Gene expression of pro- and anti-inflammatory factors in peri-implant diseases

Objectives: This study assessed the gene expression of pro- and anti-inflammatory cytokines (IL-12, TNF-α, IL-4, IL-10) and osteoclast factors (RANKL and OPG) in sites exhibiting different stages of peri-implant diseases. Methods: Peri-implant soft tissues (n=48) were harvested from healthy implants (HI), mucositis (MC), initial peri-implantitis (IP) and severe peri-implantitis (SP) for mRNA expression analysis by quantitative PCR. Results: IL-12 and TNF-α expressions were significantly higher in SP, followed by IP and MC (p<0.05). IL-4 expression was higher in HI, followed by MC, SP and IP. IL-10 expression was the lowest in HI (p<0.05) while no significant differences were detected among diseased groups (p>0.05). OPG was higher in HI, followed by IP, SP and MC. Expression of RANKL progressively increased as peri-implantitis severity increased. The highest OPG/RANKL ratio was observed in HI and the lowest in SP (p<0.01). Conclusion: This study demonstrated that different patterns of cytokines and osteoclastic factors expressions are related to different stages of peri-implant diseases.