Natural history of treatment outcomes for teeth with large amalgam and crown restorations.

The natural history of posterior teeth treated with a four or more surface amalgam restoration (LA) or a large amalgam restoration and a full-coverage crown (LAC) were compared over five- and 10-year periods. Subsequent treatment information was used to construct Treatment Outcome Trees (TOT), which described treatment that the teeth received after placement of LA and LAC restorations. Data were collected for all treatments provided to patients who received a four or five surface LA in 1987 or 1988 at the University of Iowa, College of Dentistry (UICD). The probability that these teeth would receive subsequent treatment and the type of subsequent treatment were placed into a TOT. In general, a higher percent of teeth with an LA received subsequent treatment and were more likely to receive major treatment (root canals, extractions, crowns) five years post placement than teeth with an LAC. Between five and 10 years, this trend continued, with the percentage of teeth with an LA receiving subsequent treatment increasing more (48% to 64%) than teeth with an LAC (12% to 22%). Regardless of the initial restoration type (LA/LAC), women were less likely to receive subsequent treatment and major treatment compared to men. The use of a TOT was found to be an effective observational approach for evaluating the natural history of teeth with alternative restorative treatment.