The success of an implantological rehabilitation is determined by multiple surgical factors (implant position, implant distribution, number of implants, implant size, bone and gingival regeneration...), patients' personal factors (general health, oral hygiene, hereditary factors, previous periodontitis, smoking, bruxism...), and prosthetic factors (restorative materials and prosthesis design).

It is on this last point that we are going to focus because, despite being of vital importance, it is the least publicized and explained. Among the different points that can intervene in the design of the prosthesis, such as the emergence profiles, the spaces to facilitate hygiene, the design of the pontics, the length and shape of the transepithelial abutments... there are some that affect edentulous mandibular patients: mandibular flexion, weight of the prosthesis, impact against the antagonist, and the importance of the design of the prosthesis and the restorative material.

It is well known that there is a flexion, a deformation of the mandible when the person opens the mouth and/or protrudes, but what is not well known is the problems it causes to the prosthesis and the implants if a correct design and a good choice of the restorative material are not made. Among the most known problems are: fracture of the prosthesis, loosening of the screws, pain and/or dysfunction during opening or protrusion, peri-implant bone loss and loss of the implants.

By means of photographs, radiographs and numerous references, we will review the existing problems and provide different solutions, both in terms of design and restorative materials, to reduce the risk of prosthesis and/or implant failure in these edentulous mandibular patients.