Attrition is the physiologic wear of teeth as a result of heavy chewing, biting, or wearing against other teeth (like from orthodontic malocclusion). Abrasion is similar, but is due to external forces like aggressive brushing or use of dental instruments.

Normal teeth have an outer layer of enamel (the hardest substance in the body), then underlying dentin which makes up of the bulk of the tooth, and finally the inner pulp canal which is where the blood vessels and nerves reside. Teeth with attrition appear shortened in height due to loss of enamel and dentin. With slow wear, crown surfaces become smooth and flat, with tan-to-brown reparative dentin visible in the center. Teeth with rapid wear may have exposed pulp canals. Incisors showing attrition may be due to a level bite (see Orthodontics) or secondary to skin allergies. Tennis balls and frisbees are often the cause of wear of the canines and premolars. The surface of a tennis ball is similar to fine sandpaper, especially when dirt and grit are present. Dogs that chew on metal cages or fences often display canine attrition on the backside of the teeth (show photo). Chewing on excessively hard objects (see list) results in attrition of premolars and molars.

Teeth with slow enough wear will often display what is called reparative (aka tertiary) dentin. The process of laying down reparative dentin is a protective mechanism of the body. As enamel is worn off and the underlying regular dentin is exposed, odontoblast cells lining the pulp canal respond and form reparative dentin on the pulpal side of the exposed dentin. The pulp recedes behind this deposited mineralized layer and remains protected from exposure. Reparative dentin appears as a darker colored stain in the areas of the tooth that are most worn. It is denser than regular dentin and lacks organized tubules.

If tooth wear occurs slowly and adequate reparative dentin is formed, the tooth pulp may be unaffected and treatment may not be necessary. However, if attrition takes place rapidly, the pulp may become inflamed (see Pulpitis). Further, rapid attrition can result in pulp canal exposure, followed by bacterial infection, tooth root abscess, and eventual tooth death.

Diagnostics
Dental attrition necessitates a complete oral exam including orthodontic assessment. Transillumination may be performed to evaluate pulp vitality. A dental explorer, drawn across the worn tooth surface should feel smooth. For complete tooth evaluation, dental x-rays are needed. Signs of endodontic pathology may include wider than normal pulp canals due to odontoblast death and delayed maturation; narrowed, strictured, or obliterated pulp canals due to accelerated calcification; periapical radiolucency; and/or internal or external root resorption.

What to do

• For teeth displaying gradual attrition yet no pulp compromise or canal exposure, treatment may not be necessary. Monitoring is advised and efforts should be made to rectify the cause.
• For teeth with rapid wear or fracture, with healthy pulp and no canal exposure, a dentinal bonding agent may be considered. This material seals dentinal tubules and prevents influx of bacteria and bacterial by-products. The provided protection is temporary and the sealant eventually will be lost to attrition itself. However, benefit may be obtained in that the pulp is protected long enough to produce a natural seal through the production of reparative dentin. (Note: Dentinal sealants provide no benefit for teeth that have already formed a protective barrier of reparative dentin.)
• When wear is extensive and pulp canal exposure has resulted, endodontic treatment or extraction are required (see Fractured teeth). In some cases of severe attrition, metal crown placement may be considered to provide structural protection to the weakened tooth.