Pit and Fissure Sealants
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Direct answer
A pit and fissure sealant is a flowable resin or glass ionomer material bonded into the deep occlusal anatomy of a newly erupted molar so that the plaque-retentive groove becomes a cleansable surface, and its caries-preventive effect lasts exactly as long as it stays retained. The resin versions, descended from Buonocore's 1955 acid-etch discovery, rely on 37% phosphoric acid creating microporosities into which the sealant forms resin tags — which makes isolation, not the material, the decisive clinical variable. Properly placed and maintained, sealants cut occlusal caries in permanent molars by roughly 70–80% over the early years and are a cornerstone of the high-risk child's plan at ages 6–7 and again at 11–13.
What you must remember
- Indications: deep, retentive pits and fissures in newly erupted first (about 6–7 years) and second (about 11–13 years) permanent molars of high-risk children; sound, shallow, self-cleansing grooves need not be sealed.
- Contraindications: frank cavitation or dentine caries on radiograph means restoration, not sealing; partially erupted teeth that cannot be isolated wait.
- Materials: Bis-GMA-based resins (light-cured or autopolymerised; filled, unfilled, opaque or tinted) give best retention; glass ionomer-based sealants retain poorly but release fluoride and suit the uncooperative child or an un-isolable, partially erupted tooth.
- Technique sequence: clean with plain pumice (fluoride pastes leave films that resist wetting), isolate — rubber dam is gold standard — etch 15–30 seconds with 37% phosphoric acid, rinse and dry to a frosty white enamel, apply and cure, then check margins and occlusion.
- Saliva contamination after etching is the commonest cause of early loss; the surface must be re-etched, not "dried and carried on".
- Retention is the whole story: a lost sealant returns the tooth to baseline risk, so recall checks with explorer and radiographs — a defective sealant over hidden caries is worse than none — are part of the therapy.
- Evidence in one line: sealed permanent molars develop roughly 70–80% less occlusal caries than unsealed controls over the first couple of years, sustained where recall maintenance happens.
- Adjuncts: enameloplasty for selected deep anatomy, fluoride-releasing and moist-tolerant formulations, and interim therapeutic sealants as a bridge to full cooperation.
Sealing a first permanent molar, step by step
A 7-year-old high-risk child returns with all four first permanent molars newly erupted. The mandibular pair is chosen first because it has reached the occlusal plane and can be isolated. Rubber dam is placed — cotton rolls are the compromise if the clamp is intolerable — and the occlusal surface is brushed with a slurry of plain pumice. After rinsing and gentle drying, 37% phosphoric acid gel is painted over the grooves only for 15–30 seconds, rinsed for a similar time and dried: the enamel turns matte, chalky white, the visual proof of the etch pattern. If the tongue touches the tooth at this moment, everything stops and the surface is re-etched, because bonding to a contaminated etch is the failure nobody sees for six months.
The sealant is flowed along the grooves, teased with a probe to chase air from the deepest fissures, light-cured, and checked — an explorer must catch at no margin, and articulating paper confirms no premature contact. The maxillary molars, still two-thirds erupted, are booked for six weeks later rather than sealed through a puddle of saliva; meanwhile their grooves get fluoride varnish as an interim. At every recall the sealants are probed: intact, leave; partially lost but caries-free, refresh; carious beneath, restore. Sealant is a service, not an event.
The examiner's favourite traps
MCQs here are procedural: acid concentration (37% phosphoric), time (15–30 seconds), visual endpoint (frosty white enamel), and the response to saliva contamination (re-etch, never just re-dry). The etching-time subtlety for primary teeth — the aprismatic enamel layer leads some texts to advocate marginally longer etching — turns up as a single-best-answer. The material question is comparative: resin wins retention, glass ionomer wins where isolation is impossible and fluoride release matters; answering "glass ionomer retains better" inverts the evidence. Finally, the applied MCQ describes a partially lost sealant over dark fissures — the defensible answer is investigate and restore if caries is confirmed, since a leaking sealant seals bacterial nutrition inside.
Frequently asked questions
Who discovered acid etching, and what does it achieve?
Michael Buonocore, in 1955; etching creates microporosities in enamel into which resin flows and polymerises as tags, giving micromechanical retention.
When should a tooth not receive a sealant?
When it has cavitated occlusal caries or dentine involvement on radiograph, or is too partially erupted to isolate — sealing is deferred, not attempted through contamination.
Why choose a glass ionomer sealant despite poorer retention?
For uncooperative children or partially erupted molars that cannot be dried: it tolerates moisture, bonds chemically and releases fluoride, as an interim until a resin sealant is possible.
What happens if saliva touches etched enamel before placement?
The etched surface is contaminated and bond strength collapses; it must be re-etched before sealing.
How effective are sealants, and for how long?
Sealed molars show roughly 70–80% less occlusal caries than unsealed controls in the early years, with protection persisting as long as the sealant is retained and maintained.