Any surgical or invasive procedure carries risks. Before proceeding, you should seek a second opinion from an appropriately qualified health practitioner.
Composite fillings bond directly to your tooth, which results in less healthy tooth removal. Amalgam(metal) fillings require additional preparation to provide anchors for the solid amalgam.
Composite fillings are not as hard and inflexible as amalgam fillings, which means stresses caused by biting and chewing can be distributed more naturally and reduce the risk of your tooth cracking.