For the past several decades, a significant decline in the prevalence of dental caries in children in the developed countries has been well-documented. Among all tooth surfaces 12.5% are occlusal, but these account for two-thirds of total caries in children. Caries tends to occur more in deep and narrow pits and fissures. Pits and fissures are eight times as vulnerable as the smooth surface to caries. Caries occurring in the pits and fissures account for 80% to 90% of the total caries status in permanent teeth and primary teeth they account for 44% of the whole.
Pits and fissures are more prone to caries development than smooth surfaces of the tooth which can be due to the morphological complexity of these surfaces, which in turn can lead to increased plaque accumulation and decreased levels of caries protection on pits and fissures. Plaque accumulation and susceptibility of caries are greater during the eruption of the molar teeth. Caries susceptibility in individuals is greater for early initiation and progression of caries among these sites.
Occlusal fissures are deep invaginations of enamel, they can be extremely diverse in shape and have been described as broad or narrow funnels, constricted hourglasses and multiple invaginations with inverted ‘Y’ shaped divisions and irregularly shaped.
Nagano (1960) gave a classification for fissures:
V type: Wide at the top and gradually narrowing towards the bottom (34%), tends to be self-cleaning, are shallow and wide, somewhat caries resistant and non-invasive technique is recommended.
U-type: They constitute 14% of fissures and consists of similar width, shallow and wide, tend to be self-cleaning and somewhat caries-resistant and non-invasive technique is recommended.
I-type: Extremely narrow slit (19%). It is deep, narrow and quite constricted resembling a bottleneck, caries susceptible and requires invasive technique.
IK- type: Seen as narrow slit associated with a larger shape at the bottom (26%), requires invasive technique, very susceptible to caries.
Inverted Y type: 5% to 10%
Other types: 7%
However, because of morphological variations, it is not always possible to categorize a tooth as having one particular type of fissure.
Indication for sealant use includes:
Newly erupted both primary molars and permanent bicuspids and/or sticky grooves and fissures.
Stained pits and fissures with minimum decalcification of opacification and no softness at the base of the fissure.
A tooth in question should have erupted less than four years ago.
A deep or regular fissure, fossa or pit is present, especially if it catches the tip of the explorer.
The fossa selected for sealant placement is well isolated from another fossa with a restoration present.
An intact occlusal surface is present where the contra-lateral tooth surface is carious or restored.
If there is no radiographic evidence.
Patient at moderate or high risk of developing dental caries for a variety of reasons.
Patients with incipient caries.
Patients who have sufficiently erupted permanent teeth with susceptible pits and fissures.
Patients who have existing pits and fissures that are anatomically susceptible.
Use of other preventive treatment such as systemic or topical fluoride therapy, to inhibit interproximal caries formation.
Uncooperative behavior limits the use of sealants due to hampering of adequate field or isolation techniques throughout the procedure. Other contraindications include:
Well established cavitated caries lesion.
Proximal caries, existing on the other surfaces of the tooth with definitive caries diagnosis.
A large restoration is present on occlusal surface.
If pits and fissures are self-cleansing.
Life expectancy of primary tooth is very less.
When a patient is allergic to sealant material.
Pit and fissure that has remained caries-free for four years or longer.
An individual with no previous caries experience and well coalesced pits and fissures.
In children who are too young to cooperate during the procedure.
Tray set-up: the tray should be set up before the procedure, and set up to the practitioner's preferences.
Tooth selection should include those with deep pits and fissures, interproximal caries with no occlusal involvement, and high caries susceptibility.
Preparation of tooth:
Cleaned using handpiece or toothbrush
Then rinsed with water
Prophylaxis should be carried out using pumice slurry applied with a rubber cup or pointed bristle brush
After pumice, rinse tooth well
If the fissure is widened with the help of a burr, it is an invasive pit and fissure technique
Acid-etching may be enough for cleaning of a tooth surface.
The techniques deployed varies depending on the procedure.
Isolation of the tooth:
Most critical part of sealant placement
Rubber dam could be used
Cotton rolls may also be used
Bibulous pads over opening of parotid ducts
Suction should be used
Permanent molars: Ivory 14 or 14A
Newly erupted molars: Ivory 8A
Saliva absorbers may also be used
Sldo, an ejector-moisture control system could be used, like a bite block or rubber tongue shield, connected to a high-speed evacuation line.
Most frequently used: 37% orthophosphoric acid (gel/liquid)
Gel applied either directly with special application tips or with a small disposable brush
Liquid etchant: brush or small cotton pledget
Should be applied to all the susceptible pits and fissures and extend up to cuspal inclines
Most important and critical step of the procedure
Must make sure that etchant does not come in contact with soft tissue. If it does, wash thoroughly. It may cause burning or oral mucosa, staining of clothes etc.
Etch for 15 seconds for permanent molars, 15 to 30 seconds for primary teeth. Fluorosed teeth require additional etching time.
If glass ionomer cement is being used, etching is not required: surface conditioner may be used.
Etching produces micro porosities: resin extends into these porosities and forms tags: these retaining the sealant on to the surface of the teeth.
Rinse well with air water spray for 30 seconds.
Dry tooth surface for 15 seconds with uncontaminated compressed air.
If cotton roll isolation has been used, replace cotton rolls.
Frosted white opaque appearance is seen. This is because 5 mm to 10 mm of the original surface is removed.
If this appearance is not seen, repeat acid etching.
If the surface becomes contaminated, re-etching must be done.
Sealant placement and curing:
Many sealant kits have their own dispensers and own set of steps, they must be followed.
Apply sealant, allow to flow into pits and fissures.
In mandibular teeth, apply sealant to the distal aspect, allow to flow mesially.
In maxillary teeth, apply sealant to mesial aspect, allow to flow distally.
Use a fine brush, mini sponge, and carry sealant material up to the cuspal inclines.
Air bubbles should not be incorporated.
After sealant has set, wet cotton pellet- wipe surface so that air inhibited layer of non-polymerized resin is removed and failure of this step leaves an objectionable taste in the patient's mouth.
Chemically cured sealant:
Follow manufacturers instructions carefully
Working time is limited
Liquid and catalyst is in 1:1 ratio
Visible light cured sealant:
10 to 20 seconds: exposure to visible light
Tip of curing light should be held 3 mm to 5 mm from the surface of sealant.
Evaluate the sealant:
Visually and tactically
Take the explorer and attempt to dislodge it
After evaluation, remove isolation and let the patient rinse.
Evaluate the occlusion of scaled tooth surfaces
Occlusal high points
If unfilled, tell patient all will be ok in a few days
If filled, check the occlusion with articulating paper – round finishing bur
If not done well, 15 seconds of etching and repeat procedure
If two unsuccessful attempts, wait until remineralization occurs.
Annual recall: 5% to 10% of sealants require repair or replacement annually
Complications can be due to various causes including:
Contamination may result from either saliva or calcium phosphate products
Inadequate surface preparation: improper cleaning
Incomplete or slow mixing of self-cure
Too slow application of material results in thicker mix
Over extension of material beyond conditioned tooth surface
According to few studies the release of major sealant components, like Bisphenol A (BPA), impairs the development, health and reproductive system in animals.
However, the American Association of Pediatric Dentistry Guidelines reiterates that the US Drug and Food Administration (FDA) and the American Dental Association (ADA) have concluded that the low-level of BPA exposure from dental sealants poses no known health risks.
Sealants can be used as a preventive measure for total caries prevention program along with the optimum use of fluoride, reduced frequency of sucrose intake and maintenance of good oral hygiene. Pit and fissure sealants provide 100% caries prevention on the occlusal surface as long as the sealant is retained on the tooth surface. Complete retention rate up to one year is approximately 85% to 100%. Subsequently, retention rate comes down to around 50% in five years time. Once the retention rate comes down to 50%, it requires total replacement of the sealant.
Use of sealants which are non-transparent helps to identify the presence or absence of the sealant during their recall. It can be noted that retention of fissure sealants on permanent teeth is greater than primary teeth. On account of difficulties of sealant retention on primary teeth due to enamel structure differences. Caries reduction effectiveness of sealant is equally good in primary and permanent teeth.
Sealant as a therapeutic measure
It is seen that during initial caries if the teeth are sealed the number of viable bacteria decreases leading to inhibition of caries progression. This led to the concept by Bodecker "When in doubt, seal" rather than when in doubt fill.
Enhancing Healthcare Team Outcomes
Public Health applications
Use of sealants on a public health basis is very limited due to the professional time and cost involved. The cost-benefit ratio in the case of sealants is 0.88 dollar, which is more than the benefit when compared with water fluoridation (5.5). The average time for sealant application is 9 minutes 24 seconds per child. It is worthy to say that use of sealants must be related more to the preventive philosophy and conservation of the tooth structure than to the cost benefit ratio. Healthcare workers including nurses should routinely examine the oral cavity of children and refer them to the dentist if they note caries.