假牙或称义齿是一种替代牙齿的辅助设备。一般用于代替由于意外事故、天生缺失或牙齿老化脱落等而无法正常使用的牙齿。

由于金的耐腐蚀性符合口腔内的环境，所以古代的假牙多为黄金制成。即使是现代，由于金合金的细微延展性，可令表面与其他牙齿吻合，所以修复效果比陶瓷制的大臼齿好。在文化角度，有些文化喜欢制作金牙齿在门牙上。 现代的假牙一般由瓷、合金等材料制成。 由于钛合金的生物兼容性且与金一样高强度而耐腐蚀，所以钛合金常用于假牙种植。

Dentures, also known as false teeth, are prosthetic devices constructed to replace missing teeth; they are supported by the surrounding soft and hard tissues of the oral cavity. Conventional dentures are removable (removable partial denture or complete denture). However, there are many different denture designs, some which rely on bonding or clasping onto teeth or dental implants (fixed prosthodontics). There are two main categories of dentures, the distinction being whether they are used to replace missing teeth on the mandibular arch or on the maxillary arch.