An abfraction lesion (“lesion” refers to an area of tooth damage) is a loss of enamel or dentin (or both) from the tooth surface and is believed to be caused or produced by one or more of the following:
1. Erosion or corrosion: tooth surface loss (demineralization) caused by chemical action such as gastric acids involved with acid reflux disease, highly-acidic foods and beverages, or bulimia. Toothbrush abrasion can make erosion/corrosion worse.
2. Excessive chewing/biting forces, such as grinding (bruxism)
3. Clenching the teeth
4. Malocclusion (bite problems)
5. Tongue thrusting habits
Biting and Chewing Forces Due to the strength of the jaw muscles, maximum biting forces of 400 pounds per square inch can be achieved and then transferred to the teeth. Grinding, clenching or malocclusion can result in teeth receiving traumatic loading forces that can cause tooth structure to bend or flex repeatedly and over time, can result in stress lines, cracks and fractures in tooth enamel and/or dentin.
Although this mechanism is not yet well understood, the bending forces put on the enamel may cause it to break down or dissolve, damaging the tooth in the process by removing part of the protective enamel layer. For example, at the gum line area of the tooth, a section of enamel can break down where the crown meets the root (at the CEJ, or cementoenamel junction) causing exposure of the sensitive dentin and/or root surface underneath. These forces can also damage (crack or break) tooth restorations, such as fillings, porcelain veneers and crowns.
Acid Reflux Acid reflux is often called acid indigestion, “sour stomach” or heartburn and happens occasionally to most people. Chronic acid reflux is referred to as GERD (gastroesophageal reflux disease) and is a relatively common condition experienced by, and diagnosed in, children and adults. GERD can cause erosive damage to the esophagus if not treated. Acid reflux is also thought to affect the mouth by exposing the teeth to very strong gastric acids, primarily hydrochloric acid. If GERD is not treated, over time the exposure to these gastric acids can make tooth structure more susceptible to erosion/corrosion (dissolving away), or contribute to erosion or abfraction when combined with toothbrush abrasion (i.e. improper tooth brushing by use of a hard bristle brush, use of abrasive toothpastes or overuse of electric toothbrushes). While GERD is treatable with prescription medications, patients may not be fully aware they have the condition – some patients may dismiss GERD as only “mild heartburn” and self-medicate with over the counter antacids.
Excessive/Traumatic Forces on Teeth Patients are often unaware of the excessive or traumatic forces being put on their teeth, and when an abfraction lesion occurs, patients often visit their dentist complaining of tooth sensitivity. Some patients may notice an abfraction by the appearance of a “notched out” area of the tooth at the gumline, which may also appear like an exposed root surface. Following an examination by the dentist to evaluate the bite (occlusion) and to either confirm or rule out conditions such as toothbrush abrasion, erosion (caused by acid reflux, bulimia, or excess soft drink consumption), tooth decay (caries) and cracked tooth syndrome, an accurate diagnosis of abfraction can be made.
Determining the Cause of an Abfraction Abfractions are very common and most often occur on posterior teeth such as the premolars (bicuspids) and molars. Before an abfraction lesion can be effectively treated/restored, the source and/or cause of the abfraction must be diagnosed and resolved if possible. If the cause of the abfraction is not diagnosed and corrected, the harmful forces or effects on the tooth/teeth will continue, and this can cause a new abfraction to form around the restoration that was intended to treat the problem, or possibly cause the restoration itself to fail.