Dental veneers are thin shells, usually made of porcelain, covering the teeth's front surface. The veneers are purely cosmetic, improving the shape, color, and size of the teeth. Dental crowns fit over the top of the teeth like caps. While dental crowns can also improve the look of damaged teeth, they also prevent further damage, protecting the tooth from infection and restoring function. Crowns last longer than veneers, which need replacing about every ten years.