Influence of off-axis loading of an anterior maxillary implant: a 3-dimensional finite element analysis

PURPOSE: To evaluate the influence of the stress/strain distribution in bone around an anterior maxillary implant using 2 types of bone and under 3 different loads. MATERIALS AND METHODS: A premaxillary finite element model featuring an implant and its superstructure was created. Six different testing conditions incorporating 2 types of cancellous bone (high density and low density) under 3 different loading angles (0, 30, and 60 degrees) relative to the long axis of the implant were applied in order to investigate resultant stress/strain distribution. RESULTS: The maximum equivalent stress/strain increased linearly with the increase of loading angle. For each 30-degree increase in loading angle, the maximum equivalent stress in cortical bone increased, on average, 3 to 4 times compared with that of the applied axial load. In addition to loading angle, bone quality also influenced resultant stress distribution. For the low-density bone model, a substantial strain in the cancellous bone was found not only near the implant neck but also at the implant apex. CONCLUSION: To achieve a favorable prognosis under off-axis loading of an anterior maxillary implant, careful case selection for appropriate bone quality and precise occlusal adjustment should be attempted to optimally direct occlusal force toward the long axis of the implant.