Receding gums occur when the gums (gingiva) pull away from the teeth. This causes the teeth to look longer than normal and exposes the roots (cementum). Those with receding gum lines may have toothy smiles. They may also be more sensitive to hot and cold or sweet and sour sensations (sensitive teeth). Root caries (cavities), decay, infection and tooth loss are also more likely when gums recede.

Gums are attached to the teeth and provide a protective seal to keep germs such as bacteria from entering the body through blood vessels in the mouth tissue. Healthy gums are pink and fit snugly against the bottom of the crown, the portion on the tooth visible above the gum line. When gums recede, there is loss of this attachment to the teeth and more of the cementum (root covering) is exposed. The cementum is thinner and less durable than enamel.

Teeth become sensitive because tiny tubules in the dentin (a layer of the tooth beneath the enamel and cementum) are more exposed to stimuli (e.g., hot and cold). Nerve endings in the tooth can interpret signals from those hypersensitive tubules as sharp pain. The discomfort can last a few seconds and subside or ease into a dull ache.

Improper cleaning techniques (brushing too hard and using a hard-bristled toothbrush) are a key reason for gum recession. Many people put too much pressure on the brush or snap the dental floss too tightly between teeth. This causes abrasions on the gums. Over time, the gums retract and recede from the gum line (gingival atrophy).

Other forms of trauma, such as oral piercings, can damage the inner mouth tissue, causing irritation, abrasions and bleeding – all of which can lead to gum recession.

The spaces or pockets formed between teeth and gums when gums recede can harbor food particles and encourage rapid growth of harmful bacteria. Cavities in the tooth’s root can develop as the plaque and bacteria attack the cementum. Uncontrolled plaque and bacteria on the gums and teeth can also increase the risk of developing a more serious gum condition called periodontal disease.