Augmentation of Exposed Implant Threads with Autogenous Bone Chips: Prospective Clinical Study

BACKGROUND: Autogenous bone chips can be harvested during drilling of implant sites and may be used as a graft material for bone augmentation and coverage of exposed implant threads. PURPOSE: The aim of this prospective study was to evaluate the possibility of augmenting exposed implant threads with autogenous bone chips. MATERIALS AND METHODS: Twenty-one consecutive patients treated with screw-shaped oral implants with exposed threads due to buccal fenestration or marginal defects were augmented with autogenous bone harvested with a bone trap during drilling of the implant site. Both marginal (9 sites) and fenestration defects (12 sites), with 4 to 14 exposed implant threads, were registered clinically and with photography. The number of exposed implant threads was measured before and at second-stage surgery 6 months after augmentation. RESULTS: Complete bone coverage of the exposed implant threads was seen in 12 of the 21 implant sites. Six sites showed one to two remaining exposed threads, two showed about 40% coverage, and one showed flattening of the defect but with eight of nine exposed threads at 6 months follow-up. The mean bone gain was 81% in patients with a marginal defect and 82% in patients with a fenestration defect. CONCLUSION: The results from this clinical study show that it is possible to gain bone over exposed implant threads by augmentation with autogenous bone chips.