Natural or palatal positioning of immediate post-extractive implants in the aesthetic zone? Three-year results of a multicentre randomised controlled trial

Purpose: To evaluate whether there is a difference in aesthetic outcomes positioning immediate post-extractive implants in the natural position (where the tooth should have been in relation to adjacent teeth/implants) or approximately 3 mm more palatally. Materials and methods: Just after tooth extraction, 20 patients requiring one single immediate maxillary post-extractive implant, from second premolar to second premolar, were randomly allocated to receive either an implant positioned in the natural 'central' position where the tooth should have been (central group; 10 patients) or approximately 3 mm more palatally (palatal group; 10 patients) according to a parallel-group design at two different centres. When needed, sites were reconstructed and bone-to-implant gaps were filled with granules of anorganic bovine bone, covered by resorbable collagen barriers. Implants were left submerged for 4 months and rehabilitated with provisional crowns, replaced after 4 months by metal-ceramic definitive crowns. Patients were followed to 3 years after loading. Outcome measures were: crown and implant failures, complications, aesthetics assessed using the pink aesthetic score (PES), peri-implant marginal bone level changes and patient satisfaction, recorded by blinded assessors. Results: Three patients from each group dropped out up to 3 years after loading. One implant failed in each group (14%), the difference being not statistically significant (difference in proportion = 0.00; 95% CI: -0.39 to 0.39; P = 1.000). Two palatal group patients and one natural position patient had a complication each, the difference being not statistically significant (difference in proportion = 0.14; 95% CI: -0.28 to 0.52; P = 1.000). Three years after loading, the median PES was 12.5 (interquartile range [IQR] 5.0) for the central and 10.0 (IQR 10.0) for the palatal group, the difference being not statistically significant (median difference = -1.5; 95% CI: -10.0 to 5.0; P = 0.476). Three years after loading, patients of the central group lost 0.25 (IQR 0.40) mm of peri-implant marginal bone and those of the palatal group 0.20 (IQR 0.88) mm, the difference being not statistically significant (median difference = 0.15 mm; P [Mann-Whitney U test] = 0.486). Patients of both groups were equally satisfied at 3 years after loading for both function and aesthetics (both P = 0.699). Conclusions: These preliminary results suggest that positioning of immediate post-extractive implants 3 mm more palatally may not improve aesthetics; however, the sample size of the present study was very limited, thus larger trials are needed to confirm or reject the present findings.