Biomechanical Analysis of Stress Fields in Atrophic Posterior Maxilla with Implant-Supported Cantilever Crown

Implant-supported cantilever crowns can serve as a viable alternative in certain clinical scenarios to circumvent additional surgical procedures either prior to or concurrently with implant placement. Despite the favorable clinical results seen with cantilever crowns, concerns have been raised regarding the long-term biomechanical implications and associated technical challenges. Multiple research investigations have demonstrated that implant-supported cantilever crowns have the potential to generate heightened stress concentrations within the underlying alveolar bone. The aim of the study is in the biomechanical analysis of stress fields in atrophic posterior maxilla with implant-supported cantilever crown. Functionally important two molars loss was analyzed to provide the implant placement in atrophic maxilla with types III and IV bone, when implantation is complicated due to insufficient bone height (less than 10 mm), low bone density and rigidity, thin cortical core (thickness less or equal to 0.5 mm). In such challenging conditions, placement of cantilever crowns was proposed as an advanced approach. The recommendations for practitioners were formulated after thorough modeling of bone-implant interface with preliminary evaluation of stress fields in adjacent bone. Two (narrow and wide) implants of two lengths were studied (4.5×5.0 mm, 4.5×8.0 mm, 6.0×5.0 mm, 6.0×8.0 mm) as the supports for two teeth loss restoration. Also, a wide spectrum of human bone elasticity parameters was studied in order to generalize the results of the study to wide range of patients (patient-specific approach). Validation of FEA algorithms was provided to receive necessary accuracy of numerical analysis and support developed clinical recommendations. Based on the conducted research results, we draw the attention of implantologists to the fact that the load-bearing capacity of proposed cantilever crown which are supported by short plateau implants is predetermined by the adjacent bone strains because bone stresses in all studied restorative structures were less than the bone ultimate strength.