The Role of MMP-8 on the Health Status of Peri-Implant Tissues: Preliminary Results

Background & Aim: Peri-implant diseases include mucositis and peri-implantitis, and its diagnosis evaluates inflammation, pocket depth, bleeding-on-probing, and implants bone loss. These measurements detect disease history rather than activity, are non-specific, and supply information at examination. Crevicular fluid analyses provide early and objective evidence about the inflammatory process through several proteolytic enzymes, an association between metalloproteinases-8 (MMP-8) and peri-implant diseases can aid early condition identification, leading to prompt treatment increasing implant longevity. The aim of this research is to evaluate the significance of MMP-8 in peri-implant crevicular fluid. Methods: This cross-sectional study was performed on 50 implants from 50 consecutive patients of the University of Bologna Perio-Implant division and 4 private practices. Calibrated operators measured implant probing depth (PD) and bleeding on probing (BOP). Implants were divided into 3 groups (Healthy, Mucositis and Peri-implantitis) following the inclusion criteria: 3 year minimum functional load and periapical x-rays within 6 months. Exclusion criteria were: peri-implant therapies within 3 months, antibiotic/probiotic therapy within 6 months, pregnancy, estrogen-progestin therapy, type I and II diabetes. MMP-8 samples were standardly collected through paper membranes circumferentially inserted in the implant sulcus/pocket, and ELISA tests were run. Results: MMP- 8 mean value resulted significantly higher in Peri-implantitis group (p = 0.03). Lower 95% confidence interval MMP- 8 limits presented an increasing trend from Healthy to Peri-implantitis, not evidenced in higher levels. A significant correlation was observed between PD and MMP- 8 (p = 0.03), no significant relationship with BOP was detected. Conclusions: MMP-8 levels significantly differed between the 3 groups and are correlated to PD. A MMP-8 threshold must be identified to clarify the shading boundary between health and mucositis.