Survival rates of short dental implants (≤6mm) compared with implants longer than 6mm in posterior jaw areas: A meta-analysis.

Abstract

To systematically review randomized controlled clinical trials (RCTs) reporting on the long-term survival and failure rates, as well as the complications of short implants (≤6mm) versus longer implants (>6mm) in posterior jaw areas. Electronic and manual searches were conducted to identify studies, specifically RCTs, reporting on short dental implants (≤6mm) and their survival and complication rates compared with implants longer than 6mm. Secondary outcomes analyzed were marginal bone loss and prosthesis survival rates. Ten RCTs fulfilled the inclusion criteria and featured a total of 637 short (≤6mm) implants placed in 392 patients, while 653 standard implants (>6mm) were inserted in 383 patients. The short implant survival rate ranged from 86.7% to 100%, whereas standard implant survival rate ranged from 95% to 100% with a follow-up from 1 to 5years. The risk ratio (RR) for short implant failure compared to standard implants was 1.29 (95% CI: 0.67, 2.50, p=0.45), demonstrating that overall, short implants presented higher risk of failure compared to longer implants. The heterogeneity test did not reach statistical significance (p=0.67), suggesting low between-study heterogeneity. The prosthesis survival rates from the short implant groups ranged from 90% to 100% and from 95% to 100% for longer implant groups, respectively. Short implants (≤6mm) were found to have higher variability and lower predictability in survival rates compared to longer implants (>6mm) after periods of 1-5years in function. The mean survival rate was 96% (range: 86.7%-100%) for short implants, and 98% (range 95%-100%) for longer implants. Based on the quantity and quality of the evidence provided by 10 RCTs, short implants with ≤6mm length should be carefully selected because they may present a greater risk for failure compared to implants longer than 6mm.