Our office prefers to use tooth-colored fillings. Silver amalgam fillings were the most common many years ago, and are still very good if used properly. Tooth-colored restorations are functionally just as good, if not better, and are virtually invisible. Restoring your tooth's function and natural appearance are achievable goals in this day and age.
Gold is also an excellent alternative for large restorations, onlays, or crowns.
Crowns are necessary when a tooth is generally broken down and fillings won't solve the problem. If a tooth is cracked, a crown holds the tooth together to seal the cracks so the damage doesn't get worse. Crowns are also used to support a large filling when there isn't enough of the tooth remaining, to attach a bridge, protect weak teeth from fracturing, restore fractured teeth, or cover badly shaped or discolored teeth. The dentist's main goal is to create crowns that look like natural teeth. That is why dentists take an impression.