Notch Down-Regulation and Inflammatory Cytokines and RANKL Overexpression Involvement in Peri-Implant Mucositis and Peri-Implantitis: A Cross-Sectional Study.

OBJECTIVES Notch signaling pathway, known to influence bone resorption in several oral diseases, has not been analyzed in peri-implantitis yet. Therefore, the aims of the present study were to determine the levels of Notch cascade, bone remodeling mediators and pro-inflammatory cytokines, in conjunction with clinical parameters, in subjects with peri-implant mucositis and peri-implantitis. MATERIAL AND METHODS Clinical parameters: peri-implant probing depth (PPD), bleeding on probing (BOP), suppuration on probing (SUP) and plaque index (PI) were recorded. Samples were collected from 130 participants, divided into peri-implantitis (PI), peri-implant mucositis (PM) and healthy implants (HI) group. Relative expression levels (REL) of Notch 1, Notch 2, Jagged 1, Hes 1, Hey 1, TNF-α, IL-17, IL-1β, IL-6, RANKL and OPG mRNA were determined by reverse transcriptase-real-time polymerase chain reaction (RT-qPCR). Quantitation of Notch 1, Il-17 and IL-6 proteins was performed using ELISA assays. RESULTS All clinical parameters were significantly higher in PI compared to HI. Significant decrease of Notch 1, and higher REL of Hey 1, IL-1β, IL-6 and RANKL were found in PI compared to HI. PM showed significant increase of IL-1β REL in comparison to HI. In PI vs PM, significantly higher REL was found for Hey 1, TNF-α, IL-17, IL-1β, IL-6 and RANKL. Additionally, higher protein concentrations of IL-6 and IL-17 were detected in PI vs. PM and vs. HI group. CONCLUSION The combined effect of Notch 1 down-regulation and elevated expression of some key inflammation modulators might result in osteoclast activity increase and subsequent osteolysis in peri-implantitis.