Evaluation of the Estimated Role of Yes‐Associated Protein in the Etiology of Peri‐Implantitis: A Case–Control Study

ABSTRACT Objective To investigate for the first time the difference in Yes‐associated protein (YAP) gene expression and protein levels in the peri‐implant crevicular fluid of healthy osseointegrated titanium implants and those showing early signs of peri‐implantitis before loading; and to investigate the immunomodulatory effect of titanium on YAP expression by comparing YAP protein levels around healthy implants with those in the gingival crevicular fluid of healthy teeth. Materials and Methods Sixty‐six systemically healthy individuals were recruited. Fold change in YAP gene expression was evaluated by q‐PCR, and YAP protein level was measured by ELISA in clinical conditions of peri‐implant health ( n = 22) and peri‐implantitis ( n = 22) before insertion of implant‐supported prosthesis to avoid the effect of loading on mechanosensitive YAP. The level of YAP protein was measured in healthy periodontal tissues ( n = 22) in the absence of traumatic occlusion and compared with healthy peri‐implant environment. Results Statistical analysis revealed that YAP gene expression relatively increased by 35% in the presence of peri‐implantitis with a non‐significant p ‐value of 0.938. YAP protein levels pairwise comparison between the studied groups was statistically significant with p ‐value < 0.005. The least value of YAP was in healthy periodontium, followed by healthy peri‐implant tissue and finally a remarkable increase in the presence of peri‐implantitis. Gender was a significant predictor of YAP, with higher levels in females in the presence of implants. Conclusion YAP is a recent biomarker that can predict the presence of inflammation in the peri‐implant environment. YAP protein levels are the highest in the presence of titanium implants and early clinical and radiographic signs of peri‐implantitis. Studying the YAP‐related osteoimmunology of the peri‐implant environment offers new insights into a better understanding of the osseointegration process and titanium‐induced peri‐implantitis.