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Implant stability measurements using resonance frequency analysis in the grafted maxilla: a cross-sectional pilot study.

BACKGROUND
High failure rates have been presented for implants placed in grafted bone. The bone graft-implant interface constitutes a most complex healing situation, where the time scale for osseointegration and development of implant stability currently is not known.


PURPOSE
The aim of the study was to measure the stability of implants placed in grafted bone after various follow-up periods.


METHODS
Implant stability measurements by means of resonance frequency analysis were performed in 10 patients previously treated with a Le Fort I osteotomy and interpositional bone grafts. The implants were placed 3 to 4 months after the grafting procedure. Sixty-seven Brånemark implants were subjected to resonance frequency analysis measurements at fixture placement and up to 5.5 years after implant surgery. Periapical radiographs were used for assessment of marginal bone levels.


RESULTS
The radiographic examinations showed marginal bone loss with time during the 5.5-year follow-up. The resonance frequencies varied from 5860 to 8440 Hz. When accounting for abutment length and marginal bone level, there was a tendency of increasing resonance frequency with time. Two implants with low resonance frequencies failed during the prosthetic phase.


CONCLUSION
The results indicate an increased implant stability with time, which may reflect bone formation, remodeling, and maturation at the implant interface.