Single versus splinted short implants at sinus augmented sites: A systematic review and meta-analysis.

Objective: This review primarily evaluated the success, survival and failure rates of implants shorter than 10 mm restored with single-unit or splinted fixed dental prostheses in maxillary sinus augmented sites.

Material And Methods: Two reviewers independently performed the systematic search of electronic databases, including MEDLINE, EMBASE and CENTRAL, up to September 2019 with no language restriction. A supplemental hand search consisted of screening 13 journals. The inclusion criteria were: primary studies reporting implant, prosthetic and patient-reported outcome measures (PROMs) of extra-short and short implants placed in conjunction with sinus floor elevation in partially dentate patients, restored with single- and splinted-crowns for direct comparison, with a minimal 1-year follow-up. Weighted arithmetic mean (WAM) of the implant survival was performed according to the type of prosthesis. This was confirmed by using Review Manager software to perform meta-analysis.

Results: Two observational studies reporting on 106 tapered, press-fit, sintered porous-surfaced implants with a length ranging from 5 mm to 9 mm were included in this systematic review. Of these, 20 and 86 implants were restored with single and splinted prostheses, respectively. The risk ratio (RR) was 1.16 (95% CI: .31-4.30, p = .58, I² = 0%) for individually restored implants failure when compared to splinted implants, indicating that short dental implants restored with single crowns could have a 16% higher possibility of failure if compared to implants with splinted crowns. The heterogeneity value was not statistically significative (p = .58). No statistical difference in the implant survival rate of the two types of analysed prostheses was observed after WAM (p= .923). The level of evidence for the included studies ranged from low (4) to fair (2B).

Conclusion: Similar clinical outcomes up to a 9-year follow-up were observed in single and splinted porous-surfaced implants shorter than 10 mm located in sites with sinus lift. However, the conclusion shall be interpreted with caution due to the level of evidence and limited number of included studies included in this systematic review.