The coronoid-maxillary space defines the distal maxillary rims, and it is usually tightened during mouth opening. It has been reported that its adequate filling or its overfilling is helpful in prosthesis retention. There are two types of individual anatomical variations, that can affect the size of this space. In fact, the coronoid process can be vertical or lateral. In the first case, the coronoid-maxillary space is reduced in oral opening, therefore the prosthesis edge must be thin. In the latter case, the space increases or does not vary during mouth opening, therefore the prosthesis must be thicker in order to obtain its adequate retention.