Both removable and non-removable prostheses can be fitted on a dental implant. Crowns on implants are fixed on abutments, or superstructures, that attach to the body of the implant. The crown fixed on the implant can be metal-ceramic, zircon-ceramic and porcelain. Fixation of the prosthodontic fixation can be either cement-retained or screw retained. All on 4, All on 6 is a removable structure fixed by a locking system on a bar connected between 4 or 6 implants. This type of removable prosthesis is comfortable on implants, is good for maintaining hygiene, and is ideal for implant revision. It is mainly used in the case of atrophied alveolar ridge: if we try to avoid surgical manipulations when it’s complicated to create an additional bone.