The sensation of a tooth feeling sore, tender, or “bruised” suggests a problem deeper than a simple surface ache. This feeling is described as tenderness when biting down or a dull, deep pressure, distinct from the sharp sting of cold sensitivity. Understanding the underlying structures that cause this unique discomfort helps identify the source and guide the next steps toward relief.
Why Teeth Can Feel Sore
The perception of a bruised tooth does not come from the hard enamel or dentin, which lack the nerve endings to register that type of pain. Instead, the soreness originates in the sophisticated support system that holds the tooth within the jawbone. This system is the periodontal ligament (PDL), connective tissue fibers that function as a shock absorber.
The PDL acts like a hammock, suspending the tooth in its socket and cushioning it against the forces of chewing and biting. When excessive pressure or trauma occurs, the PDL fibers become strained and inflamed, much like a sprained ankle. Because the PDL is richly supplied with nerve endings, inflammation translates directly into tenderness, making the tooth sensitive to pressure. While the dental pulp can contribute to a deep, aching pain, the specific bruised sensation is usually rooted in the strained ligament.
Causes Related to Pressure and Stress
One of the most frequent mechanical causes of a bruised sensation is chronic teeth grinding or clenching, known professionally as bruxism. This often unconscious habit subjects the teeth to immense pressure that overworks the PDL. The constant strain on the ligament fibers leads to inflammation, which is then felt as generalized soreness or tenderness upon waking or throughout the day.
Acute physical trauma, such as a sports injury, a fall, or biting down unexpectedly on a hard object like a seed or ice, can also cause an immediate “sprain” of the periodontal ligament. While the tooth may not be visibly chipped or broken, the impact damages the fibers connecting the root to the bone. This can cause the tooth to feel tender to the touch, sometimes lasting several days to a few weeks as the ligament attempts to heal.
Another source of localized stress is a malocclusion, often caused by a recent dental restoration, such as a new filling or crown, that is slightly “high.” If a restoration is not perfectly contoured, it can cause disproportionate biting force to be concentrated on that single tooth. This uneven pressure repeatedly slams the tooth into its socket, inflaming the underlying PDL and creating a bruised feeling every time the teeth meet. Adjusting the bite is necessary to relieve this mechanical stress.
Causes Related to Inflammation and External Sources
The bruised feeling can also be a symptom of inflammation or infection originating from within the tooth or from an external source. A common example of referred pain comes from the maxillary sinuses, air-filled cavities located just above the roots of the upper back teeth. When a sinus infection (sinusitis) causes inflammation and mucus buildup, the resulting pressure can press down on the tooth roots and nearby nerves.
This pressure-induced irritation is perceived by the brain as a dull, bruised ache in the upper teeth, even though the teeth themselves are healthy. Sinus-related tooth pain often affects multiple upper teeth at once, and it may worsen when bending over or lying down due to changes in fluid pressure. This deep ache is distinct from the pain caused by a cavity and usually resolves once the underlying sinus issue is treated.
Internal Inflammation and Infection
When the pain originates from inside the tooth, it is often due to pulpitis, which is inflammation of the dental pulp containing the nerves and blood vessels. This condition results from deep decay, a hairline crack, or repeated dental procedures that compromise the pulp chamber. As the pulp swells within the rigid confines of the tooth structure, the pressure builds, leading to a deep, throbbing, or bruised sensation that can be difficult to pinpoint.
An advanced infection that has traveled through the tooth root and formed an abscess at the tip can also create significant soreness. This infection creates swelling and pus that puts intense pressure on the bone and surrounding PDL, leading to a tooth that feels pushed up or extremely tender to pressure. Active periodontal disease, which involves inflammation and infection of the gum and bone tissue supporting the tooth, can similarly cause chronic tenderness around the root.
Seeking Diagnosis and Relief
Because the feeling of a bruised tooth can stem from mechanical stress, infection, or referred pain, professional diagnosis is necessary to determine the underlying cause. If the soreness persists for more than a day or two, or if it is accompanied by swelling, a fever, or an inability to close your mouth, it requires immediate attention from a dental professional. Ignoring persistent soreness risks allowing an infection to spread or a mechanical issue to cause permanent damage.
Diagnosis
During an examination, the dentist will use several diagnostic tools to isolate the source of the pain. These may include dental X-rays to check for signs of infection at the root tip or bone loss, and a careful assessment of your bite to identify any high spots on restorations. The dentist may also use tapping tests or temperature sensitivity tests to determine if the pain is coming from the ligament or the internal nerve.
Immediate Relief
While waiting for your appointment, you can take steps to manage the discomfort and prevent further irritation. Over-the-counter anti-inflammatory medications can help reduce the swelling in the periodontal ligament and surrounding tissues. It is also helpful to stick to a soft diet, avoid chewing on the sore side, and consciously try to relax your jaw muscles to minimize clenching.