Question) Implant lifespan

I had two molar implants placed in my late 40s, so it has been about 12 years now. However, the implant sites keep getting inflamed and swelling easily. Sometimes, the swelling is so severe that I cannot chew food on that side, causing me to suffer for days. I know I need to visit the dentist for a check-up, but I keep putting it off. So, I would like to know if I need to get new implants and what the lifespan of dental implants is. I would appreciate the advice of anyone who has experienced something similar.