Pit and Fissure Sealants: Indications, Technique, and Evaluation

Core Review

Rationale for Sealants

Pit and fissure caries account for approximately 90% of caries in children and adolescents. The occlusal surfaces of posterior teeth are anatomically susceptible to caries because:

• Pits and fissures are narrow, deep, and difficult for toothbrush bristles to penetrate
• Plaque accumulates and stagnates in these protected areas
• The enamel at the base of pits and fissures is often thinner than on smooth surfaces
• Fluoride is less effective in preventing pit-and-fissure caries than smooth-surface caries (fluoride's benefit is primarily on smooth surfaces)

Sealants work by creating a physical barrier that seals the pit and fissure system, preventing bacteria and fermentable carbohydrates from accessing the susceptible enamel.

Indications

Sealants are indicated for:

1. Deep, retentive pits and fissures — The primary indication. The anatomy must be susceptible to caries; shallow, self-cleansing grooves do not benefit from sealants.

1. Children and adolescents — Primary and permanent molars should be evaluated for sealants as soon as they are fully erupted and can be isolated:
   • Primary molars: if deep pits and fissures and high caries risk
   • Permanent first molars: evaluate around age 6-7
   • Permanent second molars: evaluate around age 12-13
   • Premolars: evaluate when fully erupted

1. Incipient (non-cavitated) pit-and-fissure caries — White or brown discoloration in the fissure without cavitation. Sealants arrest these lesions by sealing off the bacterial nutrients.

1. Patients at elevated caries risk — Regardless of age. Adults with high caries risk may also benefit.

1. Intact occlusal surfaces with deep anatomy — The best candidates: teeth that are caries-free but anatomically susceptible.

Contraindications

Sealants are NOT indicated when:

1. Obvious cavitation exists — The carious lesion has cavitated through the enamel. Sealant cannot restore lost tooth structure; a restoration is needed.

1. Proximal caries requiring restoration — If the tooth needs a Class II restoration, the occlusal surface will be included in the preparation.

1. The tooth is not fully erupted — Incomplete eruption prevents adequate isolation. The distal portion of a partially erupted molar cannot be sealed effectively. Wait for full eruption.

1. Shallow, well-coalesced pits and fissures — The anatomy is not caries-susceptible; sealant provides no benefit.

1. Inadequate isolation possible — Uncontrollable moisture contamination compromises bond strength. If the tooth cannot be kept dry during the procedure, sealant failure is likely.

1. Existing restoration covers the occlusal surface — Sealant is redundant.

Sealant Materials

Resin-Based Sealants (most common):

• Composition: Bis-GMA or urethane dimethacrylate resin, similar to composite resin
• Setting mechanism: Chemically cured (auto-polymerizing) or light-cured (visible light polymerization). Light-cured is more common and allows controlled working time.
• Filled vs. Unfilled:
  • Unfilled: Better flow into pits and fissures; may be more wear-resistant in thin sections
  • Filled: May have better abrasion resistance but slightly thicker and may require occlusal adjustment
• Color: Clear, tinted (allows visibility for evaluation), or opaque white
• Advantages: Proven long-term retention, high caries prevention efficacy
• Disadvantages: Technique-sensitive (requires absolute moisture control, acid etching)

Glass Ionomer Cement (GIC) Sealants:

• Composition: Fluoroaluminosilicate glass + polyacrylic acid
• Setting mechanism: Acid-base reaction
• Advantages:
  • Release fluoride (sustained release over time, and rechargeable from topical fluoride)
  • Hydrophilic — can be placed in moist environments (less moisture-sensitive than resin)
  • Chemical bond to enamel and dentin
• Disadvantages: Lower retention rates compared to resin-based sealants; more brittle
• Indications: Partially erupted teeth where moisture control is difficult, high caries risk patients (fluoride release benefit)
• Role: Often used as a transitional sealant until the tooth fully erupts and can be sealed with resin

Resin-Modified Glass Ionomer (RMGI):

• Combines properties of GIC (fluoride release, moisture tolerance) and resin (better strength, light-curable)
• Compromise material; may be used for sealants in difficult-to-isolate situations

Sealant Placement Protocol (Resin-Based)

The success of a sealant depends on meticulous technique. Each step is critical:

1. Clean the Tooth Surface

• Use a bristle brush or rubber cup with pumice or non-fluoridated prophylaxis paste
• Fluoride-containing paste should be avoided — fluoride can interfere with the acid-etch process
• Air-polishing with sodium bicarbonate may also be used for cleaning
• Rinse thoroughly — all cleaning material must be removed

2. Isolate the Tooth

• Rubber dam is ideal (best isolation) but not always practical for sealants in young children
• Cotton rolls + isolation device (Isolite, Dry-Tip, etc.) + saliva ejector
• The tooth must remain COMPLETELY DRY from this point forward
• If saliva contamination occurs at any point before curing, re-etching is required

3. Etch the Enamel

• 37% phosphoric acid gel applied to the pits, fissures, and 1-2 mm beyond onto the surrounding cusp inclines
• Etch time: 15-30 seconds (primary teeth may require slightly longer, 30 seconds)
• The acid creates microporosities in the enamel (Type I and II etching patterns) by selectively dissolving enamel prism cores or peripheries
• These microporosities allow resin tags to form, creating micromechanical retention
• Do not let the etch contact dentin (if the fissure is deep and reaches dentin, this is acceptable for sealing incipient lesions)

4. Rinse Thoroughly

• Rinse for at least 15-20 seconds to remove all acid
• Inadequate rinsing leaves acid residue that interferes with bonding

5. Dry the Tooth

• Air-dry until the etched enamel appears frosty white (chalky)
• Frosty appearance confirms adequate etching
• If the enamel does not appear frosty, re-etch
• Once dried, DO NOT allow moisture contamination

6. Apply Bonding Agent (Optional but Recommended)

• A thin layer of unfilled resin bonding agent can increase sealant retention, especially under less-than-ideal moisture control
• Light-cure the bonding agent before applying sealant

7. Apply Sealant Material

• Dispense sealant into the pits and fissures
• Use an explorer tip or applicator to guide material into all areas
• Avoid incorporating air bubbles
• Do NOT overfill — excess material creates occlusal interference

8. Light-Cure

• Follow manufacturer's instructions for curing time (typically 20-40 seconds)
• Ensure the light tip is as close as possible to the sealant surface

9. Evaluate

• Check with explorer for complete coverage, voids, and bubbles
• Check occlusion with articulating paper — if high, adjust with a finishing bur
• Verify sealant retention at each recall visit
• If partial loss occurs, re-etch and re-seal the exposed area

Evaluation and Maintenance

At each recall visit, sealants should be evaluated:

• Completely retained: No intervention needed. Continue to monitor.
• Partially lost: If the exposed pit/fissure is caries-free, re-etch (15 seconds) and re-seal the area. If caries is detected, restoration is indicated.
• Completely lost: Re-evaluate the tooth. If still caries-free and anatomy remains susceptible, re-seal.
• Staining at margins: May indicate microleakage; evaluate for caries. If no caries, monitor. If caries suspected, explore with a sharp explorer or restore.

Sealant longevity: Resin-based sealants have reported complete retention rates of 50-70% at 5-10 years. Partial retention (with the sealant in the deeper portions of the fissure where it is most needed) provides continued protection. Sealants should be routinely evaluated and repaired/replaced as needed.

Evidence for Sealant Effectiveness

• Sealants reduce occlusal caries by approximately 80% over 2 years and 60% over 4-5 years compared to unsealed teeth
• Sealants are effective in both children and adolescents
• Effectiveness is directly proportional to retention — the better the sealant stays in place, the more effective it is
• Sealants placed over incipient (non-cavitated) caries arrest the lesion progression because the bacteria are sealed off from nutrient sources

Clinical Application

Scenario: An 8-year-old presents for a recall visit. Tooth #19 (mandibular left first molar) has deep, stained pits and fissures with no cavitation. The tooth is fully erupted and can be isolated. The child has moderate caries risk (2 interproximal lesions on primary molars).

Decision: Sealant indicated. Deep, retentive anatomy + moderate caries risk + fully erupted tooth capable of isolation.

Procedure: Clean with pumice, isolate with cotton rolls and saliva ejector, etch 37% phosphoric acid for 20 seconds, rinse 20 seconds, dry to frosty appearance, apply bonding agent (thin layer, light-cure), apply sealant, light-cure, evaluate occlusion.

Common Traps

• TRAP: Sealing a tooth with cavitated caries. If a probe sticks in the fissure and there is softness at the base (cavitation), a restoration is needed.
• TRAP: Using fluoride-containing prophy paste before etching. Fluoride can react with the acid etch and create calcium fluoride deposits that interfere with resin penetration.
• TRAP: Placing sealant on a partially erupted tooth with a resin-based material. The distal portion cannot be isolated; use GIC as a transitional sealant or wait for full eruption.
• TRAP: Not drying the etched enamel to a frosty appearance. If the enamel is not frosty, the etch is inadequate or there has been saliva contamination.
• TRAP: Skipping evaluation at recall. Sealants require maintenance just like restorations.