Enamel Erosion or a Cavity: What Is Happening to Your Tooth?

Why your tooth looks or feels different

A sharp twinge with cold water, a tooth that looks more yellow than it used to, a chalky white spot near the gumline, or a filling that no longer matches the tooth around it. These are the signs that bring people in, and they can come from either erosion or decay. From the outside the two can look alike, which is why the cause has to be sorted out before the fix.

The difference comes down to where the acid comes from. In a cavity, bacteria make the acid. In erosion, the acid arrives already made, in a drink, a food or from the stomach. That one distinction changes what the dentist looks for and what you can do at home.

How a cavity forms

The National Institute of Dental and Craniofacial Research describes it plainly: tooth decay begins when bacteria in your mouth make acids that attack the tooth's surface. Those bacteria live in plaque, the sticky film that keeps forming on teeth, and they produce acid every time they meet sugars or starches. With repeated exposure, such as frequent snacking or sipping sweet drinks, enamel keeps losing minerals.

Early on, this shows up as a white spot where minerals have been lost. At that stage decay can still be stopped or reversed, because enamel can rebuild itself using minerals from saliva and fluoride. If more mineral is lost than replaced, the enamel breaks down and a cavity forms. Early decay usually has no symptoms; as it advances it can cause toothache and sensitivity to sweets, hot or cold.

Decay tends to be local. It favors the chewing grooves of back teeth, root surfaces exposed by receding gums (the ADA notes that root cementum is softer than enamel), and the edges of old fillings that have cracked or started to leak. The post on how cavities form and how long it takes covers the timeline.

How erosion happens

Erosion skips the bacteria. The ADA names soft drinks, especially soda and sports drinks, as the main culprit, and points out that carbonation raises the acid level of any drink regardless of flavor, so sugar-free versions still count. Citrus fruit and juice, sour candies and other acidic foods add to the load. The post on diet soda and your teeth explains why the sugar-free label does not protect enamel.

Stomach acid is the other common source. With acid reflux (GERD), the ADA notes that gastric acid can reach the mouth throughout the day, and erosion is often worse during sleep, when you swallow less and make less saliva. Reflux tends to wear the inside and chewing surfaces of teeth, a pattern a dentist may notice during an exam before you have noticed any symptoms.

The ADA states that tooth erosion is permanent. Signs include pain or sensitivity to hot, cold or sweet drinks, a yellowish color as thinner enamel lets the darker dentin underneath show through, fillings that start to look different from the tooth around them, and a higher cavity risk over time, because worn enamel is easier for bacteria to attack.

Dry mouth makes both worse

Saliva is the mouth's main defense against acid. The ADA describes it as the primary defense against tooth decay: it washes away food, neutralizes acids produced by bacteria, and carries the minerals that help enamel recover between acid attacks. When saliva runs low, both decay and erosion speed up, and the ADA notes that extensive decay can occur without it.

Dry mouth is usually a side effect rather than a disease on its own. Antihistamines, decongestants, pain medications, diuretics and some reflux medications can all reduce saliva, as can certain medical conditions. If your mouth is often dry, mention it at your visit; the post on how dry mouth affects your teeth covers what helps.

What your dentist does for each

Both start with an exam at a dental checkup. The dentist looks at the pattern of wear, checks for soft or sticky areas, and may take X-rays, which can show decay between teeth before it is visible. Expect questions about soda, sports drinks, citrus, heartburn and medications, because the answers often point to the cause.

• Early decay (white spot): fluoride applied in the office may stop or reverse it, along with better plaque control at home.
• A cavity: the decayed material is removed and the tooth is filled; the practice uses tooth-colored composite fillings. A larger cavity may need a crown.
• Erosion with no cavity: the goal is to stop further loss. Your dentist may suggest fluoride or desensitizing toothpaste, diet changes, and a referral to your physician if reflux is suspected.
• Erosion with damage: worn or sensitive teeth may need fillings, bonding or crowns to rebuild the surface and cover exposed dentin.
• Either one with sensitivity: the guide on why teeth are sensitive explains the options, from desensitizing toothpaste to in-office fluoride.

Habits that protect enamel from both

Most of the advice overlaps, which is convenient. The ADA's oral hygiene basics of brushing twice a day with fluoride toothpaste and cleaning between teeth daily protect against decay, and a few timing changes protect against erosion. Adults who get frequent cavities or have thin, sensitive enamel may also benefit from extra fluoride; the guide on fluoride for adults explains the choices.

• Wait about an hour after acidic food or drink before brushing, so saliva can re-harden the softened enamel first.
• If you drink soda or sports drinks, use a straw, sip and swallow rather than holding the drink in your mouth, and avoid sipping all day.
• Rinse with water after something acidic, or follow it with milk or cheese, which help neutralize acid.
• Chew sugar-free gum to boost saliva, especially if your mouth is dry.
• Limit snacking and keep sugary or starchy foods to mealtimes, so acid attacks happen less often.
• If you have heartburn or reflux, talk to your physician; treating the stomach problem protects the teeth.