Marginal Bone Changes on Ultraclean, Micro-Threaded Platform-Switched Implants Following Restoration: 1- to 4-Year Data.

The aim of this clinical study was to retrospectively evaluate changes in bone following final abutment insertion and functional loading and to evaluate bone status relative to implant type, width, and length; placement into healed bone and extraction sockets; immediate provisionalization; abutment type (single-unit, multi-unit, cementable stock abutment, custom abutment, ti-base, UCLA); cementable restoration, screw-retained restoration, splinted restoration, and single-unit restoration. Fifty consecutive patients with 87 implants were evaluated radiographically following final abutment insertion and functional loading to their latest follow-up radiograph. Follow-up evaluation time from final abutment insertion ranged from 11 months (335 days) to 4 years (1,484 days), with an average of 831 days (2.3 years). Mesial and distal surfaces were examined and graded as bone improved, bone maintained, and bone decreased. A total of 174 surfaces were graded (87 implants). Thirty percent of implant surfaces showed bone improvement following restoration, 62% of implant surfaces showed bone maintenance, and 8% showed bone decrease (range 0.1 mm to 1 mm). This retrospective study showed an unusual phenomenon of bone improvement following restoration for 30% of implant surfaces. Eight percent of the surfaces showed bone decrease but at a maximum of 1 mm. This places 100% of the followed implants well within established criteria for successful implant bone maintenance. There was no statistical difference among the groups in age, gender, implant diameter, implant length, implant location (maxilla versus mandible, anterior versus posterior), and prosthetic procedures. Additional highly controlled prospective studies are being planned to validate and further the authors' knowledge.