Introduction: “if the tooth is healthy, why touch it?”
This question is sometimes raised at a hygiene appointment when, for example, a child’s freshly erupted six-year molar is still intact: “if it’s healthy, why seal it?”. It is a good, sensible question — and fissure sealing is precisely the answer to it. Fissure sealing involves placing a thin layer of material (a fissure sealant) into the deep grooves on the chewing (occlusal) surface of the molars, before caries has a chance to develop in them. It is neither “pre-emptive treatment” nor drilling — it is a purely preventive, painless and non-invasive procedure.
In this article we explain, on the basis of current clinical research: whether sealing really reduces the risk of caries, when the best moment for the procedure is, how long a sealant lasts, how it differs from fluoride varnish application, and what — and until what age — the National Health Fund (NFZ) reimburses in Poland. We want parents, after reading this, to be able to assess calmly whether and when this procedure makes sense for their child.
Key conclusions in brief
- Does it protect? Yes — sealants significantly reduce the risk of caries on the occlusal surfaces of the permanent molars (evidence from randomised trials).
- When? Soon after the tooth has fully erupted — first and foremost the “six-year molars”, usually between the ages of 6 and 8.
- How often? A sealant does not require routine reapplication; what matters is periodic checking of its integrity and topping it up where needed.
- What determines effectiveness? Durable retention of the sealant within the fissure — more than the type of material itself.
Do fissure sealants protect against caries — what the research says
Yes — in children, fissure sealing reduces the risk of caries on the occlusal surfaces of the first permanent molars, and the effect is greater the better the sealant stays on the tooth. In a pragmatic randomised trial in children at high caries risk, the fissure sealant produced a higher success rate after 3 years (no need for invasive treatment) than fluoride varnish alone.
According to PubMed, in a Norwegian split-mouth study (each child served as their own control group) of 409 children aged 6–10 at high caries risk, the fissure sealant achieved a 94.1% success rate after 36 months, and fluoride varnish 89.6% — a statistically significant difference, albeit below the 10% threshold regarded as clinically important (Uhlen-Strand et al., J Dent Res 2024). In turn, an analysis of a nationwide sealing programme in Taiwan covered hundreds of thousands of children and showed that, in the first permanent molars, participation in the programme was associated with a reduction of at least 10% in the risk of caries treatment, with a further reduction of around 30% in teeth in which the sealant had actually been retained (Lin et al., J Dent 2023). Put simply: sealants work, and the key to their effectiveness is durable adhesion within the fissure.
Why fissures are so prone to caries
The occlusal surface of the molars is not smooth — it is covered by deep, winding grooves and pits (fissures). In many children these are narrower than a single toothbrush filament, so even careful brushing does not remove dental plaque and food debris from their depths. It is precisely there, in the nooks inaccessible to the toothbrush, that caries in children’s permanent teeth most often begins.
The problem intensifies during eruption. A freshly erupted six-year molar remains partly covered by gum for many months, is harder to clean thoroughly, and its enamel is not yet fully mature (mineralised). Fissure sealing then acts as a physical barrier: it fills the grooves, smooths the occlusal surface and cuts bacteria off from the most vulnerable sites, giving the enamel time to mature.
It is worth keeping this in proportion, however. A sealant protects only the occlusal surfaces on which it has been placed — it does not protect the interproximal surfaces between the teeth or the area near the gum. Sealing is therefore one element of prevention, not a substitute for it: it does not do away with toothbrushing, flossing and limiting sugar. We write about this more fully in our guide to preventing caries in children (https://klinikamdo.pl/en/blog/how-to-protect-teeth-effectively-against-tooth-decay-learn-the-principles-of-prevention/).
When to seal — the timing window and the child’s age
The most important rule is this: a tooth is sealed soon after it has fully erupted, once the occlusal surface can be kept dry and the fissures are still healthy. Sealing a partly erupted, moist tooth too early risks poor adhesion of the sealant; too late means caries may already have started in the fissure.
Priority goes to the first permanent molars, the “six-year molars”, which usually erupt at around the age of 6, often unnoticed by parents (no primary tooth falls out before them). The second permanent molars (the “seven-year molars”) erupt at around the age of 12 and are also sometimes sealed. In our dental practice at Modern Dental & Orthodontics (Klinika MDO) we observe that it is precisely the eruption of the six-year molars that most often escapes carers’ attention — which is why a routine check-up at this age is so important.
| Tooth | Typical eruption age | Sealing window | Note |
| First permanent molar (six-year molar) | approx. 6 years | ages 6–8 | Priority |
| Second permanent molar (seven-year molar) | approx. 12 years | ages 11–14 | |
| Premolars (first and second premolars) | 9–12 years | after eruption | Fissures usually shallower — individual decision |
| Primary molars | 1.5–3 years | individually | Evidence weaker than for permanent teeth (see below) |
The decision to seal a specific tooth always depends on individual assessment: the depth of the fissures, the child’s caries risk and whether the tooth can be properly kept dry. In a child with very shallow, self-cleansing fissures and low risk, the dentist may consider sealing unnecessary — and that too is the right decision.
How the fissure sealing procedure works
Sealing is one of the gentlest procedures in the paediatric surgery — with no drilling and usually without anaesthesia. It proceeds in several steps: thorough cleaning of the occlusal surface, isolation of the tooth from saliva (a dry field is crucial for the sealant’s durability), acid etching of the enamel in the case of resin-based sealants, placement of the material into the fissures, curing (for resin-based sealants — with a curing light) and a check of the bite. The whole procedure for a single tooth usually takes a few minutes.
The technically most difficult element is maintaining dryness — moisture from saliva is the most common cause of the sealant later coming away. In younger or less cooperative children this can be a challenge, which is why good preparation for the appointment genuinely translates into the durability of the procedure. Our guide on how to prepare your child for their first dental visit may help (klinikamdo.pl/en/blog/preparing-child-first-dental-visit/).
There are no restrictions after the procedure — the child can eat and drink straight away. A sealant is not, however, “placed once and for all”: it is subject to wear and may partly chip away, which is why at every check-up the dentist assesses its integrity and, if necessary, tops up any loss of material. It is precisely this periodic monitoring that distinguishes effective sealing from a procedure that is “ticked off and forgotten”.
Resin-based or glass-ionomer sealant — and how long it lasts
Two main groups of materials are used in practice: resin-based sealants (based on composite resins) and glass-ionomer sealants (glass-ionomer materials that release fluoride). They differ in durability and technical requirements. Resin-based sealants, especially filled ones, usually adhere better to the tooth over longer follow-up, but they require very good isolation from saliva. Glass-ionomer sealants are more tolerant of moisture and release fluoride, but more often undergo partial wear.
In a 2-year split-mouth study in children aged 6–13, filled resin-based sealants showed significantly higher complete retention than glass-ionomer sealant, while both types protected against caries where they remained fully retained on the occlusal surface (Reić et al., Int J Paediatr Dent 2022). This is an important practical conclusion: effectiveness is determined not so much by the “magic” of a particular material as by whether the sealant still fully covers the fissure. The dentist therefore matches the choice of material to the situation — the child’s age and cooperation, the ability to maintain dryness, and the caries risk.
It is worth keeping perspective here: over short follow-up the differences between materials tend to be small. A meta-analysis of randomised trials found no significant differences in retention or in caries prevention between a hydrophilic resin-based sealant and the alternatives (conventional resin or glass-ionomer) at 6 and 12 months (Alsabek et al., J Dent 2021). Only longer follow-up, such as the 2-year work by Reić et al., more clearly differentiates the durability of individual materials — and it is durability, rather than the type of sealant itself, that most strongly translates into protection.
In fairness, it should be added that sealing primary teeth has a weaker evidence base than sealing permanent teeth. In a randomised trial in pre-school children, a glass-ionomer sealant placed on primary molars gave an effect similar to fluoride varnish, and its retention after one year was low (Ying Lam et al., Caries Res 2021). Primary prevention therefore remains centred on the first permanent molars, and the decision to protect primary teeth is made on an individual basis.
Is fissure sealing safe for a child
This is one of parents’ most common concerns — particularly the question of compounds released from resin materials. It is worth separating two things. First, the procedure itself is safe and non-invasive: no healthy tooth tissue is removed, there is no drilling, and the occlusal surface is merely covered with a thin layer of sealant. Second, sealing materials are medical devices approved for use in dentistry, and their cured layer is stable; any exposure to resin components is trace, short-lived and limited to the moment the sealant is placed.
In practice, the risk arising from untreated caries developing in the fissure — pain, the need for drilling and, in extreme cases, root canal treatment or loss of the six-year molar — is incomparably greater than the theoretical concerns associated with the sealant itself. If a parent has particular doubts (e.g. about a specific ingredient), it is worth discussing them with the dentist before the procedure — the choice of material can be adjusted. A thorough explanation of these matters before the sealant is applied usually dispels the anxiety completely, so it is worth asking all your questions at the start of the appointment.
Fissure sealing versus fluoride varnish — they are not the same
These two procedures are sometimes confused, yet they work differently. Fissure sealing is the mechanical filling of the grooves of the occlusal surface with a durable material — a physical barrier at one specific site. Fluoride varnish application is the coating of all tooth surfaces with a fluoride varnish that strengthens the enamel and supports remineralisation — it acts broadly, but does not fill the fissures and needs to be repeated usually every 3–6 months.
In practice these are not competing methods but complementary ones: the sealant protects the most vulnerable fissures of the six-year molars, while fluoridation supports the resistance of the whole dentition, including the smooth and interproximal surfaces. In the Norwegian study cited above, in children at high risk the sealant proved somewhat more effective than varnish alone in protecting the occlusal surface (Uhlen-Strand et al., J Dent Res 2024), which does not mean that fluoridation should be abandoned — on the contrary, the best results come from combining both approaches with home hygiene.
The most frequently asked questions from parents
Does fissure sealing hurt?
No, sealing does not hurt. It is a non-invasive procedure, with no drilling and usually without anaesthesia: the dentist cleans the occlusal surface, dries the tooth and places the sealant into the fissures. For a child it can simply be boring, as they have to lie with their mouth open for a few minutes, but it should be neither painful nor unpleasant.
At what age is it best to seal teeth?
The first permanent molars (six-year molars) are usually sealed between the ages of 6 and 8, soon after they have fully erupted. The second permanent molars (seven-year molars) are usually protected at around the age of 11–14. The best moment is when the tooth can already be kept dry and the fissures are still healthy and free of caries.
How often does sealing need to be repeated?
A sealant does not require routine reapplication at fixed intervals, but it is subject to wear and may partly chip away. At every check-up, therefore, the dentist assesses its integrity and, if necessary, tops up any loss of material. Regular check-ups matter more here than a predetermined “expiry date” for the sealant.
Is a sealant enough to keep a child free of caries?
It is not enough. A sealant protects only the occlusal surfaces on which it has been placed — it does not protect the interproximal surfaces between the teeth or the area by the gum. Nor does it replace toothbrushing, flossing, limiting sugar and fluoridation. The best results come from combining sealing with daily, consistent home prevention.
Are primary teeth sealed?
Sometimes yes, but the decision is always individual. The evidence for the effectiveness of sealing primary teeth is weaker than for permanent teeth, and sealant retention on primary teeth can be low. In children at high caries risk the dentist may consider this procedure, but the priority remains the first permanent molars.
What happens if a sealant partly comes off?
Partial loss of a sealant is no cause for panic, but it does require assessment by the dentist — because caries can develop in an exposed fissure. One should therefore not assume that “a tooth sealed once is protected forever”; the integrity of the sealant is checked routinely at check-ups and topped up if necessary.
Key takeaways
- Fissure sealing reduces the risk of caries on the occlusal surfaces of the permanent teeth, and its effectiveness depends above all on durable retention of the sealant within the fissure.
- The priority is the first permanent molars (six-year molars); the best moment is ages 6–8, soon after full eruption.
- A sealant protects only the occlusal surfaces and does not replace hygiene, fluoridation or limiting sugar.
- Effective sealing requires periodic checking of integrity and, where necessary, topping up the material.
Read more:
- Paediatric dentistry: klinikamdo.pl/en/offer/paediatric-dentistry/
- Professional hygiene and prevention: klinikamdo.pl/en/offer/hygiene-and-whitening/
- How to prepare your child for their first dental visit? https://klinikamdo.pl/en/blog/how-to- prepare-a-child-for-a-first-visit-to-the-dentist/
- How to effectively protect teeth from caries? https://klinikamdo.pl/en/blog/how-to-protect-teeth-effectively-against-tooth-decay-learn-the-principles-of-prevention/
Sources
Source 1
Links https://doi.org/10.1177/00220345241248630 │ https://pubmed.ncbi.nlm.nih.gov/38716723/
Description Uhlen-Strand M-M, et al. „Fissure Sealants or Fluoride Varnish? A Randomized Pragmatic Split-Mouth Trial.” J Dent Res. 2024;103(7):705-711.
Source 2
Links https://doi.org/10.1016/j.jdent.2023.104587 │ https://pubmed.ncbi.nlm.nih.gov/37321335/
Description Lin P-Y, et al. „Real-world effectiveness of national pit and fissure sealants program in Taiwan.” J Dent. 2023;135:104587.
Source 3
Links https://doi.org/10.1111/ipd.12924 │ https://pubmed.ncbi.nlm.nih.gov/34664337/
Description Reić T, et al. „Retention and caries-preventive effect of four different sealant materials: A 2-year prospective split-mouth study.” Int J Paediatr Dent. 2022;32(4):449-457.
Source 4
Links https://doi.org/10.1159/000517390 │ https://pubmed.ncbi.nlm.nih.gov/34284374/
Description Ying Lam PP, et al. „Glass Ionomer Sealant versus Fluoride Varnish Application to Prevent Occlusal Caries in Primary Second Molars among Preschool Children: A Randomized Controlled Trial.” Caries Res. 2021;55(4):322-332.
Source 5
Links https://doi.org/10.1016/j.jdent.2021.103816 │ https://pubmed.ncbi.nlm.nih.gov/34560227/
Description Alsabek L, et al. „Efficacy of hydrophilic resin-based sealant: A systematic review and meta-analysis.” J Dent. 2021;114:103816.