Fissure Sealing in Children: Does It Really Protect Teeth from Decay?

Fissure sealing is one of the most common preventive procedures in paediatric dentistry, and also the one parents question most. The usual question is: wouldn’t it be simpler just to brush well?

Answering that requires understanding why the chewing surface is the most vulnerable area and why a brush genuinely cannot cope there.

What fissures are and why they are vulnerable

Fissures are the grooves and depressions on the chewing surface of molars and premolars. They form the relief needed to grind food.

The problem is their shape. Fissures vary: some are wide and shallow and clean easily; others are narrow and deep, shaped like a drop or a flask, with a narrow entrance widening inside. The bristle of a toothbrush is usually thicker than the entrance to such a fissure and physically cannot reach the bottom.

Plaque stays inside, bacteria carry on working, and decay begins there — often unnoticed: the entrance looks only slightly darker while a cavity has already formed beneath it.

An additional factor is immature enamel. Immediately after eruption, the enamel of a permanent tooth has not finished mineralising and continues to mature over several years. This is when the tooth is most vulnerable, and this is when sealing is most appropriate.

How sealing works

The principle is simple: the fissure is filled with a flowable material — a sealant — which hardens and forms a barrier. Plaque can no longer reach the depths, and the surface becomes smooth and easy to clean.

Two types of material are used. Composite sealants retain better on the surface but require a dry working field, which is not always achievable with a child or on a partly erupted tooth. Glass ionomer sealants are less sensitive to moisture and additionally release fluoride, strengthening the surrounding enamel, but they resist wear less well. Guidelines do not establish a clear advantage of one type over the other — the dentist chooses to suit the situation.

The procedure does not involve the living tissue of the tooth, so in the great majority of cases it is well tolerated and needs no anaesthesia. The tooth is cleaned, the surface conditioned, the sealant applied and cured with a light. It takes a few minutes per tooth.

A word about doubtful fissures — where the entrance is darker and the dentist cannot see the base. Sometimes a fine bur is used to open the entrance slightly to assess the depth before sealing. This is not an obligatory step: current recommendations permit sealing early lesions without opening, provided the coverage is hermetic and remains so. The decision rests with the dentist, based on the specific picture.

Does it really work

Yes, and specifically on the chewing surface. The method is part of standard preventive programmes in many countries precisely because it delivers a predictable effect in the most vulnerable area.

But its limits matter. A sealant protects only the surface it covers — the chewing one. It has no effect on the interproximal surfaces between teeth or on the areas near the gum, where decay also develops. Sealing therefore replaces neither brushing, nor flossing, nor regular check-ups.

A second limitation is that the effect depends on the quality of placement. A tooth poorly isolated from saliva gives a weak bond, the sealant is lost sooner and the protection goes with it. A common worry — that decay progresses faster under a partly debonded sealant than on an unsealed tooth — is not borne out by reviews: the risk there is comparable to no sealing at all. So the danger lies not in the coating itself but in protection quietly disappearing, which is precisely why follow-up is needed.

At what age it is done

The reference point is not age as such but the moment a particular tooth erupts, and it is best done as soon as possible afterwards.

The first permanent molars erupt at roughly six or seven — the “sixes” that are often mistaken for primary teeth because they appear without any predecessor falling out. For that reason they are frequently overlooked, and they are the most vulnerable.

The second permanent molars follow at roughly twelve or thirteen. Premolars come in between.

Primary molars are also sealed if a child has deep fissures and a high risk of decay.

The key rule: the tooth must have erupted enough to be isolated from saliva. If part of the chewing surface is still covered by gum, the procedure is postponed. The dentist assesses this under children’s dentistry.

How long it lasts and what comes next

A sealant is not permanent — it is not a filling. It gradually wears under chewing load, and part of the coverage can chip away.

Monitoring at routine check-ups is therefore essential. The dentist checks the integrity of the coating and restores it if needed. That check is not a formality: a lost sealant means the tooth is unprotected again, and parents usually have no idea. The frequency of check-ups is set by the dentist according to the child’s risk level.

With proper monitoring the method works as intended: while the enamel matures and the child learns to care for their teeth independently, the most vulnerable surface stays protected.

Who benefits most

Not all children equally. Sealing gives the greatest benefit to those with deep narrow fissures; those who have already had decay in their primary teeth — the most reliable predictor; those whose hygiene is inadequate or who struggle to brush independently; those wearing braces; and those whose diet is high in carbohydrates with frequent snacking.

If the fissures are wide and shallow, hygiene is good and there has never been decay, the dentist may reasonably recommend observation and remineralising therapy instead of sealing.

The decision, in other words, is made individually after an examination rather than on the principle of “every child, straight after eruption”. Where cavities already exist, they are treated under filling of teeth.

Questions parents ask

Does it hurt? Generally not. The procedure does not involve the living tissue of the tooth and in its standard form needs no anaesthesia. For many children sealing becomes a good first “treatment” experience precisely because it usually passes without unpleasant sensations.

Can they eat afterwards? Yes, usually straight away. A composite sealant cures fully under the light, so there are no restrictions. After a glass ionomer the dentist may advise avoiding hard food for a few hours.

Will the tooth feel different? For the first day the child may notice the tooth sitting “higher”. The dentist checks the bite and removes any excess material at the appointment, so the sensation usually passes quickly. If it persists, an adjustment is needed — a matter of minutes.

Does sealing replace fluoride treatment? No, the methods complement each other. A sealant mechanically closes the fissures, while fluoride preparations strengthen the enamel on all surfaces, including those a sealant does not cover.

What if part of the coating chips? Book a check-up without waiting for the routine visit. Restoring a sealant is simple, and a tooth without protection is back in the risk zone.

Conclusion

Fissure sealing does reduce the risk of decay on the chewing surface — in the area where a brush genuinely cannot cope because of the anatomy of the grooves and the immature enamel of a newly erupted tooth.

But it is not universal protection: the interproximal and cervical areas remain exposed, so hygiene and check-ups stay essential. Nor is it a “do it and forget it” procedure — a sealant needs checking, because protection can disappear without anyone noticing.