Journal of Prosthetic Dentistry

Immediate or delayed loading protocols for two-implant mandibular overdentures: A systematic review and meta-analysis of randomized controlled trials


      Statement of problem

      The immediate loading protocol for 2-implant mandibular overdentures has been widely reported. Nevertheless, the clinical effects reported in different articles are quite different.


      The purpose of this systematic review and meta-analysis of randomized controlled trials (RCTs) was to compare the clinical effects of immediate and delayed loading of 2-implant mandibular overdentures.

      Material and methods

      The review followed the guidelines of Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA). PubMed, Cochrane Library, Web of Science, Embase, Scopus, ScienceDirect, CBM, CNKI, and Wan Fang databases were searched electronically for RCTs published before March 25, 2020. Two authors independently conducted literature screening, quality assessment, and data extraction. The outcomes of interest were implant failure rate, marginal bone loss (MBL), implant stability quotient (ISQ), periotest value (PTV), and patient satisfaction.


      A total of 2498 unduplicated records were identified. After full-text analysis, 7 eligible RCTs were included. All studies were followed for at least 12 months, and the meta-analysis was based on this. The meta-analysis showed that the implant failure rate in the immediate group was higher than that in the delayed group, but there was no statistically significant difference (I2=0%; n=7; risk difference [RD]=0.03; 95% confidence interval [CI]=-0.01 to 0.08). The difference of MBL between immediate and delayed loading was not significant (I2=88%; n=6; mean difference [MD]=-0.04; 95% CI=-0.16 to 0.24). Because of the limited articles reporting on ISQ, PTV, and patient satisfaction, no quantitative analysis was conducted for these outcomes.


      Although the implant failure rate was more likely to favor the delayed group, available evidence indicates no statistical difference in implant failure and marginal bone loss between immediate and delayed loading protocols.
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