Implant Failure and Marginal Bone Loss Between Axial and Tilted Implants: An Umbrella Review with Meta-analysis

Purpose: To summarize and analyze all the evidence available concerning marginal bone loss (MBL) and implant failure between tilted and axial implants. Materials and Methods: An electronic literature search was conducted without any language restrictions, and only systematic reviews with meta-analysis or meta-analysis studies were included. Relative risks (RRs) and the differences in mean (MD) were calculated with 95% confidence intervals (Cls) for the assessed outcomes (in mm) of implant failure and MBL. Results: In total, eight studies were included. Based on the short-term results, a nonsignificant mean difference (MD = 0.00; 95% CI;-0.01-0.02; P value = .75) was recorded between tilted and axial implants supporting full-arch dentures. A significant mean difference was recorded at 3-year follow-up (MD = 0.08 95% CI = 0.05-0.11; P value < .00001) and at long-term follow-up (MD = 0.18; 95% CI =0.15-0.20; P value < .00001). A nonsignificant difference was observed between tilted and axial implants regarding implant failure (RR = 1.02; 95% CI = 0.85-1.23; P value = .81). Conclusions: Based on the high- and moderate-quality studies with low risk of bias included in this review, no significant difference in outcome regarding implant failure was observed between tilted and axial implants supporting full-arch or fixed partial dentures.