Purpose: To compare the clinical outcome of single implants placed immediately after tooth extraction with implants placed 6 weeks after tooth extraction (immediate-delayed placement), and with implants placed after 4 months of extraction and socket healing (delayed placement). Materials and methods: Two hundred and ten patients requiring a single implant-supported crown to replace a tooth to be extracted were randomised to receive immediate post-extractive implants (70 patients), immediate-delayed implants at 6 weeks (70 patients), and delayed implants after 4 months of healing (70 patients), according to a parallel group design. When needed, patients of the immediate and immediate-delayed group had the socket grafted with a bone substitute and covered with a resorbable membrane at implant placement. Sockets randomised to delayed implants were grafted in the same manner if poorly preserved or in the aesthetic areas (from second upper to second upper premolars). Implants inserted with at least 25 Ncm torque were left to heal unloaded for 4 months, whereas those inserted with less than 25 Ncm were left to heal unloaded for 6 months. Temporary crowns were delivered and were to be replaced by definitive ones after 4 months. Outcome measures were crown and implant failures, complications, peri-implant marginal bone level changes, aesthetics assessed using the pink esthetic score (PES) and patient satisfaction recorded by blinded assessors. Results: Three patients dropped out from the immediate, five from the immediate-delayed and six from the delayed group up to 4-months post-loading. Four implants (6.0%) failed in the immediate, four (6.2%) in the immediate-delayed and one (1.6%) from the delayed group (P (chi-square test) = 0.369). Apart from the crown failures due to implant losses, no other crown had to be remade. Five immediate, six immediate-delayed and three delayed implants were affected by one complication each (P (chi-square test) = 0.601). Mean peri-implant marginal bone loss after 4 months was -0.17 ± 0.11 mm (95% CI: -0.20; -0.15) at immediate, -0.20 ± 0.09 mm (95% CI: -0.23; -0.18) at immediate-delayed, and -0.24 ± 0.12 mm (95% CI: -0.27; -0.21) at delayed placed implants (P (Kruskal Wallis test) = 0.006). At delivery of definitive crowns, 4 months after loading, the mean total aesthetic score was 12.48, 12.38 and 11.71 in the immediate, immediate-delayed and delayed groups, respectively (P (Kruskal Wallis test) < 0.001). All patients were fully satisfied with both function and aesthetics, and would undergo the same procedure again, with four exceptions (one from the immediate, one from the immediate-delayed and two from the delayed group), who were partially satisfied with the aesthetics (P = 0.785). Conclusions: No statistically significant differences for failures, complications and patient satisfaction were observed when placing single implants immediately, 6 weeks or four months after tooth extraction; nevertheless failures and complications were more frequent for immediate and immediate-delayed placed implants. Bone level changes were similar between the different procedures, but the aesthetics showed better results for immediate and immediate-delayed implants.
Keywords: delayed implants, immediate-delayed implants, immediate post-extractive implants, single implants, socket preservation
Conflict-of-interest statement: This trial was partially funded by Nobel Biocare Services AG (code: 2010-894), the manufacturer of the implants evaluated in this investigation, however data belonged to the authors and by no means did the manufacturer interfere with the conduct of the trial or the publication of the results.
