Clinical success of single crowns supported by short implants-a systematic review and meta-analysis

Short dental implants (SDIs) have emerged as a promising, less invasive alternative to conventional-length implants (CLDIs) for oral rehabilitation in patients with limited bone height, reducing the need for additional surgical procedures while maintaining functional and aesthetic success. This systematic review and meta-analysis aimed to answer: "Do single crowns supported by SDIs have a clinical success rate comparable to (or non-inferior to) that of CLDIs?", focusing on survival rates, periodontal health, marginal bone loss (MBL), and biological complications. A comprehensive search was performed in Embase, Lilacs, PubMed/MEDLINE, Science Direct, Scopus, Google Scholar, and ProQuest, including all available years. Randomized and non-randomized clinical trials comparing single crowns supported by SDIs and CLDIs were included. Studies had to assess survival, periodontal health, MBL, and biological complications. Retrospective, non-comparative, and unspecified designs, reviews, and case reports were excluded. Screening and selection were conducted through titles, abstracts, and full-text reviews. Following PRISMA guidelines, data extraction and quality assessment were performed. The review was registered in PROSPERO. Risk of bias was evaluated using RoB2 and ROBINS-I, and meta-analyses were conducted with random-effects models, with a statistical significance of p < 0.05. The outcomes evaluated were implant survival, MBL, and probing depth (PD), measured by standardized mean differences (SMD) and relative risks (RR) with 95% confidence intervals (CIs). A total of 1146 potential studies were identified; 626 were screened, 30 fully reviewed, and 17 included. All studies showed a high risk of bias. SDIs presented survival rates comparable to CLDIs in both splinted (RR = 0.98; 95% CI = 0.96-1.00; p = 0.05) and non-splinted single crowns (RR = 0.96; 95% CI = 0.91-1.00; p = 0.07). MBL showed a small but statistically significant reduction for both (non-splinted: SMD = - 0.11; p = 0.03; splinted: SMD = - 0.41; p = 0.01), with lower PD in non-splinted crowns (SMD = - 0.64; p = 0.03). This systematic review with meta-analysis suggests that SDIs achieve clinical outcomes comparable to, and not inferior to, CLDIs for splinted or non-splinted single crowns regarding implant survival up to 10 years. Despite methodological limitations, SDIs may represent a viable and less invasive treatment alternative.