Short Dental Implants (6 mm) Versus Standard Dental Implants (10 mm) Supporting Single Crowns in the Posterior Maxilla and/or Mandible: 2-Year Results from a Prospective Cohort Comparative Trial

Abstract

Objectives The purpose of present study was to compare short (6 mm) with longer implants with the same surface use in the posterior maxilla and/or mandible. Material and Methods A total of 110 implants of 6 or 10 mm in length were placed with an internal hex (n = 60) and with a conical connection (n = 50) but the same material, surface and design, supporting single crowns in the posterior maxilla and/or mandible. Outcomes measured were implant survival and marginal bone level changes up to 24 months after loading. Results Final group consisted of 105 implants: 6 mm (n = 58) and 10 mm (n = 47). Success rate after 24 months was similar between treatment groups (98.3% vs. 100%; P = 0.361). Failure rates of the short implants in mandible (1/18, 5.6%) and in maxilla (0/40, 0%) were also not significantly different (P = 0.133). Success rate after 2 years was similar between internal hex vs. conical connection implants (100% vs. 97.7%; P = 0.233). Subjects lost statistically significant marginal peri-implant bone in both groups, but without differences (6 mm group: 0.38 mm [95% CI = 0.09 to 0.67] vs. 10 mm group: 0.43 mm [95% CI = 0.15 to 0.61]; P = 0.465 at 24 months), in relation also to type of implant (internal hex vs. conical, P = 0.428 at 24 months) or operator (P = 0.875 at 24 months). Conclusions Short implants may be successful in the posterior areas during the first 24 months of loading, with similar outcomes to 10 mm long implants, supporting their use as a valid option in selected cases. However, larger and longer follow-ups of 5 years or more are needed.