Three-dimensional maxillary bone models were constructed using the CT-images of a male and a female patient. The distribution of Young's modulus was estimated from the bone mineral density distribution. Six implants were embedded into these maxillary models and for each model, a metal prosthesis was attached to the tops of the implants. Finite element analysis of these maxilla models was then performed in order to characterize the effects of bone quality on the stress state under an equivalent loading condition. In both the models, strain energy density was concentrated especially around the right-molar implant, suggesting that bone damage and absorption might take place in this region. A modified replacement of the right-molar implant was introduced into the female model and successfully reduced the concentration of strain energy density. It is thus concluded that this kind of 3-D modeling could clinically be used to predict the optimal implant treatment for each of the patients.