Using restorations borne totally by anterior implants to preserve the edentulous mandible

Background. This study quantifies the changes in bone height of the posteri or area of the edentulous mandible when the load of complete dentures is bo rne entirely by anteriorly placed osseointegrated implants. Methods. Thirty-three patients, of whom there were radiographs from the beg inning of implant loading and from a follow-up visit at least three years l ater (a mean of 6.6 years later), were included in the study. Working with panoramic radiographs, the authors took height measurements in the premolar area (15 millimeters distal to the most distal implants). A valid correcti on factor was available because implants of known length were proximal to t he area being evaluated. Results. The authors calculated descriptive statistics using means, standar d deviations, medians and proportions as appropriate. A P-value of less tha n .05 was considered significant. Of the 33 subjects, most showed increases in bone height-29 (87.9 percent) on the right side and 28 (84.9 percent) o n the left side. The mean change in all subjects was +1.0 nam (range -0.8 t o +3.3 mm). A comparison of mandibular height at implant placement vs, foll owup showed a statistically significant increase bilaterally (P < .001). Conclusions. This study demonstrates that dentures for edentulous mandibles that are borne totally by implants in the anterior area conserve or enhanc e the bone of the posterior portion of the mandible. An important future st udy should test the effect of implant-assisted restorations for the edentul ous mandible that load the posterior ridge (a bar clasp, for example). Clin ical Implications. One of the considerations in planning treatment for the edentulous mandible should be the preserving effect of totally implant-born e restorations vs. the continued resorption of the body of the mandible wit h conventional dentures.