What is a filling
Sometimes a portion of a tooth can be broken by an accident or damaged by decay. In both cases, after having removed the damaged part, the tooth may be restored with a filling. The filling restores the morphology of the tooth and protects the pulp of the tooth from various noxious stimuli. There are 5 main types of fillings: amalgam, composite resin, bonding, on-lays and sealants (preventive fillings).

The amalgam or “black filling” is a filling material that was widely used by dentists in the past because of its durability. Today, however, its use has been almost abandoned, mainly due to the poor aesthetics and the significant improvement in the properties of other filling materials such as the composite resins. In addition, amalgam fillings are considered to be deleterious for the body since they contain traces of mercury.

Amalgam fillings in posterior teeth

The composite resin or simply composite or “white filling” is currently the most common material for fillings. The technological progress has enhanced remarkably its mechanical properties which are now comparable or even superior to those of the amalgam fillings. Moreover, the excellent esthetics that it offers makes it, definitely, a better choice that the amalgam filling. Indeed, the large variety of shades or even the possibility of combining composites of different shades can lead to an outcome that satisfies even the most aesthetically demanding patient. Finally, because the composite filling binds to the tooth it requires a very conservative preparation of the tooth.

Sometimes between teeth there are spaces, “black triangles” that trap food or create aesthetic problems. These spaces may naturally be present due to the spacing between the teeth or may be caused when the gingiva (gums) recede due to periodontal disease. No matter the cause, in many cases, the dentist can close very conservatively these spaces and improve the overall esthetics. The technique employed is called bonding and the dentist builds with composite the side surfaces of the teeth. Hence, very conservatively, without preparing the teeth for crowns and without pain the dentist can effectively resolve the patient’s esthetic concern. The bonding technique has developed significantly over the past few years and due to the excellent esthetic results it is considered an integral part of aesthetic dentistry.

When the destruction of the tooth is quite extensive then the reconstruction with an amalgam or composite filling may not be possible. In such cases, the restoration of the tooth with an on-lay may be the treatment of choice. The on-lay is a restoration from composite resin or ceramic (porcelain), which is fabricated in the laboratory. Specifically, after preparing the damaged tooth the dentist takes an impression of the tooth and sends it to the laboratory. The lab technician will then manufacture the on-lay which fits precisely in the prepared site of the tooth. Then the dentist will permanently cement the on-lay on the tooth.

However, when the destruction of the tooth is so extensive that there is a risk for tooth fracture the construction of a crown may be a safer and more predictable treatment choice.

Manufacturing an on-lay in the laboratory

The chewing (occlusal) surfaces of the posterior teeth have deep grooves that retain easier food and bacteria. Therefore, these areas are more susceptible to caries (decay). Preventive fillings or “sealants” smoothen out these grooves and hence reduce the risk for dental caries. The preparation of the tooth for a sealant is very conservative and does not require the removal of any tooth structure.

 Τοποθέτηση sealant σε οπές-σχισμές και αύλακες δοντιών
Filling teeth grooves with sealants


Sealants can keep up to 10 years, however it is recommended to monitor them during the regular dental visits. If needed the dentist can repair the sealants by adding extra material or replace them.

The sealants are placed, mainly, at children as soon as the first permanent posterior teeth erupt. The first permanent molars erupt between 5 and 7 years and the second molars erupt between 11 and 14 years. Premolars may also need sealants. Finally, teenagers and young adults without decay and fillings can also benefit from the placement of sealants. Indeed sealants have been proven to be an excellent investment since they may prevent from long and costly treatments such as fillings, crowns, bridges, implants etc.

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