Provided is an apparatus for assessing interface integrity between a medium and an implant. A first signal is translated from a motion of an impact body during impact with an abutment connected to the implant. In some embodiments, the first signal is filtered using a zero phase shift filter and then used for assessing the interface integrity. Since no phase shift is introduced, the interface integrity is accurately assessed. In another embodiment, the apparatus maintains a system model for impacting the impact body against the abutment. The apparatus analytically determines an interface property by applying a system property that has been determined to the system model. An accurate system model allows for an accurate assessment. According to another broad aspect, there is provided a method of conducting the impact test. According to the method, a person ensures that the impact body impacts against a consistent portion of the abutment.