Discoloration means the tooth is in trouble.

When a tooth is traumatized such that the pulp bleeds without breaking the tooth, it is called tooth contusion. A contused tooth will first appear pink due to the fresh blood trapped in the dentinal tubules. With time, the discoloration becomes brown or gray as the blood components break down. In severe tooth contusions, chronic pulpitis and pulp necrosis are the most likely outcomes. Ideally, a contused tooth should be treated to alleviate pain and to save the tooth.

Teeth that look to be worn-down can be painful.

When pets aggressively chew on abrasive or hard materials, teeth dentinal tubules or, in severe cases, pulp becomes exposed; this is called tooth abrasion. In cases where the tooth’s hard protective enamel wears away over time, dentin is exposed, but pulp might survive. However, when the wear is rapid or aggressive, pulpitis, pulp necrosis and apical abscesses are likely outcomes.

Attrition refers specifically to wear caused by an opposite tooth, which happens in patients with malocclusion; where mandibular teeth abnormally contact maxillary teeth.

Under certain conditions, any tooth can be broken.

Tooth fractures can be caused by major trauma, but can also result from chewing on materials that are harder than the tooth, such as bones. Tooth fractures are classified based on the severity of damage to the tooth. In so-called uncomplicated tooth fractures, the dentinal tubules are exposed, while complicated tooth fractures, exposure of the pulp canal takes place. Further classification indicates whether the crown, root, or both are involved.

Uncomplicated tooth fracture: With these fractures, exposed dentinal tubules cause a pulp reaction, and in severe cases, significant pulp inflammation (pulpitis), which is very painful. Uncomplicated fractures may be superficial (farther away from the pulp) or deep (closer to the pulp). Superficial uncomplicated fractures may allow the pulp to heal, but deep ones pose a high risk for chronic pulpitis, pulp necrosis and apical abscess.

Complicated tooth fracture: Complicated tooth fractures by definition expose the pulp, which results in rapid development of painful pulpitis. Without treatment, chronic pulpitis progresses to pulp necrosis, and results in apical root abscess.

A common human problem that also affects dogs.

In caries disease, teeth develop lesions that damage the physical structure of the tooth. These lesions are the result of acid-producing oral bacteria destroying enamel and dentin.

Normally, these bacteria are in contact with all oral surfaces and the body’s defenses keep their numbers low enough that they do not cause harm. When these defenses are disrupted or overwhelmed by certain unbalancing conditions, the bacteria proliferate and produce acid that dissolves the hard tissues of the tooth. Caries lesions expose dentinal tubules and cause pulpitis, so they are exceptionally painful. When allowed to progress, pulp necrosis and tooth root abscess can result.

Tooth resorption can be mild and non-painful, or it may be destructive and extremely painful.

Tooth resorption is a process where the normal tissues of the tooth are replaced with another type of tissue. There are multiple contributing factors- some known, and some unknown, and several different categories, or types, that have a variety of outcomes. For example, one less problematic form is root replacement resorption, which is generally mild, limited, and may be a normal part of aging. At the opposite end of the spectrum are feline tooth resorptive lesions, which cause progressive destruction of the tooth structure; this leaves severely painful defects on tooth surfaces. Other types of resorption can result from trauma, chronic inflammation, mechanical compression, oral tumors, or systemic disease. All of these are distinctly different from caries disease, which is caused by acid-producing oral bacteria.