A 67 years old guy came and asked me to do treatment. He made a grimace at first, showed attitude of doubt to dentists, and was suffering from severe pain. He said he went to one of the famous private hospitals in Tokyo, a few days ago, because of the pain in his lower front teeth. But, it seemed that the dentist treated a wrong tooth which didn’t erase his pain. On X-ray, I could see the next tooth had a black round inflammation image around the tip of the root, which was a real cause of the pain. I began to do root canal treatment and then, saw pas flushing out from inside through the root canal. The pain subsided immediately. When I finished the treatment, he said he wanted whole teeth fixed. He had worked as a diplomat in Finland and Sweden and now is a commentator in TV news program and a writer of some books. I felt transformation happened in his mind from doubt to trust toward me. I carried out sinus-lift, implants, and capping, namely full mouth reconstruction. Building trust is time consuming, but losing it is quite immediate. Keeping trust from patients is my subject for the rest of my life. Transformation from grimace to smile of patients makes me feel inner peace.