Repair Rather Than Replace Defective Amalgam Restoration

Rosemary Frei

July 29, 2011

July 29, 2011 — Repairs of amalgam restorations can endure for at least 7 years, report investigators from the University of Florida, Gainesville, in the July issue of Journal of the American Dental Association. The investigators conclude that repairing may be a better option than replacing amalgams after they develop localized defects.

"If the dentist is not sure that the defective area can be removed by polishing or sealing the affected area, another conservative and predictable approach would be to repair the restoration by locally removing only the deteriorated area and restoring it," said lead investigator Valeria Gordan, DDS, MS. "Replacement should only take place if the clinician cannot properly remove the defective areas without removing the entire restoration."

In the study, none of the repairs were downgraded or had failed at 7-year follow-up, compared with a 5% failure rate and a 16% downgrade rate for amalgam replacements.

However, a community dentist contacted by Medscape Medical News for comment said that this research may be of little relevance to many of his colleagues.

"I haven’t used amalgam in 20 years, and only about half the dentists in the country do use it," said Gary L. Henkel, DDS, owner of Horsham Dental Elements in Horsham, Pennsylvania. "Sweden, Norway, and Denmark have banned its use, and its use in this country is currently under review. I’m not sure why anyone would want to put so much time and effort into a material that is most likely on its way out."

To document whether there are indeed good reasons for dentists to restore rather than replace defective amalgam restorations, Dr. Gordan, a professor and researcher in the Department of Restorative Dentistry at the University of Florida, Gainesville, College of Dentistry, and colleagues prospectively followed 50 patients for 7 years. The patients were aged 21 to 77 years, and they had 113 defective amalgam restorations diagnosed during treatment at the college. All of the restorations were on posterior teeth.

The investigators determined, as an inclusion criterion, that each defective restoration had a score of 'Bravo' according to the modified US Public Health System criteria in marginal adaptation or anatomic form. The researchers also used these criteria to evaluate the clinical quality of the restorations immediately after treatment and at 1-, 2-, and 7-year recall examinations.

The researchers assigned the restorations with localized defects to the following treatment groups: 20 to repair, 23 to sealing of defective margins, 23 to refinishing, 22 to total replacement, and 25 to no treatment.

Nineteen (17%) of the 113 restorations were not available for any of the follow-up examinations. Furthermore, 2 of the remaining 94 restorations were unavailable at 1-year follow-up and 38 were unavailable at 2-year follow-up. The team has previously reported the results of the 1- and 2-year follow-up (Oper Dent. 2006;31:418-425).

At 7-year follow-up, only defective restorations that had received no treatment or sealant were upgraded, at 4% in each of these groups. There was no change in many of the restorations; the highest percentage in this category was among the repairs, at 57%, followed by replacement in 42% and sealant in 39%.

However, sealant led the downgrade category, at 35%, followed by no treatment at 17% and replacement at 16%. There was a 7% downgrade rate among the refinished group and a 0% downgrade rate among the repairs. Few failures occurred: 5% in the replacement group, 4% in the no-treatment group, and no failures in the other groups.

The investigators also performed another analysis in which they excluded restorations that were lost to follow-up before the 7-year recall visit and that had not already been classified as a downgrade or a failure. This yielded a 93% upgrade or no-change rate in the repair group compared with a 63% rate in the replacement group. However, the replacement group had a 26% downgrade rate and an 11% failure rate, compared with 7% and 0%, respectively, in the repair group. Refinishing, sealant, and no treatment also had higher downgrade or failure rates than did repair, although none of the differences were statistically significant.

The study was supported by the University of Florida, Gainesville. Dr. Gordan has disclosed no relevant financial relationships.

JADA. 2011;142:842-849. Abstract


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