Dental tartar is hardened plaque that has mineralized on your teeth. Once soft, sticky plaque sits on a tooth surface long enough, minerals from your saliva crystallize within it, turning it into a crusty deposit that you can’t brush or floss away. Tartar (also called calculus) can form in as little as one to 14 days after plaque first appears, and it typically reaches 60 to 90 percent of its full mineral hardness within about 12 days.
What Tartar Is Made Of
Tartar is mostly inorganic mineral, primarily calcium phosphate and calcium carbonate, held together with a smaller fraction of organic material like proteins and carbohydrates. Think of it as a cement-like shell built from the same minerals floating in your saliva. It bonds tightly to tooth enamel and root surfaces, which is why no amount of vigorous brushing at home can chip it off.
How Plaque Turns Into Tartar
The process starts with bacteria. A thin film of bacteria constantly forms on your teeth, feeding on food particles and producing acids. As these bacteria metabolize, they raise the pH of the surrounding environment. When the local pH climbs above roughly 7.6, conditions become ideal for calcium and phosphate in your saliva to crystallize directly within the bacterial film. The bacteria essentially armor themselves with minerals drawn from saliva, and the soft plaque gradually hardens into tartar.
Saliva flow plays a big role in where tartar shows up first. The areas of your mouth closest to salivary glands get the heaviest mineral exposure. That’s why tartar tends to build up fastest on the inside surfaces of your lower front teeth and the outer surfaces of your upper molars, right where saliva enters your mouth.
Above the Gumline vs. Below It
Not all tartar is the same, and location matters a lot for your health.
- Supragingival tartar sits above the gumline where you can see it. It usually appears as a yellowish or off-white crusty buildup, most noticeable behind the lower front teeth. It’s cosmetically unpleasant and traps more plaque, but it’s also the easier type for your dentist to spot and remove.
- Subgingival tartar forms below the gumline, inside the small pocket between your tooth and gum tissue. It tends to be darker, sometimes brown or black, because it picks up pigments from blood in inflamed gum tissue. This type is far more damaging because it sits in direct contact with delicate gum and bone tissue, and you have no way of knowing it’s there without a dental exam.
Why Tartar Causes Gum Disease
Tartar’s rough, porous surface creates an ideal home for bacteria to attach and multiply. The deposit acts like a reef, constantly accumulating new layers of living bacteria on top of its mineralized surface. Because tartar tends to collect right along the gumline, these bacteria sit in constant contact with gum tissue, producing toxins that trigger chronic inflammation.
In the early stage, this shows up as gingivitis: red, swollen, bleeding gums. If the tartar isn’t removed, the inflammation can progress to periodontitis, where the immune response starts breaking down the bone and connective tissue that hold your teeth in place. Advanced periodontitis leads to deepening pockets around teeth, pus, exposed roots, and eventually tooth loss. The chronic inflammation involved in periodontitis doesn’t stay confined to your mouth, either. Researchers have linked it to increased risk of cardiovascular disease and complications in managing diabetes, because inflammatory signals and bacteria can enter the bloodstream through damaged gum tissue.
How Dentists Find and Remove It
Supragingival tartar is easy to spot during a visual exam. Subgingival tartar is trickier. The standard method involves sliding a thin metal probe or explorer along the root surface below the gumline, feeling for the rough texture of calculus against what should be smooth tooth structure. This tactile approach works reasonably well, but it misses a lot. One study comparing probe detection to microscopic examination found that probing identified residual tartar on 19 percent of root surfaces, while microscopic evaluation revealed it on 58 percent. Traditional dental X-rays aren’t much help either, unless the buildup between teeth is substantial. For cases that need more precision, some offices use periodontal endoscopes (tiny cameras that illuminate the root surface inside the pocket) to visualize flat, burnished deposits that a probe can’t feel.
Removal itself relies on scaling, either with hand instruments or powered devices. Ultrasonic scalers use a water-cooled metal tip vibrating at high frequency to fracture tartar off the tooth surface. The vibration breaks the bond between the mineral deposit and the enamel or root, while the water spray flushes debris out of the pocket. Your dental team controls tip angle and pressure carefully, because too much force or prolonged contact can damage the root surface. For significant subgingival buildup, the procedure is called scaling and root planing, which involves cleaning below the gumline and smoothing rough spots on the root to discourage new tartar from forming.
Preventing Buildup at Home
Since tartar is mineralized plaque, prevention comes down to removing plaque before it has a chance to harden. Brushing twice a day and flossing daily disrupts the bacterial film during the window before mineralization begins. Tartar-control toothpastes add a chemical layer of protection. Most contain pyrophosphates, which work by blocking calcium phosphate crystals from forming in plaque. Some formulations include zinc, which elevates zinc levels in saliva for several hours after brushing and independently inhibits the crystal growth that turns plaque into calculus. These ingredients can slow new tartar formation on the surfaces you can reach, but they do nothing against deposits that already exist.
People who produce a lot of saliva, have naturally alkaline saliva, or tend toward heavy plaque buildup will form tartar faster regardless of how well they brush. For heavy formers, professional cleanings every six months (or more frequently if your dentist recommends it) are the only reliable way to keep tartar from accumulating to the point where it threatens gum health.