The Vipeholm Experiment.
Sweden are mostly known as a not very scary country. With good and mostly accessible dental care.
The Vipeholm experiments were a series of human experiments where patients of Vipeholm Hospital for the intellectually disabled in Lund, Sweden, were fed large amounts of sweets to provoke dental caries (1945–1955). The experiments were sponsored both by the sugar industry and the dentist community, in an effort to determine whether carbohydrates affected the formation of cavities.
The experiments provided extensive knowledge about dental health and resulted in enough empirical data to link the intake of sugar to dental caries.[1] However, today they are considered to have violated the principles of medical ethics.
Hey, you are institutionalized and suffering and powerless - let's make your teeth rot out of your skull. For uhhh science.