###### Abstract  
The main purpose of this work was to construct a clinically valid numerical model of a mandibular Kennedy class I patient rehabilitated with a conventional removable partial denture and another two with implant-assisted removable partial dentures at two different implant locations. The selected patient was classified as ASA I and its mandible geometry reconstruction was performed by the conversion of the Cone-Beam computed Tomography (CBCT) scan raw medical data into a 3D model and subsequent conversion to a CAD file by reverse engineering methods. The soft tissue and removable denture geometries were also included in the CAD model as well as implants, ball attachments and matrix. Moreover, periodontal ligament was modelled by offsetting the mesh of the root surface of each tooth. The finite element results showed that the installation of a dental implant in each of the bilateral dentulous regions helps providing support and retention to the extension bases of the Removable Partial Denture (RPD) and significantly reduces the vertical and anterior-posterior displacements, regardless of its position.  
implant; removable partial dentures; finite element method; Mandibular Kennedy Class I  
11659. 11659.  
possible to provide maximal support and stability, particularly in the mandible. However, they also admit the possibility of placing the implants in a mesial position adjacent to the abutment teeth (natural teeth supporting and retaining a removable partial denture), whenever these are poor to provide support or to avoid unesthetic claps in maxillary rehabilitations. Only two non-clinical studies considered in the work of [PERSON] et al. comprised the biomechanical evaluation of the use of dental implants in mandibular Kennedy Class I situations, that is the study of movement and deformation of the biological structures (abutment teeth, bone, mucosa, etc.) under forces applied over the prosthesis and implants. One of those studies, performed by [PERSON] et al. [13], used an experimental setup to measure the pressure under a conventional or an implant-assisted removable partial denture with the implants placed distally. The results indicated that the implant support contributed to the reduction of displacement at the distal extension of the removable partial dentures and decreased the pressure on soft tissues. The other study [14] also considered in the above-mentioned revision, evaluated the biomechanical efficacy of placing implants underneath the denture base to obtain stable occlusal support, using an in-silico bi-dimensional model. The authors considered the possibility of implant support in the distal (second molar), mesial (first premolar) or intermediate position (second premolar). Compared to the conventional removable partial denture option, the least stress was obtained at the temporomandibular joint using the implant in the distal position, followed by the intermediate and mesial positions.  
The study of [PERSON] et al. was the first to use the finite element method (FEM) to evaluate the biomechanical effect of the implant support in the structures involved, namely denture, mandibular bone and temporomandibular joint. In the time following that study, several researchers have been using the finite element method to evaluate the stress distribution over the mandibular bone due to the screwed overdenture positioned on dental implants [15; 16; 17; 18; 19; 20]. In this study, three-dimensional finite element analysis is also used to clarify the criteria for implant positioning within the edentulous span in prosthetic treatments with IARPD (implant assisted removable partial dentures). The primary aim is achieved by evaluating the different patterns of stress in the prosthetic structure for variations of the implant positioning in the edentulous area.