Detailed Notes on Dental Sealants

Dental Sealants

Definition and Purpose

Fissure sealants are materials applied to the occlusal pits and fissures of caries-susceptible teeth. They form a protective layer through micromechanical or chemical bonding, blocking caries-producing bacteria from accessing nutrients. Pit-and-fissure sealants flow over the occlusal surface, penetrating deep fissures inaccessible to toothbrushes. Once hardened, they establish a barrier between the tooth and the oral environment.

Historical Perspective

• 1895: Wilson - placement of dental cement in pits and fissures to prevent caries.

• 1923 & 1936: Hyatt - advocated early insertion of small restorations in deep pits and fissures before carious lesions developed, termed "prophylactic odontotomy."

• 1929: Bodecker - suggested enameloplasty, broadening deep fissures with a large round bur to make occlusal areas self-cleansing.

Disadvantages of Early Methods

• Enameloplasty and prophylactic odontotomy are treatment procedures requiring a dentist, not preventive approaches.

• Enameloplasty often requires removing more sound tooth structure than a small restoration.

• Unsuccessful methods included topical application of zinc chloride and potassium ferrocyanide, ammoniacal silver nitrate, and copper amalgam.

• Doing nothing and waiting for a definite carious lesion often results in tooth loss due to lack of periodic exams.

Key Developments

• Buonocore (1955): Introduced the acid etch and bonding technique for resin-based materials, earning the title "Father of Adhesive Dentistry." His research focused on developing a sealant to prevent occlusal caries on posterior teeth.

• 1960s: Bowen converted resins into acceptable restorative materials by introducing bisGMA and fillers for physical reinforcement and controlling setting shrinkage. Bisphenol A-Glycidyl Methylacrylate (Bis-GMA) sealants became the sealant of choice.

• Smith: Recognized the biological benefits of the polyalkenoic acid group and combined these with zinc oxide to develop polycarboxylate cements, the first materials with self-adhesion and fluoride-releasing capabilities.

• Wilson et al. (1985): Modified polycarboxylate cements using powdered glass instead of zinc oxide, introducing glass-ionomer cements for restorative and preventive uses.

Development of Occlusal Caries

Pit and fissure caries are the first lesions encountered in children. Site-specific risk factors include:

1. Morphology of pit and fissure systems

2. Eruption stage

3. Functional use

Criteria for Selecting Teeth for Sealant Placement

Sealants should be applied based on careful clinical judgment, considering:

• Caries-free patients with caries-free occlusal surfaces fully erupted for over 3 years generally do not need sealants.

• If caries has affected one or more permanent molar teeth (or if there's a history of caries in primary teeth), remaining sound fully erupted pits and fissures should be sealed.

Factors Influencing Sealant Placement

• Oral hygiene of the patient

• Individual history of dental caries

• Dietary habits

• Patient cooperation and reliability in keeping recall appointments

• Tooth type and tooth morphology (fissure morphology: V, U, Y, I, types)

Timing and Risk

• The time from tooth emergence to full occlusion is critical for caries initiation.

• Longer eruption times increase occlusal caries risk (e.g., molars with 12-18 months eruption time vs. premolars with a few months).

• Seal susceptible sites on permanent teeth soon after eruption as a preventive measure.

Indications

A sealant is indicated if:

• The fossa selected for sealant placement is well isolated from another fossa with a restoration.

• The area selected is confined to a fully erupted fossa even if the distal fossa cannot be sealed due to inadequate eruption.

• The selected tooth has an intact occlusal surface when the contralateral tooth surface is carious or restored.

• An incipient lesion exists in the pit and fissure area.

• Sealant material can be flowed over a conservative class I composite or amalgam to improve marginal integrity and prevent recurrent decay.

Adult Teeth

Sealants should be placed if there's evidence of existing or impending caries susceptibility (e.g., excessive sugar intake, drug- or radiation-induced xerostomia).

Contraindications

A sealant is contraindicated under these circumstances:

• Patient behavior doesn't permit adequate dry field techniques.

• An open, frank, carious lesion exists on the same tooth.

• Caries exists on other surfaces of the same tooth where restoration will disrupt an intact sealant.

• A large occlusal restoration is already present.

Ideal Sealant Materials

The desired clinical outcomes from sealants are to prevent the establishment and stop the progression of carious lesions. The technique must provide good retention, a long-term seal, and be non-technique sensitive.

Requirements of an Ideal Material

• Biocompatibility

• Low viscosity

• Low solubility

• Esthetically acceptable and visible to facilitate reassessment

Types of Materials

• Unfilled or lightly filled composite resins

• Glass ionomers

Requisites for Sealant Retention

Placement of pit and fissure sealants is technique sensitive. For sealant retention, the tooth surface must:

1. Have a maximum surface area (increased by acid etching)

2. Have deep, irregular pits and fissures (offer better surface contour for retention and protect the sealant from shear forces)

3. Be clean

4. Be absolutely dry and uncontaminated with saliva residue

Sealants are retained mainly by adhesive forces.

Sealant Placement Guidelines

Step 1: Prepare the Teeth (Surface Cleanliness)

• Acid etching alone is often sufficient for surface cleaning.

• Remove heavy stains, deposits, debris, and plaque from the occlusal surface.

Step 2: Isolate the Teeth

• Adequate isolation is critical.

• Use a rubber dam, cotton rolls, or bibulous pads to maintain a dry field.

• Rubber dam provides ideal dryness for an extended time.

  • Disadvantages of Rubber dam include: discomfort during clamp placement, need for local anesthetic in some instances, difficulty in securely placing a clamp onto a partially erupted tooth

• If cotton rolls become moist, replace them, repeating etching if saliva contacts the etched surface.

Step 3: Dry the Surfaces

• Dry teeth with air for 20–30 seconds.

• Ensure no moisture comes out of the air syringe tip.

Step 4: Etch the Surfaces (Increasing the Surface Area)

• Apply 37% phosphoric acid etchant for 20 seconds.

• Etch fluorosed teeth for 15 seconds longer.

• Apply etchant to all susceptible pits and fissures and extend it up the cuspal inclines.

• If etched areas are not covered by the sealant, the normal appearance of the enamel returns in 1 hour to a few weeks due to remineralization.

Step 5: Rinsing and Drying the Teeth

• Rinse the occlusal surface for 10 seconds.

• Dry the surface for 10 seconds.

• The dried tooth surface should have a white, dull, frosty appearance.

• If areas lack this appearance, re-etch.

• The presence of saliva on the tooth is even more detrimental than water because its organic components interpose a barrier between the tooth and the sealant.

Step 6: Application of Sealant Material

• Place material in the fissures where there is the maximum depth.

• Ensure the sealant fills the fissures and has some bulk over the fissure.

• Bring the material to a knife edge approximately halfway up the inclined plane.

• Additional sealant can be added to voids without additional etching.

Step 7: Evaluate the Sealant

• Check the finished sealant for retention.

• If it doesn't adhere, repeat procedures with 15 seconds of etching.

• If two attempts fail, postpone sealant application until remineralization occurs.

• Check the occlusion and adjust if necessary.

  • Resin sealants are retained better on recently erupted teeth than in teeth with a more mature surface

  • They are retained better on first molars than on second molars.

  • They are better retained on mandibular than on maxillary teeth.

Step 8: Re-evaluation

• Schedule an initial 3-month recall to check for sealant loss, then evaluate on a six-month basis.

• Sealants become difficult to see or discern tactilely over time.

• If a sealant is lost, teeth that have been sealed have fewer carious lesions due to tags retained in the enamel.

These provide an additional anticariogenic effect. Fluoride can be added by:

1. Adding a soluble fluoride to the unpolymerized resin.

2. Adding an organic fluoride compound that binds chemically to the resin to form an ion exchange resin.

Fluoride-releasing sealants exhibit antibacterial properties and greater artificial caries resistance.

Glass Ionomer Sealants

Advantages

• Chemically adhere to the tooth surface with minimal preparation using Polyacrylic acid, which prepares the enamel without etching.

• Provide an anti-caries effect due to long-term fluoride release and recharge.

• Water-based and more technique tolerant.

Considerations

Should be considered when:

• Four-handed dentistry is not available

• Lack of patient's full co-operation

• There is bleeding or gingival fluid seepage

• Moisture control is compromised

Glass ionomer is best suited for protecting erupting teeth when inserted under the operculum.

Colored Versus Clear Sealants

• Colored sealants allow precise placement and easy monitoring of retention.

• Clear sealants may be more esthetically acceptable and allow observation of caries progression under the sealant.

Light-Cured Versus Self-Cured Sealants