Reliable. Tooth-healthy Smile Project is a national public welfare project jointly sponsored by Beijing Lianci Health Poverty Alleviation Foundation and China Children's Charity Relief Foundation. It is more formal and protected by law, so the tooth-strengthening smile project is more reliable. Engineering refers to the process of transforming existing entities into man-made products with expected use value through organized people by applying relevant scientific knowledge and technical means according to a set of envisaged goals.