Soft Tissue Augmentation Around Dental Implants: Techniques, Timing, and Comparative Efficacy—A Systematic Review and Network Meta-Analysis

Aim: The peri-implant soft tissue phenotype, including keratinized tissue width (KTW) and mucosal thickness (MT), plays a pivotal role in maintaining peri-implant health and stability. Various soft tissue augmentation (STA) procedures have been developed to enhance these components, employing different grafting techniques and materials. The aim of the present systematic review is to compare the effectiveness of different techniques as well as different surgical timing in order to establish their relative efficacy. Methods: A systematic review and Bayesian network meta-analysis (NMA) was conducted following PRISMA-NMA guidelines. Randomized controlled trials (RCTs) evaluating STA around dental implants were included, focusing on KTW and MT gain as primary outcomes. Pairwise and indirect comparisons were performed using a hierarchical Bayesian model with Markov chain Monte Carlo simulations. Treatment effects were expressed as mean differences (MD) with 95% credible intervals. Additionally, subgroup analyses explored apically positioned flap (APF)-based and bilaminar techniques separately, while meta-regression assessed the influence of surgical timing. Results: A total of 48 RCTs were included in the qualitative analysis, and 46 in the NMA. For KTW gain, APF + free gingival graft (FGG) was the most effective treatment [range of MD: 0.22–4.11 mm], whereas APF alone showed limited efficacy compared to no intervention. Bilaminar techniques did not result in significant KTW gain. For MT gain, bilaminar techniques showed the best results, with connective tissue graft (CTG) displaying the best performance [range of MD: 0.02 to 0.94 mm], followed by xenogeneic collagen matrix and buccally displaced flap. Timing did not significantly influence MT gain, while “delayed time points” might positively influence KTW. Longitudinal analysis showed variability in stability across treatments, with APF + FGG and CTG maintaining higher performance over time. Conclusion: APF + FGG is the most reliable approach for increasing KTW, while CTG remains the gold standard for MT enhancement. The choice of technique and graft material appears more critical than surgical timing. Long-term stability of tissue dimensions and standardization of reporting across future trials are essential to refine clinical decision-making in STA procedures.