Relationship between gingival and peri-implant sulcular fluid active matrix metalloproteinase-8 concentration and clinical indices in healthy and diseased conditions

Aim: The study was to evaluate the active matrix metalloproteinase-8 (aMMP-8) concentration in gingival crevicular fluid (GCF) and in peri-implant sulcular fluid (PISF) in healthy and diseased conditions, before and after non-surgical treatment, and to compare it with the various clinical parameters used to estimate the gingival and peri-implant inflammation. Methods: Plaque index/modified PI (PI/mPI), gingival index/simplified GI (GI/sGI), probing depth (PD), bleeding on probing index/modified BOPI (BOPI/mBOPI), radiographic bone loss/radiographic marginal bone loss (rBL/rMBL), and GCF/PISF samples were evaluated, before and 3 months after non-surgical treatment, GCF/PISF samples were analyzed by a chair-side mouth-rinse test (ImplantSafe®) in combination with a digital reader (ORALyzer®). Results: In all groups, aMMP-8 median levels were statistically higher in the PISF than in GCF and they did not change after treatment. Moreover, it was statistically higher in Group 3 (periodontitis/peri-implantitis) compared to the other groups. A positive correlation of the GCF/PISF and aMMP-8 median concentration was seen with increasing PD and BOPI/mBOPI values. A higher covariation of aMMP-8 mean levels in GCF with PD was found when compared to PISF levels. aMMP-8 mean levels in PISF expressed a higher covariation with increasing grades of sGI, rMBL, and BOPI while aMMP-8 GCF concentration established a better covariation with PD and PI. Conclusions: PISF of sites with peri-implant mucositis and peri-implantitis showed higher levels of aMMP-8 compared to sites with gingivitis and periodontitis. Compared to clinical indices, aMMP-8 concentration in GCF/PISF can be a beneficial adjunctive diagnostic tool for early identification and screening of the risk of peri-implant diseases. After non-surgical therapy, PISF aMMP-8 concentration remained mostly unchanged, while the GCF concentration of aMMP-8 significantly decreased.