Clinical evaluation of short, machined-surface implants followed for 12 to 92 months

Bone resorption following tooth loss often limits the quantity of bone available for implant placement. The purpose of the present study was to evaluate the clinical outcome of 10-mm or shorter machined-surface implants when used exclusively in the treatment of various forms of edentulism.

Two hundred sixty-nine screw-type Brånemark System implants (Nobel Biocare), 10 mm or shorter, were placed in 111 consecutively treated patients. Of the total, 88.8% were placed in the mandible and 11.2% were placed in the maxilla; 95.2% were used to treat partially edentulous situations, including single-tooth losses, of which 96.6% were in the premolar and molar regions. The patients were followed for periods of 12 to 92 months.

Of the 269 placed implants, 12 were lost. The overall survival rate was 95.5%. Bone quality 2 and 3 (Lekholm-Zarb classification of 1985) was found in 88.8% of the treated sites. There was no statistical difference in the survival rate of the 10-mm implants when compared to the shorter series (P > .05) or between the various implant diameters. The mean marginal bone loss was 0.71 +/- 0.65 mm.

The failure rate of 4.5% compares favorably with that of implants of different shape, surface characteristics, and length. Bone quality appeared to be the critical factor in implant survival, rather than bone quantity, in this patient series.

This study supports the survival of short, machined-surface implants when used for the treatment of partial edentulism in bone of good quality.