A prosthesis is an object used to replace natural tissue. Examples of a prosthesis might be a denture, a bridge or a crown. Pre-prosthetic surgery is a procedure used to improve the shape of hard or soft tissues of the oral cavity. These procedures are undertaken to facilitate the fabrication of a better fitting prosthesis.
The most common type of pre-prosthetic surgery is removal of excessive soft tissue that has formed in association with a poorly fitting denture. Removal of the excessive soft tissue allows a new denture to be constructed with improved stability.
Some people will have problems with the shape of their jaw bone such that fabrication of a denture without removal of bone would cause issues with mouth ulcers and pain when wearing the denture. The most common places to have excessive bone are in the midline of the hard palate and on the tongue and side of the lower jaw. These bone lumps are referred to as a torus.