Complex sentence: In 1939 he founded the Department of Biological Chemistry, and headed it until 1969 the founder of one of the theories of the origin and development of dental caries, known as Sharpenak's theory of caries.
Split into simpler sentences: In 1939 he founded the Department of Biological Chemistry and headed it until 1969. Founder of one of the theories of the dental caries, known as Sharpenak's theory of caries.