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 today permitted in Norway) 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 yr, 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.
NIOM’s scientists have contributed to four of the chapters of this annual odontology update. Topics covered by our staff are the use of glass ionomers in primary teeth, ceramic fractures, nanomaterials and dental laser safety. Summaries in English are provided. See Publications.
Håkon Valen, DDS and PhD candidate, starts in a full -time position on February 1st. His background is microbiology, and his research will be conducted in collaboration with the Norwegian public dental health competency centres.
Frode Staxrud, DDS, has a part-time position as visiting scientist in 2014. His project investigates the repair and extension of composite restorations.