Natural or palatal positioning of immediate post-extractive implants in the aesthetic zone? 1-year results of a multicentre randomised controlled trial

Purpose: To evaluate whether there is a difference in aesthetic outcomes positioning immediate postextractive implants in the natural position (where the tooth should have been in relation to adjacent teeth/implants) or about 3 mm more palatally. Materials and methods: Just after tooth extraction, 30 patients requiring one single immediate maxillary post-extractive implant, from second 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; 15 patients) or about 3 mm more palatally (palatal group; 15 patients) according to a parallel group design at three different centres. When needed, sites were reconstructed and bone-toimplant 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 1 year after loading. Outcome measures were: crown and implant failures, complications, aesthetics assessed using the pink esthetic score (PES), peri-implant marginal bone level changes and patient satisfaction, recorded by blinded assessors. Results: Two patients from the palatal group dropped-out up to 1 year after loading. One implant failed in each group (6.7%), the difference being not statistically significant (difference in proportion = -0.01; 95% CI -0.20 to 0.18; P (Fisher's exact test) = 1.000). One patient from the central group was affected by one complication, vs two palatal group patients (two complications); the difference being not statistically significant (difference in proportion = -0.09; 95% CI -0.32 to 0.15; P (Fisher's exact test) = 0.583). One year after loading, the mean PES was 9.93 ± 2.67 for the central and 8.75 ± 4.37 for the palatal group; the difference being not statistically significant (mean difference = 1.18; 95% CI: -1.87 to 4.23; P (t test) = 0.427). One year after loading, patients in the central group lost on average 0.23 ± 0.17 mm of peri-implant marginal bone and those of the palatal group 0.24 ± 0.25 mm, the difference being not statistically significant (mean difference = -0.01; 95% CI: -0.23 to 0.21; P (t test) = 0.926). Patients in both groups were equally satisfied at 1 year after loading for both function and aesthetics (P (Mann-Whitney U test) = 0.494 and P (Mann-Whitney U test) = 0.076, respectively). Conclusions: These preliminary results suggest that positioning of immediate post-extractive implants 3 mm more palatally is not improving aesthetics, however, the sample size of the present study was limited, thus larger trials are needed to confirm of reject the present findings. Conflict-of-interest statement: The manufacturer of the implants - Mozo-Grau Ticare, Valladolid, Spain - used in this investigation, donated the implants and partially supported this trial. However, data belonged to the authors and by no means did the sponsor interfere with the conduct of the trial or the publication of its results.