This practice-based study aimed to record the use of restorative materials, the type of restoration by class, and the reason for and the age of failed restorations in primary teeth by means of a survey of placement and replacement of restorations in 1996 and 2000/2001. Written alternative criteria for placement and replacement of restorations were provided for the participating clinicians. Details on 2281 restorations showed that primary caries was the main reason for inserting restorations in primary teeth. Replacements of failed restorations represented 14% of the fillings (n = 2040) in 1996 and 9% in 2000/2001 (n = 241). More than 80% or the fillings in primary teeth were of tooth-colored material, predominantly of the light-cured type. About 50% of failed amalgam and glass ionomer-type restorations were replaced due to secondary caries. The median age of amalgam restorations (3 years) was significantly higher than that of tooth-colored restorations (2 years). Any possible advantage of a cariostatic effect of glass ionomer-type materials is apparently annulled by their short longevity compared with amalgam.

Placement and replacement of restorations in primary teeth.
Mjør IA, Dahl JE, Moorhead JE.
Acta Odontol Scand. 2002 Jan;60(1):25–8.