An infected tooth can look surprisingly different depending on how far the infection has progressed. In early stages, the tooth itself may appear normal while the surrounding gum shows redness and swelling. As the infection advances, you may notice the tooth changing color, a visible bump on the gum, pus drainage, or swelling that extends into the face and jaw.
Changes to the Tooth Itself
A healthy tooth is some shade of white or off-white. When the inner tissue (the pulp) becomes infected and starts to die, the tooth often darkens noticeably. The color shift happens because blood from damaged vessels seeps into the tiny tubes that make up the tooth’s inner structure. As that trapped blood breaks down, it leaves behind iron-rich deposits that stain the tooth from the inside out.
The specific color tells part of the story. A tooth turning dark gray, grayish-blue, or dark brown typically signals that the pulp tissue has died. A pinkish hue can mean the tooth is being slowly dissolved from the inside, a process called internal resorption. A yellowish discoloration, especially one that develops later, usually means the body has tried to wall off the infection by filling the pulp chamber with extra mineral deposits. Not every infected tooth changes color, though. Some infections progress without any visible discoloration at all, particularly in the early stages.
What the Gums Look Like Around an Infected Tooth
The gum tissue surrounding an infected tooth often provides the most obvious visual clues. Redness and puffiness right at the gum line are common early signs. As an infection deepens, you may see a small, pimple-like bump on the gum near the root of the tooth. This bump is a drainage channel the body creates to release pressure from the buildup of pus below. It may appear white or yellowish at its center and can come and go over weeks or months. When it opens, you might notice a salty or foul taste in your mouth.
In more advanced infections, the gum may look shiny and stretched from swelling. You might also see pus oozing from around the tooth itself or from between the tooth and the gum line. The tissue can appear deep red or even purplish compared to the healthy pink gum elsewhere in your mouth.
Swelling Beyond the Mouth
One of the more alarming visible signs of a tooth infection is swelling that spreads beyond the gum. Depending on which tooth is infected, swelling can appear along the jawline, in the cheek, or up toward the eye. An infected lower tooth often causes swelling under the jaw or along the neck, while an upper tooth infection may cause the cheek or the area beside the nose to puff up. The skin over the swollen area may feel warm and look taut or red.
You may also notice tender, swollen lymph nodes under your jaw or along the sides of your neck. These feel like firm, marble-sized lumps and are a sign your immune system is actively fighting the infection.
Slow Infections vs. Fast Ones
Not all tooth infections look or feel the same, and the visual signs depend heavily on the type.
A slow-building chronic infection can be deceptively quiet. It often causes little or no pain and may only show itself as that small gum bump that drains pus intermittently. You might not even realize you have an infection until a dentist spots bone loss on an X-ray. These chronic infections can simmer for months.
An acute infection, by contrast, announces itself aggressively. It comes on fast with spontaneous, throbbing pain, and the tooth becomes extremely tender to any pressure. Swelling develops rapidly and can distort the shape of your face within hours. You may also feel generally unwell, with a fever and fatigue. The gum around the tooth looks angry and inflamed, and pus may be visibly present.
Earlier still, before the pulp has died, an infection in its reversible stage shows almost no visual signs. Pain comes only when something cold or sweet touches the tooth and fades within seconds. At this point, the tooth looks completely normal from the outside, and even an X-ray may show nothing unusual near the root.
What a Dentist Sees on X-Rays
Much of what makes a tooth infection dangerous is invisible to the naked eye. Dentists rely on X-rays to see how far the infection has spread beneath the surface. A telltale sign is a dark shadow at the tip of the tooth’s root, which indicates that the infection has started destroying the surrounding bone. The larger that dark area, the more bone has been lost.
In some cases, especially when the infection may have spread into the neck or deeper facial tissues, a 3D CT scan gives a more detailed picture. This helps determine whether the infection is contained near the tooth or has moved into spaces that could become dangerous.
Signs the Infection Is Spreading
Certain visual and physical changes signal that a tooth infection has moved beyond the tooth and into surrounding tissues. Swelling in the face, cheek, or neck that keeps growing is a serious warning sign. Difficulty opening your mouth, sometimes called lockjaw, means the infection has reached the muscles involved in chewing. Difficulty breathing or swallowing suggests swelling is affecting the airway or throat, which is a medical emergency.
Other signs of spreading infection include a fever that won’t break, swollen lymph nodes, a general feeling of being very unwell, and a rapid heart rate. A red streak or area of firmness spreading outward from the swelling also suggests the infection is moving through tissue. These signs warrant immediate care, not a wait-and-see approach.