Abstract
Objective This study was designed to assess the effect of nonrigid connectors (NRCs) and their location in the success of tooth-and-implant-supported fixed prostheses in the maxillary anterior region by finite element analysis (FEA). Materials and Methods Three 3D FEA models were designed, presuming maxillary lateral incisor and canine to be extracted. Implant (replacing canine), abutment, bone (spongious and cortical), central incisor (containing dentin, root cement, gutta-percha, and casting post and core), periodontal ligament, and three three-unit cemented PFM prostheses (a rigid one and two nonrigid) were modeled. The NRC was once in the tooth side and once in the implant side. The prostheses were loaded twice: 250N to the incisal edges (0° to the long axis) and 200 N to the cingula (45° to the long axis). The von-Mises stress and vertical displacement were analyzed. Results Under both vertical and oblique loadings, the rigid model presented the highest stress. Under vertical loading, the NRC caused a significant decrease in the applied stress to the prosthesis, bone, implant, and tooth. Locating the NRC in the tooth side decreased the applied stress to the prosthesis and NRC. Under oblique loading, prosthesis and implant tolerated less stress in the presence of an NRC. Placing the NRC in the tooth side resulted in the least stress in all of the components except for porcelain and patrix. Vertical displacement of the tooth apex was approximately equal in all models. Conclusion Using an NRC on the tooth side is the most efficient method in reducing the applied stress to prosthesis, implant, tooth, and bone. The amount of intrusion is not dependent on using an NRC or not.
Highlights
Implants have played an essential role in the edentulous patients’ treatment since they were introduced by professor Branemark [1]
Some studies supported the idea of using rigid prostheses to avoid the intrusion of natural teeth as a result of using nonrigid connectors (NRC) (e.g., Al-Omiri et al [8], Gross and Laufer [10], Carillo et al [17], Chee and Jivraj [21], and Ting et al [22]), while some others argued that there is no significant difference between the tooth intrusion in the rigid and nonrigid prostheses (Breeding et al [13], Garcia and Oesterle [23], and Ormianer et al [24])
The effects of the NRC location were assessed. e null hypothesis was that nonrigid connectors were not effective in reducing the applied stress to the prosthesis and implant
Summary
Implants have played an essential role in the edentulous patients’ treatment since they were introduced by professor Branemark [1]. As the number of residual teeth has increased in the group of younger elderly, there has been an increasing interest in using fixed partial prostheses because of the higher quality of life they provide in comparison to removable dentures [2]. Both implant-supported and tooth-and-implant-supported fixed prostheses can be used for partially edentulous patients’ oral rehabilitation. The effects of the NRC location were assessed. e null hypothesis was that nonrigid connectors were not effective in reducing the applied stress to the prosthesis and implant
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