Evidence from multiple histopathological studies confirms that new decay frequently develops along the margins and cavity walls of dental amalgam fillings due to microleakage and plaque accumulation.
Papers [1], [3], and [4] specifically investigate the histopathology of caries around silver amalgam fillings, demonstrating that cavity wall lesions and demineralization consistently occur at the amalgam-tooth interface (microleakage areas). Therefore, the claim is well supported.