WHAT CAUSES GUM RECESSION?

Gum recession is the undesirable condition in which the edge of the gum tissue, called the “gingival margin”, moves down onto the root surface of one or more teeth.  An important concept to understand about gum recession is that the gum tissue is supported by the underlying bone, therefore when recession does occur, what we are really observing is a change to the gum position due to changes to the supporting bone. This may result in an unsightly appearance, increased tooth sensitivity, and/or an increased likelihood of getting a cavity on the root surface of the involved tooth/teeth.  For such a common condition, affecting over 50% of our adult population, you might think that the causes of gum recession have been well understood for decades. In reality, there is still much debate about its causative factors.  It has been proposed that recession is multifactorial, with one type being associated with anatomic factors and another type with physiological or pathological factors. Let’s list the factors that have been purported to cause gum recession, (clinically referred to as “gingival recession”), and explain the reasoning behind each factor.

1. Aging:  Getting older does not necessarily cause gingival recession however increased age is certainly correlated with an increased prevalence of gingival recession.  At least two studies have found that the frequency of gingival recession increased with age and was greater in men than in women of the same age. In essence, all of the factors that have the ability to affect gingival recession simply have longer to act the older a person becomes, therefore aging is a factor in the prevalence of recession.
2. Anatomic Factors: Because gum recession is simply a reflection of changes to the supporting bone beneath the gum tissue, a lack of bone growth around the roots of the teeth can be a cause of gingival recession. Therefore, if a lack of bone growth around a tooth root causes the width of a tooth to be wider than the bone it is housed in, gum recession will result. Similarly, if a tooth does not erupt in a normal direction out of the jaw bone (i.e. slightly to the side and not straight), there will be thin or inadequate bone on one side of the tooth and thick bone on the opposite side; thin bone is more susceptible to breakdown and thus may be a cause for gingival recession, while an absence of bone over the root surface, (referred to as a dehiscence), can also cause gum recession.
3. Orthodontic Tooth Movement:  The movement of teeth in the jawbones using orthodontics (wires, brackets, and springs) is normally a harmless process. On the other hand, occasionally teeth are moved with orthodontic forces in such a manner that the roots are pushed beyond their boney housing, called the alveolus.  This results in a portion of the root having no bone covering it, (usually on the cheek side rather than the tongue side), and therefore causes the gums to recede onto the root surface. This is the exact same process as the example in section B, only the movement of the tooth outside the alveolar bone is cause by a dentist rather than occurring naturally.
4. Periodontal Disease:  Periodontal disease is a bacterial process that causes breakdown of the bone around the roots of teeth. Just like the walls of a house hold up its roof, the bone supports the gum tissue.  If the bone gets destroyed in the process of periodontal disease, the gums may “collapse” in places around the teeth causing a movement of the gums relative to the enamel thus creating recession. Typically someone that has recession due to gum disease would have large spaces between their teeth and gums since the bone that would normally support the gum tissue between the roots is destroyed.
5. Trauma: Repeated trauma to gum tissue may cause the gum tissue to recede. This trauma can take many forms:
1. Vigorous tooth brushing, especially with a toothbrush that doesn’t have soft bristles.  Many studies have found a relationship between tooth brushing technique and gum recession; the purported cause of the recession is the “saw-like” mechanical abrasion of the toothbrush bristles against the gum tissue.  A V-shaped notch in the root surface often accompanies this gum recession.
2. Aberrant frenal attachment:  It is argued by some that the thin bridge of tissue that connects the inside of the lip to the gums (called a frenulum) may create a pulling force, which causes gum recession.  In the literature, there does not seem to be much agreement on this theory however.
3. Occlusal Trauma:  Occlusion is the term we use to describe the way the upper teeth come into contact with the lower teeth. The forces put upon the teeth are determined by many factors including the alignment of the teeth with one and other, the biting pressure put upon them, as well as which and how many teeth contact one and other. When one or more of these factors create “traumatic” stresses on the teeth, it is believed by some that these stresses are transferred to the alveolar bone surrounding the roots, thus creating gum recession. (Remember that gum recession is caused by a lack of supporting bone.)  
4. Hygiene:  It’s been determined that gingival recession occurs more frequently in individuals with good rather than poor oral hygiene. The theory is that those people who have good oral hygiene brush more frequently or too vigorously  thus creating gum recession.  There has been at least one study that found a positive correlation between brushing frequency and gingival recession.