Platform switching and immediately loaded post-extractive implants. Multicenter double-blind RCTs

This study aimed to evaluate soft- and hard- tissues response to immediately loaded post-extractive implants using platform switching concept. In 18 patients, selected for single-tooth replacement in anterior maxillae, 20 implants (Global®, Sweden & Martina, Italy), 5.5mm platform diameter, were placed immediately after extraction. Jumping distance was filled using Bio-Oss Collagen® (Geistlich, Switzerland). Immediately after insertion, each implant was randomly assigned to test and control treatments: 10 implants were connected with 3.8mm diameter abutment (test group) and 10 with 5.5mm diameter abutment (control group). A provisional was adapted for non-functional immediate positioning. Two months after, definitive rehabilitation was performed. Radiographic assessments, periodontal indices, facial marginal mucosal level (REC) and papilla height (PH) were measured by an independent observer when implant was placed (baseline), definitive prosthesis inserted and every six months thereafter. REC, PH and radiographic bone loss at mesial and distal aspects of the implants were evaluated using an image analysis software Mean follow-up was 20 months. All 20 implants were clinically osseointegrated. In the test group, x-R analysis showed a bone resorption of 0.33mm (SD=0.19mm). The mean values were statically significant (p≤ 0.005) compared to control group mean values (1.32mm, SD=0.30mm). The test group showed a +0.18mm REC gain. PH gain was +0.25mm. The mean values were statically significant (p≤ 0.005) compared to control group (PH=-0.32mm; REC=-0.54mm). No differences between two groups in periodontal indices were found. This study suggests that immediately loading with subsequent platform switching can provide peri-implant hard tissue stability, with a corresponding soft tissue preservation.