Cavities are caused by bacteria in your mouth that feed on sugars and produce acid. That acid gradually dissolves tooth enamel, creating a hole. The process requires three things: bacteria, sugar, and time. Poor oral hygiene, frequent sugar exposure, and dry mouth all accelerate the process. Cavities are preventable — but once a hole forms, it cannot heal on its own.
What You'll Learn
How Cavities Form
Your mouth is home to hundreds of species of bacteria. Some of these bacteria — particularly Streptococcus mutans — feed on the sugars and starches in the food you eat. As they digest these sugars, they produce acids as a byproduct.
These acids attack tooth enamel — the hard outer layer of your teeth. Enamel is the hardest substance in the human body, but it is not immune to acid. Over time, repeated acid attacks weaken and dissolve the mineral structure of enamel in a process called demineralization.
Saliva helps neutralize these acids and remineralize enamel between meals. But when acid attacks are frequent — from constant snacking or sipping sugary drinks — saliva cannot keep up, and a cavity begins to form.
What Increases Your Cavity Risk
Frequent sugar and starch consumption
Every time you eat sugar or starch, bacteria produce acid for about 20 minutes. Frequent snacking means your teeth are under near-constant acid attack.
Sugary and acidic drinks
Soda, juice, sports drinks, and even sparkling water are acidic and feed cavity-causing bacteria. Sipping them throughout the day is especially damaging.
Poor oral hygiene
Infrequent brushing and skipping flossing allow plaque — a sticky film of bacteria — to accumulate on teeth and between them.
Dry mouth
Saliva is your mouth's natural defense against cavities. Medications, medical conditions, and mouth breathing can reduce saliva flow and dramatically increase cavity risk.
Deep grooves and pits in teeth
Back teeth (molars and premolars) have deep grooves where food and bacteria collect. Dental sealants can protect these surfaces.
Gum recession
When gums recede, the root surfaces of teeth become exposed. Root surfaces are softer than enamel and more vulnerable to decay.
How to Prevent Cavities
Brush twice a day with fluoride toothpaste — fluoride strengthens enamel and makes it more resistant to acid
Floss once a day to remove plaque and food from between teeth where your toothbrush cannot reach
Limit sugary and acidic foods and drinks — and when you do have them, have them with meals rather than as snacks
Drink water throughout the day — especially fluoridated tap water, which helps remineralize enamel
Chew sugar-free gum after meals to stimulate saliva production
Get professional cleanings every 6 months to remove tartar that brushing cannot
Ask about dental sealants for back teeth, especially for children
Frequently Asked Questions
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