Double-blind randomized controlled trial study on post-extraction immediately restored implants using the switching platform concept: soft tissue response. Preliminary report

To evaluate the soft tissue response to immediately placed implants using the platform switching concept.

In 22 patients, 22 implants of 5.5 mm platform diameter were placed immediately into fresh extraction sockets in maxillae without compromised bone tissue. Eventual post-extraction bone defects were filled using bovine bone matrix mixed with collagen. Immediately after insertion, implants were randomly divided: 11 implants were connected with a 3.8 mm diameter abutment (test group) and 11 with a 5.5 mm diameter abutment (control group). A provisional crown was adapted and adjusted for non-functional immediate positioning. Two months later, definitive prosthetic rehabilitation was performed. Periodontal parameter, buccal peri-implant mucosal changes (REC), mesial and distal papilla height (PH) and vertical height of jumping distance (VHG) were measured at the time of implant placement, of definitive prosthesis insertion and every 6 months thereafter.

The mean follow-up was 25 months. All implants were clinically osseointegrated. The test group showed a +0.18 mm REC gain. PH gain was +0.045 mm on average. The mean values were statistically significant (P< or =0.005) compared with the control group (PH=-0.88 mm; REC=-0.45 mm). No difference between the two groups in periodontal parameters was found. The mean value of bone filling was 7.51 mm in the test group (97.4% of VHG) and 8.57 mm in the control group (95.2% of VHG). No statistically significant difference was found between the two groups.

This study suggests that, in a limited time period of 2 years, immediately placed implants with subsequent platform switching can provide peri-implant tissue stability.