Placing restorations due to dental caries is still a commonly performed treatment by dental practitioners in Norway. The aim of the thesis was to explore dentists’ treatment decisions on approximal caries and to assess the longevity of approximal restorations in posterior teeth and reasons for their failure. The research employed a questionnaire and included a practice-based study.

The questionnaire revealed that 7% of Norwegian dentists would restore approximal lesions confined to enamel in 2009, compared with (in similar studies) 18% in 1995 and 66% in 1983. A saucer-shaped preparation technique was most favoured in 2009. As restorative material, resin composite was preferred by 95% of the dentists.

In the practice-based study, amalgam (not permitted in Norway today) was placed significantly more often in male patients with previous caries experience (DMFT) and severe caries, and in molars. After an average follow-up period of 4.6 years, the mean annual failure rate was 1.6% for amalgams and 2.9% for composite resin restorations (p = 0.02). Multilevel Cox-regression analyses identified low age of the patient, high previous caries experience, deep cavity size, saucer-shaped preparation technique and one specific brand of composite resin (Filtek Z100) as factors predisposing to significantly reduced longevity of composite resin restorations.

The results indicate that some mechanical retention in small Class II preparations could improve the longevity of approximal restorations.

The work included in the thesis was carried out at the Dept. of Paediatric Dentistry and Behavioural Science, Faculty of Dentistry, University of Oslo, in cooperation with the Public Dental Health Service in Hordaland.

Read more
Kopperud SE. Treatment decisions on approximal caries and longevity of Class II restorations. Thesis (PhD), Faculty of Dentistry, University of Oslo, 2013. ISBN: 978-82-91757-87-2.
Kopperud SE, Tveit AB, Gaarden T, Sandvik L, Espelid I. Longevity of posterior dental restorations and reasons for failure. Eur J Oral Sci. 2012;120:539–548.
Vidnes-Kopperud S, Tveit AB, Espelid I. Changes in the treatment concept for approximal caries from 1983 to 2009 in Norway. Caries Res 2011;45:113–120.
Vidnes-Kopperud S, Tveit AB, Gaarden T, Sandvik L, Espelid I. Factors influencing dentists’ choice of amalgam and tooth-colored restorative materials for Class II preparations in younger patients. Acta Odontol Scand 2009;67:74–79.


NIOM Newsletter February 2014