Retrospective study on immediate functional loading of edentulous maxillas and mandibles with 690 implants, up to 71 months of follow-up.

PURPOSE

The aim of the present study was to describe immediate functional loading of completely edentulous maxillas and mandibles by fixed provisional prostheses and to compare cumulative survival rates between maxillas and mandibles. Contributing factors including implant diameter, system, configuration, type of abutment connections, position of implants, and insertion torque values were investigated.

PATIENTS AND METHODS

From August 2001 to March 2007, 111 patients treated at the Associated Brånemark Osseointegration Center, Hong Kong, who received immediate functional loading of implants by fixed completely edentulous provisional prostheses were reviewed. Marginal bone changes were measured.

RESULTS

There were 48 edentulous maxillas and 85 edentulous mandibles, in total 133 arches. Twenty-two cases received simultaneous maxillary and mandibular rehabilitation. Three hundred nineteen implants were used for the maxilla and 371 implants for the mandible, in total 690 implants. A mean of 6.65 fixtures was used to reconstruct an edentulous maxilla and a mean of 4.36 implants for an edentulous mandible. The mean follow-up period was 29.5 months, ranging from 11.5 to 71 months. Six hundred seventy-two of 690 implants (97.4%) had been followed up at least 1 year. Four implants failed in the maxilla and 5 implants failed in the mandible. Mean marginal bone loss was 0.07 mm after 1 year. Mean failure time was 2.89 months postoperatively (range, 2 to 5 mo). In those failed implants, maximal insertion torque values were significantly lower than those of successful ones. The immediate loading protocol constituted cumulative survival rates of 98.7% for the maxilla and 98.7% for the mandible, with an overall cumulative survival rate of 98.7%. There was no significant difference in survival rates between the maxillas and mandibles (chi(2) exact test, P = 1.000). The implant survival rate was found to be not related to implant diameter, system, configuration, type of abutment connections, and position of implants (P > .05).

CONCLUSION

The immediate loading protocol by fixed provisional prostheses proved to be an effective method in restoring completely edentulous maxillas and mandibles, and the maximal insertion torque value may be a prognostic factor in determining success.