The durability of primary molar restorations: associated with placement and replacement

As part of a large retrospective study of the durability and lifespan of 2229 restorations (1898 amalgams and 331 stainless steel crowns) in primary molars of 226 pediatric patients attending a dental school clinic, the costs associated with first placement and later replacements of the restorations were examined. Individual restoration histories were followed for up to 9 years, computerized, and restorative costs assessed retrospectively using a scale of cost units. Of 1483 firstplacement amalgams, 69% did not require replacement throughout the study; 73% first replacements and 86% second replacements did not require subsequent replacement. The frequency of replacement of Class I amalgams with Class II amalgams was low (9-16 %), and low for replacement with crowns (11-12%); the frequency of replacement of Class amalgams with crowns was also low (9-18%). The majority (77%) of primary molars were maintained to either exfoliation (mean 48.2 + 21.2 months SD) or to the end of the study (mean 50.9 + 18.2 months)for a total investment of approximately the cost of 2 one-surface amalgams. The cost to maintain these molars for one year of good service was approximately half the cost of a one-surface amalgam. Crowned molars followed to exfoliation (mean 47.7 + 19.2 months) or to the end of the study (mean 50.1 + 15.2 months) required a total investment of approximately 3 times the cost of a one-surface amalgam. Overall comparisons (disregarding age of child at placement) indicated that crowns were a more costly service than amalgams and provided similar periods of good service.