The aim of the present prospective clinical study was to analyze the feasibility of inserting Brånemark fixtures according to a one-stage procedure including transmucosal healing and to subsequently evaluate the predictability of osseointegration as well as the potential of such implants for stabilizing complete overdentures in the edentulous mandible. Five patients (2 women, 3 men), completely edentulous in the mandible and with a mean age of 60 years, volunteered for this study. Two fixtures of various length (10-20 mm) and 3.75 mm in diameter were inserted in the lower canine regions. A standard surgical procedure including a midcrestal incision was used. After the placement of the fixtures, healing abutments, which are normally used during second-stage surgery, were inserted instead of the usual cover screws. Three months after implant placement a clinical and radiographic examination was performed to confirm the presence or absence of osseointegration of the fixtures prior to exchanging the healing abutments with the spherical attachments. Finally, different clinical (Plaque Index, Bleeding Index, probing depth, Periotest mobility) and radiographic (bone loss, peri-implant radiolucency) parameters were recorded 9 months after loading of the fixtures by means of a complete mandibular overdenture, retained by two ball attachments in the canine regions. All fixtures were perfectly stable (mean Periotest values of -2) and presented favorable peri-mplant soft tissue conditions, and no patient was complaining about any particular symptom. As far as retention and stability of their implant supported overdenture was concerned, the participants without exception considered the therapeutic result as being perfectly adequate.(ABSTRACT TRUNCATED AT 250 WORDS)