Dental implants (screws for fastening false teeth) have been coated with bisphosphonates (drugs that slow down removal of bone). Patients get one such screw and one without coating, by a surgeon who does not know which is which. The screws are compared by measuring how well fixed they are by a vibration measuring technique, and x-rays. The hypothesis is that the bisphosphonates will improve fixation.

Inclusion Criteria:

• Need for at least 2 dental implants, which are to be inserted in bone of reasonably similar quality.

Exclusion Criteria:

• Systemic or immunologic disease, alcoholism, uncontrolled diabetes and smoking.
• Local exclusion criteria were: previous tumour, trauma and surgery.
• Also patients with Cawood & Howell class IV - VI maxilla-bone were excluded.