The term “bruised tooth” is commonly used to describe the internal trauma a tooth sustains after a significant blow, even though teeth cannot bruise like skin or muscle tissue. This injury, often called a dental concussion, involves damage to the delicate structures within and around the tooth. When a tooth experiences blunt force, the resulting pain, tenderness, and discoloration mimic a soft tissue bruise. Recognizing these anatomical changes is important for determining when professional dental evaluation is required to prevent long-term damage.
Why Teeth Don’t Bruise (And What Happens Instead)
A true bruise occurs in soft tissues because they contain capillaries that rupture and release blood, which then pools under the surface. Teeth are primarily composed of hard, non-living tissues—enamel and dentin—which lack the necessary blood vessels to sustain a bruise. Trauma is instead focused on two main areas: the pulp and the periodontal ligament.
The dental pulp, located deep inside the tooth, houses the nerves, connective tissue, and blood vessels. An impact can cause inflammation within this confined space, known as pulpitis, or rupture the blood vessels at the root tip, leading to internal bleeding. Because the pulp is encased in hard dentin, the resulting pressure can compromise the blood supply and lead to the death of the pulp tissue.
The periodontal ligament (PDL) is a network of fibers that anchors the tooth root to the jawbone. When struck, the PDL acts as a shock absorber, and its fibers can become stretched or torn. This injury results in localized tenderness and pain when biting down or touching the tooth. A dental concussion refers to trauma where the PDL is damaged without the tooth becoming noticeably loose or displaced.
Identifying the Signs of Internal Tooth Injury
The symptoms that lead people to describe a tooth as “bruised” are visible evidence of internal damage. Tooth discoloration is a primary sign, often developing days or weeks after the initial trauma. This graying, yellowing, or darkening is caused by the breakdown products of blood that leaked from ruptured vessels inside the pulp chamber. As hemoglobin is metabolized, it stains the surrounding dentin, making the tooth appear darker than adjacent teeth.
Patients may experience increased sensitivity to extreme temperatures, particularly cold, or a lingering, throbbing pain. This sensitivity results from inflammation (pulpitis), where the damaged nerve is irritated by thermal changes. A concussed tooth may also feel mildly loose or tender to the touch, especially when chewing. This tenderness is due to the inflammation of the periodontal ligament, which makes closing the mouth painful.
Professional Diagnosis and Treatment Options
A professional dental examination is necessary to accurately assess the extent of the internal injury after a significant impact. The dentist uses diagnostic tools to determine the vitality of the dental pulp. A pulp vitality test, often involving a cold stimulus, checks for nerve response; a lack of response may indicate that the pulp has died.
X-rays are taken to check for damage such as root fractures or changes in the supporting bone structure. They can also reveal widening of the periodontal ligament space, which confirms injury to the supporting fibers. Based on these findings, the treatment path is determined.
For mild dental concussions where the pulp is still vital, the initial treatment is careful monitoring over several months. The tooth may heal on its own, but follow-up appointments are necessary to ensure the nerve remains healthy. If the pulp dies (becomes non-vital), indicated by persistent discoloration or a negative vitality test, endodontic treatment (a root canal) is required. This procedure removes the dead and infected pulp tissue to save the tooth structure and prevent infection.