The computer-based method allows the computerized planning of a surgical implantology procedure, using computed tomography (CT) of the maxillary bones and prosthesis. This procedure, however, is not error-free, unless the operator has been well trained and strictly follows the protocol. A 70-year-old woman whom was edentulous asked for a lower jaw implant-supported prosthesis. A computer-guided surgery was planned with an immediate loading according to the NobelGuide technique. However, prior to surgery, new dentures were constructed to adjust the vertical dimension. An interim screwed metal-resin prosthesis was delivered just after the surgery; however, after only two weeks, it was removed because of a complication. Finally, a screwed implant bridge was delivered. The computer guided surgery is a useful procedure when based on an accurate 3D CT-based image data and an implant planning software which minimizes errors.