Number of dental abutments influencing the biomechanical behavior of tooth‒implant-supported fixed partial dentures: A finite element analysis

Background. Local or systemic issues might prevent installing a sufficient number of dental implants for fixed prosthetic rehabilitation. Splinting dental implants and natural teeth in fixed dentures could overcome such limitations. Therefore, this study aimed to evaluate the influence of the number of dental abutments in the biomechanics of tooth‒implant-supported fixed partial dentures (FPDs). The null hypothesis was that increasing the number of abutment teeth would not decrease the stress over the abutments and surrounding bone. Methods. Left mandibular lateral incisor, canine, premolars, and molars were reconstructed through computed tomography and edited using image processing software to represent a cemented fixed metal‒ceramic partial denture. Three models were set to reduce the number of abutment teeth: 1) lateral incisor, canine, and first premolar; 2) canine and first premolar; 3) the first premolar. The second premolar and first molar were set as pontics, and the second molar was set as an implant abutment in all the models. Finite element analyses were performed under physiologic masticatory forces with axial and oblique loading vectors. Results. After simulation of axial loads, the stress peaks on the bone around the implant, the bone around the first premolar, and prosthetic structures did not exhibit significant changes when the number of abutment teeth decreased. However, under oblique loads, decreasing the number of abutment teeth increased stress peaks on the surrounding bone and denture. Conclusion. Increasing the number of dental abutments in tooth‒implant-supported cemented FPD models decreased stresses on its constituents, favoring the prosthetic biomechanics.

Evaluation of sealing between abutment and inner connection of cone morse dental implant

Introduction: The adaptation of prostheses fixed over implants involves biomechanical aspects that are directly associated with treatment success. Objective: The aim of this in vitro study was to evaluate the presence of microgaps in the abutment/inner connection interface of cone morse dental implants. Materials and methods: Two groups of implants were analyzed. The first group (n = 16) employed single-manufacturer dental implants and abutments, whereas the second group (n = 16) combined multi-manufacturer materials. The sets were analyzed through scanning electron mi­croscopy, wherein microgaps between the implant connection and the abutment were observed. Results: Group 1 had an average microgap of 5.69 μm (SD ± 8.46 μm). Group 2 had an average microgap of 1.24 μm (SD ± 0.44 μm). A significant difference was found between the two groups (p = 0.002). Conclusion: Within the limitations of this study, results suggest that the group formed by multi-manufacturer implants and abutments (group 2) had smaller microgap values, and, therefore, a higher in vitro adaptation of components. DESCRIPTORS | Dental Implants; Dental Abutments; Scanning Electron Microscopy.