Two contradictory hypotheses on the role of
dietary carbohydrates in health and disease shape how dental-systemic associations are regarded. On one side, Cleave and Yudkin postulated that excessive dietary fermentable
carbohydrate intake led-in the absence of dental interventions such as
fluorides-first to
dental diseases and then to systemic diseases. Under this hypothesis, dental and systemic diseases shared-as a common cause-a diet of excess fermentable
carbohydrates.
Dental diseases were regarded as an alarm bell for future systemic diseases, and restricting
carbohydrate intake prevented both dental and systemic diseases. On the opposite side, Keys postulated the
lipid hypothesis: that excessive dietary
lipid intake caused systemic diseases. Keys advocated a diet high in fermentable
carbohydrate for the benefit of general health, and
dental diseases became regarded as local dietary side effects. Because general health takes precedence over dental health when it comes to dietary recommendations,
dental diseases became viewed as local
infections; interventions such as
fluorides, sealants,
oral hygiene, antimicrobials, and dental fillings became synonymous with maintaining dental health, and
carbohydrates were no longer considered as a common cause for dental-systemic diseases. These opposing dietary hypotheses have increasingly been put to the test in clinical trials. The emerging trial results favor Cleave-Yudkin's hypothesis and may affect preventive approaches for dental and systemic diseases.