Finding tooth decay beneath silver fillings

What is it about?

Finding caries beneath amalgam or silver filling margins is a challenging clinical problem because of the nature of the material. Typically, older amalgam restorations may cause marginal staining but, visually these margins may appear intact and sound. This study examined four methods for detecting tooth decay around silver fillings and found that The Canary System was the most accurate, finding tooth decay 95% of the time.

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Why is it important?

Up until 26 years ago, amalgam or silver filings were used to restore or repair tooth decay. A large number of amalgams are removed each year, Each time a tooth is operated on or cut into it causes trauma to the pulp or nerve tissue. Finding decay around the silver filling is challenging. Amalgam is dense, radiopaque and reflects light from its surface. Both tooth decay and stain from the silver filling will turn the enamel around the filling black making it difficult to detect decay. The study found that visual examination of the filing or using devices such as SPECTRA and DIAGNODent could not provide accurate diagnostic information about the existence of tooth decay. The glow or fluorescence from the amalgam prevented Spectra from detecting any marginal caries. DIAGNOdent was also unable to consistently differentiate healthy from carious tissue at various distances from the amalgam margins. However, The Canary System was able to detect 95% of the lesions around the amalgam margins. X-Rays could only examine one area of the filling (base of the filling below the gum line) and could not detect tooth decay around biting surface or sides of the filling.

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