What are dental sealants and how do they prevent tooth decay?

Tooth decay is the deterioration or destruction of tooth enamel – the hard outer layer of the tooth – characterised by the formation of cavities. If left untreated, these cavities grow and can reach the inside of the tooth, at the level of the pulp chamber, where the nerve endings are located. At this stage, toothache and tooth sensitivity occur.

Tooth decay is mainly caused by bacteria, but other factors can also contribute to its development. It frequently occurs when foods rich in carbohydrates (sugars and starch) remain on the teeth for long periods. These include milk, fizzy drinks, raisins, sweets, biscuits, fruit juices, cereals and bread.

The bacteria that normally live in the mouth break down these foods into acids. When combined with saliva, these acids and food debris form dental plaque, which adheres to the surface of the teeth. Over time, the acids erode the enamel and lead to the development of tooth decay.

All children have bacteria in their mouths, so they are all at risk of developing tooth decay. The risk is higher when there are:

• high levels of cariogenic bacteria;
• a diet high in carbohydrates;
• drinking water with low or no fluoride content;
• poor oral hygiene.

Delaying treatment for tooth decay can lead to more extensive dental damage, affecting the nerve and causing infectious complications. Ultimately, this can even lead to tooth loss. These situations require complex fillings or root canal treatment, which are more labour-intensive and costly procedures compared to a simple dental filling. 

Dental sealants are a method of preventing tooth decay, which involves applying a protective material to the grooves and pits on the chewing surfaces of permanent or primary molars and premolars, as well as to certain surfaces of the upper incisors, in patients at high risk of tooth decay.

Dental sealants penetrate the fissures and anatomical cavities of the tooth and form a physical barrier on its surface, protecting it against the build-up of bacterial plaque and the action of acids. 

Materials used

Sealant materials can be divided into two main categories, depending on their setting mechanism:

• Glass ionomers – these set through an acid-base reaction and have the advantage of releasing fluoride;
• Composite resins – these set by polymerisation, usually activated by a dental light-curing lamp;
• There are also hybrid materials (resin-modified glass ionomers or polyacid-modified resins), which combine the properties of both categories. 

Dental sealants provide extra protection by covering the chewing surfaces of molars and premolars, areas prone to the build-up of bacterial plaque.

A dental sealant is a thin layer applied to the tooth that acts as a permanent protective barrier for the enamel.

Main benefits

• Prevention of tooth decay – reduces the risk of lesions which, if left untreated, may require complex fillings or root canal treatment.
• A simple and painless procedure – carried out quickly, without anaesthesia, ensuring the patient’s comfort.
• Maintaining oral health – even with rigorous oral hygiene, the back molars are difficult to clean properly, and these are best protected by sealing.
• Lower costs in the long term – compared with the treatments required for decayed or severely damaged teeth.
• Easy to repair – if the material comes loose, the dentist can restore the seal with a simple and quick procedure. 

Dental sealants are most commonly recommended for the first permanent molars, which erupt at around the age of 6. However, they can also be applied to primary teeth or other permanent teeth (molars and premolars) with fissures, in patients at high risk of tooth decay.

The ideal candidates for this procedure are:

• children at the age when the first permanent molars erupt;
• adolescents with a high predisposition to caries;
• adults with hard-to-clean tooth surfaces and an increased risk of developing caries. 

• Thorough oral hygiene – brushing twice a day and flossing. Sealants protect the chewing surfaces, but not the spaces between the teeth.
• Regular dental check-ups – to check the condition of the sealants and have them replaced if necessary.
• Avoid hard and sticky foods – such as toffee or hard sweets, which can damage the protective layer. 

The role of dental prophylaxis in the effectiveness of dental sealants

Dental prophylaxis aims to prevent, rather than treat, oral diseases. It includes the removal of bacterial plaque and tartar, the application of caries-preventive agents, the assessment of existing dental work, and patient education on proper oral hygiene.

Dental sealants form part of preventive measures designed particularly for children, but are also beneficial for teenagers or adults at high risk of tooth decay. Combined with proper oral hygiene and healthy eating habits, they become an effective method of preventing tooth decay.

In short, the success and durability of sealants depend directly on adherence to preventive care guidelines and regular dental check-ups.