Purpose: To evaluate the predictive value of microRNAs (miRNAs) found in peri-implant crevicular fluid (PICF) in the prognosis of peri-implant bone resorption.

Materials and methods: Seven patients were rehabilitated with fixed partial dentures each supported by two dental implants (total of 14 implants). At 3 months post-implant insertion, a sample of peri-implant mucosa and a sample of PICF were taken at each implant site. MiRNAs were extracted from the samples and analyzed through microarray technology. MiRNAs extracted from PICF were compared with miRNAs extracted from soft peri-implant tissue and related with peri-implant bone resorption measured at the 5-year follow-up.

Results: During the 5-year follow-up, no dropouts and no implant failures were recorded. The mean bone resorption was 1.98 mm (median: 2 mm). Extracellular miRNAs were recovered in well-detectable amounts in all PICF samples. Specific miRNA expression profiles were predictive of bone resorption. Fourteen miRNAs that were altered in PICF in case of bone resorption were also altered in the soft peri-implant tissue of the same implant sites.

Conclusion: MiRNAs may be used as biomarkers of peri-implant bone resorption, and their presence in PICF lays the foundations for the development of a noninvasive and site-specific liquid biopsy.