Dental Wear, Prevention, and Treatment
Dental wear is due to a variety of reasons, including erosion, tooth bending (flexure), abrasion (e.g. toothbrush), and tooth to tooth contact (attrition). Usually, a combination of causes is responsible for damage in an individual, but this discussion will be limited to the tooth to tooth wear.
The above series shows the progress of wear on different patients. Enamel should wear at a rate of 11 microns a year in a healthy situation. That is only about 1 mm in 90 years. The top photo is on an 11-year-old, with most of the original enamel intact. The bottom photo shows repair done with a laser and composite bonding done at an early stage.
Teeth are composed of four parts – enamel, dentin, cementum (covering of the root) and the pulp (blood vessels and nerves). The tooth components important in this issue are enamel and dentin. Enamel is the hardest substance in the body and completely encases the crown of an erupting tooth. With use, some enamel is lost, though there is an adequate thickness of enamel to protect a tooth for a lifetime with normal wear and tear. With abnormal (pathological) wear, the enamel is completely lost in some areas, which exposes the underlying dentin. Since dentin wears seven times faster than enamel, even if the original cause of the problem is stopped, the dentin will still degrade fairly quickly. The undermined neighboring enamel, which is brittle, will start to chip away. This whole portion of the tooth then breaks down at a relatively rapid pace. It can easily lead to a 50% loss of height of a lower front tooth, and sometimes greater, all the way to the gum line.
Teeth rarely stay together in normal daily activities. Thus, damage from tooth to tooth contact is classified as abnormal or pathological. The destruction comes from the biting muscles not releasing properly when the teeth hit together and move. Movement under compression causes friction – this is “grinding” or “bruxism”. Although some people are aware of daytime grinding, most problems occur while sleeping. There are certain times in the sleep cycle when clenching and grinding occur, and the most severe activity is usually early morning. About 5% of the population is “hard wired” for bruxism. Other people often grind because a tooth or teeth do not fit together properly and the body tries to “erase” the ill-fitting area.
The most common treatment for bruxism is a customized “bite guard”. This is typically an acrylic appliance made to fit all of either the upper or lower teeth. It does protect the teeth but does not stop the grinding activity. This may lead to strain or damage to the temporomandibular joint (TMJ). A better adaptation is to add a small, flat, raised “plane” on the front of the bite guard. This “turns off”, or at least decreases the contraction of the biting muscles. An alternative to coverage of all the teeth in an arch is a small device (NTI) utilizing the flat, raised portion, but covering only a few front teeth. Sometimes it is necessary to adjust the way the teeth hit together by reshaping the teeth (occlusal equilibration) or tooth movement (orthodontics or Invisalign).
When damage to the teeth has already occurred, the teeth need to be restored to a healthy, functional, and attractive state. In the early stages, a laser can be used to create a small groove in the tooth surface where the dentin is exposed. A dental composite is bonded within the groove to create a stronger, more resistant surface. In later stages, porcelain veneers or crowns must be used. Sometimes root canals and/or periodontal surgery is necessary. A simple exam can detect these problems early. The sooner the wear issue is dealt with, the better, but it is never too late to maintain what you have.