The widespread use and broad acceptance of osseointegrated dental implants, as a means of retaining and supporting mandibular overdentures, established a group of patients with potentially stable three-dimensional reference structures which could be used to examine the morphological changes of the surface contours of the mandibular ridges distal to dental implants. Traditionally, changes in ridge morphology and quantity tended to be measured radiographically but besides the inherent drawbacks of radiographs per se a further drawback is the exposure of the patient to ionising radiation. The aim of this study was, therefore, to attempt to detect any changes in the surface contour of the posterior saddle areas over a one-year period by an alternative, non-radiographic method using serial casts of residual ridges of a group of patients. A prospective clinical study was undertaken on sixteen patients aged 36-72 years which involved the making of sequential impressions of the implant containing mandibular denture-bearing area. The residual ridges of the serial casts produced were examined using established instruments and various computer software programmes that allowed the orientation, recording and measurement of the mandibular casts. The reliabilities of the various recording and measuring devices used throughout the study have also been verified. Statistical analysis revealed that the detected reductive changes in the surface contour of the posterior residual ridge areas, in terms of unit area, following the wearing of an implant-retained mandibular overdenture over a one-year period were highly significant. It is concluded that the methodology of the study presented in this thesis can be used reliably as an alternative to radiographical examination for detecting changes that occur in the distal denture-bearing area of the implant containing edentulous mandible when implant-retained overdentures are used over a one-year period, or possibly longer. Thus, the method presented in this study may be used to contribute to a reduced exposure to ionising radiation for patients wearing mandibular implant- retained overdentures.