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Early loading of machined-surface Brånemark implants in completely edentulous mandibles: healed bone versus fresh extraction sites.

BACKGROUND
Restoration of edentulous mandibles with dental implants installed with a two-stage or one-stage surgical approach, yet with delayed loading, is a predictable and successful treatment.


PURPOSE
The present prospective study evaluated the success up to 3 years of function of nonroughened machined-surface Brånemark System implants (Nobel Biocare AB, Gothenburg, Sweden) loaded early or immediately with a fixed 12-unit bridge.


MATERIALS AND METHODS
In total, 184 implants were installed in 36 patients: 30 with healed bone and 6 with some remaining teeth, which were extracted simultaneously with implant installation. The provisional or final prostheses were installed 0 to 52 (mean 18.2) days later.


RESULTS
Thirteen of 184 (7.1%) implants failed within 3 months of loading in 5 of 36 (13.9%) patients: 1 of 153 implants (0.7%) failed in healed bone, and 12 of 31 (39%) failed in fresh extraction sites. This consequently meant a loss of 3 of 36 (8.3%) prostheses, all in the extraction group. No implants were lost during 3 years of functional loading (16 patients, 75 implants). The average marginal bone level measured initially and after 1, 2, and 3 years was 0.8 mm (SD = 0.5), 1.0 mm (SD = 0.4), 1.1 mm (SD = 0.3), and 1.4 mm (SD = 0.5), respectively.


CONCLUSIONS
Four to six Brånemark implants with nonroughened machined titanium surfaces can be loaded early or immediately with cross-arch restorations in healed mandibulary bone, but this cannot be recommended for fresh extraction sites.