Introduction

Pits and fissures of the occlusal surfaces of the posterior teeth are more prone to caries development than the smooth surfaces due to their morphological complexity, making dental hygiene more challenging leading to increased plaque accumulation [1]. The enamel in pits and fissures cannot receive the same protection given by fluorides comparing to the enamel in the smooth surfaces [2].

The use of pit and fissure sealants provides a physical barrier that inhibits microorganisms and food particles accumulation, preventing caries initiation, and arresting caries progression [3][4].

Permanent first molars, followed by second molars, show the highest caries prevalence. The management of occlusal caries on permanent molars represents a significant challenge because the onset of caries occurs soon after they erupt into the oral cavity. The effectiveness of pit and fissure sealants relays on their long-term retention [4].

Anatomy and Physiology

The morphology of the occlusal surface of the molars is extraordinarily variable. Occlusal fissures are deep invaginations of enamel that 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.

• V type: they are wide at the top and gradually narrowing towards the bottom. They are shallow and wide and tend to be self-cleaning, somewhat caries resistant, and non-invasive technique is recommended.
• U-type: They are also shallow and wide, tend to be self-cleaning and somewhat caries-resistant, and non-invasive technique is recommended.
• I-type: They are extremely narrow slits. They are deep, narrow, and quite constricted, resembling a bottleneck, caries susceptible, and may require invasive technique.
• IK- type: They are seen as a narrow slit associated with a larger shape at the bottom, may require invasive technique, very susceptible to caries.

However, because of morphological variations, it is not always possible to categorize a tooth as having one particular type of fissure [2].

Indications

Pit and fissure sealants can be utilized as a primary prevention tool when the tooth or the patient is at an increased risk of experiencing caries or as a secondary prevention method interrupting the progression of incipient caries.

The indications for placing a pit and fissure sealant are as follow:

1. Pits and fissures of deciduous teeth in children when the tooth, or the patient, is at an increased risk of experiencing caries [5].
2. Pits and fissures of permanent teeth in children and adolescents when the tooth, or the patient, is at risk of experiencing caries [6][7].
3. Pits and fissures of permanent teeth in adults when the tooth, or the patient, is at risk of experiencing caries [6][7].
4. Incipient carious lesions (non-cavitated) of pits and fissures in children, adolescents, and adults [8].
5. Pit and fissures of primary and permanent teeth should be considered in children and young people with medical, physical, or intellectual disabilities, mostly when systemic health could be jeopardized by dental disease or the need for dental treatment [9].

Contraindications

Dental professionals should decide to place a pit and fissure sealant based on the patient's risk, not the age or time lapsed since tooth eruption [10]. If the patient does not exhibit any risk factors or is at low risk of developing carious lesions, there is no need to perform this preventive measure at that time. However, it is essential to highlight that all children should be regularly monitored for any changes in cariogenic risk factors or clinical or radiographic changes [9].

Equipment

There are two main materials used in pit and fissure sealants, resin-based and glass ionomer sealants.

Resin-based sealants are the first choice of treatment, and glass ionomer sealants may be utilized as a provisional agent when the placement of a resin-based sealant is indicated, but absolute isolation cannot be achieved, and therefore moisture control is compromised.

Glass ionomer sealants contain fluoride that can help to prevent caries through their release over a prolonged period [11].

The rest of the equipment typically includes:

• Air/water syringe
• Mouth mirror
• Explorer
• Excavator tip
• Two by two gauze squares
• Cotton rolls
• Cotton pellets
• Forceps/cotton pliers
• Articulating paper
• Curing light
• Handpiece
• Dappen dish with pumice

Preparation

The need and the method for surface cleansing of pits and fissures before placing a sealant may seem controversial. Some authors have suggested using pumice or air-polishing instruments to obtain an optimal acid-etch pattern of the enamel. At the same time, others believe that acid etching alone is sufficient for surface cleaning [9].

Technique or Treatment

Isolation of the Tooth

Moisture control is the most crucial aspect of the pit and fissure sealant placement, and therefore absolute isolation using a rubber dam is preferred. As a result of inadequate isolation, the enamel porosities formed during etching can be filled by any fluid blocking the resin tags, decreasing the retention of the material. There are cases where absolute isolation is not possible, or it is not practical, like in the case of newly erupted teeth due to the need for local anesthesia to place the clamp. In such cases, a dry field can be achieved by cotton rolls and isolation shields, and clever use of the evacuation tip. The application of glass ionomer may be considered as a temporary measure.

Acid Etching

• Most frequently used: 37% orthophosphoric acid (gel)
• Gel applied either directly with special application tips or with a small disposable brush
• Should be applied to all the susceptible pits and fissures and extend up to cuspal inclines
• Etch for 15 seconds for permanent molars, 15 to 30 seconds for primary teeth. Teeth with dental fluorosis require additional etching time
• If glass ionomer cement is being used, etching is not required, and a surface conditioner may be used
• Rinse well with air-water spray
• Dry the tooth with uncontaminated compressed air until a frosty white opaque appearance is seen
• If cotton roll isolation has been used, replace cotton rolls
• If this appearance is not seen, repeat acid etching
• If the surface becomes contaminated, re-etching must be done [12]

Sealant Placement and Curing

Many sealant kits have their own dispensers and instructions that must be followed.

• Apply sealant, allow to flow into pits and fissures
• In mandibular teeth, apply the sealant from the distal aspect, allow flowing mesially
• In maxillary teeth, apply the sealant from the mesial aspect, allowing to flow distally
• Use a fine brush, mini sponge, and carry sealant material up to the cuspal inclines
• Air bubbles should not be incorporated

Visible Light Cured Sealant

• 10 to 20 seconds: exposure to visible light
• The tip of curing light should be held 3 mm to 5 mm from the surface of the sealant

• After the sealant has set, wipe the surface with a wet cotton pellet 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

Evaluate the Sealant

• Visually and tactically

Evaluate the Occlusion of Scaled Tooth Surfaces

• Check the occlusion with articulating paper – round finishing bur
• Annual recall: 5% to 10% of sealants require repair or replacement annually

The retention of sealants can be evaluated through visual and tactile examinations. When the sealant has been lost or partially retained needs to be reapplied [4]

Follow-up

Sealed surfaces should be clinically and radiographically regularly monitored. Bitewing radiographs are recommended for radiographical assessment, which should be performed as often as the risk status indicates it. However, the risk status may change over time; for that reason, other susceptible sites, like proximal surfaces, should be monitored.

In the case of defected sealants, dentists must reapply them to maintain marginal integrity [9].

Complications

An unsuccessful pit and fissure sealant placement may be due to:

1. Contamination may result from either saliva or calcium phosphate products
2. Inadequate surface preparation
3. Incomplete or slow photopolymerization
4. Air entrapment
5. Overextension of the material beyond conditioned tooth surface

Toxicity

According to a few studies, the release of significant sealant components, like bisphenol A (BPA), impairs the development, health, and reproductive system in animals. However, the American Association of Pediatric Dentistry Guidelines, 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.

Clinical Significance

It is estimated that about one-fourth of children and more than one-half of adolescents present dental carious lesions in their permanent teeth [13]. The occlusal surfaces of the posterior teeth are the most susceptible to caries development due to pits and fissures with complex morphologies that make them the perfect habitat for caries development. There is sufficient evidence to believe that sealants are an effective method to prevent this undesired disease. A study performed in children has shown a 37% decreased risk of dental caries with the placement of pit and fissure sealants compared with the control group. Compared to no sealant use, the use of pit and fissure sealants reduced the risk of developing dental caries by 44% after three years in the first permanent molars [3]. 

Caries risk assessment is the most important part of the decisionmaking process, and there is a need to reevaluate a patient’s caries risk status periodically.

Enhancing Healthcare Team Outcomes

Pit and fissure sealants technique can be used as part of primary prevention, anteceding the development of dental caries, or as a secondary prevention measure stoping the disease progress. It is a tool for caries prevention on an individual basis or as part of a public health measure for at-risk populations [4]. Therefore it is imperative that all dental specialties professionals, including preventive dentistry, public health dentistry, restorative dentistry, pediatric dentistry, oral medicine, endodontics, and general dentistry professionals, are aware of the high prevalence of pit and fissure caries and that dental sealants should be indicated based on a caries risk assessment in each patient.