Why teeth become black?
This can be for a few reasons. Mostly, it is stains from too much tea, coffee, or from smoking. A big cavity can also look black. Sometimes if a tooth gets hurt, it can die from inside and become dark. Better to show a dentist to know the real problem.
Black teeth can occur due to extrinsic stains or intrinsic problems. Extrinsic stains usually happen when the enamel surface collects discoloration from food, drinks like tea, coffee, red wine, or habits such as smoking. Intrinsic causes are deeper, like cavities, dead pulp, or trauma that kills the inner tissue of the tooth. If only the surface is stained, professional cleaning or whitening can help. But if the discoloration is because of decay or pulp death, a dentist may need to do a root canal or crown.
In my experience as a dental student, blackening of teeth often points to poor oral hygiene combined with diet. For instance, people who rarely floss allow plaque to harden into tartar. This tartar then traps pigments and bacteria, giving a black or brownish color. A less common but serious cause is dental caries (tooth decay). When cavities are left untreated, they can appear as black spots and gradually destroy the structure of the tooth.
From a purely scientific angle, tooth color is determined by light reflection on enamel and dentin. When enamel is eroded due to acidic foods, brushing too hard, or age, the underlying dentin (which is naturally yellow or darker) becomes more visible. If bacteria invade and cause necrosis, the internal tissue can appear black. So, black teeth are a visual symptom of multiple possible underlying issues, ranging from surface stains to deep structural damage.
Personal note: When my grandmother’s teeth turned black, it wasn’t stains from coffee but actually medication side effects. Some liquid iron supplements and even certain antibiotics in childhood (like tetracycline) can cause permanent discoloration of teeth. It’s important to remember that not all blackened teeth are due to neglect — sometimes medical history plays a role.
When people ask why teeth become black, they usually hope for a single answer. But really, it could be: - Decay/cavities - Staining from diet/smoking - Trauma (dead tooth) - Medication side effect - Genetics (some enamel is naturally weaker) The only way to know for sure is a dental check-up with an X-ray.
Children’s teeth can also turn black if there’s baby-bottle tooth decay. This happens when babies are put to sleep with milk bottles, and sugar rests on their teeth overnight. The sugar attracts bacteria that produce acid, eroding the teeth quickly and leaving them black. Parents must clean the baby’s gums and teeth regularly to prevent this.
I grew up in a rural area where people chewed tobacco and betel nut. Over years, I noticed their teeth would turn dark brown to completely black. This happens because the chemicals in tobacco seep into enamel pores. Unlike simple coffee stains, these marks are extremely stubborn. In some cases, people developed oral cancer too. So cultural habits also explain why teeth become black.
In my clinic, I’ve seen athletes using protein shakes and energy gels. These contain sugar and stick to teeth, leading to black pits and cavities if not cleaned immediately. Also, some people grind their teeth (bruxism), which wears off enamel, making stains more pronounced. Surprisingly, even chlorhexidine mouthwash, often prescribed for gum problems, can stain teeth dark if overused.