All materials involved in the models were assumed to be
isotropic, homogenous, linearly elastic and static. The implants in
contact with the bone were assumed to be completely osseointe-grated. The properties of materials used in this study, including
Young’s modulus and Poisson’s ratio, were obtained from early
literatures (Geng etal.,2001), and that of the bones were
calculated according to Zannonietal.’s study(Table 1). They have
proved that Young’s modulus has a fixed relationship with the
apparent density of bones, which is equivalent to the gray value
more rational which were almost like that in Model 1 .Besides, in
the two models the four abutments suffered fewer torque forces
than that without zygoma implants(Figs. 5–7).