflammation and infection of the gums, bones and tissues that anchor teeth to the jaw.

Brushing too hard and too vigorously, and using hard-bristled toothbrushes, can cause the gums to recede. Applying too much pressure on the teeth, scraping or raking the brush horizontally across the gums (rather than gently pressing) or snapping dental floss between the teeth (rather than gliding it through) causes abrasions, injury or trauma to the gums. This irritation can lead to inflammation, redness and bleeding. After months or years, gums can begin to recede (gingival atrophy).

Gum recession associated with periodontal disease is part of the body’s immune response to bacteria on the gums and teeth. The immune system’s reaction to toxins produced by these bacteria can cause inflammation and, eventually, gum recession.

Age can also cause receding gums, especially if the gums have been subjected to aggressive brushing. In addition, older women can have bone loss associated with lack of estrogen and osteoporosis. As the alveolar bone supporting the gums and teeth erodes, this can cause gums to recede.

Gum recession can also be caused by:

• Abnormal oral frenum. The piece of tissue connecting the lip muscles to the gums between the two front teeth can pull too tightly on gums in both the upper and lower jaw. In the upper teeth, the tissue is called the maxillary labial frenum (frenulum). When talking and eating, the frenum moves in line with the upper teeth and gums. If the frenum is too tight, it pulls against the gums causing them to recede. A gap can form (gapped teeth or maxillary diastema). In the lower jaw, a similar process can occur with the mandibular labial frenum (located on the lower outside gums) and the lingual frenum (the cord under the tongue that connects the tongue to the floor of the mouth). A condition called tongue-tied results when the lingual frenum is too tight. In addition to causing gum recession and gapped teeth in the lower teeth, being tongue-tied can also cause speech difficulties.
  
  
• Misaligned or crooked teeth.  When teeth are crooked or curved into or away from the natural line of teeth (dentition), gums do not fit snugly against them. A tooth that is positioned in the arch (by dropping down from the upper jaw or pushing up in the lower jaw) also does not have normal gum attachment. These misalignments can cause gum recession around the affected teeth and create bite problems (malocclusion).
  
  
• Mouth trauma or injury. When teeth are knocked out or when mouth surgery stitches burst open (dehiscence), gums can recede around the tooth. Oral piercing with jewelry that rubs against gum tissue can also cause the gums to recede.