The line formed long before dawn Saturday for the health fair organized by the group Flying Doctors, reported the Riverside Press Enterprise.
According to a fair spokesperson, dental care was in such high demand, that a maximum of 120 patients could be seen. Those who were turned away were told they would be contacted later with a list of dentists who would provide free care.
The event also offered health insurance information, hearing and vision screenings for children, haircuts and manicures.
It was only the second appearance in the U.S. for Flying Doctors, which usually visits rural Latin America. Riverside is the first urban area the group has visited.
The Associated Press contributed to this report.