Teeth with large amalgam restorations and crowns: factors affecting the receipt of subsequent treatment after 10 years.

BACKGROUND: The authors evaluated the factors associated with the receipt of subsequent treatment by teeth restored with a large amalgam restoration or a large amalgam restoration and crown restoration after 10 years. METHODS: The authors used retrospective data from the University of Iowa College of Dentistry (Iowa City, Iowa) administrative database and patient records to evaluate patient and tooth factors for their association with the two primary outcomes: receipt of any subsequent treatment and receipt of catastrophic treatment (extraction, endodontic therapy). RESULTS: The authors followed 518 teeth over a 10-year period (49 percent with large amalgam restorations and 51 percent with crowns). Sixty-four percent of the large amalgam restorations and 32 percent of the crowns received subsequent treatment during the 10 years. In addition to restoration type, the patient's sex, history of grinding teeth and having a broken tooth were related to the tooth's receiving subsequent treatment. Twenty-two percent of large amalgam restorations and 12 percent of crowns received catastrophic treatment with the odds of teeth with large amalgam restorations receiving a catastrophic treatment being 2.1 times the odds of teeth with crowns receiving catastrophic treatment. CONCLUSIONS: Teeth with crowns were less likely to receive any treatment or catastrophic treatment over 10 years than were teeth with large amalgam restorations. Patient and tooth factors also were related to a tooth experiencing subsequent treatment. CLINICAL IMPLICATIONS: Teeth with crowns received less subsequent treatment than teeth with large amalgam restorations. This could be related to both the difference in longevity between the two restorations, as well as how appropriately treatment was planned for each procedure. Cost differences between the two restorations need to be factored into the decision-making process.