Tooth fillings with extended life span

Dental fillings and adhesives, including special bulk-fill composites, have been investigated by manufacturers in a recently completed research project at the University of Debrecen's Faculty of Dentistry. The work of the research team was recognised by the publication award of the Gróf Tisza István Foundation for the University of Debrecen.

The aesthetic composite fillings, which are used in both adult and paediatric dentistry and match the colour of the teeth almost exactly, have now virtually replaced the less attractive-looking amalgam used previously.

Composites are produced by mixing filler particles into a flexible resin for reinforcement, which ultimately results in a resin-like material. This will harden when placed in the drilled cavity of the tooth and illuminated with a special light.


Despite the fact that the physical and chemical properties of these composites have improved a lot in the last decades, the lifetime of the fillings made of them is still limited in the oral cavity, 5-10 years in favourable cases.

In the past, these fillings were replaced in their entirety by dentists in case of fracture, discolouration, secondary caries or wear. For almost ten years, however, the question has arisen among professionals whether it is possible to repair composite fillings instead of replacing them.

- The complete removal of a partially inadequate filling is not always justified, as some areas of the filling are still functioning well and because each such procedure involves sacrificing healthy tooth material, the filling becomes larger and larger, and the preparation can also cause irritation of the periodontium," explained Renáta Martos, a Publication Award-winning assistant professor at the Department of Conservative Dentistry, Faculty of Dentistry, University of Debrecen, and member of the Dental Materials Research Group.

She said that if repair is opted for, not only will less drilling be needed, but treatment time will also be shortened, making the intervention more cost-effective. However, in order to properly bond the new layer to the old sealant, it is necessary to pre-treat the surfaces and apply a well-functioning adhesive, a so-called adhesive. This can significantly extend the life of a filling.

- In our research group we investigate these material groups, working with hydrophobic resin systems, composites and dental adhesives. Unfortunately, the composition of filling materials varies widely, so it is difficult to find a universally applicable protocol for repair," said Renáta Martos.

The researchers published their findings in the official journal of the International Academy of Adhesive Dentistry. They report on the performance of some modern adhesives in the repair of a special so-called bulk-fill composite (a material often used in the field of molars for large-scale restorations).

- I hope that the work in the research laboratory at the University of Debrecen's Faculty of Dentistry will contribute to the development of the dental profession with many useful research results in the future. The Publication Award that I have just won is a great motivation for this," the specialist emphasised.

Press Centre