Comparison of RANKL and OPG levels in peri-implant crevicular fluid between healthy and diseased peri-implant tissues. A systematic review and meta-analysis

Abstract

Objectives: To assess RANKL and OPG levels, as well as RANKL/OPG ratio, in peri-implant crevicular fluid (PICF), in dental implants presenting peri-implantitis (PI) in comparison to healthy implants (H) and to implants with peri-implant mucositis (MU).

Materials and methods: An electronic search based on the PICO framework, supplemented by hand searching, was conducted in MEDLINE and EMBASE, using the Ovid interface from 1996 up to and including the 17^th of December 2019 in order to identify relevant clinical studies. A combination of MeSH terms and text words was utilized for this purpose. Sequential screenings at the title, abstract, and full-text levels were performed independently and in duplicate. A random-effects meta-analysis was conducted and mean value standardized differences, between PI and H groups, were utilized as effect sizes.

Results: Out of 1961 titles, which were revealed by the search strategy, 11 articles fulfilled the inclusion criteria and were incorporated in the systematic review. Meta-analytical processing was performed for RANKL (4 articles), OPG (5 articles), and RANKL/OPG ratio (5 articles) in PI and H groups. The total effect for RANKL mean differences between PI and H groups indicated a tendency but not a statistical significance (P = 0.078) in favor of the PI group, while no statistically significant differences were found for OPG and the ratio levels in the examined groups.

Conclusions: There is limited evidence that levels of the examined biomarkers, RANKL, and OPG as well as the RANKL/OPG ratio, in PICF, may be considered strong indicators for distinguishing between healthy and inflamed peri-implant sites.

Clinical relevance: Biomarker identification in PICF, which could differentiate between healthy and diseased dental implants, might represent a valuable non-invasive method suitable for implant pathology and implant therapy prognosis.

Keywords: Biomarkers; Dental implants; OPG; Peri-implantitis; RANKL; Systematic review and meta-analysis.