Three tools, three different jobs
Parents often hear three similar-sounding terms at checkups and wonder which one their child needs. The simplest way to sort them out is to ask what each one is meant to do. One blocks decay from starting in deep grooves, one strengthens enamel, and one helps manage a cavity that has already formed. Many children benefit from more than one over time.
Side-by-side comparison
| Dental sealant | Fluoride varnish | Silver diamine fluoride (SDF) | |
|---|---|---|---|
| What it is | A thin plastic coating bonded to a tooth’s chewing surface | A concentrated fluoride coating painted on teeth | A liquid containing silver and fluoride painted on a cavity |
| Main purpose | Prevention: keeps food and bacteria out of deep grooves | Prevention: strengthens enamel and helps early weak spots | Treatment: helps stop an active cavity from progressing |
| Where it goes | Mostly permanent molars; sometimes baby molars | All tooth surfaces | Only the cavity or cavities being treated |
| Drilling or numbing? | No | No | Usually no |
| How it looks afterward | Clear, tooth-colored or slightly tinted | Teeth may look slightly yellow or dull until brushed | Treated decay turns dark brown or black |
| Repeat visits | Checked at routine visits; may need repair or replacement | Often repeated on a schedule based on cavity risk | May be reapplied; follow-up is important |
Dental sealants: a shield for back teeth
The chewing surfaces of molars have deep pits and grooves where a toothbrush bristle cannot always reach. A sealant is a thin coating that fills those grooves so food and bacteria are less likely to settle in them. The CDC describes sealants as a way to protect the back teeth from decay, and they are typically placed on a child’s first permanent molars around age 6 and second permanent molars around age 12. The tooth is cleaned and dried, the sealant is applied, and a special light hardens it. Learn more on our dental sealants page.
Fluoride varnish: strengthening enamel
Varnish is painted on, sets quickly, and delivers a concentrated dose of fluoride in a small amount. Teeth may look a little dull at first, and the dentist may suggest soft foods for the rest of the day. The AAPD and ADA describe fluoride treatments at intervals that depend on a child’s cavity risk. See our fluoride treatments page, and our guide on fluoride safety for more.
Silver diamine fluoride: managing active cavities
SDF is brushed onto a cavity. It can help stop decay from spreading and may reduce sensitivity. It is sometimes helpful for very young children, for children who find longer treatment hard, or as a bridge while other care is planned. The trade-off is cosmetic: treated areas turn dark. SDF does not replace a filling in every case, and some teeth still need restorative care later. Your dentist will explain whether it makes sense and what to expect. Details are on our silver diamine fluoride page.
Tell the dental team about any allergies, including to silver, before SDF is used. Staining can also affect skin and clothing if the liquid touches them, so the team takes care to protect your child during application.
Talking with your child about it
Most of these treatments are quick and painted or placed on the tooth. Use simple, honest words such as “we’re going to paint your teeth” or “put a shield on your back teeth,” and avoid telling your child that nothing will feel strange. Preparing them helps the visit go more smoothly. Our first dental visit guide has more ideas.
If a cavity is already large
Some cavities need a filling or a crown instead of, or after, a non-drilling approach. We talk through options on our fillings and crowns page.
What to expect after each treatment
All three work best alongside daily brushing with fluoride toothpaste, so none of them is a reason to skip home care. Your dentist will give instructions specific to the product used, and these are general ideas.
- Sealants: they can wear over time, so avoid chewing ice or very hard objects, and have them checked at routine visits.
- Fluoride varnish: teeth may look dull for a while. Soft foods and delayed brushing may be advised for the rest of the day.
- SDF: dark spots are expected and show where the decay was treated. Keep brushing, and come back for any follow-up the dentist suggests.
- All three: limit frequent sugary drinks and snacks, which keep feeding the bacteria that cause decay.
Common myths
“A sealant means my child no longer needs fluoride” is not accurate, because sealants cover only the chewing surface and varnish protects other surfaces. “Baby teeth do not matter” is also not accurate. Baby teeth hold space for permanent teeth and help with chewing and speech, so cavities in them deserve attention.
Which one might my child need?
These examples are illustrations only. Your dentist decides after examining your child.
- Permanent molars just coming in: sealants are often discussed.
- Higher cavity risk or early white spots: fluoride varnish may be recommended.
- An active cavity without severe symptoms: SDF may be an option.
- Pain, swelling or a large cavity: further evaluation and possibly a filling, crown or other care is needed.
- Many children: a combination of home care, varnish and sealants.
What about insurance and OHP?
Coverage for preventive and treatment services depends on the member’s plan and eligibility, and we verify benefits before the visit. Families with the Oregon Health Plan can read our OHP pediatric dentist page, and others can see insurance and financing. To discuss which approach fits your child, Dr. Richard Hsu, DMD, a pediatric dentist, and our team are happy to help.
How does a dentist decide which treatment a child needs?
Dentists weigh cavity risk, the tooth, and the child’s age and cooperation. The same child can need different tools at different ages, and the plan can change at each checkup.
Factors that often raise cavity risk include:
- Past cavities or visible white spots.
- Frequent snacking or sipping on sugary drinks.
- Deep grooves on new molars.
- Medicines or conditions that dry the mouth, or special health care needs that make brushing hard.
- Braces or other appliances that trap food.
| Stage | Tools often discussed |
|---|---|
| Toddlers with early white spots | Fluoride varnish, brushing coaching, diet changes |
| Preschoolers with active cavities | Silver diamine fluoride, fillings, or crowns |
| Around age 6 and 12 | Sealants on new permanent molars |
| Teens with braces | Fluoride, careful cleaning, sealants as needed |
Are dental sealants safe? What about BPA?
Dental sealants are considered safe by the ADA and CDC. Some sealant materials have contained trace compounds related to BPA, but the amount a child could be exposed to is very small. Ask your dentist which material is used if you have concerns.
Can silver diamine fluoride be used on front teeth?
It can, but the dark staining is more visible there. Many families choose SDF for back teeth, where color matters less, or as a bridge to a later restoration. The dentist will explain your options before using it. Always mention a silver allergy before treatment.
How long do sealants last, and what makes them fail?
Sealants often last for years, but they can chip or wear. Saliva or moisture while the sealant is placed, chewing ice, and very hard foods can shorten their life. Checking them at routine visits lets the dentist repair or replace one before decay sneaks in.
Learn more about dental sealants, silver diamine fluoride, and fluoride treatments. Our sealants guide and OHP sealants and fluoride page can help families in Beaverton, Aloha, and Hillsboro plan next steps.
This article is general education, not a diagnosis or a substitute for an exam. If your child has swelling, fever or serious pain, call us right away; in a life-threatening emergency, call 911.