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| REVIEW ARTICLE |
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| Year : 2014 | Volume
: 5
| Issue : 4 | Page : 253-257 |
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Pit and fissure sealants in pediatric dentistry
George Babu1, Shanthala Mallikarjun2, Bobby Wilson2, Chandru Premkumar2
1 Department of Pedodontics, Kannur Dental College, Anjarakandy, Kannur, Kerala, India
2 Department of Pedodontics, Coorg Institute of Dental Sciences, Karnataka, India
| Date of Web Publication | 20-Nov-2014 |
Correspondence Address:
George Babu
Department of Pedodontics, Kannur Dental College, Anjarakandy, Kannur - 670 612, Kerala
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/0976-433X.145131
Caries on the occlusal surface of dentition is a significant dental health problem. Molars and premolars are the most vulnerable teeth to caries attack. The high susceptibility of these teeth to caries is directly related to morphology of their occlusal surface. Fluoride's great success in preventing tooth decay on smooth surfaces has made dental caries largely a disease of rough irregularities. Enamel surfaces with pits and fissures receive minimal caries protection from either systemic or topical fluoride agents, the reason for ineffectiveness of fluorides in the pit and fissure caries may be related to the differences in enamel thickness and the inaccessibility of the base of pits and fissures to topical fluorides. The most efficient way to prevent pit and fissure caries is by effectively sealing the fissures using resins called pit and fissure sealants. Keywords: Glass ionomer sealants, pit and fissure sealants, prophylactic odontomy
How to cite this article:
Babu G, Mallikarjun S, Wilson B, Premkumar C. Pit and fissure sealants in pediatric dentistry. SRM J Res Dent Sci 2014;5:253-7 |
| Introduction | |  |
Dental caries remains as one of the most widespread disease of mankind. It is the single most common chronic childhood disease. Caries in children begins shortly after eruption of the deciduous teeth and continue to increase at a remarkable rate in their school age. Deep pits and fissures favor food retention and are difficult to clean by routine brushing. It provides a favorable environment for the oral microorganisms to thrive and convert the carbohydrates to acids, leading to demineralization of the enamel. [1] The most efficient way to prevent pit and fissure caries is by effectively sealing the fissures using resins called pit and fissure sealants.
| History of pits and fissure | | |
There have been many attempts made within past decades to prevent the development of caries, in particular occlusal caries as it was once generally accepted that pits and fissures of teeth would become infected with bacteria within 10 years of erupting into the mouth [Table 1].
| Classification of pit and fissure sealants | | |
Based on filler content
Sealants are classified into filled and unfilled resin systems in regard to the presence or absence of filler particles in the system, but most of the self-cured resins are unfilled. [8] The filled sealants contain microscopic glass beads, quartz particles, and other fillers used in composites resins. The fillers are coated with products such as silane, to facilitate their combination with the bisphenol A and glycidyl methacrylate (BIS-GMA) resin.
The fillers make the resin more resistant to abrasion and wear. In contrast, unfilled sealants wear quicker, but usually do not need occlusal adjustment. Unfilled resins will penetrate deeper into the fissure system, and therefore perhaps be better retained. Filled resins have shown to be effective in caries prevention. [9] Filled resins are opaque and are available in tooth-colored or white shades. Unfilled resins are color less or tinted transparent materials. [10]
Based on the color of the sealants
In March 1977, the first colored sealant (3M™ ESPE™ Concise™ White Sealant) was introduced to the US market. [11] These sealants are easily visible and chair side time is saved at follow-up. Furthermore, parents are reassured when they can see the sealants on their child's teeth. As the sealant is clearly visible to the child, it is of benefit to encourage the child to look periodically for any sealant loss. This constant reminder of the presence of a preventive agent will help in the motivational aspects of preventive program. [12] Tinted and opaque fissure sealants have the advantage of more accurate evaluation by the dentist at recall. In 2001, dental manufacturers have introduced sealants that change colour during polymerization. The Helioseal Clear Chroma Ivoclar Vivadent AG changes from clear to green after photo - polymerization. The 3M™ ESPE™ Clinpro™ Sealanth as a pink color when applied and converts to a white opaque mass after light curing. [13]
First generation sealants
The first sealant material that utilized the acid etch technique was introduced in the mid 1960's and was a cyanoacrylate (CA) substance. [6] CAs were activated with an ultraviolet light source at a wavelength of 365 nm. Nuva Seal® was the first successful commercial sealant in market, in 1972 [11] CAs were not suitable as sealant material owing to bacterial degradation of the material in the oral cavity overtime. To overcome these CAs were replaced with second generation sealant materials, which were found to be resistant to degradation and produced a tenacious bond with etched enamel. [6]
Cyanoacrylates were first described in 1949 and their potential as adhesives was quickly recognized. Various homologues of CA adhesive have been studied and used, including methyl-, ethyl-, isobutyl-, isohexyl-, and octyl-CA. Its clinical applications in dentistry and medicine, especially as tissue adhesives and sealing materials. CA adhesive is a compound synthesized by condensation of a cyanoacetate with formaldehyde in the presence of a catalyst. [14]
In preventive dentistry, CA was also the first material modified for use as a pit and fissure sealant to help prevent dental decay, especially on the occlusal surface. However, because this material biodegrades and does not last long in the oral cavity, it was later replaced with other dental materials, such as GMA dimethacrylate. [6]
Second generation sealants
The second generation sealants are the dimethacrylates, which represent the reaction product of BIS-GMA ,which is considered by its originator to be a hybrid between a methacrylate and an epoxy resin . Second generation sealants are auto polymerizing and set upon mixing with a chemical catalyst - accelerator system. They are generally "self-cured" or "chemically cured" without the need of an external ultraviolet source. [6] Most commercial sealants available today are BIS-GMA dimethacrylates or urethane dimethacrylates based products. [11] Auto polymerizing resins generally performed better than the early ultraviolet light initiated resin sealants. [7] Ripa (1985) reviewed the results of >5 dozen clinical studies on the effectiveness of first generation (ultraviolet - initiated) and second generation (chemically initiated) sealants. The sealants were evaluated from 1 to 7 years after placement, second generation sealants provided superior retention and caries protection than the first generation sealants. [15]
Third generation sealants
The third generation sealants are photo activated resins which contain a diketone initiator such as Camphoroquinone and a reducing agent such as tertiary amine to initiate polymerization. Use of visible light source requires eye protection due to the intensity of the light created. [6] The evaluation of third-generation or visible light activated sealants falls into the present era of clinical testing in which retention, rather than caries inhibition, constitutes the principle criterion of success. Retention of sealant material is the main determinant for the caries preventive effect of sealant. [15]
A study was conducted to compare the retention of auto polymerized and light polymerized Delton fissure sealants in 207 sealed tooth for 5 years showed that, there was 59% complete retention of auto polymerized sealants and 48% of the light polymerized sealants at the end of the study period. [16]
Fourth generation sealants
Fluoride the pivot of preventive dentistry continues to be the cornerstone of caries prevention programs. [17] In order to maximize the exposure time of fluoride on enamel for improved prevention of dental caries, fluoride-releasing materials have been developed. The literature has reported a decrease in enamel solubility and secondary caries on treatment with fluoride dental materials based on the fact that increased fluoride uptake by adjacent enamel prevents demineralization and promotes mineralization. [18] Early in the development of sealants, it was recognized that the addition of fluoride to a sealant, or perhaps to the enamel prior to sealant application, could have the potential benefit of additional caries protection. [11]
Brown and Selwitz was the first to formulate a polyurethane fluoride containing sealant material that would release fluoride on the enamel surface for an extended period of 24 h to 30 days. [19]
Two methods of fluoride incorporation into pit and fissure sealants are used. In first method, fluoride is added to unpolymerized resin in the form of a soluble fluoride salt. After the sealant is applied to the tooth, salt dissolves and fluoride ions are released, Helioseal-F is produced based on this procedure. The second method of incorporating fluoride is by addition of an organic fluoride compound that is chemically bound to the resin to form an ion exchange resin; Teethmate F-1 is based on this method. [18] More recently, a commercially available sealant with fluoride was marketed that purportedly releases fluoride (fluoroshield). Fluoride releasing sealants have shown antibacterial properties as well as greater resistance to artificial caries in comparison to nonfluoridated sealants. [17]
| Glass ionomer cement used as sealants | | |
The glass ionomer cement (GIC) developed by McLean and Wilson in 1960's have been indicated as restorative materials, bases and cementing agents. It is also used as sealing agents for pits and fissures, due to their improved properties such as: [20]
- Hydrophilic properties and good adhesion to tooth structure.
- Biocompatibility of the polycarboxylate cements with the translucency and hardness.
- Fluoride release of the silicate cements.
The glass ionomer sealant was believed to be a useful product, based on the chemical composition, handling and fluoride release properties, despite reports that these sealants have very low retention rates. [21] GIC is more suitable for use in young children with incompletely erupted molars as the retention of GIC is not dependent on complete moisture control. [22]
The primary advantage of GIC over conventional BIS-GMA sealants is the capability of glass ionomer to release fluoride, which among other beneficial effects may result in an increased resistance of fissures to demineralization. [6],[23] Simonsen concluded that differences in caries prevention between resin-based and glass ionomer sealants remain equivocal. [24] The caries preventive effect of a glass ionomer sealant depends on both retention of the sealant and fluoride release. The poor retention of glass ionomer sealants probably precludes them from use as sealants, particularly in lieu of evidence of superior caries prevention despite the poor retention. [11] In the literature, caries preventive effects are reported to prevail even after the visible loss of the GIC sealant. [25]
One main reason for the loss of the glass ionomer sealants could be inadequate adhesion of the cement to the enamel surface. [23] In addition, glass ionomer sealants may have been exposed to saliva before it had completely set, which could predispose to surface degradation and early loss of sealant. [5] With the introduction of resin modified glass ionomer, properties regarding, adherence, esthetics and manipulation have been improved. In addition, maintenance of anticaries and cariostatic effect has been obtained due to their continuous fluoride release. [21]
Indications and contraindications [26],[27] for the use for fissure sealants explained in [Table 2].
Age period for sealant placement
The disease susceptibility of the tooth should be considered when selecting teeth for sealants not the age of the individual.
- Ages 3 and 4 years are the most important times for sealing the eligible deciduous teeth.
- Ages 6-7 years for the first permanent molars.
- Ages 11-13 years for the second permanent molars and premolars. [18]
Occlusal fissures are classified into five types U, V, Y, I, IK based on fissure morphology. [28] The shallow wide V and U shaped fissures tend to be self-cleansing and somewhat caries resistant. The deep narrow I and IK shaped fissures are susceptible to caries.
Application of pit and fissure sealant
Cleaning the pit and fissure surfaces
Plaque and debris might interfere with the etching process or sealant penetration. Historically, it has been advocated to clean the surfaces with bristle brush and pumice. Use of prophy pastes, especially those with fluoride, have been discouraged because it was thought that the fluoride might make the enamel surface less reactive to the etchant and thereby reduce the bond strength. Air abrasion also has been suggested for preparation of the occlusal surface before sealant application.
Isolation of the tooth
Adequate isolation is the most critical aspect of the sealant application process. Salivary contamination of a tooth surface during or after acid etching will have a deleterious effect on the ultimate bond between enamel and resin. The rubber dam, when properly placed, provides the best, most controllable isolation, and for an operator working alone, it ensures isolation from start to finish. Cotton roll isolation offers some advantages over rubber dam isolation.
Etching
Introduction of acid etch technique has made the sealing of occlusal surfaces more effective. The most critical step in sealant application technique is acid conditioning or acid etching procedure. Etching enhances the tooth's receptivity to bonding with the sealant. During this critical step, meticulous maintenance of a dry tooth surface is essential for bonding to be successful. [29] The conventional 60 s etching was first used by Ripa and Cole.
Increased etching time for deciduous teeth is attributed to various reasons like:
- Deciduous teeth have less mineral and more organic material in the enamel.
- Deciduous teeth have a larger internal pore volume and thus more exogenous organic material.
- Deciduous teeth have more prism less enamel on their surface than do permanent teeth.
- The prism rods in deciduous teeth approach the surface at a greater angle and thus are more difficult to etch.
Three characteristic etching patterns occur following exposure of sound enamel to phosphoric acid. [12]
- Type 1 etching pattern: Prism cores lost but Prism peripheries remain - honeycomb appearance.
- Type 2 etching pattern: Prism peripheries are lost, Prism cores appear to be relatively intact - cobble stone appearance.
- Type 3 etching pattern: Some regions of etched enamel show a generalized surface roughening and porosity with no exposure of prism cores or peripheries.
Thoroughly rinse and dry the tooth
Many of the sealant manufacturers recommend rinsing the tooth for 20-30 s to remove the etchant. An exact rinse time is probably not as important as ensuring that the rinse is long enough and thorough enough to remove all of the etchant from the surface. Drying the tooth with compressed air is likewise done not for a specific time but rather for a specific result. A tooth that is completely dried will exhibit a chalky, frosted appearance. {30}
Application of sealant
During sealant application, all the susceptible pits and fissures should be sealed for maximum caries protection. This includes buccal pits of mandibular molars and lingual grooves of maxillary molars. The sealant material can be applied to the tooth in a variety of methods. Many sealant kits have their own dispensers, some preloaded that directly apply the sealant to the tooth surface. Some common problems occur during sealant application. Small bubbles may form in the sealant material. If these are present, they should be teased out with a brush before polymerization. Unfilled sealants have a low viscosity that makes them prone to pooling in the distal pit area of maxillary molars due to patient position and gravity. This can be rectified by applying the sealant judiciously or by removing excess amounts with a brush.
Evaluation
The sealant should be visually and tactually inspected for complete coverage and absence of voids or bubbles. Attempts should be made to dislodge the sealant with an explorer. If the sealant is dislodged, the tooth should be carefully inspected to see that no debris has been left in the fissure, which may have interfered with the bond. Small voids in the sealant can be repaired simply by adding new material to the void and polymerizing. Some sealants will be completely or partially lost and will require reapplication. During routine recall examinations, it is necessary to re-evaluate the sealed tooth surface both visually and tactually for loss of material, exposure of voids in the material and caries development. The need for reapplication of sealants is usually highest during the first 6 months after placement.
| Conclusion | | |
Caries is a problem for patients of all ages. Along with proper diet, fluoride, and biofilm control, pit and fissure sealants should be considered as part of an overall preventive program rather than an isolated procedure. Ideally, high-risk patients should have sealants placed on all posterior permanent teeth upon eruption. Proximal caries or self-cleansing pits and fissures are contraindications for dental sealants. The dental practitioner should be familiar with the various categories of sealants and the specific application methods for each product. With proper placement and maintenance, sealants can last years.
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[Table 1], [Table 2]
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