The 'gold' standard. Dental gold is about 60% gold alloy which is meant to match the hardness of the enamel of opposing teeth so both wear about evenly, an important trait.Gold does not tarnish or corrode and has some bacterial inhibiting quality. Gold crowns are strong and will not break. However, gold crowns obviously are not considered esthetic; they are gold colored. So usually gold crowns are used for lower back molars because they don't show there.