Cavities change appearance as they progress, starting as faint white spots and eventually becoming visible holes with dark discoloration. In the earliest stage, you might not notice anything at all without drying the tooth surface first. As decay advances through the layers of your tooth, the signs become harder to miss: color shifts from white to brown to black, the surface texture roughens, and eventually a physical pit or hole forms.
The Earliest Stage: White Spots
Before a cavity becomes a cavity, your tooth gives a subtle warning. The first visual sign is a small, chalky white spot on the enamel. This happens because acids from bacteria dissolve minerals just beneath the tooth’s surface, creating tiny pores inside the enamel. Those pores scatter light differently than healthy enamel, producing an opaque, matte-white patch that lacks the natural gloss of the surrounding tooth.
These white spot lesions are easy to miss. In many cases, they’re only visible after the tooth surface has been dried, since saliva fills in the pores and masks the color difference. If you’ve ever noticed a dull white patch on a tooth after brushing that seems to disappear once your mouth is wet again, that’s what early demineralization looks like. At this point, the surface is still intact and the damage is potentially reversible with fluoride and better oral hygiene.
Color Changes as Decay Progresses
If that white spot isn’t addressed, the color darkens in a predictable sequence. As decay works deeper into the enamel, the white patch turns light brown. This brownish discoloration means the enamel is actively breaking down, and small holes may start forming at this stage.
Once decay reaches the dentin, the softer layer beneath your enamel, the spots darken further to a deeper brown. Dentin decays faster than enamel because it’s less mineralized, so things can accelerate quickly at this point. If the decay continues inward and reaches the pulp (the innermost tissue containing nerves and blood vessels), the discoloration may turn dark brown or black. At this advanced stage, you’re likely also experiencing pain, sensitivity, or both.
Sometimes you’ll see a grayish or bluish shadow showing through what looks like intact enamel. This happens when dentin underneath has decayed significantly while the enamel surface above it remains mostly whole. The discolored dentin shows through the translucent enamel like a bruise under skin, and it’s often easier to spot when the tooth is wet.
What the Surface Feels and Looks Like
Beyond color, cavities change the physical texture of your tooth. Early on, the enamel surface loses its smoothness and becomes slightly rough or chalky to the touch. As the cavity grows, you may notice an actual pit, divot, or hole in the tooth. These openings often start small, sometimes barely visible, but widen and deepen over time if left untreated.
The surface around a cavity can feel sticky when you run your tongue over it. Healthy enamel is smooth and hard. A decayed area feels different: softer, tackier, sometimes with a sharp edge where enamel has chipped away. Cavities on the chewing surfaces of molars tend to form in the natural grooves and pits of the tooth, making them look like the fissure has widened or deepened unnaturally. On flat surfaces, a cavity is more likely to appear as a distinct spot or divot surrounded by otherwise normal-looking enamel.
Cavities You Can’t Easily See
Some of the most common cavities form between teeth, where you can’t see them in a mirror. These interproximal cavities are one reason dental X-rays exist. You might notice indirect signs: a dark shadow visible when light passes through the tooth, floss that shreds in a particular spot, or sensitivity when biting down. But in many cases, cavities between teeth produce no visible signs at all until they’re fairly advanced. Your dentist detects these primarily through X-rays, since even clinical examination with specialized lighting tools has limits for catching decay in these tight spaces.
Cavities vs. Stains
Not every dark spot on a tooth is a cavity, and telling the difference matters. A few key distinctions help:
- Location and pattern: Stains from coffee, tea, or tobacco tend to affect broad areas or multiple teeth at once. A cavity typically appears as a single, localized spot on one tooth, often in a groove, pit, or along the gumline.
- Color: Stains can be yellow, brown, or even greenish, and they usually look uniform. Cavity discoloration tends toward brown, black, or gray and may look like it’s coming from within the tooth rather than sitting on the surface.
- Texture: A stained tooth still feels smooth and hard. A cavity often feels rough, sticky, or soft. If you can feel a pit or catch a spot with your fingernail, that’s more consistent with decay.
- Visible holes: Stains don’t create openings in the tooth. If you see an actual hole or pit alongside the discoloration, it’s almost certainly a cavity.
Decay Around Existing Fillings
Teeth that have already been filled can develop new cavities along the edges of the restoration. This recurrent decay forms when small gaps or cracks develop between the filling material and the tooth, letting bacteria sneak underneath. Visually, the signs include brown or black staining around the margins of a filling, visible cracks or chips in the filling itself, or a filling that looks like it no longer fits flush with the surrounding tooth. The filling may appear raised, sunken, or slightly shifted compared to how it originally looked. If you notice darkening specifically around the border of an old filling, that’s worth getting checked.
What Each Stage Looks Like at a Glance
- Stage 1 (demineralization): Chalky white spot, visible mainly on a dry tooth, no hole yet.
- Stage 2 (enamel decay): White spot darkens to light brown, small hole may form.
- Stage 3 (dentin decay): Darker brown discoloration, noticeable pit or hole, likely sensitivity to hot, cold, or sweets.
- Stage 4 (pulp involvement): Dark brown or black spots, larger hole, significant pain possible.
- Stage 5 (abscess): Extensive visible damage, swelling in the gum near the tooth, potential pus drainage.
The tricky part is that cavities in their earliest, most treatable stages are also the hardest to spot. By the time a cavity is clearly visible as a dark hole, the decay has already progressed well beyond the surface. Regular dental exams catch what your mirror can’t, particularly cavities between teeth or beneath the enamel surface that are invisible from the outside.