Survival Rates of Short Dental Implants (≤ 6.5 mm) Placed in Posterior Edentulous Ridges and Factors Affecting their Survival after a 12-Month Follow-up Period: A Systematic Review

Abstract

Purpose: Dental implant placement in atrophic ridges is challenged by availability of bone and proximity to vital structures. Although short dental implants have been considered favorable, there is no consensus regarding their long-term survival and factors affecting it. This systematic review addressed the focused question, "What is the survival rate of short dental implants (SDI; length ≤ 6.5 mm) placed in posterior edentulous ridges without any ridge augmentation procedures and followed up for 12 months post-prosthetic loading, and what are the factors affecting their survival?"

Materials and methods: Based on a search of the indexed literature, 51 studies fulfilling the inclusion criteria were quantitatively reviewed. Overall SDI survival and factors influencing survival, such as anatomic location, surgical protocol, time of loading, type of prosthesis retention, nature of prosthesis, implant stability, crown-to-implant ratio (C/I ratio), and marginal bone loss at follow-up were evaluated. SDI survival based on clinical factors was compared to overall survival using odds ratio (OR), and continuously distributed data were evaluated using Pearson's correlation (P < .05).

Results and conclusion: Based on this review, SDI placed in edentulous posterior regions of the maxilla and mandible have survival rates (96.45%) similar to those of conventional-length implants after a follow-up period of 12 months post-prosthetic loading. Except for smaller implant diameter (OR = 1.59, 95% confidence interval [CI] = 1.03-2.43, P < .05), screw-retained restorations (OR = 2.11, 95% CI = 1.25-3.57, P < .01), and C/I ratio ≥ 2 (Pearson's R = -0.694, P < .01), other variables relating to implant surgery, prosthetic loading, nature and type of prosthesis, and follow-up did not significantly affect SDI survival.