Complex sentence: Drawing severe criticism since its introduction, several well-designed studies in the 1930s discredited FIT and it was generally discarded by conventional medicine by the 1940s amid overwhelming consensus of its falsity and deleterious effects, whereupon fillings and root canals were again favored over extractions.
Split into simpler sentences: Drawing severe criticism since its introduction, several well-designed studies in the 1930s discredited FIT. It was generally discarded by conventional medicine by the 1940s amid overwhelming consensus of its falsity and deleterious effects, whereupon fillings and root canals were again favored over extractions.