The ABCs of Sealants

There is strong clinical evidence to support the use of dental sealants in the prevention of pit and fissure caries, especially when placed on the permanent molars of high-risk individuals soon after tooth eruption.^1–3 Parents/caregivers, however, may not know what sealants are or how they help prevent tooth decay. Therefore, oral health professionals must be prepared to educate parents/caregivers and answer questions related to the benefits and limitations of sealants. Photographs, models, and other instructional aides can be helpful when explaining how sealants work.

A basic explanation for parents/caregivers is that a sealant is a material applied to the pits and fissures or grooves of the teeth to prevent cavities.⁴ Sealants protect at-risk pits and fissures by making surfaces more cleansable and by preventing accumulation of plaque, bacteria, and food debris. They are ideally placed before the onset of a caries lesion; however, they can also be used on early noncavitated lesions to prevent further progression. By sealing over an early noncavitated lesion, the caries process is inhibited by preventing bacteria’s access to fermentable carbohydrates.⁵

APPROPRIATE POPULATIONS

Caries management by risk assessment (CAMBRA) is a key element in deciding who should receive dental sealants. CAMBRA evaluates risk factors and protective factors to determine an overall caries risk profile. Tooth-level and patient-level factors must be considered to determine if a child is at risk of developing caries, especially on molars. Tooth-level factors include the depth of pits and fissures, whether cusps are well-coalesced, if enamel is well formed, and whether a caries lesion is already present. Patient-level factors include dietary patterns, oral hygiene practices, caries history, and salivary quantity and quality.

Children at low caries risk may not benefit from sealants because they are not likely to develop caries lesions. A change in either tooth-level or patient-level factors, however, may warrant the application of sealants in previously low-risk individuals.

MATERIALS

The two most widely used sealant materials are resin and glass ionomer.⁶ While each material presents unique benefits, resin materials should be used whenever possible because they exhibit greater retention and wear resistance than glass ionomers.⁶ Resin systems are technique sensitive and rely heavily on moisture control because saliva contamination can adversely affect the micromechanical bonding to tooth structure.

Resin sealant materials vary significantly in their filler content and color. They can be unfilled or filled, and opaque, colored, clear, or tooth-colored. Some materials change from colored to natural looking after the resin is cured. The benefit of a colored or opaque sealant material is that the sealant’s presence can be verified at future appointments. Increased filler content improves wear resistance, though materials with high filler content can be too viscous to flow into the depths of pits and fissures. During the early years of sealants, a self-curing sealant system was widely used. Clinicians now commonly utilize materials that are “command-cured” using a dental curing light. While both show similar retention rates, clinicians tend to prefer the physical properties of these materials.⁷

If isolation is not possible and a tooth warrants immediate sealant placement, then glass ionomer is the material of choice.⁸ Glass ionomer is an excellent interim material because it also releases fluoride.⁹ The material chemically bonds to tooth structure following the application of a polyacrylic acid conditioner. Traditional glass ionomers come in a variety of colors. Setting times vary as they are self-cured.

TIMING

Patients and parents/caregivers may not know when new teeth are erupting, so these areas may be at risk of plaque accumulation and caries due to inadequate brushing. Enamel is at increased risk of developing a lesion immediately after erupting into the oral environment because it is not fully matured or calcified.¹⁰ Resin sealants should be placed as early as isolation permits. Attempting to place sealants on a partially erupted tooth may lead to failure. Isolation is difficult if some portion of the tooth is not exposed to the oral environment (eg, due to a gingival operculum).¹¹ The presence of an early lesion on a partially-erupted tooth is an indication for a glass ionomer sealant. Although the risk of developing caries in a tooth with a fully- or partially-lost sealant does not exceed the risk in a never-sealed tooth, resin sealants should not be placed unless adequate isolation is achievable.¹²

APPLICATION

A four-handed technique should be used to place sealants when possible because it decreases the likelihood of moisture contamination and clinical failure.¹³ However, there is only mild evidence to show that the longevity of sealants placed using four-handed dentistry is greater than those placed with a two-handed technique.¹³

The first step to placing a sealant is to clean the tooth because residual plaque or debris will prevent adequate bonding of the material to the tooth. This can be done with a toothbrush, explorer, or a contra-angle brush with pumice.¹⁴ Some modern technologies include the use of air abrasion to create a clean and roughened surface; however, there is insufficient evidence to show this technique offers more benefits than other cleaning methods. Furthermore, routine mechanical preparation of pits and fissures is contraindicated because it does not improve sealant retention and may introduce a cavitation to the lesion.¹⁵

After cleaning the tooth surface, an isolation technique is selected. Behavior can significantly impact isolation, so it is important to ensure that a child’s reaction does not compromise sealant quality. The placement of a sealant on a young child is an opportunity to introduce the child to dental treatment and dental materials. Using a “tell-show-do” approach can be an especially effective behavior management technique.

While rubber dam isolation offers excellent moisture control, the need for local anesthetic for rubber dam clamp placement may be burdensome.¹⁶ For this reason, isolation with cotton products remains the most widely used technique. With resin sealant materials, the tooth surface should be etched with 37% phosphoric acid for 15 seconds on primary teeth and 30 seconds on permanent teeth. Recommended etching times may vary depending on the manufacturer and whether the etchant is liquid or gel. After the appropriate amount of time has lapsed, the tooth should be completely rinsed and dried until the enamel has a frosted appearance.

A bonding system may also be utilized. Multiple studies show increased sealant retention with the use of bonding systems,¹⁷ which typically include the application of a primer and bonding agent in a dual-dose or single-dose system. It is important to gently blow air on the bonding agent to release the solvent and prevent the bulking of bonding material when light-cured.

The final step is the placement of the sealant material. Sufficient sealant material should be applied to all pits and fissures without creating excess bulk. Clinicians frequently apply the material using the sealant syringe tip (if command curing) and follow-up with an explorer or microbrush to carry the material though all occlusal anatomy. Once the material is set—either by self-cure or command-cure—the sealant should be inspected closely both visually and tactilely with an explorer to ensure there are no voids or marginal discrepancies. Curing times of up to 40 seconds may be necessary if an opaque material is used.¹⁸

Additional sealant material can be applied to a previous layer if saliva has not contaminated the oxygen-inhibited layer. The occlusion should be verified to ensure there are no premature contacts on the sealant material. If heavy contacts are noted, they should be adjusted with a handpiece and bur. It is particularly important for oral health professionals to inspect sealants at follow-up visits and reapply them as necessary.

CONCLUSION

Oral health professionals must follow key principles and best practices for patient selection and clinical sealant placement. These include the following:

• Sealant placement should be based on individual caries risk.
• Sealants are cost-effective when placed on the permanent molars of individuals at high caries risk; they also can exert preventive effects on any tooth with at-risk pits and fissures.
• Dental professionals must strictly follow manufacturer recommendations for the material chosen.
• The longevity of resin sealant retention is heavily dependent on proper isolation and careful attention to each clinical step.
• Dental sealants offer an excellent adjunct to other prevention strategies and should be encouraged in clinical practice.

Oral health professionals play an important role in preventing dental caries through patient education and the delivery of preventive services. As such, they should be familiar with the clinical recommendations for sealant placement, as they will be called upon to provide patients and parents/caregivers with information about sealants’ efficacy.

REFERENCES

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15. Francescut P, Lussi A. Performance of a conventional sealant and a flowable composite on minimally invasive prepared fissures. Operative Dentistry. 31(5): 543-550, 2006.
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From Dimensions of Dental Hygiene. June 2014;12(6):32,34.