Dentistry has radically changed since the mid 20th century in America. Tooth loss in America has been declining steadily almost everywhere except rural areas.

Fluoride toothpaste did not become widely available until the mid 1950's with Crest, and then the ADA required it. With more and more water systems adding fluoride in the late 20th century tooth decay slowed dramatically.

Before that people were scrubbing their teeth with all sorts of crazy shit like penicillin, ammonia, and even radium.

Dental caries and periodontal disease are the major causes of tooth loss.22,23 Until roughly the 1970s, virtually all children and adults in the United States had dental caries, and almost all adults developed periodontal disease.24,25 As shown in Figure 1,in the 1950s approximately 80 percent of children thirteen to fifteen years of age had gingivitis. Peri-odontitis was observed to begin in the late teenage years and to increase almost linearly until early middle age after which close to 100 percent of the adult population under sixty years was affected.

https://www.researchgate.net/publication/7844870_The_Oral_Health_Information_Suite_OHIS_Its_Use_in_the_Management_of_Periodontal_Disease#pf2