Appearance characteristics. The appearance of the crown depends on what it is made of. Crowns that have replaced teeth in the back of the mouth are often made of metal or ceramic on metal. The best metal for these prosthetics is gold, which does not tarnish or interact with the body and lasts a very long time. Porcelain is often used for the front teeth. These crowns can be made to match the size and color of the patient’s other front teeth with great exactitude. Nowadays, dentists and oral surgeons make use of computer assisted design to create virtual implants. These computer models let them know what the actual implants will look like in the patient’s mouth.