Fluoride and sealants for kids: how they protect teeth
Two quick, gentle treatments can add a strong layer of protection to your child's daily brushing.
Fluoride varnish strengthens enamel and helps reverse very early decay, and it is painted on in under a minute. Sealants are thin coatings that fill the deep grooves on back teeth, where most childhood cavities start. Used together with daily brushing, they lower a child's risk of cavities. Both are safe and need no freezing.
What fluoride does
Fluoride is a mineral that makes enamel more resistant to acid. It also helps repair tiny weak spots before they turn into cavities. Children get fluoride from toothpaste and, in Toronto, from community drinking water.
A professional fluoride varnish is a stronger, sticky coating painted onto the teeth. It sets quickly when it touches saliva and slowly releases fluoride over the next several hours.
Toronto adds a small, regulated amount of fluoride to tap water. Many bottled waters and home filtration systems, such as reverse osmosis, remove most of it. If your family drinks mainly bottled or filtered water, mention it at your child's visit.
How fluoride varnish is applied
- The teeth are wiped or brushed clean
- Varnish is brushed onto each tooth in a thin layer
- Your child can eat soft foods soon after, but skip hard, hot or sticky foods for the rest of the day
- Wait until the next morning to brush the varnish off
- The teeth may look slightly yellow or dull until then
What sealants are
The chewing surfaces of molars have deep pits and grooves. Toothbrush bristles often can't reach the bottom of them, so food and bacteria settle there. A sealant is a thin, tooth-coloured plastic coating that flows into the grooves and hardens, leaving a smoother surface that's easier to keep clean.
Sealants are most often placed on the first permanent molars, which come in around age six, and the second molars, around age twelve. Some baby molars and adult premolars with deep grooves may also benefit.
Sealants work best on teeth that have no decay. If the dentist sees a very early, shallow weak spot in a groove, a sealant can sometimes be placed over it to stop it from progressing.
How sealants are placed
- The tooth is cleaned and kept dry with cotton or a small isolation device
- A mild solution roughens the surface so the sealant can grip
- The sealant is painted into the grooves
- A blue curing light hardens it in seconds
- The bite is checked and the sealant is smoothed if needed
Keeping protection in place
Sealants can last several years but may wear or chip. We check them at each visit and repair them when needed. Fluoride varnish is usually repeated every three to six months for children at higher risk of decay. Your dentist will recommend a schedule based on your child's teeth, diet and history.
Frequently asked questions
Is fluoride safe for young children?
Yes, in the right amounts. Health Canada and the Canadian Dental Association support fluoride toothpaste and varnish for children. Use a rice-grain-sized smear under age three and a pea-sized amount from age three to six.
Do sealants replace brushing?
No. Sealants protect the chewing grooves only. Brushing and flossing are still needed for the sides of each tooth and the gums.
Does my child need freezing for sealants?
No. Placing a sealant doesn't involve drilling or needles in most cases.
Are fluoride and sealants covered?
Many insurance plans and the Canadian Dental Care Plan include them for children. We can check your child's coverage before the visit.
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Trusted health information
General information only; not a substitute for an exam. Reviewed by Dr. Sayeh Maralani, DDS, general dentist. Last updated 2026-11-03.
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