Posterior mandibular ridge resorption in patients with overdentures supported by two or four endosseous implants in a 10 years prospective comparative study. M.H.M.de Jong / P. Wright / H.J.A. Meijer / N. Tymstra / University Medical Center Gronigen Study evaluated the effectiveness of treatment with 2 or 4 endosseous implants with an overdentures over a 10 year period. Sixty edentulous patients with mandibular heights of 12 to 18 mm were treated with overdentures supported by IMZ implants. Split into two groups, one with two and the second with 4 implants. Panoramic radiographs were taken and compared for bone loss. Control and standardization of measurements and technique was tightly controlled. Results: There was a statistically significant difference between the two treatment protocols. Bone area index was reduced 10% for the 2 implant protocol and 6% for the 4 implant group. Conclusion: There was a significant reduction in bone loss when implants are used to stabilize an overdenture. Confounding factors such as age, gender, initial height, and number of years the patient had been edentulous failed to show a significant effect. Int. J. Oral Maxillofac Implants 2010; 25:1168-1174