In selected sites, short, rough-surfaced dental implants are as successful as long dental implants: a critical summary of Pommer B, Frantal S, Willer J, Posch M, Watzek G, Tepper G. Impact of dental implant length on early failure rates: a meta-analysis of observational studies. J Clin Periodontol 2011;38(9):856-863.

CLINICAL QUESTION: In adult patients, do short dental implants (< 10 millimeters) lead to failure rates similar to those for longer implants (≥ 10 mm) in the first year of loading? REVIEW
METHODS: Two independent reviewers searched three electronic databases and 29 journals for articles published from January 1998 to January 2008. The authors included in the review only English-language, prospective observational studies in which the allocation decision occurred in the course of usual treatment. Also, implants must have been placed in nonaugmented healed jawbone after a conventional healing period of three to six months. The primary outcome measured was implant failure within the first year of prosthetic loading, determined on the basis of established criteria.1 A meta-analysis was carried out in which the authors compared the association between implant length and failure. In addition, the authors performed subgroup analyses of failure as a function of the implants’ diameter, surface texture and location in the maxillary or mandibular arch. MAIN
RESULTS: Fifty-four trials, including 19,563 dental implants (with only a 2.4 percent dropout rate), met the inclusion criteria. The results of the meta-analysis, which consisted of 40 studies (2,223 short implants and 14,158 long implants), showed that shorter implants had an overall failure rate statistically significantly higher than that for long implants within the first year of loading (odds ratio [OR] = 1.8; 95 percent confidence interval [CI], 1.3-2.5). The results of subgroup analyses showed a statistically significant difference in failure rates for short and long implants in the maxilla, but no difference in the mandible. However, with the possible exception of the anterior maxilla, the failure rates for rough surfaced implants in the two groups (1,298 short implants and 7,544 long implants) were not statistically significantly different (OR = 1.1; 95 percent CI, 0.6-2.1). The authors found no association between implant diameter and failure rates within one year of prosthetic loading.
CONCLUSIONS: With the possible exception of the maxillary anterior area, rough-surfaced short implants with a minimum length of 7 mm present no additional risk of failure within the first year of loading.