Gum that has moved away from the crown of a tooth seldom returns to its original position. Understanding why requires looking beneath the visible tissue.
Gum follows the bone underneath
The gum margin sits at a fairly consistent distance above the bone crest supporting the tooth, held there by fibres attaching to the root surface.
Where that bone recedes, the soft tissue above it has nothing to sit on and settles downward to a new level.
Since the position is dictated by the underlying support, restoring the visible margin usually means restoring what supports it, which soft tissue cannot do on its own.
The causes divide into two groups
Inflammatory recession follows bacterial deposits at the gum margin and the bone loss that accompanies persistent inflammation. It typically affects multiple sites.
Mechanical recession follows repeated physical trauma, most often forceful horizontal brushing with a hard brush, and tends to appear on prominent teeth on the cheek side.
Thin gum tissue and roots sitting close to the outer bone surface make either type more likely, and those features are largely inherited.
Exposed root behaves differently from enamel
Root surface is covered by cementum, a thin layer far softer than enamel, and beneath it lies dentine threaded with tubules connecting to the nerve.
Fluid movement within those tubules is what produces sensitivity to cold, air and sweet stimuli on exposed roots.
Root surfaces also decay more readily than enamel, dissolving at a milder acidity, which changes what preventive measures a dentist will discuss.
Grafting adds tissue rather than reversing loss
Where coverage is needed, tissue can be moved from elsewhere in the mouth or a substitute material placed to rebuild thickness over the exposed root.
Success depends on how much bone remains between and around the teeth, since the graft needs a blood supply and a stable base to survive on.
Whether a given site is suitable is a periodontal judgement, and the assessment includes measuring attachment levels rather than looking at the margin alone.
Stopping progression is the realistic aim
Most management focuses on removing the cause, whether that is bacterial deposits, brushing force, or an appliance pressing on the tissue.
Recession that continues after the apparent cause is addressed suggests something else is driving it and warrants further investigation.
Changes in gum position, increasing sensitivity or teeth appearing longer are all reasons to be examined rather than monitored at home.