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 post-extractive 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-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 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.