Although a cause–effect relationship between experimental biofilm accumulation and the development of experimental peri‐implant mucositis was claimed in the two studies mentioned previously, the case for a true cause–effect relationship would be strengthened by the proof of reversibility to pre‐experimental levels of mucosal health. In the study by Salvi et al., the GI at implant sites dropped significantly less compared with that at tooth sites following 3 weeks of reinstituted oral hygiene practices. Moreover, pre‐experimental levels of GI were not reached at implant sites 21 days after reinstitution of self‐performed biofilm control. This indicated that resolution of experimental peri‐implant mucositis in humans may take longer than 3 weeks (Table 1). In contrast to the study by Salvi et al., all clinical parameters assessed in an elderly patient sample (i.e., ≥70 years) returned to pre‐experimental levels after 3 weeks of reinstituted biofilm control, thus documenting reversibility of experimentally induced peri‐implant mucositis.

Resolution of experimental peri‐implant mucositis was achieved in both studies at the host biomarker level, as identified by the decrease to pre‐experimental values of crevicular fluid pro‐inflammatory biomarkers. These outcomes corroborated the findings of a study in which levels of interleukin (IL)‐1β, tumor necrosis factor‐alpha (TNF‐α), and transforming growth factor‐beta2 (TGF‐β2) were determined in crevicular fluid samples of 25 subjects before and after a 3‐week period of abolished oral hygiene and after 69 days of re‐established oral hygiene practices. While TNF‐α and TGF‐β2 levels did not change during the experimental period, IL‐1β yielded a significant increase after 3 weeks of abolished oral hygiene and was reversed to pre‐experimental levels after 69 days. Although the period of reinstituted oral hygiene was shorter at 3 weeks in the studies by Salvi et al. and Meyer et al., IL‐1β crevicular fluid levels returned to pre‐experimental values, thus confirming the outcomes obtained by Schierano et al.