Tooth fissures are small furrows or dimples on the occlusal surfaces of molars that run between the cusps of the tooth. Each molar usually has a longitudinal fissure, from which several transverse fissures emerge. Bumps and fissures are important in order to chew the food with the teeth as finely as possible, but this relief is problematic for oral hygiene. This is because caries bacteria can easily settle in the longitudinal and transverse fissures on the tooth surface, which are difficult to completely remove with a toothbrush.
This is because the deepest parts of the fissures are often narrower than the diameter of the bristles, so that bacterial plaque cannot be removed as part of daily oral hygiene. This is made more difficult by the fact that behind the so-called fissure entrance there is often still space of up to one millimetre until the fissure base is reached on the tooth surface.
The posterior teeth are particularly susceptible to fissure caries in the first two years after their breakthrough, which is why dentists recommend fissure sealing to protect the toothache. If possible, this should be done within six months of the breakthrough of the teeth. Then the young tooth is completely mineralized and can be effectively protected against caries by fissure sealing for up to 10 years.
How is a fissure sealing carried out?
There are two different methods of fissure sealing: Preventive fissure sealing, which is always used when the teeth are not yet visibly discoloured (an indication of incipient caries), and invasive fissure sealing.
With preventive sealing, the tooth to be treated is first drained and then professionally cleaned by the dentist. Then the tooth surface is roughened by applying 35 percent phosphoric acid and then dried with compressed air. The thin sealing material is then applied to the prepared tooth and distributed. In order to harden the sealant, the tooth is then irradiated with a special light to form a dense and stable plastic coating. At the end of the treatment, the dentist checks whether any imperfections have been caused by the sealing and, if necessary, carefully grinds them before remineralizing the enamel, which has been roughened by the acid, with fluoridation. The fluoride penetrates into those areas of the enamel that have not been coated with sealant.
With invasive fissure sealing, darkly discoloured areas in the fissures are removed with special instruments to ensure that no further caries has formed under the discoloration. Further treatment corresponds to preventive sealing.
After sealing the fissures, the patient should refrain for about an hour from everything that interferes with the effect of fluoridation, i.e. eating and drinking, chewing gum or brushing his teeth.
Which materials are used?
Today, dimethacrylate-based plastics are often used for fissure sealing, sometimes with additional fluoride additives to additionally protect the enamel. An alternative to plastic sealing is cement, or more precisely glass ionomer cement. This material has the advantage that it can release more fluoride than plastic to the tooth, but its durability is limited in comparison to elastic plastic sealing, spalling occurs much more frequently with less elastic cement.
Are there possible side effects?
The German Society of Dentistry, Oral Medicine and Maxillofacial Surgery (DGZMK) states that only two cases have become known worldwide in which patients have reported severe allergic effects (http://www.kzbv.de/fissurenversiegelung.66.de.html). However, there are reports that the plastics used release formaldehyde and monomers (reactive molecules). However, the DGZMK points out that the amounts are so small that a health impairment can be ruled out if the application was carried out properly.
Does a fissure seal replace a visit to the dentist?
After six months at the latest, a follow-up examination by the dentist is necessary, as the sealant can flake off completely or partially. Experience has shown that this happens within 4-6 months, so the appointment for a check-up should be made directly after the sealant has been applied.
And even if a fissure seal can reduce the risk of tooth decay, it does not replace daily oral hygiene. The sealant only protects the fissures on the molars, but caries can also form on other teeth or the interdental spaces. Regular tooth cleaning with a brush, toothpaste and dental floss is therefore indispensable in order to maintain healthy and vital teeth for as long as possible.