Whenever a tooth has severe decay, fracture, or has a large, old filling, a crown may be necessary. A crown will cover and bind together the remaining tooth structure, thereby strengthening and improving the function and appearance of your teeth. Crowns require two appointments for completion. Types of crowns include: metal crowns which are made of gold or alloys, porcelain-fused-to-metal crowns which combine the strength of metal with the aesthetics of porcelain, and full porcelain ceramic crowns which are the ideal cosmetic option.