Meta-analysis of Randomized Controlled Trials Comparing Clinical Outcomes Between Short Implants and Long Implants with Bone Augmentation Procedure

Purpose: The purpose of this meta-analysis was to assess and compare clinical outcomes of short implants versus long implants placed in conjunction with a bone augmentation procedure. Materials and Methods: The eligible studies were searched from PubMed, Embase, Springer link, and the Cochrane library databases up to 23 January 2015. Prosthesis failures, implant failures, complications, and marginal bone loss were the clinical outcomes measured. The pooled weighted mean difference (WMD) or risk ratios (RRs) and their 95% confidence intervals (CIs) were used to measure the effect size of continuous variables and dichotomous variables, respectively. A random-effects model was performed to assess the effect size. Results: Nine eligible studies including 480 short implants (≤ 8 mm) and 503 long implants (≥ 9.3 mm) were selected for this meta-analysis. Compared with the long-implant group, a notable decrease in the short-implant group was found for complications at the 5-year follow-up (RR = 0.34, 95% CI: 0.15 to 0.79, P .05) and for marginal bone loss at the 1-year (WMD = -0.08, 95% CI: -0.15 to -0.02, P .05), 3-year (WMD = -0.43, 95% CI: -0.63 to -0.23, P .05), and 5-year (WMD = -0.57, 95% CI: -1.10 to -0.04, P .05) followups. No significant differences were found between the short-implant and long-implant groups for other variables (P > .05). Moreover, the results were not obviously changed when stratified by implants placed in the mandible and maxilla. Conclusion: Implants ≤ 8 mm in length are considered to be a suitable alternative treatment when bone height is not adequate for standard implants. Keywords: dental implants, meta-analysis, randomized controlled trial