A dental filling is more durable if the enzyme activity of the tooth can be inhibited. Professor Leo Tjaderhane of the Department of Pedodontics, Cariology and Endodontology at the University of Oulu, together with wide international collaborative team, has been developing this method with funding from the Academy of Finland.
Composite dental fillings have one problematic feature, in that the bond between the filling and the dental tissue deteriorates over time – in fact, sometimes by as much as 50 per cent in one year. As the bond deteriorates, it may allow bacteria to enter and this brings a high risk of further tooth decay.
Professor Tjäderhane has researched the occurrence of certain enzymes, matrix metalloproteinases (MMPs), in the dental tissue and their role in dental conditions. The MMPs break down the extracellular matrix, including collagen, which is a major component of dentin. As a result of international research collaboration, Tjäderhane's research team has shown that human dentin contains the key MMP for breaking down collagen. The bonding of composite resins with dental tissue is based on the use of collagen bonds, and the tooth's own MMPs are responsible in part for the deterioration of the bond over time. By inhibiting the activity of these enzymes, the research team has succeeded in significantly slowing down the deterioration of the bond between dental tissue and a composite filling, and in some cases to prevent deterioration completely.
The best results have been obtained in clinical trials, where deterioration of the bond has been more or less completely prevented. MMP enzyme activity in the tooth can be rapidly and easily inhibited when a filling is put in place by using chlorhexidine, a substance which is already on hand at all dental practices. This means that the research results are immediately applicable in dental care for the best benefit of the patients. The research in question also strongly indicates that MMP inhibitors might help slow down tooth decay. These observations are based only on animal testing so far, so further research on the subject will be needed before pratical applications can be made available.
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