Purpose: This systematic review and meta-analysis aimed to compare the primary stability of immediate implants placed in fresh sockets to implants placed in healed sites.
Materials and methods: A systematic search was conducted of the PubMed, Scopus, Web of Science, Embase, Clinicaltrials.gov and Cochrane databases, and the grey literature. The risk of bias was assessed using the Risk of Bias 2 and Risk of Bias In Non-randomized Studies of Interventions tools (both Cochrane Collaboration, London, UK). Primary stability was assessed through resonance frequency analysis (implant stability quotient) and insertion torque. Subgroup analyses were performed to investigate factors that impact the outcome. Meta-analyses of mean difference were conducted using random-effects models. The certainty of the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation approach. The study was registered in the International Prospective Register of Systematic Reviews (no. CRD42022304379).
Results: Out of 2,317 studies published up to and including January 2024, 4 randomised and 5 non-randomised studies were included, representing 438 individuals with a total of 515 implants (265 in healed sites and 250 placed immediately). Seven studies were included in the meta-analysis of implant stability quotient and showed an overall mean difference of 5.66 (95% confidence interval 1.52 to 9.79), favouring the healed sites group. Implant torque meta-analysis did not present statistical differences (mean difference 4.22; 95% confidence interval −1.04 to 9.51). Concerning the subgroup analyses, higher stability was seen in the immediate implant placement group for wider implants. In conventional implants, the difference in implant stability quotient was 8.09 (95% confidence interval 3.43 to 12.75). The certainty of evidence was very low for both analyses.
Conclusion: Higher primary stability was achieved in the healed sites group, with statistical significance but unclear clinical relevance; however, wider implants appeared to counter the lower stability of implants placed immediately. Due to the very low certainty of evidence, the results should be interpreted with caution.